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GB/T 37778-2019: Recommended process for laser beam welding on stainless steels Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid
Similar standardsGB/T 37778-2019: Recommended process for laser beam welding on stainless steels---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT37778-2019GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 25.160.10 J 33 Recommended process for laser beam welding on stainless steels Issued on. AUGUST 30, 2019 Implemented on. MARCH 01, 2020 Issued by. State Administration for Market Regulation; Standardization Administration of PRC. Table of ContentsForeword... 3 1 Scope... 4 2 Normative references... 4 3 Terms and definitions... 5 4 Symbols... 6 5 General requirements... 7 6 Design requirements... 8 7 Quality requirements... 10 8 Welding procedure... 19 9 Inspection and test methods... 25 10 Repair of weld defects... 28 Appendix A (Informative) Typical joint design and recommended process parameters of stainless steel welding... 30 Appendix B (Informative) Inspection test method... 31 Appendix C (Informative) Common defects in laser beam welding on stainless steel and countermeasures... 36 Appendix D (Informative) Simplified work test piece... 37ForewordThis standard was drafted in accordance with the rules established by GB/T 1.1-2009. This standard was proposed by and shall be under the jurisdiction of the National Welding Standardization Technical Committee (SAC/TC 55). The main drafting organizations of this standard. CRRC Qingdao Sifang Locomotive and Rolling Stock Co., Ltd., Baoji Petroleum Steel Pipe Co., Ltd. (National Petroleum and Natural Gas Pipe Engineering Technology Research Center), Guangzhou Special Pressure Equipment Testing and Research Institute, Harbin Welding Research Institute Co., Ltd., Fujian Provincial Industrial Equipment Installation Co., Ltd. The main drafters of this standard. Han Xiaohui, Yang Zhongwen, Li Maodong, Zhang Zhiyi, Lu Ansong, Ma Yin, Xu Shidong, Su Jinhua, Lei Zhen, Zhu Shaohua, Jiang Yuan. Recommended process for laser beam welding on stainless steels1 ScopeThis standard specifies the recommended process specifications, including general requirements, design requirements, quality requirements, welding procedure, inspection and test methods, weld defect reassembly, for laser beam welding on stainless steels. This standard applies to laser beam welding on stainless steel which has a thickness of 0.6 mm ~ 5 mm.2 Normative referencesThe following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard. GB/T 2651 Tensile test method on welded joints GB/T 2653 Bend test methods on welded joints GB/T 3323 Radiographic examination of fusion welded joints in metallic materials GB/T 3375 Welding terminology GB 7247.1 Safety of laser products - Part 1.Equipment classification and requirements GB/T 9445 Non-destructive testing - Qualification and certification of NDT personnel GB/T 18490.1 Safety of machinery - Laser processing machines - Part 1. General safety requirement GB/T 18851.1 Non-destructive testing - Penetrant testing - Part 1.General principles3 Terms and definitionsThe terms and definitions as defined in GB/T 3375, GB/T 19866, GB/T 19867.4 as well as the following terms and definitions apply to this document. 3.1 Appearance quality The appearance effects of the face of weld and root surface, such as the quality requirements for spatter, penetrated fusion, smoothness, point imperfections and scratches and other minor defects. 3.2 Smoothness An indicator for evaluating the degree of unevenness on the back of welds of incomplete penetration lap joints. 3.3 Point imperfection Non-penetrated point-like protrusions or depressions formed by local excessive heat of welding area. 3.4 Scratch Marks on a smooth material surface due to mechanical effects.4 SymbolsThe following symbols apply to this document. t - Thickness of base metal; ΔL - The distance between two imperfections (pores, shrinkage); s - Depth of fusion;5 General requirements5.1 General For laser beam welding on stainless steel, in addition to meeting the requirements of this standard, the welding operation shall also comply with the requirements of relevant product standards (such as GB/T 25343.1). Laser beam safety shall comply with the requirements of GB 7247.1 and GB/T 18490.1 and related technical documents. 5.2 Personnel qualifications 5.2.1 Product assembler Product assemblers shall understand the laser beam welding technology and pass pre-work process training before starting operations. 5.3 Process equipment 5.3.1 Laser beam welding equipment Laser beam welding equipment shall be regularly inspected to be in normal working condition. 5.3.2 Tooling and fixture The tooling and fixture shall use the materials, which have good heat dissipation conditions and can form a good protection for stainless steel, such as aluminum alloy or copper alloy. 5.4 Workpiece 5.4.1 Materials Stainless steel raw materials shall meet the design requirements; their performance indicators shall meet the requirements of GB/T 33239; it can meet the high-precision forming requirements of laser beam welded parts. 5.4.2 Processing requirements The parts can be processed by punching, laser cutting, stamping or other suitable methods. The processed parts shall be removed of residual burrs at the cutting part. 5.5 Environmental requirements The welding site shall be kept clean and have necessary isolation measures.6 Design requirements6.1 General principles For the design documents and drawings of the product, it shall be based on the product usage to determine the design requirements, such as mechanical properties, structural form, appearance quality, etc. 6.4 Quality level requirements for imperfections According to the different mechanical properties and appearance quality requirements of the weld, the imperfections are divided into six levels. level B, level BF, level C, level CF, level D, level DF, based on severe, medium, ordinary. See Table 1 for details. 6.5 Weld inspection level requirements The inspection level of each joint is determined according to the weld quality level of the joint, as detailed in Table 2. 6.6 Mechanical performance requirements of welded joints 6.6.1 Tensile strength of butt joints The tensile strength of the butt joint shall not exceed the lower limit of the tensile strength required by the standard of base metals of lower strength grade; if the strength of the base metal is obtained through the cold rolling process, the tensile strength of the joint shall not be lower than the lower limit of the tensile strength of the base metal before cold rolling. 6.6.2 Tensile shear strength of lap joint The tensile shear force when the weld length of the lap joint is 30 mm may, if there is no special requirement, be carried out according to the requirements of Table 3.7 Quality requirements7.1 Limit value of imperfection size 7.1.1 Butt joint 7.1.1.1 Undercut 7.1.1.4 Misalignment The misalignment of the welded joint (Figure 4) shall meet the requirements of Table 7. 7.1.3 T-joint For different levels of T-joint weld offset, the specified joint axis limits (see Figure 9) are controlled in accordance with Table 12. 7.2 Acceptance criteria for weld imperfection 7.2.1 Cracks In all types of welded joints, all cracks except for microcracks (the length and width of the crack are less than 1 mm) are not allowed to exist. Crater cracks are not allowed, for levels B/BF, C/CF welded joints; local crater cracks are allowed, for level D/DF welded joints (the crack length and width are both less than 1 mm). 7.2.7 Other imperfections 7.2.7.1 Spatter Whether the spatter (Figure 15) is allowed or not, for the levels B, C, and D, it shall be implemented according to product technical conditions or through negotiation between the two parties. For levels BF, CF, DF welds, the spatter is not allowed on the face of weld, however, it is allowed on the root surface. 7.2.7.2 Melt through The laser beam penetrates the opposite side of the welding surface to form a perforation. Whether the welds of levels B, C, D are allowed or not depends on the specific application conditions; it is not allowed for the welds of levels BF, CF, DF. 7.2.7.3 Point imperfections Whether point imperfections are allowed for welds of levels B, C, D depends on the specific application conditions; welds of levels BF, CF, DF do not allow protrusion, however, it allows dents; 7.2.7.4 Smoothness The smoothness is the height difference H between the base metal of the back of the weld and the center of the back of the weld at a distance of 15 mm from the center of the weld (Figure 16).8 Welding procedure8.1 Welding procedure qualification 8.1.1 General requirements When performing process qualification, the general butt weld test piece and T- joint test piece shall be assessed according to the requirements of GB/T 29710; the lap weld test piece shall be prepared according to the requirements of 8.1.2. 8.1.2 Test piece for lap weld 8.1.2.2 Shape and size of test piece for lap penetration weld The lap penetration weld (double layer) is as shown in Figure 18. Lap penetration welds include the following types. 8.1.3 Test and inspection Various test pieces shall be tested and inspected according to Table 16.See Chapter 9 for specific methods. 8.1.4 Conformity assessment All test and inspection items shall be judged according to Chapter 9; they shall be qualified if they meet the restrictive requirements. In case of unqualified items, it is allowed to double the quantity of test pieces for retest. If the additional test piece still does not meet the relevant requirements, the welding procedure qualification is unqualified. 8.3 Welding 8.3.1 Assembly before welding The grinding wheel blades, chisels, pressing devices, hammers and other craft tools are all dedicated for stainless steel, to avoid direct contact between carbon steel and stainless steel. 8.3.2 Welding control requirements 8.3.3.2 During welding During the welding procedure, the welding sequence and welding procedure parameters shall be continuously monitored or regularly checked. 8.3.3.3 After welding After the welding is completed, it shall carry out the appearance quality inspection of the welded joints and the conformity inspection of the product drawings; meanwhile, retain the inspection records.9 Inspection and test methods9.1 Inspection method 9.1.1 Visual test (VT) Visual test of appearance shall be carried out in accordance with GB/T 32259. Check the weld surface for defects such as cracks, surface grooves, incomplete penetration; check the misalignment of the joint and the amount of surface depression, etc.; judge and record in accordance with the provisions of Chapter 7. 9.1.3 Non-destructive testing 9.1.3.1 Penetration testing (PT) Penetration testing is carried out in accordance with GB/T 18851.1; the acceptance level shall meet the requirements of GB/T 26953 or relevant documents. 9.1.3.2 Radiographic testing (RT) Radiographic testing is carried out in accordance with GB/T 3323. 9.2 Test method 9.2.1 Transverse tensile test 9.2.1.1 Method The transverse tensile test shall be carried out at room temperature (or other specified temperature). The specimens and test methods for transverse tension of butt joints shall comply with the requirements of GB/T 2651. 9.2.1.2 Qualified level Unless otherwise specified before the test, the tensile strength of the specimen shall generally not be lower than the minimum value specified in the base metal standard. 9.2.2 Bend test 9.2.2.1 Method The bending specimen and test of the butt joint shall meet the requirements of GB/T 2653. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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