42MnMo7无缝钢管开裂分析  

42MnMo7 Seamless Steel Pipe Cracking Analysis

作　　者：黄佑启[1] HUANG Youqi(Hengyang Valin Steel Tube Co.,Ltd.,Hengyang 421001,China)

机构地区：[1]衡阳华菱钢管有限公司,湖南衡阳421001

出　　处：《金属材料与冶金工程》2023年第1期20-24,共5页Metal Materials and Metallurgy Engineering

摘　　要：通过化学成分分析、金相检验和扫描电镜观察等方法,对42MnMo7地质钻杆用无缝钢管在拉伸试验过程中出现的夹持端开裂原因进行了分析。结果表明:材料成分正常,非金属夹杂物控制在较低水平;但裂纹附近的金相组织分析发现钢管内壁存在马氏体等异常组织,并呈现明显的自回火特征,冲击断口呈现典型的解理断口形貌。经调查发现,生产过程中高压水除鳞水环故障导致冷却水从管端进行入钢管内壁,使钢管内壁局部发生马氏体转变,严重部位甚至出现了淬火裂纹,从而导致材料性能恶化,在受到夹持力时发生开裂或二次扩展,最后作者对此提出了相应的改进措施和建议。Through chemical composition analysis,metallographic inspection and scanning electron microscopy observation,the causes of cracking at the clamping end of the seamless steel pipe for 42MnMo7 geological drill rod during tensile test were analyzed.The results show that the composition of the material is normal,and the non-metallic inclusions are controlled at a low level,but the metallographic structure analysis near the crack finds that there are abnormal structures such as martensite on the inner wall of the steel pipe,there are obvious self-tempering characteristics,and the impact fracture shows a typical cleavage fracture morphology.Investigation shows that the failure of the high-pressure water descaling water ring,transfers the cooling water from the end of the pipe into the inner wall of the steel pipe,so that the maltensitic transformation occurs locally on the inner wall of the steel pipe,and even the quenching crack appears in the worse parts,resulting in deterioration of material properties and cracking or secondary expansion when subjected to clamping force.At the end,the author put forward corresponding measures and suggestions for this.

关 键 词：地质钻杆管 淬火裂纹 马氏体转变 自回火 

分 类 号：TG306[金属学及工艺—金属压力加工] TG335.1