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

Abstract

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.

Effective Case Depth and Wear Resistance of Pack Carburized SCM 420 Steel Processed Using Different Concentrations of Natural Shell Waste Powders and Carburizing Duration

“…Interestingly, the maximum effective case depth value presented in Figure 1e (2340 µm) is around 1.6 times greater than the value obtained in a previous study of alloy steel vacuum carburization using Y ion implantation (1.47 mm) at a temperature of 920 °C for 5 h [35]. Moreover, it is approximately 3.1 times higher than that achieved in a previous Figure 1a shows the microhardness profile of quenched specimens using CSP-DCSP ratio of 100%:0% for carburizing times of 3, 6, and 12 h. The surface microhardness measurements of 628.5 ± 5.385 HV, 667.3 ± 5.032 HV, and 759.4 ± 5.169 HV were obtained after 3, 6, and 12 h, respectively.…”

“…Interestingly, the maximum effective case depth value presented in Figure 1e (2340 µm) is around 1.6 times greater than the value obtained in a previous study of alloy steel vacuum carburization using Y ion implantation (1.47 mm) at a temperature of 920 • C for 5 h [35]. Moreover, it is approximately 3.1 times higher than that achieved in a previous study using a combination of arecaceae flower waste and eggshells as a carburizing media in the carburization of mild steel (0.75 mm) at a temperature of 920 • C for 5 h [14].…”

The Effect of Rare Earth Metals Alloying on the Internal Quality of Industrially Produced Heavy Steel Forgings

“…With the growing demands of customers on the mechanical properties of forgings, it is also necessary to develop new types of steel, also using nontraditional elements that were not previously used in common metallurgical practice. These elements include rare earth metals (REMs), most commonly, cerium and lanthanum, which are used to modify nonmetallic inclusions (shape control), deep purifying (deoxidation, desulphurisation, removal or reduction of elements such as P, S, As, Sb, Pb), and alloying [ 23 , 24 , 25 , 26 , 27 , 28 ].…”

Mechanical Properties of Pack Carburized SCM 420 Steel Processed Using Natural Shell Powders and Extended Carburization Time

“…Traditional heat-treatment methods fail to yield a significant improvement in the strength and hardness of low-carbon steel components. Thus, induction hardening, cold-working, immersion hardening, and case carburizing are generally preferred [5][6][7]. Among these methods, case carburizing is particularly effective and is thus one of the most commonly used [8].…”