engleski

The influence of quenchants composition on the cooling rate

Correct selection of quenching media decreases the risk of tensile stresses, and also cracking and workpiece distortion. High-performance quenching oil must have excellent oxidation and thermal resistance and low sludge formation, must be non-staining and have an elevated flash point and acceptable heat-transfer characteristics. The quenching media contain base oil and different types of additives according to application requirements. As the base oil, it is possible to use mineral oils, synthetic and natural oils separately or in combination. Mineral base oils are widely used because of their advantages in stability in comparison to natural oils, or lower prices in comparison to synthetic oils. There are numerous compounds available for use but, besides of 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 and additives, heat transfer characteristics are also changed. In this study are presented the examination results of physical-chemical properties and also cooling characteristics of new quenching oils with different compositions. Cooling curves for different compositions have been evaluated according to ISO 9950 standard.

metal heat treatment; hardening; quenchants; watermiscible quenchant fluids

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