Wang Gang, Yin Limeng, Yao Zongxiang, Wang Jinzhao, Jiang Shan, Zhang Zhongwen, Zuo Cunguo
School of Metallurgy and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331, China.
Guangdong Provincial Key Laboratory of Advanced Welding Technology, Guangdong Welding Institute (China-Ukraine E.O. Paton Institute of Welding), Guangzhou 510650, China.
Materials (Basel). 2019 May 30;12(11):1762. doi: 10.3390/ma12111762.
High-energy beam welding was introduced for pipeline steel welding to reduce pipeline construction costs and improve the efficiency and safety of oil and gas transportation. Microstructures and their distribution in X100 laser-welded joints, which determine the joints' strength and toughness, are discussed in this paper. Welded joints were prepared by an automatic 10,000-watt robot-based disc laser-welding platform for 12.8 mm thick X100 pipeline steel. Then, the grain, grain boundary, orientation, and distribution pattern of each zone of the welded joints were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and electron backscattered diffraction (EBSD) analysis techniques. The results showed that the grain boundary density, contents of the high-angle and low-angle grain boundaries, distribution states, and evolution trends of coincident site lattice (CSL) grain boundaries were essentially the same in each zone from the base metal (BM) to the weld of the X100 pipeline steel laser-welded joint. The relative content of grain boundaries above 55°, which were composed of the Σ3 type CSL grain boundary, showed a considerable impact on the mechanical properties of the joint. The content of twin grain boundaries was closely related to the thermal cycles of laser welding, and the effect of the cooling rate was greater than that of the process of austenization.
为降低管道建设成本并提高油气输送的效率和安全性，高能束焊接被引入到管道钢焊接中。本文讨论了X100激光焊接接头中的微观结构及其分布，这些微观结构决定了接头的强度和韧性。采用基于10000瓦机器人的自动圆盘激光焊接平台制备了12.8毫米厚X100管道钢的焊接接头。然后，通过光学显微镜（OM）、扫描电子显微镜（SEM）、能谱仪（EDS）和电子背散射衍射（EBSD）分析技术研究了焊接接头各区域的晶粒、晶界、取向和分布模式。结果表明，在X100管道钢激光焊接接头从母材（BM）到焊缝的各区域中，晶界密度、高角度和低角度晶界的含量、重合位置点阵（CSL）晶界的分布状态和演变趋势基本相同。由Σ3型CSL晶界组成的55°以上晶界的相对含量对接头的力学性能有相当大的影响。孪晶晶界的含量与激光焊接的热循环密切相关，冷却速率的影响大于奥氏体化过程的影响。
