高碳钢制的扁铲,由于工作部分要求HRC55～60、尾部HRC30～40、中间部分HRC25～30。过去一般的淬火方法都是整体加热,先淬工作部分,后淬尾部,然后再全部淬入硝盐或油中。这种方法往往使尾部硬度偏高,还要先进行一次中温回火使尾部硬度降下来,再进行整体低温回火。操作麻烦、生产 High-carbon steel flat shovel, due to work requirements HRC55 ~ 60, tail HRC30 ~ 40, the middle part of HRC25 ~ 30. In the past the general quenching methods are the overall heating, the first part of the quenching work, after quenching the tail, and then all the quench into the salt or oil. This method tends to tail the tail hardness is too high, but also to conduct a tempering temperature so that tail hardness down, and then the overall low temperature tempering. Operation trouble, production