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采用光学显微镜、X射线衍射、扫描电镜和透射电镜研究了正火温度对不含钛和含钛(0.14wt%)高铬马氏体耐热钢显微组织和力学性能的影响。结果表明:在1000~1150℃范围内,随正火温度的升高,不含钛的钢晶粒明显长大,而含钛钢晶粒大小基本不变;经不同温度正火和750℃高温回火处理后,两种钢的洛氏硬度值均随正火温度的升高先增后减,在1100℃正火处理时达到峰值,含钛钢的洛氏硬度均略低于不含钛的钢。1100℃×1h正火处理+750℃×1h高温回火处理后,含钛钢在晶界上存在尺寸约为2μm的TiC颗粒,在马氏体板条界附近区域内分布有高密度纳米TiC析出相。蠕变过程中裂纹易于在大颗粒TiC的界面处形核导致含钛钢的高温蠕变性能降低。
The effects of normalizing temperature on microstructure and mechanical properties of high chromium martensitic heat-resistant steel without titanium and titanium (0.14wt%) were studied by optical microscope, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that in the temperature range of 1000 ~ 1150 ℃, with the increase of normalizing temperature, the grain of the steel containing no titanium obviously grows, while the size of the titanium - containing steel does not change basically. After normalizing at different temperatures and high temperature of 750 ℃ After tempering, the Rockwell hardness values of both steels increase first and then decrease with the increase of normalizing temperature, and reach the peak value at 1100 ℃ normalizing. The Rockwell hardness of titanium steels are slightly lower than those of non-titanium steels . After 1100 ℃ × 1h normalizing treatment and high temperature tempering at 750 ℃ × 1h, TiC particles with the size of about 2μm existed in the grain boundary, and high density nano-TiC was distributed in the vicinity of the martensite lath boundary Precipitates. Cracks in the creep process tend to nucleate at the interface of large grain TiC, resulting in a decrease in high temperature creep properties of titanium-containing steels.