土铁(白口铁)变成灰口铁大都采用高温退火。但含铬的土铁采用这种方法是相当困难的,在高温下即使停留很长时间,也很难使碳化铁完全分解。根据我们试验,在退火前先进行淬火,可以得到满意的退火结果。我们试验用的铸件是合铬土铁的汽缸套(厚25公厘),化学成分是:碳2.98%,硅1.97%, Soil iron (white iron) into gray iron mostly used high temperature annealing. However, it is quite difficult to use this method with chromium-containing earth iron. It is difficult to completely decompose the iron carbide even if it stays for a long time even at high temperatures. According to our test, quenching before annealing can be satisfactory annealing results. The castings we used for the tests were cylinder liner made of chrome iron (25 mm thick) with a chemical composition of 2.98% carbon, 1.97% silicon,