Welding prone to problems and preventive measures

Because a lot of dissolved ferrite harmful physical S, P impurities. Just try to use high-quality basic coated electrodes, in order to limit the weld metal S, P, C and other content. Intergranular corrosion when heated to 450-850 sensitizing temperature zones at the grain boundary precipitation of chromium depletion theory based on the weld and heat affected zone of chromium carbide, chromium depletion caused by grain boundaries, insufficient degree of corrosion resistance. Measures to avoid the use of low or ultra-low carbon welding consumables, such as the A002 and so on; using titanium, niobium and other stabilizing element electrode, such as A137, A132 and so on. By wire or rod to weld into a certain amount of ferrite forming elements, so that the weld metal becomes duplex austenite + ferrite, (ferrite control in general 4-12%). Narrow the weld pool overheating, use a smaller and faster welding current welding speed, the cooling rate. Intergranular corrosion resistant weldment demanding weld annealing treatment after stabilization. Stress corrosion cracking Stress corrosion cracking is delayed cracking of welded joints in a particular corrosive environment when subjected to tensile stress generated. Stress corrosion cracking of austenitic stainless steel welded joints is welded joints more serious failure modes, showed no damage to the plastic brittle deformation. Stress corrosion cracking and reasonable measures to prevent the development of forming and assembly process, to minimize the degree of cold deformation, avoid forcing the assembly, the assembly process to prevent injuries caused by a variety of injuries and various assembly arc burn marks will become a source of SCC crack easily cause corrosion pits. 
Reasonable choice of welding consumables weld and base metal should be good match, does not produce any adverse tissue, such as grain coarsening and brittle martensite; take appropriate welding process to ensure good weld, does not produce any stress concentration or pitting defects, such as undercuts; take reasonable welding sequence, reducing the welding residual stress level; eliminate stress treatment after welding heat treatment, such as fully annealed or annealed after welding; difficult to implement when the heat treatment after welding hammer or using spray balls. Production management measures to control the medium of impurities, such as ammonia medium O2, N2, H2O, etc.; liquefied petroleum gas in H2S; chloride solution O2, Fe3 +, Cr6 +, etc.; corrosion treatment: such as coatings, linings or cathodic protection; adding inhibitor. Low temperature embrittlement of the weld metal of austenitic stainless steel for welded joints at low temperatures using plastic weld metal toughness is the main issue. At this point, there is a weld in ferrite is always chosen to prevent the deterioration of the pure low-temperature toughness of austenitic welding consumables and welding processes to obtain a definite adjustment austenitic welds measures adopted.