Numerical modeling from process to residual stress induced in resistance spot welding of DP980 steel

• Published in: International journal of advanced manufacturing technology 2023-04, Vol.125 (7-8), p.3563-3576
• Main Authors: Ren, Sendong, Huang, Wenjia, Ma, Ninshu, Watanabe, Goro, Zhang, Zhengguang, Deng, Wenze
• Format: Article
• Language: English
• Subjects: Automotive bodies; CAE) and Design; Computer-Aided Engineering (CAD; Current pulses; Dual phase steels; Engineering; Heat affected zone; High strength steels; Industrial and Production Engineering; Martensite; Martensitic transformations; Material properties; Mathematical models; Mechanical Engineering; Media Management; Metallurgy; Numerical models; Numerical prediction; Original Article; Phase transitions; Residual stress; Resistance spot welding; Springback; Stress distribution; Stress-strain curves; Temperature distribution; Thermal expansion
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-023-10845-z

DP980 is widely used in automotive bodies. In the present research, a numerical model was developed via the in-house finite element (FE) code JWRIAN-RSW for the multi-physics coupled process of resistance spot welding (RSW) of DP980 sheets and JWRIAN-Hybrid for residual stress. The high-temperature material properties and metallurgical behaviors of DP980 were clarified via experiment to ensure simulation accuracy. The measured thermal expansion curve indicated the austenite and martensite transformation in DP980 and clarified the critical temperatures. Material properties such as thermal expansion and stress-strain curves in heating and cooling processes were measured. The double-pulse electric current mode in RSW was employed and it was found that the molten zone disappeared temporarily between two current pulses. The final dimension of welding nugget was determined by the second pulse. The volume expansion of martensite transformation led to a clear stress drop (about 400MPa) in the welding nugget and heat-affected zone. The final value of X-stress and Y-stress on the center of surface was about 300MPa and 240MPa, respectively. Except for the solid-state phase transformation, the springback process also had a significant influence on residual stress, which cannot be ignored in numerical modeling. The predicted temperature field and residual stress distribution showed good agreement with the molten zone morphology and XRD measurements, which demonstrated the effectiveness of developed FE model.