Effect of Heat Treatment on Microstructure and Properties of Powder Metallurgy High-Speed Steel Prepared by Hot Isostatic Pressing

• Published in: Metals (Basel ) 2024-10, Vol.14 (10), p.1160
• Main Authors: Zhang, Deyin, Lu, Tianyu, Hao, Xu, Wu, Yixiao, Zhang, Jiaxun, Sun, Mingming, Jia, Baorui, Wu, Haoyang, Qin, Mingli, Qu, Xuanhui
• Format: Article
• Language: English
• Subjects: Analysis; Bend strength; Carbides; Carbon; Cleavage; Composition effects; Crack initiation; Ductile-brittle transition; Fracture mechanics; Grain boundaries; Grain size; Hardness; Heat treating; Heat treatment; High speed tool steels; Hot isostatic pressing; Iron compounds; Martensite; Martensitic transformations; Mechanical properties; Metal industry; Metal powder products; Metal powders; Microstructure; microstructure and properties; Morphology; Packaging; Phase composition; Plasma sintering; Powder metallurgy; powder metallurgy high-speed steel; Quenching and tempering; Retained austenite; Secondary hardening; Tempering; Tungsten compounds; Wear resistance
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14101160

The microstructure and properties of powder metallurgy high-speed steel prepared by hot isostatic pressing with different heat treatments have been studied. The microstructure, phase composition, effect of quenching and tempering parameters, fracture morphology, and mechanical properties of the sample are discussed in detail. The H-HSS sample presents the characteristics of the powder prior to the particle boundary and consists of carbide and ferrite, in which the carbides are fine and evenly dispersed without segregation. The bending strength and hardness of the H-HSS sample are 3112 MPa and 56.3 HRC, respectively. The Q-HSS sample is mainly composed of martensite, residual austenite, and carbides. With the increase in quenching temperature, the grain size of the matrix gradually grows, and the small carbide particles dissolve into the matrix, causing an increase in carbide size and a decrease in quantity. The bending strength and hardness of the Q-HSS sample quenched at 1210 °C achieve the maximum values of 3114 MPa and 68.8 HRC, respectively. After tempering, the martensite is transformed from a quenched lath shape to a needle shape, the residual austenite content decreases, and secondary carbides precipitate from the matrix, resulting in a secondary hardening. The T-HSS sample that is quenched at 1120 °C followed by tempering at 550 °C for 20 min has the best bending strength of 4355 MPa. However, the T-HSS sample that is quenched at 1240 °C followed by tempering at 550 °C for 120 min has a maximum hardness value of 69.5 HRC. The fracture mode of Q-HSS sample is brittle fracture, and the fracture mechanism is cleavage fracture. After tempering, the fracture mechanism of the T-HSS sample presents a transitional fracture mode between the cleavage fracture and micropore aggregation fracture.