To achieve desired microstructure and mechanical property of a manufacturing product, heat treatment process is
applied as a secondary process after forging. Especially, quenching process is used for improving strength, hardness, and
wear resistance since phase transformation occurs owing to rapid heat transfer from the surface of the specimen. In the
present paper, a study on surface temperature measurement for water quenching of eutectoid steel was investigated. In
order to determine the temperature history in experiments, three different measuring schemes were used by varying
installation techniques of K-type thermocouples. Depending on the measured temperature distribution at the surface of the
specimen, convective heat transfer coefficients were numerically determined as a function of temperature by the inverse
finite element analysis considering the latent heat generation due to phase transformation. Based on the inversely
determined convective heat transfer coefficient, temperature, phase, and hardness distributions in the specimen after water
quenching were numerically predicted. By comparing the experimental and computational hardness distribution at three
different locations in the specimen, the best temperature measuring scheme was determined. This work clearly
demonstrates the effect of temperature measurement on the final mechanical property in terms of hardness distribution.