Significance of fracture toughness for linear friction welded joint of weathering steel

IF 2.4 4区材料科学 Q2 METALLURGY & METALLURGICAL ENGINEERING

Welding in the World Pub Date : 2024-12-26 DOI:10.1007/s40194-024-01890-7

Kazuma Shimizu, Shota Nakayama, Hiroto Shoji, Takumi Kawakubo, Tomoya Nagira, Mitsuru Ohata, Hidetoshi Fujii

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Abstract

This paper examined the characteristics and significance of fracture toughness for LFW (linear friction welding) joints of weathering steel SPA-H processed under different joining conditions to control maximum temperature during LFW process. Two types of LFW joint were prepared; one was jointed under higher compressive pressure so as a maximum temperature during LFW process to be lower than the A₁-transformation temperature (A1-LFW), and the other was jointed under lower compressive pressure to be higher than the A₃-transformation temperature (A3-LFW). The fracture toughness of both joints where a crack was located at the joint interface exhibited a higher value than that of the heat-affected zone of MAG (metal active gas) welds for the same steel. These results indicated that the LFW was more effective for the joining of weathering steel compared with conventional arc welding in terms of fracture toughness. However, A1-LFW exhibited lower fracture toughness (critical CTOD) than that of base metal or A3-LFW. Thus, the significance of the test results was discussed from mechanical and metallurgical viewpoints. The fracture toughness for A1-LFW found to be deteriorated due to work hardening associated with compressive plastic straining during LFW under higher compressive pressure, where the metal heated under A₁-temperature was not completely ejected by friction but remained around the joint interface. On the other hand, the deterioration of fracture toughness for A3-LFW was found to be caused by hardening due to bainitic transformation near the joint interface, whereas the narrowness of the hardened region provided a little bit higher toughness than the intrinsic toughness of the transformed phase due to plastic constraint loss.

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耐候钢线摩擦焊接接头断裂韧性的意义

研究了在不同连接条件下控制耐候钢SPA-H线摩擦焊接头的断裂韧性特征及其意义。制备了两种LFW接头；一个在较高的压缩压力下接头，使LFW过程的最高温度低于a1转变温度（A1-LFW），另一个在较低的压缩压力下接头，高于a3转变温度（A3-LFW）。在接头界面处出现裂纹的两个接头的断裂韧性值均高于同一钢的MAG（金属活性气体）焊缝的热影响区。结果表明，与传统电弧焊相比，LFW连接耐候钢在断裂韧性方面更有效。而A1-LFW的断裂韧性（临界CTOD）低于母材和A3-LFW。从力学和冶金的角度讨论了试验结果的意义。A1-LFW的断裂韧性下降，主要原因是在较高的压压下，在a1温度下加热的金属没有完全被摩擦抛射出来，而是停留在接头界面附近。另一方面，发现A3-LFW的断裂韧性下降是由接合界面附近贝氏体相变引起的硬化引起的，而硬化区域的狭窄提供了略高于塑性约束损失引起的转变相的固有韧性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Welding in the World METALLURGY & METALLURGICAL ENGINEERING-

CiteScore

4.20

自引率

14.30%

发文量

181

审稿时长

6-12 weeks

期刊介绍： The journal Welding in the World publishes authoritative papers on every aspect of materials joining, including welding, brazing, soldering, cutting, thermal spraying and allied joining and fabrication techniques.