X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Abstract

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

Influence of six-step heat treatment on microstructures and mechanical properties of 5160 alloy steel

“…The rise expands, and an abbreviation was encountered in the y-axis intenseness. The height of XRD incurred a peak width increased as the heat treatment step raised liken with the as-sheet condition, with no residual stressed (solid line), as a description of Lozano et al [12], except in Q5 heat treatment condition. The diffraction peak width of Q1, Q4, and Q6 heat treatment conditions were shorter than a half-maximum height of as-sheet condition.…”

Duplex treatment with Hastelloy cage on AISI 5160 steel cutting tools

“…The results refined by the Rietveld method show agreement between the experimental data and calculated according to the charts selected in the analysis. The diffractograms showed the presence of the ferrite phase characteristic of the tempered AISI 5160 steel matrix [32], Fe 3 N, and Fe 4 N iron nitride phases resulting from the CCPN and PN nitriding processes [33,34], as well as the Ni–Cr and Cr–Fe phases formed from the spraying of material from the Hastelloy cage. Fe 3 N and Fe 4 N make up the diffusion layer and compounds produced in plasma nitriding and contribute to the increase in surface hardness and, consequently, wear resistance [35,36].…”

Hardening of Cylindrical Bars with Water Impinging Jet Quenching Technique

“…High compressive residual stresses on the surface can be beneficial and increase corrosion resistance, wear resistance, as well as fatigue life. [3][4][5][6] However, a component with high tensile residual stresses can lead to dimensional instability during service life. [7] Therefore, it is important to analyze the evolution of stresses during cooling and to control the effect of cooling on residual stress distribution.…”