This project investigated the effects of austenitizing temperatures and time on the
hardness of 4140 steel. The most common test for studying these effects is the Jominy End
Quench test. In this test a 140mm long and 25.4 mm in diameter sample is heated into the
austenite range for selected temperatures and times and water spray quenched at one end,
producing a varying cooling rate across the sample. Currently the Jominy End Quench test
focuses more on the hardenability of the steel. An improved model for correlating the Jominy
End Quench curves and the resulting grain size curves proposed introduce a better defined
heating and cooling cycle. The improved model obtained will optimistically result in less
time spent in research and development. Through the process of preparing, etching, and
observing the samples under an optical microscope, photomicrographs are obtained. The
experimental results show a difference between the prior austenitic grain size among the
different heating times and temperatures used. The conclusion compares the effects of
temperature and time in the grain growth of the prior austenitic grain size.