TY - JOUR

T1 - Material Characterization and Modeling for Finite Element Simulation of Press Hardening with AISI 420C

AU - Behrens, Bernd-Arno

AU - Rosenbusch, Daniel

AU - Wester, Hendrik

AU - Stockburger, Eugen

N1 - Funding Information: The authors gratefully acknowledge the support of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) within the Project 385989694 “Determining the forming limits of martensitic chromium steels for hot forming.” Further we thank Outokumpu Nirosta GmbH for providing the martensitic chromium steel AISI 420C for the investigations.

PY - 2022/1

Y1 - 2022/1

N2 - The process of press hardening is gaining importance in view of the increasing demand for weight reduction combined with higher crash safety in cars. An alternative to the established manganese-boron steel 22MnB5 is hot-formed martensitic chromium steels such as AISI 420C. Strengths of 1850 MPa and elongations of 12% are possible, exceeding those of 22MnB5. In industrial manufacturing, FE-simulation is commonly used in order to design car body parts cost-efficiently. Therefore, the characterization and the modeling of AISI 420C regarding flow stress, phase transformations as well as failure behavior are presented in this paper. Temperature-depended flow curves are determined, showing the low flow stress and hardening behavior at temperatures around 1000 °C. Cooling experiments are carried out, and a continuous cooling diagram is generated. Observed phases are martensite and retained austenite for industrial relevant cooling rates above 10 K/s. In addition, tests to investigate temperature-dependent forming limit curves are performed. As expected, the highest forming limit is reached at 1050 °C and decreases with falling temperature. Finally, a simulation model of a press-hardening process chain is set up based on the material behavior characterized earlier and compared to experimental values. The forming force, phase transformation and forming limit could be calculated with good agreement to the experiment.

AB - The process of press hardening is gaining importance in view of the increasing demand for weight reduction combined with higher crash safety in cars. An alternative to the established manganese-boron steel 22MnB5 is hot-formed martensitic chromium steels such as AISI 420C. Strengths of 1850 MPa and elongations of 12% are possible, exceeding those of 22MnB5. In industrial manufacturing, FE-simulation is commonly used in order to design car body parts cost-efficiently. Therefore, the characterization and the modeling of AISI 420C regarding flow stress, phase transformations as well as failure behavior are presented in this paper. Temperature-depended flow curves are determined, showing the low flow stress and hardening behavior at temperatures around 1000 °C. Cooling experiments are carried out, and a continuous cooling diagram is generated. Observed phases are martensite and retained austenite for industrial relevant cooling rates above 10 K/s. In addition, tests to investigate temperature-dependent forming limit curves are performed. As expected, the highest forming limit is reached at 1050 °C and decreases with falling temperature. Finally, a simulation model of a press-hardening process chain is set up based on the material behavior characterized earlier and compared to experimental values. The forming force, phase transformation and forming limit could be calculated with good agreement to the experiment.

KW - continuous cooling diagram

KW - flow curve

KW - forming limit diagram

KW - martensitic chromium steel

KW - press hardening simulation

UR - http://www.scopus.com/inward/record.url?scp=85115072743&partnerID=8YFLogxK

U2 - 10.1007/s11665-021-06216-y

DO - 10.1007/s11665-021-06216-y

M3 - Article

AN - SCOPUS:85115072743

VL - 31

SP - 825

EP - 832

JO - Journal of Materials Engineering and Performance

JF - Journal of Materials Engineering and Performance

SN - 1059-9495

IS - 1

ER -