Effect of Vegetable Oil Oxidation on Heat Transfer and Residual Stress during Quenching

Vegetable oils, especially soybean oil, exhibit substantially poorer thermal-oxidative stability than many other commonly available vegetable oils and commercially available petroleum oil quenchant formulations. Therefore, to achieve any commercially interesting performance vegetable oils must be stabilized by the addition of antioxidant inhibitors. This work describes the ability of two commercially available antioxidants, Irganox L 57 and Irganox L 109 to stabilize soybean oil against thermal-oxidative degradation. This paper will review thermal-oxidative stability and quenching performance variation with respect to time of different experimental soybean oil oil formulations containing antioxidants using an accelerated ageing test. The ASTM D6200 standard (12.5 mm dia x 60 mm) cylindrical INCONEL 600 probe with a Type K thermocouple inserted to the geometric center was used to assess relative quenching performance. The resulting impact of the different antioxidants on the heat transfer coefficient and residual stress was determined by simulating the time-temperature cooling performance after different ageing times. These cooling time-temperature curves were used to numerically simulate the resulting heat transfer coefficients using HTMod and residual stress using Abaqus. The methodology and results of this work will be discussed and a standardization of this approach as part of an overall assessment of quenchant performance will be proposed.