【摘要】 本文对经过600℃×6小时软氮化的20钢及35钢试样再进行650°—900℃不同温度加热急冷处理,然后分别对各试样进行金相、电子金相等物理检验和各种力学性能试验。其结果表明,经过软氮化后的钢件再在650℃加热30分钟时,铁的氮化物(ε·Υ′)开始分解,在750℃加热15分钟氮化物分解完毕,同时N原子向深层扩散,淬火后可获得一定厚度C—N马氏体层,进而提高了各项力学性能指标。检验发现再加热时ε相先在其和α及Υ相相界面上分解,然后在ε相相同界面分解,析出的氮原子向深层扩散。试验确定了软氮化后再加热时渗层组织变化和温度及加热时间的关系。更多还原

【Abstract】 Samples of Steel 20 and Steel 35, after liquid nitrided at 600℃ for 6 hrs., were reheated at different temperatures in the range from 650℃ to 900℃ and cooled rapidly. Then light metallography, electronic metallography and test of mechanical properties were carried out.The results showed that the nitride of Fe (ε, γ’) started to decompose in the samples reheated at 650℃ for 30 min.and decomposed completely in those reheated at 750℃ for 15 min.At the same time nitrogen atoms diffused deeper into the samples ao that the layer of martensite containing carbon and nitrogen was obtained and the mechanical properties were improved. It was also found that ε-phase decomposed earlier at α-γ phase boundaries and later at ε-ε phase boundaries.The relationship between the microstructure and the reheating temperature and time was determined in this experiment.更多还原