电、气焊在农机修理中是经常遇到的。为了防止在焊修时零件产生扭曲变形，可采用下述几种方法预防。（１）预热法。焊前把要施焊的零件加热，以减小内应力，这是防止零件变形的好方法。（２）导热法。利用导热良好的金属附在焊件基体上，以降低焊件温度和热变形。导热材料可用 Electricity, gas welding are often encountered in agricultural machinery repair. In order to prevent the parts in the welding repair distortion, the following methods can be used to prevent. (1) Preheat method. Before welding the parts to be welded to heat, to reduce the internal stress, which is a good way to prevent deformation of the parts. (2) thermal method. The use of good thermal conductivity of metal attached to the weldment matrix to reduce weldment temperature and thermal deformation. Thermal materials are available