Abstract:

Microstructure and properties of G105 steel, which was quenched at 890, 910 and 930 ℃ respectively for 150 min then tempered at 630 ℃ for 180 min, were studied by using hardness tester, tensile tester, impact tester and optical microscope. The results show that, with the increase of quenching temperature, the hardness of the steel increases. After the tempering treatment, there is no significant difference in the tempering hardness (33.2 HRC and 32.7 HRC) when the quenching temperature is 890 ℃ and 910 ℃ respectively, while the tempering hardness of tested steel quenched at 930 ℃ increases by about 1.5 HRC. The strength of the steel increases with the increase of quenching temperature, but the impact toughness increases firstly and then decreases, which is due to the precipitate of granular carbides, resulting in the impact toughness decrease. So the G105 steel quenched at 910 ℃ has better comprehensive mechanical properties.

Key words: G105 steel, quenching temperature, mechanical properties, microstructure