Effect of heat treatment process on microstructure and properties of 5Cr5Mo2V steel

doi:10.13251/j.issn.0254-6051.2021.02.010

Abstract

Abstract: Effects of austenitizing temperature and tempering temperature on microstructure and properties of the 5Cr5Mo2V steel for hot forging die were studied by Rockwell hardness tester and field emission scanning electron microscopy. The results show that after different quenching and tempering treatments, the microstructure of all the tested steel specimens is composed of tempered martensite, retained austenite and carbides. When quenched at 920-1030 ℃, the hardness of the 5Cr5Mo2V steel increases with the increase of quenching temperature and reaches the maximum value of 62.53 HRC at 1030 ℃, and then the hardness tends to be stabilized when quenched above 1030 ℃. The grains are finer when quenched at 1030 ℃, but the grains start to coarsen when the quenching temperature exceeds 1030 ℃. As tempered at 480-550 ℃, the hardness gradually increases with the increase of tempering temperature and a secondary hardening peak appears at 550 ℃. The impact absorbed energy of the tested steel is the lowest at 550 ℃, but when the tempering temperature is higher than 550 ℃, the impact properties of the tested steel gradually increase. When the tempering temperature is 600 ℃, the steel maintains a relatively high hardness (49 HRC) and the impact absorbed energy can reach 21 J. It is concluded that the optimum heat treatment process for the 5Cr5Mo2V steel is quenching at 1030 ℃ for 30 min with oil cooling and then tempering twice at 600 ℃ for 2 h with air cooling.

Key words: 5Cr5Mo2V steel, heat treatment, microstructure, mechanical properties

CLC Number:

Yin Junwei, Zhou Jian, Jiang Yehua, Chi Hongxiao, Lin Peng. Effect of heat treatment process on microstructure and properties of 5Cr5Mo2V steel[J]. Heat Treatment of Metals, 2021, 46(2): 55-60.

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