DEF Stan 03-04

Ministry of Defence Defence Standard 03-4Issue 6 Publication Date 12 August 2011 The Pre-Treatment and Protection of Steel Items of Specified Maximum Tensile Strength Exceeding 1450MPa DEF STAN 03-4 Issue 6 Contents Foreword...........................................................................................................................................................iv 0 1 2 3 4 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 6 7 7.1 7.1.1 7.1.2 7.1.3 7.2 7.3 7.3.1 7.3.2 7.3.3 7.3.4 7.3.5 7.3.6 8 8.1 8.1.1 8.1.2 8.1.3 8.1.3.1 8.1.3.2 8.1.3.3 8.2 8.2.1.1 ii Introduction........................................................................................................................................v Scope ..................................................................................................................................................2 Warning ..............................................................................................................................................2 Normative References.......................................................................................................................2 Definitions ..........................................................................................................................................3 Baking.................................................................................................................................................3 Categorisation of Steels ...................................................................................................................3 Design Authority ...............................................................................................................................4 Heat Treatment Times.......................................................................................................................4 Hydrogen Embrittlement ..................................................................................................................4 Process Control Schedule................................................................................................................4 Physical Preparation.........................................................................................................................4 Stress Relief.......................................................................................................................................4 Information to be Supplied by the Purchaser.................................................................................5 Process Control.................................................................................................................................5 Recommendations for Design and Manufacture............................................................................5 Design Considerations .....................................................................................................................5 Choice of Steel ..................................................................................................................................5 Avoidance of Stress Concentrations ..............................................................................................5 Protective Treatment.........................................................................................................................5 Type Testing ......................................................................................................................................6 Manufacture .......................................................................................................................................6 Machining and Grinding ...................................................................................................................6 Chemical Machining..........................................................................................................................6 Cold Forming .....................................................................................................................................6 Surface Rolling ..................................................................................................................................6 Protection During Manufacture........................................................................................................7 Etch Inspection..................................................................................................................................7 Physical Preparation .........................................................................................................................7 Stress Relief.......................................................................................................................................7 General ...............................................................................................................................................7 Standard Procedure ..........................................................................................................................7 Stress Relief of Items........................................................................................................................8 Items not given a Treatment to Introduce Beneficial Compressive Stresses into the Surface.8 Items given a Treatment to Introduce Beneficial Compressive Stresses into the Surface.......8 Springs ...............................................................................................................................................8 Mechanical Preparation ....................................................................................................................8 Shot Peening .....................................................................................................................................8 ........................................................................................................................11 Phosphate Treatment (Def Stan 03-11) ...15 .........................13..........................................................................................................14 Copper Electrodeposition ......................................................9 Precautions Applicable to all Treatments .....................................................................................................................13 Annex A Method for Determining Oxidizable Material in Sulfuric Acid ...............9 Protective Treatments.......11 Post-Electrodeposition Grinding.......................................................................................................12 10...........................................................................2 Sheradizing (BS 4921) ............13 10.........DEF STAN 03-4 Issue 6 8....................................................8 10.............................................................2..11 Gold Electrodeposition (Def Stan 03-17) .10 Baking .......2 8..............................................................................................................3 10 10.......................................................11 10..................................10 Physical Vapour Deposition of Aluminium....10 Zinc Electrodeposition (Def Stan 03-20) ..........................3 10......1 Tin-Zinc Alloy Electrodeposition ........................................................3 9 9..........................................1...................................................................................................1 10.................................................................................13 10...........................10 Preparation .....2 9.................11 Sprayed Coatings of Aluminium and Zinc (BS EN ISO 2063)............................13 iii Methodology ....................................2 10.....................7 10.....................................13 10..........................................................13...............14...........................................................................................8 Abrasive Blasting ................................14.....13 Surface Rolling ................................................................................15 11 Re-Processing and Re-Furbishment ........2.......................5.................................10 Hard Chromium Electrodeposition (Def Stan 03-14) ..................................2....3 10.....2.........1 10.......................................................................................2..................................................5......................................4 10.................................4 Baking Treatments to be Given to Items after Protective Processing .............................11 Paint Applied to Uncoated Steel.................14.............................................................................10 Choice of Electrolyte ..........12 Processes Permitted but not Recommended ................................9 Category 1801 MPa and Greater Steels ....................................................2 10......................................................................2 10........................................................................13 Inspection and Testing ...................................................................12 Processes not Permitted ..........................................3 Hot Dip Galvanizing ................13 10..........................................5 10........10 Protection Against Vapour Corrosion ....................8 Cleaning ................................................4 10............................................................................12 10..............................11 Nickel Electrodeposition for Engineering Purposes (Def Stan 03-27)............................................................................9 Cadmium Electrodeposition (Def Stan 03-19) .....................................................................................15 A............1 Tin Electrodeposition (BS 1872) ......................10 Preparation ..............................................................................................................................2 10.............12 10..........................................................................................2....11 Silver Electrodeposition (Def Stan 03-9)...................................................... 2 and 3) .....................................8 Category 1451 – 1800 MPa Steels............................................................................................................................................1 10................10 Baking ...........6 10......3 10...................11 Electroless Nickel Coating of Metals (BS EN ISO 4527) ............... Cadmium and Titanium Nitride (Def Stan 03-28 parts 1..........1.................................................................................9 10.........1 Tables Table 1 Table 2 Tensile Strength Criteria ....................................................................................5....10 10........................................................................................................................................................................ If any difficulty arises which prevents application of the Defence Standard. b) c) d) e) f) iv . HISTORICAL RECORD This standard supersedes the following: Def Stan 03-4 / Issue 1 dated 23 November 1971 Def Stan 03-4 / Issue 2 dated 31 March 1977 Def Stan 03-4 / Issue 3 dated 1 February 1991 Def Stan 03-4 / Issue 4 dated 2 January 1998 Def Stan 03-5 / Issue 5 dated 13 October 2006 a) This standard provides requirements for the pre-treatment and protection of steel items of specified maximum tensile strength exceeding 1450 MPa. orders etc. liability resulting from negligence) for any loss or damage however caused when the standard is used for any other purpose.DEF STAN 03-4 Issue 6 Foreword AMENDMENT RECORD Amd No Date Text Affected Signature and Date REVISION NOTE This standard is raised to Issue 6 to update its content. To the extent permitted by law. but without limitation. the MOD hereby excludes all liability whatsoever and howsoever arising (including. This standard has been agreed by the authorities concerned with its use and is intended to be used whenever relevant in all future designs. Compliance with this Defence Standard shall not in itself relieve any person from any legal obligations imposed upon them. This standard has been produced on behalf of the Defence Material Standardization Committee (DMSC) by the Corrosion Prevention and Metallic Materials Standards Production Group (E3). UK Defence Standardization (DStan) shall be informed so that a remedy may be sought. This standard has been devised solely for the use of the Ministry of Defence (MOD) and its contractors in the execution of contracts for the MOD. Any enquiries regarding this standard in relation to an invitation to tender or a contract in which it is incorporated are to be addressed to the responsible technical or supervising authority named in the invitation to tender or contract. contracts. and whenever practicable by amendment to those already in existence. DEF STAN 03-4 Issue 6 0 Introduction 0. i. and preparation of items prior to cleaning and protection. The Standard also gives advice on design. The requirements of this Standard qualify those in process specifications and override the latter where there is conflict. manufacture. 0. for instance.3 Similarly there is increasing concern regarding the use of hexavalent chromium chemicals with more and more legislation being introduced to limit its use.1 This Standard sets out the special treatments and precautions that are to be observed when protective and other surface treatments are applied to items. NOTE In the case of hexavalent chromium it is the coating process itself where the hazard exists not the end product. This is contrary to cadmium for instance where potential hazards exist during processing. including springs. it should be noted that in accordance with MOD Policy and UK Environmental (Control of Hazardous Substances) No. Every effort must be made to define alternative coatings (see Def Stan 03-36) and cadmium is only to be used where its use is permitted by regulation and no other acceptable alternative is available.2 Regulation1993. made from steel of specified maximum tensile strength exceeding 1450 MPa.e. chromium electroplate is non-toxic.2 0. use and disposal. v . Although this standard refers to the use of chromium electroplating. users should make every effort to identify alternatives (see Def Stan 03-38). Though this Standard refers to the use of cadmium. cadmium is only to be used where specific agreement has been given by the MOD. The Pre-Treatment and Protection of Steel Items of Maximum Tensile Strength Exceeding 1450MPa 1 Scope This Standard sets out the special treatments and precautions that are to be observed when protective and other surface treatments are applied to items. Zinc. made from steel of specified maximum tensile strength exceeding 1450 MPa. The requirements of this Standard qualify those in process specifications and override the latter where there is conflict.2 above.4 DStan can advise regarding where normative references documents are obtained from. users shall be fully aware of the issue and amendment status of all normative references. How to contact the helpdesk is shown on the outside rear cover of Def Stans. like its contractors. The Standard also gives advice on design. 3 3. Requests for such information can be made to the DStan Helpdesk. 3. particularly when forming part of an Invitation to Tender or contract. Publications are grouped and listed in alpha-numeric order. Metallic and Other Inorganic Coatings. including springs. Responsibility for the correct application of standards rests with users. Defence Standards or their use in no way absolves users from complying with statutory and legal requirements relating to Health and Safety at Work. and preparation of items prior to cleaning and protection. is subject to both United Kingdom and European laws regarding Health and Safety at Work.DEF STAN 03-4 Issue 6 Standards for Defence . All Defence Standards either directly or indirectly invoke the use of processes and procedures that could be injurious to health if adequate precautions are not taken.2 Reference in this Standard to any normative references means in any Invitation to Tender or contract the edition and all amendments current at the date of such tender or contract unless a specific edition is indicated. Autocatalytic (Electroless) Nickel-Phosphorous Alloy Coatings Metallic Materials: Vickers Hardness Test: Test Method Adhesion Tests for Metallic Coatings by Burnishing Adhesion Tests for Metallic Coatings by Shot Peening Adhesion Tests for Metallic Coatings by Shearing Action Hydrogen Embrittlement of Steels: Test by Slow Bending Hydrogen Embrittlement of Steels: Notched Specimen Test Specification for Electroplated Coatings of Tin Specification for Sherardized Coatings on Iron and Steel 2 . 3. Title BS EN ISO 2063 BS EN ISO 4527 BS EN ISO 6507-1 BS EN 2828 BS EN 2829 BS EN 2830 BS EN 2831 BS EN 2832 BS 1872 BS 4921 Designation Thermal Spraying. manufacture. 2 Warning The Ministry of Defence (MOD). Aluminium and their Alloys Metallic Coatings.3 In consideration of clause 3. 3.1 Normative References The publications shown below are referred to in the text of this standard. Finishing. Finishing. 4. Matt IRR. Biostable. Non-Aircraft Use. Non-Aircraft Use.1 4. Fuel Resistant. Chemical Agent Resistant. Where the steel specification specifies only the minimum tensile strength the equivalent maximum tensile strength category shall be determined from Table 1. Non-Aircraft Use. Gloss Paint. Two Component. Low VOC Cutting Fluid. Joint Service Designation Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments 4 4.3 Categorisation of Steels 4. Polyurethane Finish for Aerospace Purposes Design and Airworthiness Requirements for Service Aircraft Cleaning and Preparation of Metal Surfaces Electro-Deposition of Silver Phosphate Treatment of Iron and Steel Electro-Deposition of Chromium for Engineering Purposes Electro-Deposition of Gold Electro-Deposition of Cadmium Electro-Deposition of Zinc Mechanical Methods for the Inducement of Compressive Surface Residual Stresses Electro-Deposition of Nickel for Engineering Purposes Physical Vapour Deposition of Metals Treatments for the Protection of Metal Parts of Service Stores and Equipment Against Corrosion A Guide to the use of Chromium Plating for Engineering Purposes Guidance to the Use of Cadmium Alternatives in the Protective Coating of Defence Equipment Guidance to the Use of Alternatives to Hard Chromium Plating and Chromium Conversion Coatings for the Protective Coating of Defence Equipment Paint.3.DEF STAN 03-4 Issue 6 Title BS 7195 BS M37 BS 2X33 BS 2X34 Def Stan 00-970 Def Stan 03-2 Def Stan 03-9 Def Stan 03-11 Def Stan 03-14 Def Stan 03-17 Def Stan 03-19 Def Stan 03-20 Def Stan 03-21 Def Stan 03-27 Def Stan 03-28 Def Stan 03-30 Def Stan 03-31 Def Stan 03-36 Def Stan 03-38 Def Stan 80-54 Def Stan 80-161 Def Stan 80-206 Def Stan 80-207 Def Stab 80-208 Def Stan 91-70 ASTM F519 Designation Guide for the Prevention of Corrosion of Metals Caused by Vapours from Organic Coatings Method for the Etch Inspection of Metallic Materials and Components Specification for Two Component Epoxy Primer for Aerospace Purposes Specification for Air Drying. Priming.1 Throughout this Standard the tensile strength figures refer to specified maximum tensile strength. Zinc Chromate. Low VOC. Multi Pack Paint. Low VOC. Priming. Single or Multi Pack Paint. Spraying. 3 . Polyurethane Multi Pack. General Service. Steels shall be categorised according to specified maximum tensile strength in accordance with Table 1. Epoxy.2 Definitions For the purpose of this Standard the following definitions apply: Baking A low temperature heat treatment given after processing to reduce or eliminate the danger of hydrogen embrittlement by expelling absorbed hydrogen and/or diffusing it throughout the item. Single or Multi Pack Paint. Finishing. Zinc Phosphate. Soluble. 4. 1450 and 1800 MPa respectively. 440HV and 560HV (as determined in accordance with BS EN ISO 6507-1) shall be regarded as equivalent to 1400. hardness values of 425HV. cleaning. 4. and / or the introduction by mechanical means of beneficial compressive stresses in the surface 4.7 Process Control Schedule The document which specifies / defines: (a) (b) The sequence of manufacturing operations and processes. The control parameters and their tolerances for each individual process within the total sequence. not necessarily causing the relief of deeper internal stresses. load carrying ability or cracking (usually initiating as sub-microscopic cracks) of a metal or alloy due to the presence of Hydrogen in or on the material. 4 . electro-plating and auto-catalytic processes. phosphating. Steels which have been wholly or partly surface hardened shall be considered as being in the category appropriate to the hardness of the surface layer. 4.9 Stress Relief A low temperature heat treatment given before processing to reduce stresses in the surface of the item.DEF STAN 03-4 Issue 6 Table 1 Tensile Strength Criteria Specified Minimum Tensile Strength MPa * up to 1000 * from 1001 to 1400 from 1401 to 1800 1801 and greater * Included for comparison purposes Specified Maximum Tensile Strength MPa * up to 1100 * from 1101 to 1450 from 1401 to 1800 1801 and greater 4.3.5 Heat Treatment Times The appropriate heat treatment time commences when the items have reached the specified temperature.2 If no maximum or minimum tensile strength figure is specified for the steel. establishment or branch responsible for the detailed design of materiel to approved specifications and authorised to sign a certificate of design or to certify sealed drawings.4 Design Authority The approved firm. 4. The hydrogen can be introduced during fabrication.8 Physical Preparation Physical preparation is concerned with the reduction of deleterious internal and surface stresses. 4. pickling.6 Hydrogen Embrittlement A loss of ductility. 2. particularly when steels of tensile strength 1800 MPa and greater are selected. the pH range. tests and all other processes and treatments shall be included in the Process Control Schedule.DEF STAN 03-4 Issue 6 5 Information to be Supplied by the Purchaser The following information shall be given on the drawing.1 7. the design requirements laid down for aircraft (Def Stan 00-970) etc. 5 . operating temperature.1. steels which give the required strength with a tempering temperature greater than 300ºC should be chosen in preference to those requiring tempering at a lower temperature. pre and post-plating heat treatments. or other information from which the category can be established.2 Avoidance of Stress Concentrations 7. wide tolerance items may be metal sprayed with Aluminium or Zinc (BS EN ISO 2063) and close tolerance items may be coated with cadmium by ion vapour deposition (Def Stan 03-28 Part 2).3).1. or otherwise introduced during assembly.2 Stresses produced by press and shrink fits and tapers. 6.1 Designers should avoid selecting steels of unnecessarily high strength. e.2 In order that effective stress relief and de-embrittlement by baking can be given to the item. 7.1). including all preparatory treatments and after treatments. sharp radii and sudden changes of section should be avoided as they lead to the development of stress concentrations which promote failure both under sustained load and by fatigue.1.1.2 Details of the coating process. e.2. 7.3 All stages in the complete Schedule shall follow each other without delay. (b) Instructions concerning stress relief (see 8. These instructions shall take into account the highest temperature to which the part may be heated and the prior physical preparation.3 Protective Treatment The choice of protective treatment is normally made by the designer from Def Stan 03-30 or from the appropriate master design manual for the item in question. any galvanic or electrolytic initiation.1.1. Whenever possible processes known either not to embrittle or to produce the lowest hydrogen absorption shall be used. 7.1 Recommendations for Design and Manufacture Design Considerations Choice of Steel 7. method of agitation. Hydrogen embrittlement can be avoided by using non-electrolytic processes.1. 7 7.1 Process Control A Process Control Schedule suitable of achieving the requirements of this Standard shall be prepared by the processing contractor(s) prior to the commencement of production.g. should be kept to a minimum.1. 7. chemical composition. (c) The number of this Defence Standard and the section(s) / clauses(s) applicable.1. The susceptibility of high strength steels to hydrogen embrittlement is affected by the type of steel and the steelmaking process.g. therefore advice should be sought. 6 6. 6. 7. processing. contract or order: (a) The specification and category of the steel (see 4.1.3 Designers should seek authoritative advice and recommendations concerning the implementation of the applicable parts of this Standard.1 Notches.1. 1. are not yet established with certainty. Stress relief (see clause 8) before rolling is an advantage.2. Such inspection techniques must be defined in the Process Control Schedule.2. Methods known to be non-embrittling are available. It must therefore precede any scheduled de-embrittling treatment and in any case be followed by de-embrittlement.1.1 The final mechanical shaping of fully heat-treated items should be carried out in a way designed to avoid introducing tensile stresses or thermal abuse into the surface. If soluble oils are used. they should be of the non-activated type such as ZX-9 (Def Stan 91-70) and should be used with an oil content of not less than 15%. BS EN 2832 or ASTM F519. 7. 7. An appropriate grade of abrasive wheel shall be selected for use and the wheel regularly dressed to prevent its use in a glazed condition.3.3.3 Cold Forming Heat-treated items. embrittlement or poor adhesion. 7. BS EN 2830) may be used.2.DEF STAN 03-4 Issue 6 7. BS EN 2828). which will identify grinding damage. or oil-in-water) used should be removed as soon as possible after machining and replaced by a temporary protective. be subject to surface rolling or other treatment likely to impart compressive surface stresses (see clause 8).1 Manufacture Machining and Grinding 7. NOTE Etch inspection which makes use of acid solutions may introduce hydrogen into the surface.g. BS EN 2831 are recommended. or slow bend tests e. Any type of emulsion (water-in-oil. and of necessity this Standard contains a high proportion of descriptive and advisory matter. but if their use is essential the time of contact of the item with the oil should be kept to a minimum and should not be longer than 30 minutes at room temperature. Much laboratory work remains in progress. after final heat-treatment.3 For the detection of hydrogen embrittlement.3.4 Surface Rolling Threads and other areas containing unavoidable sharp radii should. e.1. Tool and work-piece should be held rigid and machining or grinding should be light with copious cooling of the work-piece.g.2 Chemical Machining Chemical contouring and electro-chemical machining offer attractive ways of shaping very strong steel items but may only be used subject to agreement by the Design Authority.3 7.2 Cutting oils and coolants can introduce hydrogen into the steel. other than springs. testing by burnishing (e. BS EN 2829). 7.3.3 All components of a critical nature shall be thoroughly inspected after all grinding operations by a suitable etch inspection method. Many of the special requirements and recommendations are directed to the avoidance of hydrogen embrittlement and of the harmful effect on the surface treatments and heat treatments on fatigue properties.2. 7. 6 .2 Type Testing 7. Sulfurized oils and fully activated oils should be avoided. 7. 7. 7.g. sustained load tests e. BS M37.3. and it is strongly recommended that production items should be type tested on the protected condition under the type of stress and in the kind of environment the items will meet in service.g. shall not be cold formed or straightened without the concurrence of the Design Authority. The risk is least with mineral oils with the next in order of preference being water-oil-emulsions.3. e. 7.g.1 Methods whereby aqueous protective treatments can be applied without some risk of harmful effects.g. or shearing (e.3.2 The behaviour of standard laboratory test specimens is not always a reliable guide to the behaviour of actual items.g.4 For the assessment of adhesion. shot peening (e. g. e. however.g. 7. prior to stress relief.1.230ºC for category 1801 MPa and over. 8 8. aids resistance to sustained load and fatigue failure. The stress relief treatment can be omitted for maraging steels which have been aged after final machining. NOTE 2 At the discretion of the Design Authority. the heat treatment may be undertaken at a temperature that is at least 50°C below the tempering temperature.1. nital etching. and surface stresses developed during mechanical finishing operations can be reduced by heating at temperatures of 200ºC and above.1. i.230ºC followed by cooling in still air. not be less than 24 hours at 200 . springs manufactured to certain British Standard Aircraft Series specifications. Items.3. NOTE 3 If the tempering temperature of the steel is less than 50°C above the temperature ranges stated above. not be less than 18 hours at 200 . Stress relief shall be applied before cleaning according to clause 9.1 Physical Preparation Stress Relief General 8. 8. case hardened items which are not to be electroplated on the hardened area may. any hydrogen embrittlement caused by the etching treatment will be eliminated by the stress relieving providing it is carried out immediately after etching.2 Standard Procedure The standard stress relief consists of heating the items to the highest temperature possible within the limit imposed by the tempering or ageing temperature or by any susceptibility of the steel to temper brittleness. by a suitable heat treatment.e. The relief of beneficial surface compressive stresses introduced during production should however be avoided (see 8. be stress relieved at only 130ºC for 6 hours. although items may. which have been stress relieved as a mandatory requirement for the manufacturing specification. if necessary. be degreased before heating. internal stresses developed during quenching are relieved at temperatures of 400ºC and above. NOTE 1 Suitable combinations of a shorter time at appropriate higher temperatures may be used if they have been shown not to be detrimental.DEF STAN 03-4 Issue 6 7. e. 7 .5 Protection During Manufacture Up to the time at which the final protective coating is applied. do not require further stress relief before cleaning. as a higher temperature may unacceptably reduce the hardness of the case. The period at temperature shall be as follows:• • for category 1451 – 1800 MPa. As a rule. items shall be protected with a temporary protective or a non-aggressive oil.3).6 Etch Inspection If items are given an etching treatment in an acid solution. to reveal damage to the surface caused by abusive grinding or machining.3.1 The relief of internal and deleterious surface stresses. then this treatment shall be given at this stage. 3. and in any case not more than 0.1 Cleaning Prior to protective treatment. prior to particular processes.DEF STAN 03-4 Issue 6 8. e.2 prior to chromium electrodeposition etc. as in 10. and be followed immediately by the protective treatment. 8. 8.2.5.3 Springs Notwithstanding the above. The Method numbers refer to the particular methods in Annex J of Def Stan 03-2 to be used to produce a chemically clean surface receptive to subsequent processing. If no prior stress relief is given. 8 . e.1. If necessary the peened surface of the item may be ground smooth by the removal of the minimum possible amount of metal from the surface. other than maraging steels.2). for maraging steels the final preparation for plating shall be dry grit blasting with virgin aluminium oxide.1. e.2 Items given a Treatment to Introduce Beneficial Compressive Stresses into the Surface. and design and mechanical preparation should be such that these tensile stresses can do no harm. 8.g.1.2. shot peened or dry blasted springs may be stress relieved at a temperature recommended by the manufacturer but not exceeding 230ºC. either all over or upon selected areas.1 The following treatments introduce compressive stresses into surfaces: Shot Peening The advantage of this process is that it can be controlled and that the beneficial effects persist after the surface has been ground smooth under controlled conditions.3 mm when measured by the method described in Def Stan 03-21.1.1 mm.2.3 Abrasive Blasting Methods D1 and D2 of Def Stan 03-2 may be of value in some instances (grit blasting which is used for descaling and other purposes is also used prior to metal spraying as metal spraying processes can reduce fatigue properties). 8.g.1. 9 9. The intensity of peening shall produce on an Almen A test specimen an arc height of not less than 0. then items given one of the mechanical treatments all over shall not be stress relieved after treatment and items given one of the mechanical treatments over only part of the surface shall be stress relieved after treatment by the standard procedure (8. These stresses will be balanced by tensile stresses of varying intensity elsewhere in the item.1 8.1. 8. 8.g.1.3.1.1. of bolts.2.3 Stress Relief of Items The application of stress relief should be considered in relation to the methods of mechanical preparation of items. Standard stress relief prior to these mechanical treatments is recommended and if given shall not be repeated after the mechanical treatment. described in 8.1.2) shall be applied to all items.2. Special cleaning procedures may also be required for steels. The steps selected in the cleaning sequence shall follow one another without interruption other than any necessary washing.2 Mechanical Preparation The introduction of compressive stresses into the surface is strongly recommended.2 Surface Rolling This may be carried out after heat treatment. 8.1 Items not given a Treatment to Introduce Beneficial Compressive Stresses into the Surface. items shall be cleaned by one or more of the following methods. The standard treatment (see 8.3. measurement being made from the asperities of the peened surface. 4 Abrasive cleaning (Process D).g.3 9.2.1 Category 1451 – 1800 MPa Steels Degreasing in an organic solvent (Method A1 or A2). phosphorus. Additionally.3 or 9.2 Degreasing in an aqueous alkaline solution (Method B1) with applied anodic direct current if desired. especially grit blasting (Method D1) leaves the surface very susceptible to corrosion. 9. 9.3. by jigs. 10. 9. the untreated surface shall then be coated with a temporary protective.2. and washed immediately.3.2 Items other than close-coiled springs shall not be mechanically stressed during treatment.1.6 Where electrolytic de-rusting to Def Stan 03-2 (Process K) is required.1. 9 . and after treatment the items shall be withdrawn rapidly before the current is finally switched off. Abrasive cleaning as in 9.2. Surfaces shall be clean. This Process. 10. 10. The sulphuric acid used to make up the solution shall at no time contain more than 11 ppm oxidizable material calculated as sulphur dioxide.1 Protective treatment shall follow without delay the last stage of cleaning.2.2 9. free from rust and cleaning products.1.5 If after baking a protective process has been applied to only part of the surface.2. 9.2.3 Wherever practicable treatment shall start as soon as the item enters the treatment solution. 9.4 Baking treatments shall be started as soon as possible and preferably within 3 hours of the completion of the electroplating or phosphate treatment.1.2.2. 10. 10 10. Treatment baths shall be at full operating temperature and large items should be warmed before treatment.1. and arsenic compounds in the acid promote hydrogen absorption during washing). 9.3 Alkaline de-rusting (Method K1).2.2 9. 9. Neither cathodic nor alternating current treatments shall be used. e.2. an alkaline electrolyte and anodic current shall be used.g. parts shall be connected and the current switched on before the parts are immersed in the solution. A sea-water electrolyte and cathodic current or alternating current shall not be used (unlikely because heavily rusted very strong steel items would normally be rejected for poor surface condition and poor fatigue properties). Electrodeposited or phosphated springs shall not be unnecessarily flexed before baking for the removal of hydrogen embrittlement.5 Anodic pickling in sulphuric acid solution (Process H) must be carefully controlled.DEF STAN 03-4 Issue 6 9. e.6. NOTE In certain applications the Design Authority may require baking to commence within one hour on completion of processing.1 Protective Treatments Precautions Applicable to all Treatments 10.3 Category 1801 MPa and Greater Steels Degreasing in an organic solvent as in 9.1. and further processing shall be given without delay.2.3.1 9.4. by immersion in hot water if it is not appropriate to heat them in the processing solution. Close-coiled springs should be extended only sufficiently to allow adequate coverage of the springs and the constraint should be removed immediately after post treatment washing. clips etc.2. determined by the method described in Annex A (this precaution is necessary because reduced sulphur. Alkaline treatments as in 9. 10. and similar advice and requirements apply (see 10.5.2.3 Baking Electrodeposited items shall be baked according to the requirements of Table 2 prior to passivation. Although anodic pickling is not generally allowed by 9.2 and 10.2. 8 and 9. It has however.5. 8 and 9. 10. Cadmium and Titanium Nitride (Def Stan 03-28 parts 1.3 below. 10.3 Physical Vapour Deposition of Aluminium.2. Items shall be treated in accordance with the relevant part of Def Stan 03-28. The proportions of the constituents of a normal cyanide electrolyte may influence hydrogen embrittlement. described in ASTM F519 or BS EN 2832 or the slow bend test described in BS EN 2831. Designers should consult Def Stan 03-31 before using this process.2. is it permitted.1 Preparation Items shall be prepared and cleaned as described in clauses 7.2. 10.3 for category 1800 MPa and greater steels.2 and 10. 10.5 Hard Chromium Electrodeposition (Def Stan 03-14) This process is applied to working items many of which are subject to fatigue as well as to sustained load. 10.2.4 Zinc Electrodeposition (Def Stan 03-20) During zinc electrodeposition the problems of hydrogen absorption from a cyanide solution are broadly the same as those from cadmium electroplating.1 Cadmium Electrodeposition (Def Stan 03-19) Preparation Items shall be prepared and cleaned as described earlier in clauses 7. unpassivated.DEF STAN 03-4 Issue 6 10.2.2 Choice of Electrolyte The electrolyte shall not contain brightening agents.4 Protection Against Vapour Corrosion For protection of unpainted cadmium against corrosion by organic vapours (see BS 7195) a tin flash may be applied over fully baked.1 Items shall be further cleaned as specified in Def Stan 03-14. It is strongly recommended that items made in steel subject to fatigue in service shall be prepared by shot-peening in accordance with 8.2. 2 and 3) This process does not cause hydrogen embrittlement and is the preferred method of coating cadmium. 10. A cadmium strike at a high current density (100 A/m²) may be beneficial in reducing the risk of embrittlement. 10 .2.1. 10. Proprietary cyanide electrolytes containing oxidising agents such as nitrate and pertitanate also cause less embrittlement but need careful control. a very deleterious effect on fatigue properties unless special measures are taken. The process is unsuitable for items subject to temperatures exceeding 160ºC in service. Electrolytes maintained in a high state of purity may cause less embrittlement. because of the melting point of cadmium-tin alloy (176ºC).2. Acid electrolytes may cause less embrittlement than standard cyanide electrolytes. the requirements of Def Stan 03-19 shall be followed. 10. 10.3). cadmium electroplate.1. but may have rather poor throwing power. it may be used on both categories when followed by chromium electroplating and baking.1 The Design Authority may require non-embrittling characteristics of the process to be demonstrated prior to production use and monitored thereafter. A suitable hydrogen embrittlement test is the sustained load notched tensile test. Subject to 10. Mechanical preparation of shot–peening which improves fatigue properties also improves sustained load properties.2.2. Further baking is neither required nor.2 10. 11 Phosphate Treatment (Def Stan 03-11) The general requirements of Def Stan 03-11 shall apply.8 including the appropriate baking treatment. 8 and 9. but copper-free. 8 and 9. No baking is required for hydrogen de-embrittlement after metal spraying. The items after gold electroplating shall be baked according to the requirements of Table 2. heat treatment temperature and the phosphorus content. such as a nickel strike. 10. the phosphate treatment process shall be of the accelerated. Phosphate items shall be baked according to the requirements of Table 2.6 and 10.DEF STAN 03-4 Issue 6 10. and preparation for subsequent chromium electroplating shall be in accordance with Def Stan 03-14.2 Baking Electrodeposited items shall be baked according to the requirements of Table 2. 10. Any electrolytic cleaning shall be anodic.2.5. Items shall be prepared and cleaned as described in clauses 7. The process also has a deleterious effect on fatigue properties. The items shall be prepared and cleaned as described in clauses 7.6.7. shall be carried out in accordance with clause 10.10 Sprayed Coatings of Aluminium and Zinc (BS EN ISO 2063) Providing tolerances and thicknesses allow and the requirements of BS EN ISO 2063.7 Electroless Nickel Coating of Metals (BS EN ISO 4527) Items shall be treated in accordance with the requirements of clause 10.6. For improved corrosion protection metal spraying should be followed by a full paint scheme. an etch primer shall be used but over aluminium.5. type working at a pointage not exceeding 30.3 Post-Electrodeposition Grinding A fluorescent penetrant inspection method which is capable of identifying cracks caused by abusive grinding shall be used. Electrodeposited items shall be baked according to the requirements of Table 2.2 Any prior nickel electrodeposition. the steel may be metal sprayed. Heavy electroplating has a deleterious effect on fatigue properties and it is strongly recommended that items subject to fatigue in service shall be prepared as in 10. 8 and 9. Electrodeposited items shall be baked according to the requirements of Table 2.1 and electrodeposited by the low stress sulfamate process. The general requirements of Def Stan 03-9 shall apply except that copper or brass undercoats are not permitted. 10.5. over zinc. NOTE The hardness of the electoless-nickel deposit will depend significantly on the post-deposition. 8 and 9. 10.5. e. an etch primer is optional.6 Nickel Electrodeposition for Engineering Purposes (Def Stan 03-27) The general requirements of Def Stan 03-27 apply but copper undercoats are not permitted. 10. In order to reduce hydrogen absorption. particularly those relating to adhesion. 10. 10.5. Steels may be anodically pickled as in 9. and 10.9 Gold Electrodeposition (Def Stan 03-17) The items shall first be electroplated with nickel and / or silver according to clauses 10.g. Copper electrodeposition is not permitted.1. Items shall be prepared and cleaned as described in clauses 7.8 Silver Electrodeposition (Def Stan 03-9) Items shall be prepared and cleaned as described in clauses 7. 10. 11 . are met. The present state of knowledge on temperatures and duration of baking and their effects on hydrogen embrittlement and corrosion resistance properties is incomplete but a recommended baking treatment is given in Table 2. NOTE Should the use of tin electroplating be necessary a flash coating (5µm) of nickel will reduce the chance of inter-granular penetration. 10.13. 10.13.12 Paint Applied to Uncoated Steel 10.1.1 This process is not recommended for direct application to either category of steel because of the danger of inter-granular penetration of the tin into the steel occurring at temperatures below the melting point of tin (232ºC) during the 190-220ºC baking treatment required to remove embrittlement.13 Processes Permitted but not Recommended 10. the lower end of the baking range.1 Items shall be prepared and cleaned as described in clauses 7. However.13.1. the etch primer introduces hydrogen into the base steel and a baking treatment to remove embrittling effects will be required after etch priming. Prior to painting.4.13.2 The priming coat shall be a full anti-corrosion primer and shall be selected from one of the following paint schemes.13.12. BS 2X33 Def Stan 80-54 Def Stan 80-161 Def Stan 80-206 Def Stan 80-207 Def Stan 80-208 NOTE Primer BS 2X33 is usually used with finish to BS 2X34 10. 10. 10.2 Copper Electrodeposition Copper electroplating may only be used at the discretion of the Design Authority.2 If this process is used.3 Etch priming may only be used for direct application to bare steels in either category at the discretion of the Design Authority. 8 and 9.2. mild abrasive cleaning shall be carried out (Method D2 of Def Stan 03-2 is preferred) but care shall be taken that the abraded surface is free from abrasive. dust and rust when the paint is applied. 190ºC.12. Many paint schemes which include etch primers afford corrosion protection of a high order. 12 .3 If tin electroplating is applied to baked cadmium plated surfaces for protection against vapour corrosion see 10. organic agents shall not be added to the electrolyte and the items shall be prepared and cleaned as described in clauses 7. 10.DEF STAN 03-4 Issue 6 10. Electroplated items shall be baked according to the requirements of Table 2.12.1. 8 and 9. It is not normally permitted for any purpose as it can introduce irreversible embrittlement effects and may reduce fatigue properties.1 Tin Electrodeposition (BS 1872) 10. is recommended. 3 Hot Dip Galvanizing This process shall not be used as it may adversely affect the properties of the item. 10. 10.1 Tin-Zinc Alloy Electrodeposition This process is prohibited because of the danger of inter-granular penetration of this alloy into the steel occurring at temperatures below its melting point of 200ºC during the 190-220ºC baking treatment required to remove embrittlement. After re-coating. the items shall be given the full baking treatment appropriate to the coating process.3 After stripping and before re-coating.15.15.15 10.14.1 Re-Processing and Re-Furbishment Items may only be stripped and re-coated at the discretion of the Design Authority. 10.14. 10.2 The method of stripping shall be appropriate to the coating to be removed. 10. Anodic electrolytic processed may be used but cathodic process shall not be used.DEF STAN 03-4 Issue 6 10. 13 . items shall be baked according to the re-coating requirements of Table 2.14 Processes not Permitted 10. Acid solutions should be avoided. 11 Inspection and Testing See clauses 6 and 7.2 along with the individual standards referred to in clause 10.2 Sheradizing (BS 4921) This process shall not be used as it may adversely affect the properties of the item.15.14. case hardened items not electrodeposited over the hardened area may be baked at not less than 130° for not less than 6h Note 2: hard Drawn Springs – For springs made from hard drawn wire or strip.6 Def Stan 03-27 BS EN ISO 4527 Def Stan 03-9 Def Stan 03-17 BS EN ISO 2063 Def Stan 03-11 10.4 10.DEF STAN 03-4 Issue 6 Table 2 Baking Treatments to be Given to Items after Protective Processing Standard Clause Process Specification Protective Treatment Baking Treatment at temperatures in °C and times generally in hours (h) Category 1451 to 1800 MPa Category 1801 MPa and Greater 190°-220° for 24h minimum 10.12 190°-220° for 24h minimum 190°-220° for 24h minimum 190°-220° for 24h minimum 190°-220° for 24h minimum None 170°-200° for 6h minimum 190°-200° for 45 – 75 minutes 10. the duration of baking at 190° .15 Not less than190° for not less than 6h Not less than 190° for not less than 18h Note 1: Case Hardened items – At the discretion of the Design Authority.9 10.13.2 Def Stan 03-19 Cadmium Electrodeposition MPa 1451-1500 1501-1600 1601-1700 1701-1800 None Treatment 190°-220° 16h minimum 190°-220° 18h minimum 190°-220° 20h minimum 190°-220° 22h minimum 10.10 10.8 10.3 10.5 Def Stan 03-28 (part 2) Def Stan 03-20 Def Stan 03-14 Cadmium Vacuum Ion Vapour deposition Zinc Electrodeposition Chromium Electrodeposition None 10.7 Nickel Electro-deposition (heavy) Electroless Nickel Silver Electro-deposition Gold Electro-deposition Sprayed Metal As for Cadmium Electro-deposition (Above) Peened items and unpeened items not subject to fatigue As for Cadmium Electro-deposition (Above) Unpeened items subject to fatigue 1450 – 1800 MPa: 400-480°C for 1h minimum As for Cadmium Electro-deposition (Above) As for Cadmium Electro-deposition (Above) As for Cadmium Electro-deposition (Above) As for Cadmium Electro-deposition (Above) None 130°-200° 190°-200° 4h minimum 45 – 75 minutes 190°-220° for 24h minimum 190°-220° for 24h minimum 10.1 190°-230° 24h minimum 10.230° may be reduced to not less than 8h Phosphate Treatment Paint applied to bare steel where etch primer is used BS 1872 Tin Electrodeposition After stripping and before all processing by wet methods 190°-230°C 18h minimum 14 .11 10. 1 Methodology Add 15 ml of concentrated sulphuric acid to 60 ml of distilled water. 15 .02 molar solution of potassium permanganate solution (3. The pink colour shall persist for 5 minutes indicating a presence of not more than 11 ppm oxidizable substances calculated as sulphur dioxide.10 ml of 0.3 g/l). cool. and to the mixture add 0.DEF STAN 03-4 Issue 6 Annex A Method for Determining Oxidizable Material in Sulfuric Acid A. dstan.© Crown Copyright 2011 Copying Only as Agreed with DStan Defence Standards are published by and obtainable from: Defence Equipment and Support UK Defence Standardization Kentigern House 65 Brown Street GLASGOW G2 8EX DStan Helpdesk Tel : 0141 224 2531/2 Fax 0141 224 2503 Internet e-mail enquiries@dstan. when making use of a Defence Standard encounters an inaccuracy or ambiguity is requested to notify the Directorate of Standardization (DStan) without delay in order that the matter may be investigated and appropriate action taken.mod.uk File Reference The DStan file reference relating to work on this standard is D/DStan/313/4/2 Contract Requirements When Defence Standards are incorporated into contracts users are responsible for their correct application and for complying with contractual and statutory requirements. 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