粘结相对原位合成TiC钢结硬质合金组织结构和性能的影响

Influence of bonding phase on microstructure of steel bonded Himet synthesized in situ

以钛铁粉、铬铁粉、铁粉、胶体石墨和镍粉等为原料，原位合成了nC／Cr18Ni8、TiC／Cr19A13和TiC／Ni40钢结硬质合金，并用扫描电镜、X射线衍射仪和洛氏硬度计、拉力试验机等对不同粘结相所制备的试样进行了组织结构分析和物理力学性能检测。结果表明：钢结硬质合金主要相组成为TiC、Fe—Cr—Ni和Fe—Cr固溶体，TiC晶粒细小，形状较为规则；粘结相对原位反应合成的钢结硬质合金的密度、硬度和所合成的TiC晶粒有较大影响，在相同烧结条件下TiC／Ni40钢结硬质合金的密度和硬度比TiC／Cr18Ni8和TiC／Cr19A13钢结硬质合金的高，但TiC／Ni40钢结硬质合金中所合成的TiC晶粒比TiC／Cr18Ni8和TiC／Cr19A13钢结硬质合金中合成的TiC晶粒偏聚现象严重。TiC／Ni40钢结硬质合金的硬度为60～70．5HRC，TiC／Cr18Ni8和TiC／Cr19A13钢结硬质合金的硬度多在20～50HRC之间。三者的抗弯强度为960～1452MPa。

TiC/Cr18Ni8, TiC/Cr19A13, TiC/Ni40 steel bonded carbides were in situ synthesized by sintering of ferrotianium, ferrochromium, iron, graphite and nickel mixed powders compacts. The microstructure and physical mechanical properties of the steel bonded carbides were analyzed by SEM, XRD, Rockwell hardometer and tensiletesting machine. The results show that the synthesized steel bonded carbides consist of fine, uniform TiC grains and Fe - Cr- Ni or Fe- Cr solid solution. The bonding phase affects density, hardness and TiC grain size of the steel bonded carbides. The density and hardness of TiC/Ni40 steel bonded carbide are higher than that of TiC/Cr18Ni8 and TiC/Cr19Al3 steel bonded carbide but the TiC grains segregation in TiC/Ni40 steel bonded carbide is more serious. The hardness value of TiC/Ni40 steel bonded carbide mostly lies between 60HRC and 70.5HRC, while the hardness value of TiC/Cr18Ni8 and TiC/Cr19A13 steel bonded carbide lies between 20HRC and 50HRC. Bending strength of the three kind of steel bonded carbides are between 960MPa and 1452MPa.