Abstract
DP980 is a promising light-weightening material in car body. To avoid high investment of strong cooling system, a new DP980 steel with low cooling rate requirement was developed. The mechanical properties and microstructure were analyzed under different manufacturing process. It could be concluded that the chemical composition design should be reasonable and of low cost to achieve both high strength and also austenite to martensite transformation at low cooling rate. Strength increased with coiling temperature decreasing during hot rolling, and higher annealing temperature and lower over aging temperature were favourable to higher strength. The austenite-martensite transforming could be completed at even lower rapid cooling rate of 20°C/s. Through optimized manufacturing process parameters, the new DP steel product with good mechanical properties could be obtained successfully, which provided a new option for normal production line to produce ultra high strength steel.
Highlights
According to the requirement of light weight and safety in automotive industry, advanced high strength steel had been increasingly used for car body design due to the properties of high strength and good formability[1,2]
The coil with coiling temperature of 690°C was chosen to be cold rolled with a thickness reduction rate of 50% to avoid massive rolling force or potential damage to the rolling line
The typical microstructure mainly composed of Ferrite and Pearlite after hot rolling with coiling temperature at 690°C was shown in Fig.1, in which there was apparent banded structure after hot rolling
Summary
According to the requirement of light weight and safety in automotive industry, advanced high strength steel had been increasingly used for car body design due to the properties of high strength and good formability[1,2]. The stability of its mechanical properties is very difficult to be controlled because of the high strength and high sensitivity to manufacturing process[3,4,5]. Special lines equipped with strong cooling system were built to manufacture DP980 and some even higher strength level grades. Considering the huge investment of new special lines, it’s a big challenge to manufacture DP980 in the normal production line with cooling rate no higher than 30°C/s. A new DP980 with special chemical composition and process design suitable for normal production line was developed, and it showed good mechanical properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
