利用热重分析、金相及扫描分析等手段,研究了加热温度、保温时间和加热炉内气氛对高碳铬轴承钢GCr15氧化和脱碳行为影响.结果表明:随着加热温度和保温时间增加,GCr15钢氧化铁皮厚度和脱碳层深度均呈增大趋势;随着炉内含氧量增加,氧化铁皮厚度也呈增大趋势,但脱碳层深度呈下降趋势,且含氧量达6％脱碳趋于稳定.通过热力学和动力学分析发现:随着加热温度、保温时间以及炉内含氧量增大,其对应的抛物线氧化速率常数不断增大、高温抗氧化能力增强.低于900℃时,GCr15钢氧化增重与时间呈直线规律增长;高于900℃时,呈抛物线规律增长,其对应的氧化激活能由113.9 kJ/mol增大到324.1 kJ/mol,870℃为氧化机制发生改变的临界温度.
Effects of heating temperature,holding time and furnace atmosphere on surface oxidation and decarburization of high-carbon chromium bearing steel GCr15 were studied by means of thermogravimetric analysis (TG),optical microscope (OM) and scanning electrical microscopy(SEM).The results show that with the increasing of heating temperature and holding time,the thickness of iron scale or the depth of decarburization layer increases.With the increasing of furnace oxygen content,the thickness of the iron scale increases,but the depth of the decarburization layer decreases and keeps stable when O2 content is over 6％.The results of thermodynamics and kinetics show that with the increasing of temperature and time,the oxide parabolic rate constant and oxidation resistance increase.When the heating temperature is below 900 ℃,the oxidative mass increment of the GCr15 steel exhibits a straight-line growth trend.While the temperature is over 900 ℃,it exhibits a parabolic growth trend,and the activation energy value increases from 113.9 kJ/mol to 324.1 kJ/mol.The temperature of 870 ℃ is the change point of oxidation.
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