Influence of Plastic Deformation on Martensitic Transformation During Hot Stamping of Complex Structure Auto Parts
- PDF / 2,501,330 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 77 Downloads / 268 Views
JMEPEG DOI: 10.1007/s11665-017-2579-9
Influence of Plastic Deformation on Martensitic Transformation During Hot Stamping of Complex Structure Auto Parts Yuhan Shen, Yanli Song, Lin Hua, and Jue Lu (Submitted September 6, 2016; in revised form December 23, 2016) The ultra-high strength steel auto parts manufactured by hot stamping are widely applied for weight reduction and safety improvement. During the hot stamping process, hot forming and quenching are performed in one step wherein plastic deformation and phase transformation simultaneously take place and affect each other. Thereinto, the influence of deformation on martensitic transformation is of great importance. In the present paper, the influence of plastic deformation on martensitic transformation during hot stamping of complex structure auto parts was investigated. For this purpose, a B-pillar reinforced panel in B1500HS steel was manufactured by hot stamping, and the process was simulated by finite element software based on a thermo-mechanical-metallurgical coupled model. Considering various deformation degrees, the microstructures and mechanical properties at four typical locations of the hot stamped B-pillar reinforced panel were detected. The results show that the martensitic content and the microhardness increase with the increase in the deformation amount. There are two reasons causing this phenomenon: (1) the increase in mechanical driving force and (2) the increased probability of the martensitic nucleation at crystal defects. The x-ray diffraction analysis indicates the carbon enrichment in retained austenite which results from the carbon diffusion during the low-carbon martensite formation. Furthermore, the carbon content decreases with the increase in the deformation amount, because the deformation of austenite suppresses the carbon diffusion. Keywords
hot stamping, martensitic transformation, microstructures, microhardness, plastic deformation
1. Introduction The development tendency of automobiles in future is energy-saving, consumption reduction and safety improvement. The application of UHSS in manufacturing automotive parts can not only achieve energy efficiency and emission reduction by reducing body weight, but also improve crashworthiness and security. At present hot stamping of UHSS sheets has been successfully used to produce automotive safety-related parts such as side impact beams, bumper beams, A-pillars and Bpillars (Ref 1). During hot stamping, the blank is initially heated up to an austenitizing temperature, and then nonisothermally formed and simultaneously quenched in the watercooled press tools for martensitic transformation (Ref 2). The studies on hot stamping technology of UHSS mainly focus on materials (Ref 3-5), numerical simulation (Ref 6-9) and process modification (Ref 10-13). One of the most important
Yuhan Shen and Jue Lu, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China; Yanli Song and Lin Hua, Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan U
Data Loading...
