Metallographic diagram of W6Mo5Cr4V2 (tempered at 680°C after quenching)

Introduction

Heat treatment of HCS80W6Mo5Cr4V2 is the process of heating and cooling the material in order to change its properties. The heat treatment process is divided into hardening, tempering and annealing. This material has been subject to hardening and tempering processes at temperatures of 680°C.

Hardening

The hardening of HCS80W6Mo5Cr4V2 is a process of increasing its hardness and wear resistance by increasing its steel components such as carbon and boron. A high temperature is used to induce the hardening response, which turns the steel into martensite crystals and increases its hardneability. The hardness and wear resistance of the material increase after the hardening process, but the ductility and toughness decrease.

Tempering

The tempering process subjects the material to heating and then quenching. After the quenching process, the material needs to be tempered at a range of temperatures between 260°C and 680°C for a certain period of time. During the tempering process, the already hardened material is made softer by forming tiny particles of iron-carbon alloys. The stress of the material can be relieved by this tempering process. By controlling the temperature and length of time during the tempering process, the hardness and wear resistance are reduced while the ductility and toughness are increased.

Annealing

HCS80W6Mo5Cr4V2 is also subjected to an annealing process after hardening and tempering. The annealing process helps to relieve the internal stress of the material and uniform the internal structure. In Annealing, the material is heated to above the recrystallization temperature and then cooled slowly at a suitable rate. The cooled result consists of austenitic grains with uniform sizes and shapes. By decreasing the grain size, the ductility and toughness increase while the hardnability and wear resistance decrease.

Conclusion

Heat treatment of HCS80W6Mo5Cr4V2 was conducted by subjecting the material to hardening, tempering and annealing processes at temperatures of 680°C. The hardening process increases the materials hardness and wear resistance by creating martensite crystals. The tempering process creates tiny particles of iron-carbon alloys, which help to relieve the stress and make the material softer. The annealing process relieves the internal stress and provides uniformity to the materials structure, increasing its ductility and toughness.

The heat treatment of W6Mo5Cr4V2 steel consists of annealing, quenching and tempering.

First, the steel was heated to around 1020℃ for annealing, followed by a quench in oil. It is then heated to around 680℃ for tempering and allowed to cool naturally in air.

The metallographic structure observed after the heat treatment is mainly composed of tempered martensite, with small amounts of retained austenite, as well as carbide particles distributed near grain boundaries. The large carbide particles are precipitated from the austenite matrix, while the small carbide particles are formed due to the break-up of the primary carbides during tempering. The grain boundary carbides form a network in the entire structure.

The microstructure shows that the tempered martensite has high hardness, the network carbides improve the hardness and corrosion resistance of the steel, and the retained austenite improves the plasticity of the steel.

The heat treatment of W6Mo5Cr4V2 steel has been successfully completed, and its structure and properties are expected to meet the requirements of the application.