DIN 50979 2008 EN 锌及锌合金涂层

GERMAN STANDARD July 2008 A & I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 Metallic coatings – Electroplated coatings of zinc and zinc alloys on iron or steel with supplementary Cr(VI)-free treatment Document comsists of 13 pages Standards Committee on Material Testing (NMP) within DIN DIN 50979:2008-07 2 A & I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 Contents Page Foreword ................................................................................................................................................ 3 1. Field of application ................................................................................................................. 3 2. Normative references ............................................................................................................. 3 3. Designation: ............................................................................................................................ 4 3.1. Electroplated coatings........................................................................................................... 4 3.2. Passivating ............................................................................................................................. 4 3.3. Sealing..................................................................................................................................... 4 3.4. Essential areas (functional area) .......................................................................................... 5 3.5. Examples of designations..................................................................................................... 5 4. Order data ................................................................................................................................ 5 5. Base materials......................................................................................................................... 6 6. Coating methods / Process technology ............................................................................... 6 6.1. Pretreatment and deposition of the zinc or zinc alloy coating.......................................... 6 6.2. Post-treatments ...................................................................................................................... 6 6.2.1. Passivations ........................................................................................................................... 6 6.2.2. Seals ........................................................................................................................................ 7 6.3. Drum/Trestle (parts handling)............................................................................................... 7 6.3.1. Drum parts .............................................................................................................................. 7 6.3.2. Trestle parts............................................................................................................................ 7 6.4. Hydrogen embrittlement........................................................................................................ 7 6.4.1. Basics...................................................................................................................................... 7 6.4.2. Method selection .................................................................................................................... 8 6.4.2.1. Materials with strengths < 1 000 N/mm2............................................................................... 8 6.4.2.2. Materials with strengths ≥ 1 000 N/mm2 ............................................................................. 8 7. Requirements for the coatings and test methods............................................................... 9 7.1. Coat thickness........................................................................................................................ 9 7.2. Layer adhesion ....................................................................................................................... 9 7.3. Cr(VI) absence ...................................................................................................................... 10 7.4. Resistance in short-term corrosion tests .......................................................................... 10 7.4.1. General .................................................................................................................................. 10 7.4.2. Minimum resistance of passivated zinc or zinc alloy coatings....................................... 10 8. Test report ............................................................................................................................. 12 8.1. General information ............................................................................................................. 12 8.2. Special data for coating high-strength materials with tensile strength ≥ 1 000 N/mm² ......................................................................................... 12 8.3. Test results ........................................................................................................................... 12 References ........................................................................................................................................... 13 DIN 50979:2008-07 3 A& I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 Foreword This document has been formulated by the working committee NA 062-01-76 AA “Electroplated coatings” of the Standards Committee for Material Testing (NMP). 1. Field of application This standard applies for electrodeposited and Cr(VI)-free passivated zinc coatings and zinc alloy coatings on iron materials. The zinc alloy coatings contain nickel or iron (zinc/nickel, zinc/iron) as alloy components. The main purpose in the application of the coatings or coating systems is to protect components made from ferrous materials against corrosion. This standard defines the designations for the coating systems indicated above and specifies minimum corrosion activities in the described test methods as well as the minimum layer thickness necessary for this. 2. Normative references The documents cited below are necessary for the application of this document. In the case of dated references, only the edition referred to applies. In the case of undated references, the last edition of the document (including all amendments) referred to applies. E DIN 50969-1:2008-02, Prevention of hydrogen-induced brittle fractures caused during production in high-strength steel components – Part 1: Preventative measures1) DIN EN 1403, Corrosion protection of metals – Electrodeposited coatings – Method of specifying general requirements DIN EN 15205, Determination of hexavalent chromium in corrosion protection layers – Qualitative analysis DIN EN ISO 3497, Metallic coatings – Measurement of coating thickness – X-ray spectrometric methods DIN EN ISO 9227, Corrosion tests in artificial atmospheres – Salt spray tests 1) A further standard concerning testing is in preparation. DIN 50979:2008-07 4 A & I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 3. Designation: 3.1. Electroplated coatings The electroplated coatings consists of zinc or zinc alloys corresponding to Table 1. Table 1 – Designation of the electroplated coatings Code Definition Zn Zinc coating without added alloy partner ZnFe Zinc alloy coating with a percent by weight of 0.3 % to 1.0 % iron ZnNi Zinc alloy coating with a percent by weight of 12 % to 16 % nickel 3.2. Passivating Passivating designates the production of conversion layers by treatment with suitable Cr(VI)-free solutions in order to improve the corrosion resistance of the coatings. Colourations are possible. As chromium (VI)-free passivations are new systems, a new nomenclature according to Table 2 has been adopted. Table 2 – Passivations Passivation or method group Abbreviation Colouring, appearancea of the surface Remarks Transparent passivated On Colourless to coloured iridescent Frequently referred to as “thin-layer passivation” Iridescent passivated Cn Coloured iridescent Frequently referred to as “thick-layer passivation” Black passivated Fn Black a Colour shades can occur. 3.3. Sealing Seals increase the corrosion resistance and usually have a layer thickness up to 2 µm. Seals consist of Cr(VI)-free organic and/or inorganic compounds. Products that can be removed with cold cleaner (e.g. based on oil, grease, wax) are not considered as a seal within the scope of this standard. The effect of seals on the functional properties of the component, e.g. transition resistance, weldability, compatibility with working substance, bonded joints, are to be evaluated on a component-specific basis. yul 矩形 DIN 50979:2008-07 5 A& I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 If there are special requirements for the surface functionality, the use of the seal as well as the type of sealing agent must be agreed, as the range of potential surface modifications through sealing is large. REMARK The interference colours formed through passivation are usually also remedied through sealing. Table 3 – Seals Code Description T0 Without seal T2 With seal 3.4. Essential areas (functional area) In the case of components with complex shapes, in particular components with hollow spaces, it is possible that the requirements for the resistance in the short-term corrosion tests and for the minimum thickness cannot be complied with in all areas of the electroplated surface. In these cases, the areas essential for the surface protection must be marked with a dot-dash line on the drawing. If no essential area is specified by the customer, the definition according to DIN EN 1403 applies. 3.5. Examples of designations Designation for a zinc/nickel alloy coating on a component made from steel (Fe), a smallest local layer thickness of 8 µm (8) and iridescent passivated (Cn): Eletroplated coating DIN 50979 – Fe//ZnNi8//Cn//T0 Designation for a zinc/iron alloy coating on a component made from steel (Fe), a smallest local layer thickness of 8 µm (8) and black passivated (Fn) and sealed: Eletroplated coating DIN 50979 – Fe//ZnFe8//Fn//T2 For further information on the designation, see DIN EN 1403. 4. Order data The customer must provide at least the following information to the coating company: a) Component strengths (with consideration of 6.4); b) Data on the component: Basic material, component manufacturing process, heat treatments; c) Data on the essential areas in conjunction with 3.4; d) Designation of the coating to be applied (see 3.5). If required, more detailed requirements for the coating properties and testing (e.g. appearance, sliding properties, media resistance) can be specified. If necessary, additional information on requirements or restrictions for the coating process can be given. DIN 50979:2008-07 6 A & I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 5. Base materials The coating of components from low-alloy steels with coatings according to this standard is state-of-the-art. If other iron-based materials are present (e.g. cast or sintered materials, materials with distinct components of passivation-friendly alloy elements or also materials with special strength properties), it may be necessary to specially adapt the treatment processes (pretreatment, coating, post-treatment) and, if need be, implement additional measures in order to comply with the requirements of this standard. The coating company therefore needs to have detailed information on the composition, properties and production process of the components to be coated. When coating high-strength steel parts with a tensile strength ≥ 1 000 N/mm², the preproduction (e.g. material selection, hardening, joining) has to be carried out in such way that damage due to delayed hydrogen-induced brittle fractures is eliminated with a high degree of certainty. The components to be coated must not exhibit any material, processing or surface faults which can affect the corrosion protection and/or the appearance of the coatings in an adverse or unexpected manner. The impurities (corrosion products or scale, oil, grease, dirt etc.) occurring on the surfaces of the parts to be treated must be able to be removed in the cleaning and pretreatment processes normally utilised. An agreement concerning the surface quality might be necessary, if applicable. 6. Coating methods / Process technology 6.1. Pretreatment and deposition of the zinc or zinc alloy coating In order to ensure a reliable process sequence, the complete pretreatment and coating process, physical data (treatment times, temperatures) as well as all process chemicals must be recorded, documented and optimised if need be. The individual process intervention limits as well as the frequency of the monitoring and analysis processes must be defined. The resultant measures must be described and archived by the coating company. A typical process sequence is shown below: a) Alkaline degreasing (coordinated in line with the existing oil/grease-based surface films); b) Pickling (usually HCl, inhibited); c) Alkaline electrolytic degreasing (preferably anodic); d) Metal deposition; e) Post-treatment through passivation and, if necessary, sealing; f) Drying. 6.2. Post-treatments 6.2.1. Passivations Passivations are conversion coatings and are created by immersing or spraying the components with passivation solutions. At the same time, the deposited coating reacts with the passivation solution to form a thin film protecting the metallic coating. Part of the coating is usually dissolved by the reaction. DIN 50979:2008-07 7 A& I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 6.2.2. Seals Additional organic and/or inorganic substances are applied onto or embedded in the passivation during the sealing. Layer accumulations can result, depending on the component geometry and process. These must be minimised, if possible, through suitable measures (e.g. blowing-off for trestle parts, movement of drum parts). 6.3. Drum/Trestle (parts handling) 6.3.1. Drum parts Typical drum parts are bolts, nuts and other small components. The components are introduced into the coating drums as bulk material then pretreated and provided with the coating while the drum is rotating. The drum rotation ensures that all components are coated comparably. However, surface damage can result due to the movement of the parts. It is possible to minimise the damage e.g. through reduced drum rotation or lower drop heights when emptying the drum. Nevertheless, drum coatings usually yield a lower corrosion resistance than is the case with trestle coatings. 6.3.2. Trestle parts This involves parts which have to be coated on the trestle owing to their size, design or, possibly, special requirements. During this, the parts are coated while positioned on trestles. Depending on the position of the components on the trestle, different layer properties (mainly layer thickness of the metallic coating) can result Optimisation is possible, for example, by using component-specific trestles. 6.4. Hydrogen embrittlement 6.4.1. Basics The steel parts to be coated can absorb hydrogen during the electroplating treatment for creating coatings according to this standard, e.g. during pickling, electrolytic cleaning and during the electroplating metal deposition. Active hydrogen diffused in the metal lattice preferably at energetically favourable areas (lattice structural faults, areas of high stress concentration). Hydrogen-induced, delayed brittle fractures can arise from this, while the critical interaction of: – material and material state (strength, hardness); – hydrogen absorption during the pretreatment and coating process; – mechanical parts stress, also locally depending on the design of the parts. have to be taken into account in particular. DIN 50979:2008-07 8 A & I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne nf ah rz eu ge G m bH - C us t. no . 4 98 74 28 - Su bs . n o. 0 08 49 50 1/ 00 2/ 00 1 - 2 00 8- 06 -2 4 10 :3 4: 55 Figure 1 – Interaction of material, mechanical stress and hydrogen absorption The critical parameters for the material are the tensile strength and toughness. The hazard due to hydrogen increases as the strength increases. All steel parts with a tensile strength of Rm ≥ 1 000 N/mm2 (also locally restricted, e.g. for case-hardened or cold-formed joints or in weld seam areas) are deemed to be high-strength and are classified as critical. 6.4.2. Method selection 6.4.2.1. Materials with strengths < 1 000 N/mm2 The choice of treatment method is free insofar as the requirements comply with this standard and no damage to the usage properties occurs. 6.4.2.2. Materials with strengths ≥ 1 000 N/mm2 Protection against delayed brittle fracture (hydrogen embrittlement) is paramount for the coating. The surface treatment method must be realised so that damage due to delayed hydrogen-induced brittle fractures is eliminated with a high degree of certainty. The procedure for dealing with potential defective coatings (peeling-off of coatings and new coatings) must be examined and consequences resulting from this described. The measures for minimising the risk of delayed hydrogen-induced brittle fractures and the processes necessary for this must be agreed between the customer/manufacturer and the coating company. The required process inspection and process testing accompanying production can typically be carried via stress tests on a sufficient number of suitable hydrogen-sensitive samples. The information given in E DIN 50969-1 must be observed. Material Mechanical stress (also internal or local stress) Hydrogen in the material Fracture, at critical interaction DIN 50979:2008-07 9 A& I S ta nd ar ds S ub sc rip tio n - K N O R R -B R E M S E S ys te m e fü r S ch ie ne n