CT70级低合金高强度油管用钢激光焊焊接接头性能研究

采用激光焊方法进行了CT70级油管用钢的焊接，并对焊接接头的外观、组织、硬度和力学等性能进行了检测。结果表明，激光焊焊接接头整体成形良好，无不良缺陷，焊接接头的强度、冲击韧性与母材相当，弯曲试验全部合格，焊缝及近缝区硬度明显上升。组织观察发现，冷速过快导致焊缝区铁素体变为粗大的块状，块状之间分布少量的小岛状组织，块状组织内部为大量分解不完全的富碳奥氏体。研究表明，激光焊接工艺可用于CT70级油管用钢的焊接与相关产品的制造。

Properties of Laser Welded Joint of CT70 Low Alloy High Strength Tubing Steel

CT70 grade tubing steel was welded by laser welding, and the appearance, microstructure, hardness and mechanical properties of the welded joint were tested. The results show that the laser welded joint is in good shape with no defects. The strength and impact toughness of the welded joint are equivalent to that of the base metal. The bending test is all qualified, and the hardness of the welded joint and the near weld area increases obviously. The microstructure observation shows that too fast cooling rate leads to the transformation of ferrite into coarse block, a small amount of small island structure is distributed between the blocks, and a large amount of carbon-rich austenite with incomplete decomposition is found in the massive structure. The results show that the laser welding process can be used for the welding of CT70 tubing steel and the manufacture of related products.