Experimental study of quenching behavior of quenchant prepared from gutter oil at different oil bath temperatures

The reuse of gutter oil has always been a sensitive social issue. In the heat treatment industry, engineers have also been troubled by the need to move away from dependence on petroleum derivatives for cleaner production. While vegetable oils appear to be a viable alternative, the higher cost and poor thermal and oxidative stability limit their use in the heat treatment industry. The use of gutter oil as a quenchant raw material not only makes the quenchant cost effective but also environmentally friendly. In this study, the cooling performance of fatty acid methyl ester prepared from gutter oil was evaluated and compared with soybean oil and mineral oil. Firstly, fatty acid methyl ester was obtained by esterification and transesterification of gutter oil to reduce the free fatty acid content and make it suitable for quenching and heat treatment. The experiments were carried out using an Inconel 600 standard probe according to ISO 9950. The cooling behavior of the quenching media was tested at oil bath temperatures of 40 °C, 60 °C, and 80 °C. Quenching was carried out using AISI 4340 to obtain Vickers microhardness distributions on cross-sections of heat-treated specimens and residual stresses were determined by x-ray diffraction for all test materials. The fatty acid methyl ester used for analysis produced a hardening depth equivalent to that of commercial mineral oil when quenching the AISI 4340 alloy steel. And the test results achieved cooling properties and quenching intensity comparable to mineral oil. This indicates that fatty acid methyl ester prepared from gutter oil has the potential to replace mineral oil.