Evaluation of hardness by gas nitriding process in steel SAE 1045, SEA 4140 and SAE 4340

Abstract

In this paper, the effect of nitriding time was investigated by gas at 560 ° C on the surface hardening, hardening depth and core hardness of steel SAE 4340, 4140 and 1045, this research specimens 2.54 cm were used. in diameter and 5 cm. length in total number of 54. The SAE 1045 steel specimens were austenizadas temperature of 860 ° C for 1 hour, tempered at a temperature of 500 ° C for 2 hours prior to the nitriding process. From the results it was determined that increasing nitriding time in the range of 5 to 15 hours, increasing the thickness of nitride layer and thus the surface hardness of all samples tested, the effect being greater for the time 15 hours. For SAE 1045 steel surface hardness HV 454.2 and 36.6 microns was reached. thick nitride layer. For the SAE 4140 532 HV and 28.1 microns was obtained. thick nitride layer. Finally SAE 4340 steel for maximum values were obtained at this temperature of 580.9 HV surface hardness and 27.5 microns. thick nitride layer, as previously stated was conrmed by an analysis and decision microstructural hardness across the cross section of the samples evaluated.