There are three main reasons for formation, namely hardened structure formed by martensitic transformation, welding residual stress formed by a large degree of binding, and hydrogen remaining in the weld. It has high universality and greater danger. This kind of defect may occur immediately after welding, or it may occur within a few hours, so it is also called delayed crack. The solution is to strictly control the content of sulfur, phosphorus and other harmful impurities in stainless steel pipes and welding consumables, reduce the sensitivity of hot cracks, or adjust the chemical composition of the weld metal, optimize the weld microstructure, refine the grain, Strengthen plasticity and reduce segregation also use alkaline welding materials, reduce the content of impurities in the weld, optimize the degree of segregation select suitable welding process parameters, properly increase the weld forming factor, use multi-layer multi-channel welding Method: When the arc is broken, use the same lead plate as the parent material, or gradually extinguish the arc and fill the arc pit to prevent the formation of hot cracks in the arc pit.Ĭold cracking refers to the formation of cracks when welded joints of stainless steel tubes cool to lower temperatures. Hot cracks usually occur in austenitic stainless steels, nickel alloys, and aluminum alloys. At the same time, it is pulled along the grain boundary under the action of welding stress to generate hot cracks. The main reason is that the low-melting eutectic and impurity in the molten pool metal produce severe intragranular and intergranular segregation during the crystallization process.
#Welding cracks in steel crack#
In the welding process, the welding crack formed by the stainless steel material in the weld zone and the heat affected zone cooled to the high temperature zone near the solid line is called a hot crack, and the danger is high.
Not only is it easy to scrap the stainless steel pipe, it may also cause serious accidents. This kind of defect is the most dangerous for the welded structure. According to the time and temperature of formation, there are mainly three forms of cold cracks, hot cracks and reheat cracks according to the formation site, it can be divided into vertical cracks, transverse cracks, Weld root cracks, arc pit cracks, fusion line cracks, and heat affected zone cracks. During the welding process of stainless steel pipes, cracks sometimes occur in the weld zone.
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