Development of exhaust valve seat materials for high performance engine

摘要

Recent high performance engines need valve seat inserts which have good wear resistance at high temperature, an improvement of machinability and reasonably low cost. To meet these demands we developed wear resistant exhaust valve seat insert material by using powder metallurgy process. The material system is Fe-Cr-Mo-Co-W-V-C which consists of Cr-W-Co-C and VC hard phases. To improve mechanical properties pre-alloyed powder, Fe-Co-Ni-Mo, was used as a base materials. From the microstructural analysis the hard phases are dispersed uniformly in tempered martensite matrix. Mechanical properties of the new sintered material are compared with conventional valve seat material. Pin-on-disc wear test and rig test were carried out to evaluate the wear resistance of the new sintered material. Finally, the durability of the new sintered material was confirmed by the actual engine test.