Research On Microstructure And Properties Of Iron-based High Density Sintering Materials

Due to the technical and economic advantages, ferrous powder metallurgical materials instead of a part of wrought steels and casting irons have been widely applicated in the fields of automotive industry, mechanics , chemistry and electron .However, common powder metallurgical materials have certain amount of pores and sintering structure asymmetry, which directly affect the properties of powder metallurgical materials and limit their application scope. It is necessary to enhance the density of powder metallurgical products and structure uniformity by means of reducing and eliminating pore in order to improve the mechanical and tribological properties, making use of them under heavier load conditions.In this study, the object is that we can make ferrous powder sintering materials with high density and high property. Through composition design and sintering technics study, high density and high hardness ferrous P/M materials were obtained by sintering hot-forging and tempered hot-forging.The chromium was added to FeNiMo prealloyed powders by using Cr-Fe powders ways, carbon was added to powders by using graphite powders. Powder mixtures were commingled and uniaxially pressed at 600MPa, and then hot-forging process and hot-forging temper were carried out. Influence of chromium addition on the density, microstructure and properties of the FeNiMo system prealloyed powders had been investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) and X-ray analysis. The results show that the metallographic structure of sintered materials become uniformity through sintering hot-forging and hot-forging temper after adding the chromium to FeNiMo prealloyed powders by using Cr-Fe powders ways. Microstructure is lathy martensite. After sintering hot-forging, martensite dislocation increase ,...