钢制零件的螺孔、不需淬硬的光孔或其他部位,在淬火前应予以防护。一般多用干石棉绳堵塞。如把石棉绳用水浸湿后再堵紧,则不但能很容易地堵实,而且在水冷淬火过程中亦不脱落,可有效地起到防淬作用。但要注意一点,即如果工件在盐浴中加热时,一定要充分预热,将石棉绳 Steel parts screw holes, without hardened holes or other parts, should be protected before quenching. Mostly use dry asbestos rope blockage. If the asbestos rope soaked in water and then tight, it will not only easily blocked, but also in the water quenching process does not fall off, can effectively play the role of anti-quenching. But to note that if the workpiece in the salt bath heating, we must fully preheat the asbestos rope