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

• Published in: Journal of iron and steel research, international international, 2013-11, Vol.20 (11), p.51-56
• Main Authors: YING, Liang, LU, Jin-dong, CHANG, Ying, TANG, Xing-hui, HU, Ping, ZHAO, Kun-min
• Format: Article
• Language: English
• Subjects: Applied and Technical Physics; Automotive bodies; Automotive components; Automotive engineering; Boron steels; Engineering; Fracture toughness; High strength steels; hot stamping; Iron and steel industry; Kahn tear; Machines; Manufacturing; Materials Engineering; Materials Science; Metallic Materials; multi-objective optimization; orthogonal experimental design; Physical Chemistry; Processes; ratio of strength to toughness (RST); Strength; 优化; 变形温度; 奥氏体化温度; 测试; 热冲压; 评估; 韧性; 高强度钢
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1016/S1006-706X(13)60196-X

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.