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Article

Low-Temperature Deformation Mechanism and Strain-Hardening Behaviour of Laser Welded Dual-Phase Steels

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Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0183, South Africa
2
Department of Polymer Technology, Tshwane University of Technology, Pretoria 0001, South Africa
3
Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON 2NL 3G1, Canada
*
Author to whom correspondence should be addressed.
Academic Editor: Angelo Fernando Padilha
Metals 2022, 12(8), 1317; https://doi.org/10.3390/met12081317
Received: 18 May 2022 / Revised: 16 July 2022 / Accepted: 25 July 2022 / Published: 5 August 2022
(This article belongs to the Special Issue Welding and Joining of Advanced High-Strength Steels)
This paper analysed the change in microstructure after laser welding DP800 and DP1000, the effect of the laser welds on low temperatures deformation, and strain hardening behaviour when loaded at temperatures between −40 °C and 20 °C using quasi-static strain rates (1.7 × 10−2 s−1). The results showed that the fusion zone (FZ) was fully martensitic due to the rapid cooling during welding. Owing to the severity of the heat-affected zone, the joint efficiencies of DP800-DP800 and DP1000-DP1000 welds were 99.0% and 88.7%, respectively. The UTS, YS, and work hardening exponents of the welded joints increased slightly, while the strain hardening capacity of the base metals was much higher than those of the welded joints with decreasing temperatures. The evaluated work hardening exponents of the welded joints were determined using the Hollomon equation, Afrin equation, and Crussard-Jaoul analysis are in the range of 0.2–0.47, 0.24–0.59, and 0.45–0.71, respectively. The welded joints and the base metals demonstrated only stage III strain hardening, with DP800 joints exhibited excellent uniform and total elongation ranging between 8.0–8.7% and 10.4–14.2%, respectively. Fractures were located in the base metal of welded DP800 and SCHAZ of DP1000 welds, respectfully. The fracture surfaces demonstrated characteristic dimple fractures. The uniqueness of this study is found in its design, as there is currently no known literature on the low-temperature deformation mechanism and strain-hardening behaviour of similar DP800 and DP1000 welds. View Full-Text
Keywords: dual phase (DP) steels; strain hardening; laser welding; low temperatures; dislocation density; plasticity dual phase (DP) steels; strain hardening; laser welding; low temperatures; dislocation density; plasticity
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MDPI and ACS Style

Aderibigbe, I.; Popoola, P.; Sadiku, E.; Biro, E. Low-Temperature Deformation Mechanism and Strain-Hardening Behaviour of Laser Welded Dual-Phase Steels. Metals 2022, 12, 1317. https://doi.org/10.3390/met12081317

AMA Style

Aderibigbe I, Popoola P, Sadiku E, Biro E. Low-Temperature Deformation Mechanism and Strain-Hardening Behaviour of Laser Welded Dual-Phase Steels. Metals. 2022; 12(8):1317. https://doi.org/10.3390/met12081317

Chicago/Turabian Style

Aderibigbe, Isiaka, Patricia Popoola, Emmanuel Sadiku, and Elliot Biro. 2022. "Low-Temperature Deformation Mechanism and Strain-Hardening Behaviour of Laser Welded Dual-Phase Steels" Metals 12, no. 8: 1317. https://doi.org/10.3390/met12081317

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