Research on the optimization of heat processing parameters in die-casting mould manufacturing with high-speed steel W18Cr4V

Panel: 4. Undertaking high impact actions: The role of technology and systems optimisation

Author:
Minghao Ji, Logistics Engineering College, Shanghai Maritime University, China

Abstract

At present, high speed steel W18Cr4V production of die-casting mould, usually in the form of the traditional quenching (1 time, 1280℃) and tempering process (3 times, 570℃). Processing cycle is long, large energy consumption, high cost and low efficiency. Therefore, ensure the product quality as well as to save energy and shorten the processing cycle, reduce cost that become the breakthrough and innovation of this study.

The key to break through the difficulty: by decreasing the quenching temperature and tempering temperature and times, that can save energy, shorten the mould manufacturing cycle and cost. Research materials under different heat treatment processing parameters of microstructure, residual austenite size and material for the surface roughness and surface hardness of rule and relation curve. Determine the 1150 ℃ quenching and twice (300 ℃ ~ 400 ℃, one time + 570 ℃, one time) tempering process, the residual austenite volume is 30% ~ 55% (vol %), high speed steel W18Cr4V is of high hardness, good grinding, low surface roughness.

The results indicate that quenching and tempering temperature has a significant influence on the material of residual austenite, the retained austenite content and directly affect the surface hardness of the mold. The study found that high speed steel W18Cr4V under 450℃ tempering, retained austenite into martensite. When the tempering temperature to 550℃, the residual austenite volume change is not big, when the tempering temperature of 570℃, the increase of martensite phase transformation driving force. Experimental results show: for mould products, the retained austenite content suitable for 30 ~ 55% vol. Heat treatment time reduced by 40%, save electric energy more than 35%.

Using the new process parameter, die-casting products and coining laminations are applied to the parts of micro & special motor with good effect. A new heat treatment process parameters can be used for reference in the mould manufacturing industry.