ESH: a means of improving transverse mechanical properties in tool and die steels

Abstract

Mechanical property data comparing electroslag remelted (ESR) and conventionally air-melted tool and die steels are presented. The steels studied are identified by AISI designations H 13, H 21, D 2, A 2, and A 6. Tensile test results at room temperature and at 482°C of AISI H 13 show a significant improvement in transverse ductility resulting from electroslag remelting. Introduction of sulphur as afreemachining agent in ESR H 13 slightly decreases longitudinal impact strength while it significantly reduces transverse ductility and impact strength to levels lower than in the standard air-melted analysis. Room-temperature fatigue test results on all the steels show that ESR, compared to air-melting, significantly improves transverse fatigue strength. A slight general improvement observed in longitudinal fatigue was considered not statistically significant. Sulphur added in AISI H 13 for free-machining, results in some degradation of longitudinal fatigue, but it significantly deteriorates transverse fatigue. The improvements in mechanical properties of the ESR steels are explained in terms of their improved homogeneity as evidenced by macroscopic and microscopic structures, and electron microprobe studies.