W chromium-Manganium-Molybdenum-Steel ( JIS SCM4 ) Alloy steels applied to Inlet Valves. H Silicon-Chromium ( Silchrom 1 ) ( JIS SUH 11 ) Apply to Inlet Valve only A Silicon-Chromium-Molybdenum-Steel ( JIS SUH3 ) Apply to lnlet Valves ( may apply to Exhaust Valves of light engines ) B High Chromium-Mangane Austenitic Steel ( JIS SUH35 ) ( Anti Magnetic Steel 21-4N ) Apply to Exhaust Valves of heavy duty engines. 80A Nimonic 80A ( NiCr20TiAl )