Cooling Capacity of Petroleum Oil Quenchants as a Function of Bath Temperature

Other than water, the most common quenchants used for hardening steel are based on petroleum oil base stock. Cooling capacity is dependent on a number of variables including oil viscosity and additives, agitation, and bath temperature and is characterized by critical heat flux densities and heat transfer coefficients. It is shown here that there is an optimal quench oil temperature at which the critical heat flux density reaches its maximum value. Computational results are compared with results from earlier reports. These data show that the optimal quenching temperature for petroleum oils may be used to reduce the distortion of hardened steel parts. Different methods of determining critical heat flux densities and heat transfer coefficients were considered, and the most accurate results were obtained when proprietary software was used to solve an inverse problem that simultaneously yields the current and critical heat flux densities and heat transfer coefficients versus the surface temperature. The computational approach used to determine the cooling capacity of a quench oil as a function of bath temperature is discussed here.