This work aims to study the effect of residual stresses created by quenching
processes on the fatigue behavior of low carbon steel .The quenching was achieved
from a temperature of (900 °C) using water or oil as quenching medium.
Quenching from a temperature of (850 °C) in oil was also used to produce dual
phase steel. The specimens were divided into two groups, the first was subjected to
tempering for (1 hr) at (200 °C) after quenching, and the second was without
tempering. The results showed that the specimen which was quenched in water and
tempered has the highest value of fatigue limit (356 MPa), and the specimen which
was quenched in oil from (850 °C) and tempered showed a lower fatigue limit.