j m a t e r r e s t e c h n o l . 2 0 2 0; 9(3) :2717–2726 www.jmrt.com.br Available online at www.sciencedirect.com Original Article Practical examination of the welding residual stress in view of low-carbon steel welds Hsuan-Han Lai, Weite Wu ∗ National Chung Hsing University, Department of Materials Science and Engineering, 145 Xingda Road, South Dist., Taichung City 402, Taiwan, R.O.C a r t i c l e i n f o Article history: Received 11 November 2019 Accepted 2 January 2020 Available online 14 January 2020 Keywords: Welding residual stress Heat-Affected zone Local-High stress position. a b s t r a c t The practical measurement of a welded workpiece is now feasible due to the improve- ment in the measuring instruments. There is a discrepancy between the theoretical and the measured welding stress profiles. In this study, stress analysis is performed on three low-carbon steel welds to investigate the reason behind the M-shaped stress profile. The welding residual stresses obtained from two different instruments show the same trend. A local high stress position is located in the tempered zone of the welding heat-affected zone. The solidification shrinkage leads to the compression of the un-melted metal near the fusion boundary and causes the discontinuous stress profile, resulting in the local high stress position in the heat-affected zone. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction Welding is one of the most important manufacturing pro- cesses, and the welding residual stress is an unavoidable result in the workpiece, which plays a key role in the failure of the weld part. Studies of welding residual stress in different metals has been conducted for over decays. Generally, the welding residual stress can be classified into its longitudinal and transverse components; the longitudinal one is usually higher than the transverse one [1]. The classical longitudinal welding residual stress profile is illustrated in Fig. 1. The curve resembles a Gaussian distribution; the tensile stress is high at the weld center and decreases progressively away from the ∗ Corresponding author. E-mail: [email protected] (W. Wu). center; outside the weld boundary, the tensile stress decreases rapidly and turns into a compressive stress. The boundary b indicates the area of tensile stress. This stress profile was cal- culated based on the material expansion and temperature in the past. For a long time, the welding stress was considered to be distributed in this manner. Nowadays, following the development of several non- destructive stress analyzer techniques and measurement equipment such as Barkhausen noise, X-ray diffraction, neu- tron diffraction, and ultrasonic method [2], researchers can analyze the welding stress directly from the workpiece with- out machining or damaging the specimen and obtain the actual stress profiles. X-ray diffraction and neutron diffrac- tion are two common methods of experimental measurement. They have been applied in many studies on the welding stresses of low-carbon steels [3–6]. Fig. 2 presents the longi- tudinal welding stress profiles of different low-carbon steels. All these stress profiles exhibit a common phenomenon: there https://doi.org/10.1016/j.jmrt.2020.01.004 2238-7854/© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).
Practical examination of the welding residual stress in view of low-carbon steel welds
May 22, 2023
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