中国激光, 2019, 46 (7): 0702004, 网络出版: 2019-07-11  

耐候钢激光-MAG复合焊接头的低温断裂韧性 下载: 857次

Low-Temperature Fracture Toughness of Laser-MAG Hybrid Welding Joint in Weather-Resistant Steel
作者单位
西南交通大学材料科学与工程学院, 材料先进技术教育部重点实验室, 四川 成都 610031
摘要
为研究低温下高速列车用耐候钢激光-MAG复合焊接头的断裂行为,通过低温断裂韧性试验获得接头焊缝、热影响区和母材的断裂韧度Jm。采用Boltzmann函数进行拟合分析,得到各区的韧脆转变温度。结果表明:随着温度降低,接头各区域的断裂韧性呈降低的趋势,母材的低温韧性优于焊缝的低温韧性;焊缝区的韧脆转变温度约为-65.9 ℃,热影响区的韧脆转变温度约为-70.4 ℃,均高于母材(-81.9 ℃)。通过对微观组织和断口形貌的对比分析,阐明了激光-MAG复合焊接头各区域的微观断裂机理,焊缝金属较低的低温断裂韧性主要是由晶粒粗大和存在粗大的先析铁素体造成的。
Abstract
To understand the low-temperature fracture behavior of the laser-MAG(metal active gas) hybrid welding joint of weather-resistant steel for high-speed trains, the integral values Jm of fracture toughness of the welding metal, heat-affected zone, and base material are obtained through a low-temperature fracture toughness test. The relationship between fracture toughness and temperature is fitted by the Boltzmann function, and the ductile-to-brittle transition temperature of each zone is obtained. The results demonstrate that the variation trend of the fracture toughness of each zone is reduced as temperature decreases. The base material has higher low-temperature toughness compared with the welding metal. The ductile-to-brittle transition temperatures of the welding metal and heat-affected zone are -65.9 ℃ and -70.4 ℃ respectively, both of which are higher than that of the base material (-81.9 ℃). The micro-fracture mechanism of each zone of the laser-MAG hybrid welding joint is explained based on the observation of the microstructure and fracture morphology. The poor low-temperature fracture toughness of the welding metal is primarily due to the large-size coarse grain and proeutectoid ferrite in the microstructure.

陈勇, 陈辉, 李仁东, 车小莉, 张成竹. 耐候钢激光-MAG复合焊接头的低温断裂韧性[J]. 中国激光, 2019, 46(7): 0702004. Yong Chen, Hui Chen, Rendong Li, Xiaoli Che, Chengzhu Zhang. Low-Temperature Fracture Toughness of Laser-MAG Hybrid Welding Joint in Weather-Resistant Steel[J]. Chinese Journal of Lasers, 2019, 46(7): 0702004.

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