960高强度钢激光焊接接头的组织和腐蚀性能

针对960高强度钢激光焊接接头腐蚀性能开展分析,利用扫描电镜和光学电镜分析接头微观组织;利用动电位极化技术研究接头不同区域在模拟海水中的腐蚀行为;并通过恒载荷加载装置研究接头在模拟海水中的应力腐蚀行为.结果表明,960高强度钢腐蚀规律为均匀腐蚀到点蚀再到均匀腐蚀.电化学测试结果3个区域的腐蚀速率从大到小为焊缝,热影响区,母材,且随着腐蚀的继续进行腐蚀速率减慢.热影响区粗晶区成为接头的薄弱环节,拉伸试样均断裂在热影响区.应力腐蚀使拉伸试样抗拉强度降低12%,断裂形式由韧性断裂变为准解理断裂.

Microstructures and corrosion properties of laser welded joint of 960 high-strength steel

The corrosion property of 960 high-strength steel joint by high power laser welding was studied. The microstructure of the welded joint was analyzed by scanning electron microscope(SEM) and optical electron microscopy. The corrosion behavior of the welded joint was investigated by potentiodynamic polarization. Stress corrosion sensitivity of the welded joint was investigated in simulated seawater at constant load. The results show that the corrosion process of 960 high strength steel starts with uniform corrosion, then the corrosion products drops off and the uniform corrosion forms at last. The electrochemical corrosion results show that the corrosion rate increases from weld, HAZ to base metal, and it decreases gradually with longer corrosion time. The fracture occurs at the heat affected zone due to the coarse grain of this zone in tensile test. Stress corrosion resulted in that the tensile strength of specimens decreased by 12%, and the fracture mode changed from ductile fracture to quasi-cleavage fracture.