Effects of in-situ alloying and microalloying on the microstructure and recrystallization behavior of spray-deposited SAE 1008 steel sheet

Nitrogen from the atomization gas was successfully introduced into the LDC (Liquid Dynamic Compaction) spray deposited 1008 steels during spraying. Alternatively, aluminum was introduced into the melt before the spray deposition to produce microalloyed 1008-LDC/m.a. deposit, giving larger amounts of A1N precipitates along prior austenite grain boundaries. The stability of the grains was higher when the steel was nitrogen-alloyed. Non-nitrogen-alloyed 1008 steel shows coarse, equiaxed grains, whereas the nitrogen-alloyed 1008 steels have elongated pancake-shaped grains after 700 °C annealing. Significant abnormal grain growth had taken place for non-nitrogen-alloyed 1008 steel, but no significant grain coarsening was seen for nitrogen-alloyed 1008 steels after 800 °C annealing, demonstrating the effective grain boundary pinning ability of A1N. The hardness of the nitrogen-alloyed 1008 steels after cold-rolling and after annealing was higher.