Jiangchun Wang

Bio: Jiangchun Wang is an academic researcher from Hefei University of Technology. The author has contributed to research in topics: Corrosion & Pitting corrosion. The author has co-authored 1 publications.

Effect of Mo Content on the Thermal Conductivity and Corrosion Resistance of Die Steel

Abstract: In this work, effect of Mo content on the microstructure, thermal conductivity, and corrosion resistance of the die steels was investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, laser thermal conductivity meter, electrochemical experiments, and pitting tests. The microstructure of the die steels is mainly composed of lath-shaped tempered martensite. At all the tested temperatures, the thermal conductivity of the die steels is decreased with the increase in Mo content from 1.2 to 5.0 wt.%. However, electrochemical experiments indicate that increase in Mo content in the die steels can reduce the corrosion current density and increase the charge transfer resistance in 0.5 mol·L−1 HCl solution. Furthermore, it was found that Mo in the die steels is beneficial to decrease weight loss and pitting corrosion rate, which improves the pitting corrosion resistance of the die steels.

Effect of Silicon on Thermal Stability of 4Cr3Mo2V Hot-Work Die Steel

Abstract: Thermal stability is one of the most basic high-temperature performance indices of hot die steel. It directly determines whether the mold can maintain good surface hardness, dimensional stability and material failure resistance for a long time under high temperature and high pressure, and then affect the service life of the material. In this paper, the effect of Si on the thermal stability of 4Cr3Mo2V hot-work die steel was studied. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were used to characterize the microstructure evolution. Thermodynamic analyses were carried out in combination with Thermo-Calc software to explore the mechanism affecting thermal stability. The results show that the thermal stability of the 1.0% Si-containing steel (referred to as 1.0 Si steel) sample exceeded that of the 0.3% Si-containing steel (referred to as 0.3 Si steel) sample. After tempering at 650 °C for 64 h, the matrices of the two tested steel samples mainly comprised large-sized M6C carbides. Additionally, the carbides in the 0.3 Si steel sample showed obvious aggregation growth, and a small number of round-like M23C6 carbides appeared, which decreased the hardness in the later stage of tempering. The average particle size of M6C in the 1.0 Si steel sample is 100–200 nm, the average particle size of M6C in the 0.3 Si steel sample is 100–400 nm, and 1.0 Si steel disperses and precipitates finer MC-type and M2C-type secondary carbides, so it has better thermal stability.

Impact of Particle Size Distribution in the Preform on Thermal Conductivity, Vickers Hardness and Tensile Strength of Copper-Infiltrated AISI H11 Tool Steel

Abstract: Spontaneous infiltration of a porous preform by a metallic melt provides the potential of generating metal matrix composites (MMCs) with tailored combinations of material properties at low cost. The bulk of tool inserts for injection molding must sustain high mechanical and thermal loads and simultaneously exhibit high thermal conductivity for efficient temperature control of the mold insert. To fulfill these contradictory requirements, AISI H11 tool steel preforms were infiltrated by liquid copper. The impact of the fine powder fraction (0 wt.% to 15 wt.%) blended to a coarse H11 powder in the preform on thermal conductivity, Vickers hardness and tensile strength was elucidated. The thermal conductivity of the composites could be enhanced by a factor of 1.84 (15 wt.% fine powder) and 2.67 (0 wt.% fine powder) with respect to the sintered H11 tool steel. By adding 15 wt.% fine powder to the coarse host powder, the tensile strength and Vickers hardness of the copper-infiltrated steel were 1066.3 ± 108.7 MPa and 366 ± 24 HV1, respectively, whereas the H11 tool steel yielded 1368.5 ± 89.3 MPa and 403 ± 17 HV1, respectively. Based on the results obtained, an appropriate particle size distribution (PSD) may be selected for preform preparation according with the requirements of a future mold insert.