82B线材中马氏体组织的试验研究

Experimental research to martensite in 82B wire rod

通过绘制82B线材的连续冷却曲线,并根据82B线材的基本冷却特性,采用相变前-相变时-相变后3段式冷却试验工艺模拟风冷过程,研究相变前后不同冷速对82B线材组织和性能的影响。结果表明:(1)82B线材马氏体产生的临界冷却速度为5℃/s,当冷速达到10℃/s时,由于马氏体转变温度显著低于马氏体的产生温度Ms,马氏体会显著增加。(2)对比分析相变前后不同冷速对试样抗拉强度以及断面收缩率的影响,给出优化的冷却工艺,相变前冷速为10～15℃/s,相变后冷速为1～3℃/s,并调节相变时的冷速将返温温度控制在50℃。

To research effect of different cooling speed before and after phase change on martensite and mechanical properties of 82B wire rod by drawing continuous cooling curve of the wire rod, according to basic cooling characteristic of 82B wire rod, and adopting before phase change, as phase change, after phase change three stages cooling test process to simulate wind cooling process. The result shows： （ 1 ） the critical cooling speed appearing martensite in 82B wire rod is 5 ℃/s, as cooling speed reaches 10 ℃/s, the martensite quantity rise quickly due to martensite phase change temperature below martensite starting point; （2） by comparing and analyzing the effect of cooling speed before and after phase change on tensile strength and reduction of area, the optimum cooling process was obtained, that is cooling speed 10 to 15 ℃/s before phase change, 1 to 3 ℃/s after phase change, and adjusting phase change cooling speed to control return temperature at 50 ℃.