Impact wear characteristics of engine valve and valve seat insert materials at high temperature: (Impact wear tests of martensitic heat-resistant steel SUH3 against Fe-base sintered alloy using plane specimens)

In order to simulate the wear of the valves and valve seat inserts of automotive engines, impact wear tests were conducted using rings made of a JIS SUH 3 steel valve material and disks made of a sintered alloy valve seat insert material. Test conditions were as follows : impact energy of 0.588 J ; normal air atmosphere ; ambient temperatures of room temperature, 200°C and 400°C ; and sliding speeds of 0 to 0.8 m/sec. Under these conditions, very low wear was observed for both materials subjected to impact without sliding. For impact with sliding speeds over 0.4 m/sec, a bright worn surface was observed and the wear rate was severe at room temperature and 200°C. However, at 400°C, oxidation occurred and no acceleration of the wear rate was observed at any sliding speed. These results can be explained in terms of the occurrence of oxidation and the mechanical properties of the test materials.