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New insights into the fracture behavior of advanced high strength steel resistance spot welds
Journal of Materials Processing Technology ( IF 6.3 ) Pub Date : 2021-11-22 , DOI: 10.1016/j.jmatprotec.2021.117433
Ali Chabok 1 , Huatang Cao 1 , Ellen van der Aa 2 , Yutao Pei 1
Affiliation  

While the automotive industry is striving for the reduction of car body weight to increase the fuel efficiency and to reduce CO2 emission without compromising the safety and crashworthiness of vehicles, a new generation of advanced high strength steels (AHSS) have emerged as excellent candidates to meet these requirements. However, their integration into the car body structure is associated with welding-related problems. This research utilizes a novel approach to establish a fundamental correlation between welding parameters, microstructure and mechanical performance of AHSS resistance spot welds. In-situ micro-cantilever bending experiments are executed and analyzed in a quantitative manner to evaluate the effect of texture and post-welding heat treatment on the local fracture toughness of spot welds. A striking finding is that, through a switch from single to double pulse weld scheme, the texture of martensite formed in the fusion zone becomes responsible for a significantly higher fracture toughness of the area in front of the pre-crack. In addition, it is found that paint baking heat treatment also results in a much enhanced fracture toughness through tempering of the martensitic microstructure. A quantitative correlation is made between the micro-scale fracture toughness and macro-scale mechanical performance of advanced high strength steel welds.



中文翻译:

对高级高强度钢电阻点焊断裂行为的新见解

虽然汽车行业正在努力减轻车身重量以提高燃油效率并减少 CO 2排放,同时又不影响车辆的安全性和耐撞性,但新一代先进高强度钢 (AHSS) 已成为优秀的候选材料。满足这些要求。然而,它们与车身结构的集成与焊接相关的问题有关。本研究利用一种新方法来建立 AHSS 电阻点焊的焊接参数、微观结构和机械性能之间的基本相关性。原位以定量方式执行和分析微悬臂梁弯曲实验,以评估织构和焊后热处理对点焊局部断裂韧性的影响。一个惊人的发现是,通过从单脉冲焊接方案转换为双脉冲焊接方案,在熔合区形成的马氏体织构成为导致预裂纹前面区域显着更高的断裂韧性的原因。此外,还发现油漆烘烤热处理还通过马氏体显微组织的回火大大提高了断裂韧性。对先进高强度钢焊缝的微观断裂韧性和宏观力学性能进行定量相关。

更新日期:2021-12-03
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