| dc.description.abstract | Heat treatment is defined as a combination of heating and cooling operations are
controlled in the solid state to obtain certain properties in the steel / metals or
alloys. One of these is a method of heat treatment with quenching and tempering
process. This process is carried out at a temperature of austenite (1000°C) for 60
minutes and then cooled with ice water and oil, then in-tempering at 300°C,
350°C, 400°C, 450°C, 500°C, 550°C, 600°C with a holding time 1 hour long. The
test results showed that the optimum value is 506.6 BHN hardness after
quenching in oil at a temperature of 1000°C and the tempering process average
hardness gradually decreases with increasing tempering temperature. While the
value of hardness after quenching with ice water at a temperature of 1000°C is
499.2 BHN and the process of tempering hardness obtained average gradually
decreased with increasing tempering temperature, but at temperatures of 450°C
tempering hardness obtained up 426.6 BHN. This is due to slow diffusion rate
only a small fraction of carbon that was released, the result is still hard but most of
the structure began to lose brittleness. Tensile test results showed that the
optimum value obtained yield stress (yield strength) 1155.671 MPa and limit
strength (ultimate strength) 1335.313 MPa. Fatigue test results obtained maximum
fatigue strength at 313833600 N cycles for 307680 Second with 7 kg load the raw
material. Decreasing grain size of the raw material 3.83 μm to 2.86 μm and 2.47
μm after quenching with oil and ice water, and after tempering average - average
grain size increase gradually with increasing tempering temperature. From the
research it can be concluded that the tempering process can reduce the value of
hardness and tensile strength. While the results showed that the diameter of the
micro-structure of granular materials exhibit decreasing grain diameter during the
process of heat treatment with quenching oil. Where the greater diameter of the
granules decreased mechanical properties of materials | en_US |
