TiB_2 粒子強化型高剛性鋼の機械的性質と熱間加工性

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We have investigated the mechanical properties and hot workabilities of the newly developed TiB_2-reinforced high modulus steel (HMS), considering the potential application to automobile parts. In two kinds of the HMS prepared via conventional powder metallurgical process, TiB_2 particles of a few microns in diameter were successfully incorporated into Fe-Cr ferrite (α) matrix using commercial TiB_2 powders, and finer particles less than 1 micron were synthesized through the in-situ reaction of ferro-titanium and ferro-boron powders, respectively. Young's modulus evaluated by bending tests reached 289 GPa for the HMS prepared with 30 vol% commercial TiB_2 powders, 293 GPa for the one with the same content of in-situ formed TiB_2 particles. The wear resistance was largely improved by incorporating TiB_2 particles, i.e., the wear resistance of the HMS containing more than 20 vol%TiB_2 was far greater than that of α matrix steel, and that of 30 vol%TiB_2 HMS corresponded to that of SUJ2 hard steel. The improvement of both the tensile and fatigue strength was much remarkable due to the TiB_2 particles, especially when the HMS contained in-situ formed particles. The sintered HMS provided sufficient hot workabilities at temperatures higher than 1273K in upsetting tests, and the trial forged product demonstrated a high feasibility of making automobile parts by employing the conventional equipment.
社団法人日本鉄鋼協会の論文
1998-10-01