Search Results

With society demanding automobiles that provide higher fuel efficiency, safety of occupants in collisions and that at the end of their service life can be recycled with low environmental impact, the steel industry is tackling the needs of the automobile industry by developing ever-higher performance steel materials and simulation technologies that can demonstrate the performance of steel materials at the development stage without the need for costly prototype testing. In this paper, weight reduction of automobile body in Japan will be discussed. The main items will be as follows: (1) Development of Automobile Steel Sheets, (2) Materials for Automobile Bodies, (3) Materials and Technologies (Tailored Blanks, Hydroforming and Locally Quenching) for Reducing the Weight of Panels and Reinforcing members, (4) Future Prospects.

Nippon Steel Corp. has developed a new hot-rolled steel sheet which is characterized by 1.0 to 1.6% copper addition to extra low carbon steel. This steel is worked while it is in a low strength state and thereafter the worked part is heat treated to increase the strength of it. The copper added steel sheet has a capability to increase tensile strength up to 600Mpa level from 400Mpa level by being heated to the temperature range of 750 to 950K for less than 600s. When copper remains in the solid solution state, the steel sheet exhibits as much formability as the conventional steel of the same strength level. The ductility ratio is higher than that of the conventional steel of the same strength level. This offers a greater freedom in the design of spot-weld structural joints. The fatigue properties of the base metal is as good as those of the conventional steel of the same strength level, and becomes much longer when heat treated.