Influence of carbonitriding conditions on phase composition and residual stresses for 20MnCr5 low alloy steel

This paper reports an investigation of the influence carbonitriding conditions for 20MnCr5 low alloy steel. Three gaseous were investigated based on different carbon and nitrogen potentials to attain varying levels between 0.62 0.93% mass, whereas 0.19 0.26% mass at surface. Analysis retained austenite residual stress distributions was conducted using X-ray diffraction technique. The effective case depth varied 900 1200 µm. microstructures characterized by proportions martensite, while core contained essentially bainitic microstructures. maximum amount which occurred a 50 µm from subsurface ranged 30 70% significantly influenced level surface micro-hardness hardness remaining relatively constant 450 HV1. High values stresses in martensite phase observed. signs, magnitudes, location compressive highly fraction austenite. Retained 30%, 50% lead peak residue -280, -227, -202 MPa depths 555, 704, 890 μm, respectively.
 Keywords: Carbonitriding, austenite, stress, XRD.