Fracture Performance Evaluation of Laser Beam Welded Joints Based on the Weibull Stress Criterion
Fracture Performance Evaluation of Laser Beam Welded Joints Based on the Weibull Stress Criterion
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基于威布尔应力准则的激光束焊接接头断裂性能评价
DOI：
10.1115/pvp2009-77956
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
F. Minami
中科院分区：
文献类型：
--
作者：
Yasuhito Takashima;M. Ohata;F. Minami
本文研究了一种高强度钢的激光焊接接头的断裂性能。对标准断裂韧性试件(三点弯曲试件，3PB)和拉伸板(边穿厚裂纹板，ETCP)在脆性断裂区进行了低温试验。重点在于标准断裂韧性试件的近裂纹尖端塑性约束与拉伸之间的差异，以及保护焊缝金属中的高应变免受外部载荷影响的非常窄和高度硬化的WM。与3PB试件相比，ETCP具有更高的脆性断裂临界CTOD。考虑了焊缝金属的防护作用，利用威布尔应力准则，从CTOD断裂韧性试验结果中预测了ECTP的断裂性能。结果表明，威布尔应力准则用于韧性结果的断裂传递性分析具有一定的优越性。此外，利用威布尔应力准则分析了激光焊接接头极窄、高硬度焊缝金属对韧性要求的影响。讨论了激光焊接接头独特的强度失配对满足接头性能设计要求所需的3PB激光焊接接头CTOD断裂韧性的影响，同时考虑了ETCP与3PB试件之间的约束损失对裂纹张开行为和韧性聚集的防护作用。3PB中所需的CTOD略低于弧焊接头。因此，应该注意的是，非常窄的WM和高度硬化的WM并不一定会导致焊接接头的断裂性能较差。版权所有©2009 by ASME
This paper examines the fracture performance of laser beam welded joints of a high strength steel with a notch in the weld metal (WM). The standard fracture toughness specimen (3-point bend specimen, 3PB) and tension panel (edge through-thickness crack panel, ETCP) are tested at a low temperature in the brittle fracture range. The focus lies on the difference between near crack-tip plastic constraints for the standard fracture toughness specimen and the tension, and on the very narrow and highly hardened WM shielding high strain in the weld metal from external loading. The ETCP has presented a higher critical CTOD at brittle fracture initiation than the 3PB specimen. The fracture performance of ECTP is predicted from CTOD fracture toughness test results by means of the Weibull stress criterion with the consideration of the shielding effect of the weld metal. The results show an advantage of the Weibull stress criterion for the fracture transferability analysis of toughness results. Furthermore, the influence of very narrow and highly hardened weld metal of laser beam welded joints on the toughness requirement has been analyzed by means of the Weibull stress criterion. The effect of the distinctive strength mismatch of laser beam welded joints on required CTOD fracture toughness of laser beam welded joints in 3PB necessary to meet design requirement of joint performance is discussed taking into account the shielding effect on crack opening behavior and toughness collection due to constraint loss between ETCP and 3PB specimen. The required CTOD in 3PB is a little bit lower than arc welded joints. Therefore, it should be noticed that the very narrow and highly hardened WM does not necessarily lead to poor fracture performance of the welded joints.Copyright © 2009 by ASME