微合金非调质钢的断裂韧性与断裂机理分析

The Fracture Toughness and Fracture Mechanisms of Medium-carbon Micro-alloyed Steels

本文测试了两种微合金中碳钢35MnVN和40MnVTi的断裂韧性K_IC值及不同正火处理状态下35MnVN的J_R阻力曲线。对热加工条件及组织参数对K_IC值及J积分值的影响进行了分析。结果表明,采用降低了的始锻温度以及相应低的终锻温度可提高K_IC值。组织状态相似条件下,40MnVTi的断裂韧性值比35MnVN略高些。860～950℃正火处理对改善断裂韧性效果明显,温度过高则无效果。本文还对脆性断裂机制进行了讨论。

Attempts Have been made to find the effects of hot-processing techniques on the fracture toughness of microalloyed steels through measuring the K_(IC) values of 35MnVN, 40MnVTi on different forging conditions and the J-integral values of 35MnVN on different heat-treating conditions. The results show that K_(IC) can be raised effectively by controlled forging technique. 860～950℃ normalizing wilt improve the crack resistance when higher fracture toughness is need than forging condition. Compared with the K_(IC) valne of 35MnVN with the similar metallography microstructure, the one of 40MnVTi is higher. The brittle fracture mechanisms have also been discussed.