Optimization of Quenching and Tempering Parameters for the Precipitation of M7C3 and MC Secondary Carbides and the Removal of the Austenite Retained in Vanadis 10 Tool Steel

Alejandro Gonzalez-Pociño,Juan Asensio-Lozano,Florentino Alvarez-Antolin

doi:10.3390/met9060627

Abstract

Vanadis 10 steel is a powder metallurgy processed tool steel. The aim of the present study is to analyze the microstructural variation in this steel that takes place when the process variables related to the heat treatments of quenching and tempering are modified. Specifically, the destabilization of austenite, the precipitation of secondary carbides and the amount of retained austenite were analyzed. The research methodology employed was a Design of Experiments (DoE). The percentage and types of precipitated crystalline phases were determined by XRD, while the microstructure was revealed by means of SEM-energy-dispersive X-ray spectroscopy (EDX). The destabilization of austenite was favored by tempering at 600 °C for at least 4 h. These same conditions stimulated the removal of the retained austenite and the precipitation of M7C3 secondary carbides. For the precipitation of MC secondary carbides, it was necessary to maintain the steel at a temperature of 1100 °C for at least 8 h. The highest hardness values were obtained when the tempering temperature was lower (500 °C). Tempering in air or oil did not have a significant influence on the hardness of the steel after double or triple tempering at 500 or 600 °C. These results allow the manufacturers of industrial tools and components that use this type of steel in the annealed state as a material to define the most suitable quenching and tempering heat treatment to optimize the in-service behavior of these steels.

Highlights

Tool steels for cold work are used in the manufacture of tooling used to form materials
Tempering in air or oil did not have a significant influence on the hardness of the steel after double or triple tempering at 500 or 600 ◦ C
These results allow the manufacturers of industrial tools and components that use this type of steel in the annealed state as a material to define the most suitable quenching and tempering heat treatment to optimize the in-service behavior of these steels

Summary

Introduction

Tool steels for cold work are used in the manufacture of tooling used to form materials These steels require a specific set of properties such as high hardness and wear resistance, so their carbon contents are high. The end of solidification of these steels gives rise to a ledeburitic eutectic When these steels are manufactured via conventional casting, they present a high degree of dendritic segregation, a heterogeneous microstructure and a continuous network of large carbides. These characteristics result in low toughness and high anisotropy in the steels’ mechanical properties. These steels need to Metals 2019, 9, 627; doi:10.3390/met9060627 www.mdpi.com/journal/metals

Objectives

Methods

Results

Conclusion