使用配备红外线加热炉的激光共聚焦扫描显微镜(CLSM)对3种不同碳含量的奥氏体不锈钢AISI 302, AISI 304, AISI 316L的碳化物沉积以及敏化过程进行了原位观察, 同时研究了碳含量、加热温度以及时间与碳化物沉积以及敏化带宽度之间的关系, 绘制出了不锈钢出现晶界碳化物沉积和敏化带的时间-温度曲线。结果表明：AISI 302, AISI 304不锈钢在600～1 000 ℃加热时均会出现晶界碳化物沉积, 发生敏化现象, 且碳含量高的AISI 302不锈钢相比碳含量低的AISI 304不锈钢其晶界上更容易先形成碳化物沉积和发生敏化现象; 当加热温度升高至1 100 ℃时, 两种不锈钢的晶界碳化物沉积溶解, 敏化带消失; AISI 316L不锈钢由于碳含量低, 试验时间内未观察到晶界碳化物沉积和敏化现象; 敏化带宽度随加热温度和不锈钢碳含量的增加而增加, 随加热时间的延长则先增大后减小。

The confocal laser scanning microscope(CLSM) combined with an infrared furnace was used to in-situ observe the carbide precipitation and sensitization behavior of AISI 302, AISI 304 and AISI 316L three austenite stainless steels with different carbon contents, the relationship between carbon content, heating temperature and time and carbide precipitation and sensitization band width was studied, and the grain boundary carbide precipitation appearing time-temperature curve and sensitization band appearing time-temperature curve were obtained. The results show that AISI 302, AISI 304 stainless steels would appear grain boundary carbide precipitation and sensitization behavior when they were annealed at 600～1 000 ℃, and carbide deposition and sensitization behavior could be observed more clearly and earlier on the grain boundaries of AISI 302 stainless steel with higher carbon content compared to AISI 304 stainless steel with lower carbon content. When the annealing temperature raised to 1 100 ℃, the grain boundary carbide precipitation became to dissolve and the sensitization band disappeared. Grain boundary carbide precipitation and sensitization behavior were not observed in AISI 316L stainless steel because of its lower carbon content. The sensitization band width increased with the increase of annealing temperature and carbon content, and it increased first and then decreased with the increase of annealing time.