结构在焊接以后不仅产生变形,而且内部存在着焊接残余应力。残余应力的存在对大多数焊接结构的安全使用没有影响,也就是焊后不必进行消除应力处理。有些情况下则要求消除焊接结构中的残余应力,才能保证产品质量。不仅在焊后,而且在整个焊接过程中,结构的变形和焊接应力始终存在着,并且是不断在变化着,掌握这个变化规律对于焊接的工人是很必要的,因为这种焊接应力对于可焊性不良的金属,常常成为造成焊接裂纹 The structure not only deforms after welding, but also has internal welding residual stress. The presence of residual stresses has no effect on the safe use of most welded structures, ie there is no need to stress relieve after welding. In some cases it is required to eliminate the residual stress in the welded structure, in order to ensure product quality. Structural deformation and welding stresses are always present and are constantly changing, not only after welding, but also throughout the welding process. Mastering this pattern of variation is necessary for soldering workers because this welding stress is critical for solderable Poorly-made metal, often a cause of weld cracking