Influence of heat treatment on the microstructural evolution and mechanical properties of W6Mo5Cr4V2Co5Nb (825 K) high speed steel

Yu Pan, Ziqiang Pi, Bowen Liu, Wei Xu, Ce Zhang, Xuanhui Qu, Xin Lu

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Spray forming (SF) is a newly developed rapid solidification and near-net-shape technique for preparing high-speed steels (HSSs) in recent years. However, a large amount of overspray powders will be produced in the SF process, which brings about a serious material pollution and waste. To solve this problem, a new method of the two-step sintering and subsequent heat treatment was used to fabricate high-performance W6Mo5Cr4V2Co5Nb (825 K) HSSs using the overspray powders. The microstructural evolution and mechanical properties by the heat treatment were systematically studied. Results show that near full dense 825 K alloys with many uniformly distributed carbides are obtained by the two-step sintering. After quenching and triple tempering, the alloys consist of the martensite, M6C and MC carbides, and a small amount of retained austenite. The carbides have smaller particle size of less than 3 μm and greater sphericity than the as-sintered alloy. The diffusion of alloying elements determines the dissolution and re-precipitation of carbides. The fabricated 825 K alloy quenched at 1180 °C and triple tempered at 540 °C possesses the best mechanical properties, with a hardness of 64.2 HRC and bending strength of 2858 MPa, which is much higher than that of casting alloy with similar composition. This work provides a feasible way to recycle the overspray powders.

Original languageEnglish
Article number139480
JournalMaterials Science and Engineering A
Volume787
DOIs
Publication statusPublished - 2020 Jun 10
Externally publishedYes

Keywords

  • Heat treatment
  • High-speed steels
  • Microstructure
  • Overspray powders

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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