Abstract
Fe-Mn-Ni steel is known for its small dimensional change during aging. For this reason it can possibly be used as a material for precision machine parts which are aged and nitrided after machining and susequently used without finish griding. The conventional Fe-Mn-Ni steel is however, too brittle to be used for machine parts. The purpose of the present study is to improve the toughness of steel and hardness of nitriding layer by adding vanadium.
Effect of vanadium on the strength and hardness of these steels were examined. Alloys of various compositions were melted in an arc furnace in argon atmosphere, forged and machined to test piece shape. The specimens were water quenched from 1000°C and aged at various conditions. Hardness and tensile strength were measured before and after aging.
The results are summarized as follows:
1) In the series of Fe-3%Mn-x%Ni-y%V, the highest tensile strength and hardness of 165 kgf/mm and 580 HV, respectively, were obtained at 15%/Ni and 10%V.
2) The concentration ranges of nickel and manganese being able to give age-hardening were not appreciably different between Fe-Mn-Ni steels and Fe-V-Mn-Ni ores.
