engleski

Influence of additive chemistry on the physical, chemical and cooling properties of quenching oils

Quenching is the most common method of hardening metals, which involves continuous cooling from a given austenitization temperature to achieve full transformation into martensite. Thus, optimal mechanical properties are obtained. The quenching media contain base oil and different types of additives depending on application requirements. The cooling rate mainly depends on thermal characteristics of metals, section thickness of workpieces and the quenching medium heat-removal properties. As the base oil, it is possible to use mineral oils, synthetic oils and natural oils, separately or in combination. Mineral base oils are widely used because of their advantages regarding stability in comparison to natural oils, or lower prices in comparison to synthetic oils. There are numerous compounds available for use besides their functional properties, the environmental and safety requirements have a strong influence on the components selection. Based on that the barium additives must be replaced with less harmful compounds. Petroleum derivatives should be changed with renewable base stocks that are biodegradable, as general trend in lubricant development. By changing the composition of quenching oils, base oils, or additives, heat transfer characteristics are also changed. In this study, quenching oils with different types of additives are tested and the results regarding their physical and chemical properties, as well as cooling characteristics are presented. Cooling curves of the tested oils have been evaluated according to ISO 9950 standard.

heat treatment; hardening; quenchants; quenching oils; additives; cooling properties

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