Effect of Microstructure on the Instantaneous Springback and Time-dependent Springback of DP600 Dual Phase Steel

• Published in: IOP conference series. Materials Science and Engineering Vol. 389; no. 1; pp. 12012 - 12022
• Main Authors: Li, Rongting, Mai, Ruimin, Jin, Yongxi, Han, Ruiguo, Wang, Shu
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 19.07.2018
• Subjects: Dual phase steels; Elastic recovery; Ferrite; Martensite; Microstructure; Residual stress; Springback; Tensile tests; Time dependence
• ISSN: 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/389/1/012012

Springback subject to tensile test of dual phase steel DP600 with different phase volume fractions has been observed and investigated in this study. Finite element simulations using representative volume element (RVE) generated from the real microstructure are carried out. It's revealed after tensile test unloading that the instantaneous springback values (lis) of DP600 increases with the martensite volume fraction increasing, and the proportion ψ of the time-dependent springback value (ltds) in total springback (ltds+lis) increases with martensite volume fraction decreasing. In FE simulation of the RVEs, the effective plastic stress (EPS) σe is extracted to represent the residual stress and the higher lis with more martensite volume fraction corresponds to larger variation ΔσeM of martensite phase in RVE during instantaneous springback period, which agrees with the present accepted law that the instantaneous springback is the residual stress-driven elastic recovery. After unloading finishing, the time-dependent springback proportion ψ increases with the proportion ν of EPS of ferrite phase (σeF) in total of RVE (σeRVE) increasing, which verifies the influence of the residual stress in "softer phase" on the time-dependent springback.