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I
welding procedure qualification of various standards
1
Introduction to welding procedure qualification
Welding procedure qualification is the test process and result evaluation to verify the correctness of the proposed welding procedure of weldments
It refers to the process of confirmatory test and result evaluation of the pre welding process specification in order to make the mechanical properties, bending properties of the welded joint or the chemical composition of the surfacing layer meet the requirements

Welding process is an important measure to ensure welding quality, which can confirm the correctness and rationality of the welding process instructions prepared for various welding joints
Through the welding process evaluation, check whether the service performance of the welded joint welded according to the proposed welding process instruction meets the design requirements, and provide a reliable basis for the formal formulation of the welding process instruction or welding process card

The welding procedure qualification center of the company can carry out welding procedure qualification of various standards according to the requirements of customers, including relevant domestic standards and European standards, ISO standards, AWS standards, ASME standards and other corresponding national and organizational standards required by customers

2
Purpose of welding procedure qualification:
a
Assess whether the welding unit is able to weld the welded joints that meet the requirements of relevant national or industrial standards and technical specifications;
b
Verify whether the welding process instructions prepared by the welding unit are correct

c
Provide reliable technical basis for formulating formal welding process instructions or welding process cards

3
Welding procedure qualification process
a
Prepare preliminary welding process instructions (pWPS)
b
Welding test pieces and sample preparation
c
Test pieces and samples
d
Determine whether the welded joint meets the service performance required by the standard
e
Propose the welding procedure qualification report to evaluate the proposed welding procedure instruction
4
Welding procedure qualification standard
A
Domestic part:
NB/T 47014-2011 welding procedure qualification of pressure equipment
Jgj81-2002 technical specification for welding of building steel structures
GB/T 19869
1-2005 welding procedure qualification test for steel, nickel and nickel alloys
JB/T 6963-93 evaluation of fusion welding process for steel products
B
European standard:
Iso15614-1 specification and evaluation of welding procedures for metallic materials - welding procedures, part I: arc welding and gas welding of steel, arc welding of nickel and nickel alloys
ISO15614-2 Welding procedure specification and qualification of metallic materials -- Welding procedure qualification test, Part 2: arc welding of aluminum and aluminum alloys
C
American standards (AWS and asme ):
AWS D1
1/D1
1 Code for welding of steel structures
AWS D1
2/D1
2 Specification for welding of aluminum structures
AWS D1
3/D1
3 Specification for welding of sheet steel structures
AWS D1
5/D1
5 Bridge welding specification
AWS D1
6/D1
6 Specification for welding of stainless steel structures
ASME Boiler and pressure vessel code Volume IX (IX) welding and brazing qualification
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2、 Residual stress detection
1
What is residual stress test
In the manufacturing process, components will be affected by various factors such as technology; When these factors disappear, if the above effects and influences on the member cannot disappear completely, and some effects and influences remain in the member, this residual effect and influence is called residual stress or residual stress

2
Why should residual stress test be done
Metal materials will produce different residual stresses in the process of machining and hot working (castings, weldments, forgings)
The existence of residual stress has a significant impact on the mechanical properties of materials, especially in the manufacturing and heat treatment of weldments
The existence of residual stress, on the one hand, will reduce the strength of the workpiece, making the workpiece produce process defects such as deformation and cracking during manufacturing; On the other hand, it will reduce the fatigue strength, stress corrosion and other mechanical properties of the material in the natural release process after manufacturing
Thus causing problems in use
Therefore, the detection of residual stress is of great significance for the effect of heat treatment process, surface strengthening process, stress relief process and waste analysis

3
Residual stress test and detection method
The measurement methods of residual stress can be divided into two categories: destructive and nondestructive
The destructive test method is the stress release method, which can also be called mechanical method; Lossless methods are physical methods
At present, the most commonly used mechanical method is the drilling method (blind hole method), followed by the ring core method for a certain object
X-ray diffraction is commonly used in physical methods, and other main physical methods include neutron diffraction, magnetic method, ultrasonic method and indentation strain method

Residual stress detection has been carried out at home and abroad for many years, and its measurement methods can be divided into mechanical measurement method and physical measurement method
The mechanical measurement method requires local separation or segmentation to release the stress, which will cause certain damage or even damage to the workpiece
The typical methods are slotting method and drilling method, which have mature technology and perfect theory
Among them, the small-diameter blind hole method has become a standard test method for field measurement because of its less damage to the workpiece and more reliable measurement (see astm e837-99)
Physical measurement methods mainly include ray method, magnetic method, ultrasonic method, and indentation strain method (gb/t 24179-2009), which are all nondestructive testing methods

4
Residual stress test standard
1) CB 3395-92 Residual stress test method borehole strain release method
2) SL 499-2010 Standard Test Method for measuring residual stress by borehole strain method
3) GB/T 24179-2009 metallic materials Determination of residual stress indentation strain method
4) ASTM E837-99 Small diameter blind hole method
5) Gb7704-87 X-ray stress determination method http://www
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