TiB₂粒子強化型高剛性鋼の機械的性質と熱間加工性

抄録

We have investigated the mechanical properties and hot workabilities of the newly developed TiB₂-reinforced high modulus steel (HMS). considering the potential application to automobile parts.
In two kinds of the HMS prepared via conventional powder metallurgical process, TiB₂ particles of a few microns in diameter were suc-cessfully incorporated into Fe-Cr ferrite (α) matrix using commercial TiB₂ 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 TiB₂ powders, 293 GPa for the one with the same content of in-situ formed TiB₂ particles. The wear resistance was largely improved by incorporating TiB₂ particles, i. e., the wear resistance of the HMS containing more than 20 vol%TiB₂ was far greater than that of α matrix steel, and that of 30 vol%TiB₂ HMS corresponded to that of SUJ2 hard steel.
The improvement of both the tensile and fatigue strength was much remarkable due to the TiB₂ 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.