Optimization Evaluation Test of Strength and Toughness Parameters for Hot-Stamped High Strength Steels  

作　　者：YING Liang LU Jin-dong CHANG Ying TANG Xing-hui HU Ping ZHAO Kun-min 

机构地区：[1]School of Automotive Engineering,State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian University of Technology

出　　处：《Journal of Iron and Steel Research International》2013年第11期51-56,共6页

基　　金：Sponsored by National Natural Science Foundation of China(50901011,10932003);National Basic Research Project of China(2010CB832700);"04"Great Project of Ministry of Industrialization and Information of China(2011ZX04001-21);Fundamental Research Funds for Central Universities of China(DUT12LK03)

摘　　要：Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.

关 键 词：hot stamping Kahn tear ratio of strength to toughness （RST） orthogonal experimental design multi- objective optimization 

分 类 号：TG142.4[一般工业技术—材料科学与工程]