Development and Implementation of a New Import-Substituting Tempering Oil for Steel Heat Treatment

The paper discusses the development and application of domestic hardening oil during the heat treatment of elastic terminals for rail fasteners. The paper presents the results of laboratory comparative tests of the developed oil and its imported counterpart. The study of the effect of the cooling properties of hardening oils on the hardness and structure was conducted during the heat treatment of samples made of 38Si7 steel, which is used for the production of elastic terminals. The cooling properties of hardening oils were evaluated using the UZS-2 device for determining the cooling characteristics of technological and hardening media. It has been shown that the developed prototype of the quenching oil provides a maximum cooling rate of 94.2 °C/s, a maximum cooling rate temperature of 615.8 °C, a cooling time of 7.03 s to 600 °C, a cooling time of 10.3 s to 400 °C, a cooling time of 39.3 s to 200 °C, and a cooling rate of 7.84 °C/s at 300 °C. At the same time, the hardness of the 38Si7 steel blanks after hardening is 53.2—54.6 HRC. As a result of the industrial tests, it was found that the developed hardening oil meets the requirements of the technological process of heat treatment of elastic terminals for rail fasteners made of 38SI7 steel and allows to reduce the cost of purchasing an imported analogue.

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