Effect of quenching treatment on Cr-rare earth-boronizing of 45 steel at low-temperature

Effect of quenching treatment on Cr-rare earth-boronizing of 45 steel at low-temperature was studied. Samples of 45 steel were quenched at 860 for 20, 30 and 40 min, respectively, and the quenched samples were then Cr-Rare earth-boronized at different temperatures. The boride layer was characterized by scanning electron microscopy (SEM) and its microhardness was measured by microhardness tester. Experimental results indicate that the thickness of the boride layer significantly increases by the quenching treatment. The boride layer is continuous, dense and uniform, and the saw-toothed morphology is not observed for the quenched 45 steel. Thickness of the boride layer first increases and then decreases with the increasing quenching holding time. Thickness of the boride layer is enhanced by 45.5%, 72.7% and 18.2% when the quenched samples are Cr-rare earth-boronized at 600, and thickness of the boride layer is enhanced by 50%, 62.5% and 18.8% when the quenched samples are Cr-rare earth-boronized at 650. The microhardness of the boride layer for 45 steel without and with quenching treatment both first increases and then decreases with the increasing distance from the surface of the samples. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.