Impact Wear Characteristics of Valve and Valve Seat Insert Materials for Engines at High Temperature (Plane Impact of Martensitic Heat Resistant Steel SUH3 against Fe-Base Sintered Alloy)

In order to simulate the wear of the valve and valve seat insert of actual engines, an impact wear test is conducted using a ring of JIS SUH3 steel valve material, and a disk of sintered alloy valve seat insert material. Test conditions are as follows : impact energy is 0.588 J ; atmosphere is normal air ; temperatures are room temperature, 200°C and 400°C ; sliding speed is from 0 to 0.8 m/s. Under these conditions, for impact only without sliding, very low wear is observed. Under impact with sliding conditions, at room temperature and 200°C, a bright worn surface is observed. With a sliding speed over 0.4 m/s the wear rate is severe. However, at 400°C, oxidation occurs and no acceleration of wear rate is observed at all sliding speeds. At any sliding speed and test temperature, the sintered alloy disk wear is more severe than that of the SUH3 steel ring. These results can be explained taking into consideration the oxidation and mechanical properties of these materials.