Stainless steel thick-walled pipe welding analysis,Technology

Thermal cracks of stainless steel thick-walled tube welded joints, welds and weld near the area may produce thermal cracks, weld is mainly the solidification cracks, and weld vicinity is the main liquefied cracks.

First the cause of thick-walled tube welding heat cracks, stainless steel expansion coefficient, thermal conductivity, resulting in the welding process to produce a relatively large tensile stress, tensile stress in the presence of weld condensation, crystallization of the need to cause thermal cracks during conditions. Direction of strong columnar crystals are more likely to cause segregation of hazardous substances, causing intergranular film, the crack of a very weak link.

Then the welding process factors on the thermal cracks in the welding process, due to improper welding process caused the dendrite thick in order to obtain the FA solidification mode to create the conditions to control the temperature between layers with a smaller line energy warm-up, etc., these are common processes, but also to avoid excessive welding, this will increase the imbalance in the coagulation process.

In addition to prevent thermal cracks in the welding process, the choice of welding consumables is critical, a certain amount of Mo, Ni, Cr can effectively prevent thermal cracks. However, the alloying elements on hot crack sensitivity depends on its solubility, and will result in the ability to generate low-capacity eutectic.