低合金高碳钢焊接热影响区的连续冷却转变曲线

SH-CCT Curves of Low Alloy High Carbon Steel

用Formastor-D型全自动相变测量仪,结合显微组织观察和硬度测量,测定了A、B两种低合金高碳钢焊接热影响区的连续冷却转变(SH-CCT)曲线;分析了合金元素镍对试验钢SH-CCT曲线的影响。结果表明:为保证热影响区为珠光体组织,A、B试验钢在焊后热处理时,t8/5应分别大于300 s和200 s;B试验钢的珠光体转变区与贝氏体转变区发生分离;镍可推迟奥氏体向珠光体和贝氏体转变,也可降低Ac3和Ms相变点温度。

By measuring the continuous cooling transformation curves in heat affected ZOne（SH-CCT curves） of two kinds of low alloy high carbon test steels A and B at different cooling speeds in Formastor-D phase transformation tester, combined with metallographie analysis and hardness measurements, SH-CCT curves were obtained. The effect of Ni on the SH-CCT curves was analyzed. The results showed that to ensure the heat affected zone being of pearlite, ts/5 should be longer than 300 s and 200 s respectively in the process of heat treatment after welding of test steel A and B. SH-CCT curves of the test steel B had a separation region between the pearlite transformative and bainite transformative. Ni could postpone the transforming from austenitic to pearlite and bainite,and also lower the tempteratures of Ac3 and Ms.