42CrMo钢与Q235钢焊接冷裂敏感性研究

Study on the cold cracking susceptibility of 42CrMo and Q235 steel during welding

采用理论计算、维氏硬度试验及斜Y形坡口焊接裂纹试验方法研究42CrMo钢与Q235钢焊接的冷裂纹敏感性。结果表明,中碳调质钢42Cr Mo的碳当量w(C)_(eq)为0.911 7%,具有很大的淬硬倾向,极易产生冷裂纹;斜Y形坡口试验结果表明,随着预热温度的变化,表面裂纹率没有发生改变,断面裂纹率显著降低。在预热300℃,焊后550℃保温3 h,42CrMo钢一侧的粗晶区及焊缝淬硬组织减少,维氏硬度均低于HV5350,该焊接工艺下可获得抗裂性优良的焊接接头。

The cold cracking susceptibility of 42CrMo and Q235 steel welding was researched by theoretical calculations, hardness testing on the weld joint and tekken type cracking test. Results showed that if the w(C)_(eq) was 0.911 7%, medium carbon quenched steel 42CrMo was easy to harden and susceptible to cold crack. Tekken type cracking test showed that the crack rate decreased significantly with the preheating temperature increasing. The preheated at 300, 550 ℃, heat preservation 3 hours after welding, on the side of 42CrMo steel the coarse grained and weld hardening organization reduced and hardness was less than HV5350. Excellent welded joint could be obtained under the welding processes.