Vacuum carburization of 12Cr2Ni4A low carbon alloy steel with lanthanum and cerium ion implantation

Conventional carburizing has disadvantages, such as high energy consumption, large deformation of parts, and an imperfect structure of the carburizing layer. Hence, a rare earth ion pre-implantation method was used to catalyze and strengthen the carburized layer of 20Cr2Ni4A alloy steel. In this study, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive microanalysis (EDS), transmission electron microscopy (TEM), and Rockwell/Vickers hardness testing were used to analyze the microstructure, phase composition, retained austenite content, hardness, carburized layer thickness, and carbon diffusion. The results showed that lanthanum and yttrium ions implanted into the 20Cr2Ni4A steel formed solid solutions of rare earth ions and a large number of dislocations, which improved the diffusion coefficient of carbon elements on the carburized surface and the uniformity of the carbon distribution. Simultaneously, rare earth ion implantation improved the structure and hardness of the vacuum carburized layer. Compared to the lanthanum ion implantation, yttrium ion implantation caused the structure of the carburized layer to be finer, and the carbon diffusion coefficient increased by 1.17 times; in addition, the surface hardness of the carburized layer was 61.8 HRC.

Section: Introductionmentioning

confidence: 99%

Study of the Catalytic Strengthening of a Vacuum Carburized Layer on Alloy Steel by Rare Earth Pre-Implantation

Cai-yun

Xing³

et al. 2019

“…Before grinding, the workpiece material had a very high carbon content (≥0.35 wt.%) owing to the existence of the carburized layer, which resulted in the high hardness of surface layer, and quenching treatment led to compressive stress on the surface. The microhardness gradually decreased with the depth below surface, and finally reached the value of base material (450 HV to 460 HV) [ 25 ]. The difference in the hardness gradient after grinding could be easily observed through the variation in the microhardness curves.…”

Section: Resultsmentioning

confidence: 99%

Grinding Temperature and Surface Integrity of Quenched Automotive Transmission Gear during the Form Grinding Process

Jiang

Liu²,

Yan

et al. 2022

Grinding burn is an undesired defect in gear machining, and a white layer is an indication of severe burn that is detrimental to gear surface performance. In this work, the influence of grinding parameters on the thickness of the white layer during form grinding of quenched transmission gear was investigated, and the microstructure evolution and mechanism of severe burn formation were analyzed. The grinding temperature increased with the grinding depth and grinding speed, with the highest level of ~290 °C. The thickness of the white layer exceeded 100 μm when the grinding depth was 0.03 mm, and the top layer was a plastic deformation layer followed by a fine-grained martensite layer. Coarse-grained acicular martensite was found at the interface between the white layer and softened dark layer. The mechanical effect and thermal softening mainly contributed to the formation of white layer stratification. The ground surface topography showed several scratches and typical grooves; when grinding depth increased to 0.03 mm, the grinding surface roughness Sa was relatively high and reached up to ~0.60 μm, mainly owing to severe plastic deformation under grinding wheel extrusion and the thermal effect.

“…Ion implantation not only could change the chemical composition and microstructure of the materials surface but also could help improve its tribological properties [ 13 , 14 ], corrosion resistance [ 15 , 16 ], and oxidation resistance [ 17 ]. It is reported that titanium (Ti) ion implantation could improve the wear resistance of several different steels through the formation of an amorphous surface layer [ 8 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Titanium-Implanted Dose on the Tribological Properties of 316L Stainless Steel

Wang

Zhu

et al. 2021

The effects of titanium (Ti) ion-implanted doses on the chemical composition, surface roughness, mechanical properties, as well as tribological properties of 316L austenitic stainless steel are investigated in this paper. The Ti ion implantations were carried out at an energy of 40 kV and at 2 mA for different doses of 3.0 × 1016, 1.0 × 1017, 1.0 × 1018, and 1.7 × 1018 ions/cm2. The results showed that a new phase (Cr2Ti) was detected, and the concentrations of Ti and C increased obviously when the dose exceeded 1.0 × 1017 ions/cm2. The surface roughness can be significantly reduced after Ti ion implantation. The nano-hardness increased from 3.44 to 5.21 GPa at a Ti ion-implanted dose increase up to 1.0 × 1018 ions/cm2. The friction coefficient decreased from 0.78 for un-implanted samples to 0.68 for a sample at the dose of 1.7 × 1018 ions/cm2. The wear rate was slightly improved when the sample implanted Ti ion at a dose of 1.0 × 1018 ions/cm2. Adhesive wear and oxidation wear are the main wear mechanisms, and a slightly abrasive wear is observed during sliding. Oxidation wear was improved significantly as the implantation dose increased.