GB/T 37778-2019 English PDF (GBT37778-2019)

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GB/T 37778-2019: Recommended process for laser beam welding on stainless steels
GB/T 37778-2019
GB
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 Contents
Foreword ... 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 ... 37 
Recommended process for laser beam welding on
stainless steels
1 Scope
This 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 references
The 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
principles
GB/T 19805 Qualification test of welding operators
5 General requirements
5.1 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.
5.2.2 Welding operators
Welding operators shall be trained in accordance with the relevant
requirements of GB/T 19805, and only after they have the corresponding ability
can they start operation. The welding operators holding permit shall be
evaluated regularly to ensure its validity.
5.2.3 Inspector
The inspectors include visual inspection and non-destructive testing personnel,
who shall understand laser beam welding technology and have the
qualifications specified in GB/T 9445 or have equivalent qualifications. If the
testing method exceeds the scope of GB/T 9445 or specified by equivalent
qualifications, a testing procedure equivalent to GB/T 9445 shall be developed.
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.
In order to ensure the accuracy of product assembly and meet the requirements
of laser beam welding, the tooling and fixture shall have high positioning
adjustment or other methods.
Pay attention to cleanliness during the whole process of assembly and welding
at the laser beam welding station.
The cutting of stainless steel uses dedicated stainless steel cutting and
polishing pads. In principle, the parts are cut by cold cutting. For parts where
cold cutting cannot be achieved, plasma cutting is used to cut and leave a
margin of 2 mm ~ 3 mm; then use stainless steel dedicated grinding tools are
used for grinding, until the size is guaranteed.
Confirm the product assembly quality. For lap welds, the workpieces shall be
closely attached; the assembly gap shall not be greater than 0.2 mm. It may
use feeler gauges and other tools for testing.
For butt and fillet welds, the gap is controlled according to the laser spot
diameter and welding procedure qualification results.
Prepare process documents to guide the operator in assembly and record the
results of assembly.
8.3.2 Welding control requirements
8.3.2.1 Welding sequence
Prepare laser beam welding sequence plan. The principle of welding sequence
formulation is to reduce welding distortion and improve production efficiency.
Each process of laser beam welding operation must strictly implement the
corresponding welding sequence plan.
The welding sequence plan shall at least include the following:
- Material information, including material name, code, material, plate
thickness, etc.
- Process division based on the production cycle.
- Laser beam welding seam's position number, the plate thickness
combination and welding parameters corresponding to this number are
pictorially shown in the corresponding position of the product.
- For the welding sequence of laser beam welded seam, the corresponding
program number shall be programmed by the automation equipment.
8.3.2.2 Workpiece assembly
For working conditions that cannot be assembled using tooling and fixtures,
laser beam tack welding can be used to assist in the assembly of parts. In
- Preparation of joints (such as shape and size);
- Joint assembly, fastening and tack welding;
- Set welding parameters according to WPS;
- In order to ensure the welding quality, a simplified working test piece shall
be used to confirm the state of the laser beam welding procedure
parameters. Refer to Appendix D for the test.
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.
The inspection record shall contain at least the following:
- Product drawing conformity inspection, including product basic size, shape
and position tolerance size.
- The visual inspection record of the laser beam welded seam.
- Record of laser beam welded seam's fusion state.
- Non-destructive testing report.
- Inspector’s signature.
9 Inspection and test methods
9.1 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 defect...