Influence of the Production Method and the Structure of Chromium-Nickel Corrosion Resistant Steels on the Kinetics of the Formation of the Outer Cage of Spherical Joints

Introduction . Investigating the issues of wear resistance of joints, the authors of this paper have previously studied how the features of chromium-nickel corrosion resistant steels affect the shaping of the outer cage of spherical hinges. They sintered compacts made of 12Kh18N10T, VP 304.200.30 and 304L-AW-100 at 1,200°C in vacuum for 3 hours. However, in practice, it is necessary to test different steels in different conditions. This paper describes 10Kh18N9 rolled stainless steel. Powder VP 304.200.30 was sintered at 1,150°C for 2 hours. The aim of the research is to demonstrate how the production method and the metal structure affect the kinetics of the outer cage formation and, consequently, the strength of the product. Materials and Methods . Samples made of 10Kh18N9 and VP 304.200.30 were radially compressed according to GOST 26529–85 and stretched on an UMM-5 testing machine. Hardness was measured using a Rockwell TP 5006 instrument, and microhardness was measured according to Vickers on an HVS-1000 instrument. X-ray phase analysis was performed on an XRD-6100 diffractometer. Microscopes Tescan VEGA II LMU (for electron probe studies), Quanta 200 and Altami MET -1 M (for studying microstructure and metallography) were used. Cold stamping of the outer cage with a spherical hinge flange was modeled in QForm . Results . The strength and yield strength of VP 304.200.30 were comparable to those of some chromium-nickel austenitic steels, but were inferior in terms of ductility. A comparison between 10Kh18N9 and VP 304.200.30 revealed differences in their deformation mechanisms. The critical limitation for powder steel was not the oxide phase, but the localization of oxides at particle boundaries, which provoked brittle fracture under tension. Due to the chemical heterogeneity in the particles and residual porosity, powder steel had a 6-fold lower elongation compared to rolled steel. However, under compression conditions, sintered material could reach a hardness of 195 HV, making it suitable for use in the outer cage of spherical hinges. Discussion . Analysis of the deformation characteristics of sintered and rolled steels confirmed the suitability of the proposed methodology for assessing the deformation state of samples during cold stamping of the outer cage of spherical hinges. Conclusion . The findings from this study allow us to predict the locations of macrodefects and optimize the manufacturing process for spherical hinges.