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采用SEM和TEM研究不同保温温度及时间下高氮不锈轴承钢中碳化物的演变规律,并对碳化物变化进行表征及分析。结果表明:预备组织中碳化物主要沿晶界分布,尺寸主要集中在0.4~0.8μm。在600、700和750℃保温时,碳化物的视场面积个数逐渐减少而视场面积分数逐渐增加。低于800℃保温时,少量碳化物沿晶界析出;高于800℃保温时,碳化物沿晶界和位错析出,并有少量Cr_2N析出。900℃保温时,碳化物的视场面积个数和视场面积分数减少,碳化物形成元素回溶到基体中。低于750℃保温过程中,钢中碳化物发生粗化临界尺寸为0.8μm,长棒状碳化物以自身球化的方式球化长大,碳化物圆整度频数最大值由0.65增加到0.80。钢中碳化物在700℃保温10 h时球化效果较明显。
SEM and TEM were used to study the evolution of carbides in high nitrogen bearing steel under different holding temperature and time, and the characterization and analysis of carbides were carried out. The results show that the carbides distribute mainly in the grain boundaries along the grain boundaries, and the size mainly lies in the range of 0.4 ~ 0.8μm. At 600, 700 and 750 ° C, the number of carbides in the field of view decreases and the fraction of the field of view gradually increases. When the temperature is lower than 800 ℃, a small amount of carbide precipitates along the grain boundaries. When the temperature is higher than 800 ℃, the carbide precipitates along the grain boundaries and dislocations and a small amount of Cr_2N precipitates. When the temperature is 900 ℃, the number of the field of view of the carbides and the fraction of the field of view decreases, and the carbide-forming elements are dissolved back into the matrix. When the temperature is lower than 750 ℃, the critical size of the carbides in the steel is 0.8μm. The long rod-shaped carbide grows by spheroidization and the maximum frequency of carbide roundness increases from 0.65 to 0.80. When the steel carbides are incubated at 700 ℃ for 10 h, the spheroidization effect is obvious.