An investigation on the usefulness and performance of new hot working tool steel by nitrocarburizing process

Abstract

Salt bath nitrocarburizing effects on usefulness and performance of a new grade hot working tool steel close to as either chromium AISI H11/H13 are investigated. A continuous two-step treatment is performed, consisting in hardening sequence (i.e. austenization-1050°/15 min, quenching-oil medium and twice tempering-500 and 600 ° C/2 h) followed by a salt bath nitrocarburizing process at 580 ° C for various processing times. Prior treatments yield a reliable tempered martensitic microstructure without bainite, in which are embedded complex carbides without any retained austenite content, achieving satisfactory hardness value of 53HRC. Subsequent thermochemical treatments allow relative relevant properties such as surface hardness and wear behavior through formed layers that are characterized by their basic properties (i.e. thickness, formed phases, hardness distributions and redistribution of alloying elements in the nitrocarburized layers). Based on in-house experimental data, it can be outlined that salt bath nitrocarburizing process is suitable for improving surfaces characteristics of the as-studied treated material, in a shorter time with minimal cost compared to other similar processes. Metallurgical evaluations are carried out using metallographic techniques, optical and scanning electron microscopy equipped with an energy-dispersive X-Ray spectrometer as well as X-ray diffraction techniques. Mechanical properties are achieved mainly by standard hardness and wear tests. © 2012 The Surface Science Society of Japan.