Effect of Laser Power on Microstructure and Tensile Properties of Laser Welded DP590 Steel Joints

Articles in Press

Document Type : Research Paper

Authors

1 Faculty of Chemical and Materials Engineering, Shahrood University of Technology, Shahrood 3619995161, Iran

2 Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran

10.22034/ijissi.2024.2008540.1269

Abstract

This study examined the impact of laser power on the microstructure and tensile properties of DP590 steel joints. Three joints were created using different levels of laser power (400W, 450W, and 500W), while keeping other factors constant. The results revealed that laser welding led to the formation of martensite in the fusion zone, resulting in a significant increase in hardness. However, as the laser power increased, the extent of hardness increment decreased due to the presence of acicular ferrite and Widmanestatten ferrite alongside martensite. The heat-affected zone (HAZ) of all welds exhibited a region where hardness decreased below that of the base metal (BM) because the martensite was partially tempered. This softening effect became more pronounced with higher laser power. The sample welded with a laser power of 400W failed early in the tensile test due to lack of penetration. However, the other two samples failed within the softened zone and displayed yield strength values similar to that of the BM and relatively high values of joint efficiency (92.5% for 450W and 89.5% for 500W), along with a significant reduction in elongation. Both DP590 steel and welded joints demonstrated a two-stage work hardening behavior characterized by a transient stage followed by a stage III hardening.

Keywords

International Journal of Iron & Steel Society of Iran

Articles in Press, Accepted Manuscript
Available Online from 09 March 2024

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