Effect of Vanadium Carbide on Sintering Properties and Microstructure Evolution of Powder High Speed Steel

直接添加碳化钒对粉末高速钢烧结性能及组织演变的影响研究

State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

Received: 21 October 2019

Abstract

The effects of different proportions of vanadium carbide(VC) particles instead of V powder on the density, microstructure and properties of powder metallurgy high-speed steel(PM HSS) were studied in this paper. The difference of strengthening phase composition and the mechanism of material properties under different sintering time were analyzed. The testing results show that the bonding state between elemental V and matrix is improved and the sintering densification of HSS is effectively promoted with the increasing proportion of VC particles. When holding time is 90 minutes, a large number of lath-like M₂C carbides appear in the sample structure with VC particles. When holding time is extended to 120 minutes, the M₂C carbides in the high-speed steel structure decompose completely, and a large number of fine M₆C and MC carbides are produced. The mechanical properties of HSS can be improved by increasing the proportion of VC particles. The maximum strength of HSS is up to 2597 MPa when the proportion of VC particles is 150% and the sintering time is 120 minutes. The hardness of HSS is mainly related to density and properties of strengthening phase. The hardness of HSS prepared in this experiment is about 51~52 HRC.

摘要

研究不同比例碳化钒（VC）颗粒取代单质V粉加入时对粉末高速钢致密度、显微组织和性能的影响，分析不同烧结保温时间条件下强化相组成的差异以及对材料性能的作用机理。结果表明：添加VC颗粒的比例逐渐增高时，改善了元素V与基体之间的结合状态，有效促进高速钢的烧结致密化。保温时间为90 min时，添加VC颗粒的试样组织内部出现了大量的板条状M₂C型碳化物，而当保温时间延长至120 min时，高速钢组织内M₂C碳化物分解较为完全，同时产生了大量细小的M₆C和MC型碳化物。增大VC颗粒加入的比例有助于高速钢力学性能的提高，在加入比例为150%、保温时间为120 min时取得强度最大值2 597 MPa。高速钢的硬度主要与密度和强化相的性质有关，该研究制备得到的高速钢硬度基本维持在51~52 HRC左右。