金属在焊接时所形成的焊缝和热影响区性能常常决定着焊接构件的寿命和使用性能。因为在焊接时,近缝区的金属和焊缝本身都经受一次或数次特殊的焊接热作用,使金属组织和性能发生一系列的变化。如果不事先研究这种焊接热对金属的作用,就有可能在焊接过程中造成缺陷,或在焊接结构的使用过程中引起质量事故。因此必须深入 The performance of the weld and the HAZ formed during the welding of metals often determines the life and serviceability of the welded components. Because in the welding, the near seam area of ​​the metal and the weld itself are subject to one or more special welding heat, the metal structure and performance of a series of changes. Without prior study of the effect of such weld heat on the metal, it is possible to cause defects during the welding process or cause quality problems during use of the welded structure. So we must go deep