Effect of Tempering Temperature on Carbide Precipitation and Mechanical Properties of Marine Atmospheric Corrosion Resistant Steel

The changes of mechanical properties and carbides coarsening behavior of marine atmospheric corrosion resistant steel at different tempering processes were studied. The results of tensile and impact tests showed that the best mechanical properties obtained when the steel was quenched at 940 °C and tempered at 520 °C. The impact toughness at −20 °C increased firstly and then decreased with the tempering temperature increasing. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations showed that with the increase in tempering temperature, cementite particles gradually grow up and the size of cementite particles at grain boundaries was larger than that of cementite particles in grains. The coarsening of cementite may be related to the lack of Cr element during high temperature tempering, resulting in the decrease in impact toughness.