Austenitic stainless steel in the welding characteristics: the welding process of the bomb, plastic stress and strain is very large, but rarely cold cracks. Weld joints do not exist hardened hardening zone and grain coarsening, so the weld tensile strength is high.
Austenitic stainless steel welding main problems: welding deformation; because of its grain boundary properties and some trace impurities (S, P) sensitive, easy to produce hot cracks.
2. Stress corrosion cracking
The following measures can be used to prevent stress corrosion cracking:
A. Correct selection of materials and reasonable adjustment of weld composition. High purity chromium – nickel austenitic stainless steel, high silicon chromium – nickel austenitic stainless steel, ferrite – austenitic stainless steel, high chromium ferrite stainless steel, etc. have good resistance to stress corrosion, When the microstructure of the ferrite-ferrite biphasic steel is resistant to stress, the corrosion resistance is good.
B. Eliminate or reduce residual stress. After stress welding heat treatment, the use of polishing, shot peening and hammer and other mechanical methods to reduce the surface residual stress.
C. Reasonable structural design. To avoid a greater stress concentration.
3. The embrittlement of welded joints
Hot steel should ensure that the plastic joints, to prevent high temperature embrittlement; low temperature steel with good low temperature toughness, to prevent the occurrence of low temperature brittle fracture joints.