铸铁锅的氮碳共渗

Nitrocarburizing of Cast Iron Pans

为提高耐磨性能和使用寿命,HT200灰口铸铁锅需进行气体氮碳共渗。技术要求为:经盐雾试验6 h后,铁锅表面颜色异常点少于10个,锈点少于5个。经过3次试验,得出了能使铸铁锅达到技术要求的气体氮碳共渗工艺为:采用NH_3+CO_2作渗剂,二段氮碳共渗,第1段510℃×1 h,分解率25%,第2段560℃×3 h,分解率50%～55%。

In order to improve both corrosion resistance and service life, pans made of HT200 gray cast iron needs to be gas nitrocrburized to the point where points having abnormal colour are less than 10 in amount and rusty spots are less than 5 in amount on their surface after undergoing salt spray test for 6 h. After being nitrocarburized by trial processes three times, a procedure by which the pans are gas nitrocarburized with a result conforming the technical requirements is double-stage nitrocarburizing at 510 ℃ for 1 h using ammonia dissociation rate of 25% for the first stage and at 560 ℃ for 3 h using ammonia dissociation rate of 50 to 55% for the second stage in a atmosphere consisting of NH3 and CO2.