关于“失碳”问题的探讨

Discussion on the Problem of "Carbon Depletion"

"失碳"问题是一个在保护气氛热处理中带有普通性的问题。对于钢丝、钢带等产品的危害性甚大。对其产生的原因,传统的观点认为是由于气氛的"碳势"不足所造成的。然而,按此观点做的许多努力却未能达到预期的目的。本文根据理论分析和试验结果提出,在重结晶温度(Ac_1)以下,由于钢料是由铁素体和渗碳体两相构成的,对此使用"碳势"概念是不妥当的。再结晶退火时的"失碳"主要发生在渗碳体相,钢材表面的氧化铁则是不可忽略的重要氧化剂。根据生产中气氛难以达到使渗碳体不失碳的程度,本文提出了几种解决"失碳"问题的途径,并应用于GCr15钢丝生产取得了良好的效果。

'Carbon depletion' which is harmful to some products as wires, strips. etc. is a common problem in the heat treament under protective atmosphere. According to the conventional view, the carbon depletion' resulted from the deficiency of 'carbon potential' in the atmosphere. However, many efforts which were made based on this view have failed to achieve the expected goal. On the basis of the theor(?)tical analyses and testing results, the paper pointed out that the concept of 'carbon potential' thus used here is improper since the material consist of both ferritic and cementite under the recry- stallization temperature (below Ac(?)). 'Carbon depletion' takes place mainly in the cemeatite during recrystallization annealing, and the iron-oxide on the surface of steels is the very important oxidizer not to be negligent. In production the atmosphere was hard to meet the requirement that the 'carbon depletion' won't occur to the cementite. Several ways to solve this problem have been mentioned in this paper and obtained good effects in the production of the wires GCr15 steel.