Study the effect of the chemical heat treatments on mechanical properties steel (40 Cr)


This work deals with improvement of the mechanical properties of low alloy steel (DIN 40Cr) using surface thermochemical heat treatments ,Carbonizing, Nitriding, andCarbonitriding. Carborizing processes were performed at 900 – 950 Cº for 3hrs. Nitridingprocesses were performed at 570Cº for 1.5 hrs. Carbonitriding processes were performed at840 Cº for 3hrs. Some specimens were oil quenched at 860 Cº followed by tempering at 500Cº. The microstructure, tensile, hardness, and impact tests were measured. The resultsshowed that Carbonizing, Nitriding, and Carbonitriding processes caused improvement ofmechanical properties of low alloy steel. However specimens that were subject to quenchingand tempering had better mechanical properties than specimen that were subject tocarbonizing, Nitriding, and carbonitriding.