Effect of Deep Cryogenic Treatment on Corrosion Behavior of AISI H13 Die Steel

AISI H13 die steel specimens were subjected to heating at 1020 °C followed by oil quenching and double tempering at 520 °C. Subsequently, these specimens were subjected to deep cryogenic treatment at −185 °C in liquid nitrogen environment for 16 h and then subjected to soft tempering at 100 °C once the specimens attained room temperature. Thereafter, the specimens were subjected to scanning electron microscopy (SEM) analysis and electron backscatter diffraction (EBSD) analysis. The electrochemical corrosion activity was investigated in 3.5% NaCl at 23 ± 0.5 °C by evaluating the evolution of open circuit potential over time and potentiodynamic curves, and electrochemical impedance spectroscopy study was also carried out. The heat-treated specimens exhibited better resistance to corrosion through more electropositive values of open circuit potential. This could be attributed to lower grain boundary area in heat-treated specimens as compared to 16 h cryogenically treated specimen as higher grain boundary areas behave as an anode in an electrochemical cell, thereby enhancing the rate of corrosion. According to electrochemical tests, the cryogenically treated surface is more resistant to corrosion, followed by heated alloy. However, both surface modification treatments improved the corrosion behavior of the untreated alloy.

THE EFFECT OF DEEP CRYOGENIC ON TENSILE STRENGTH AND IMPACT TOUGHNESS IN QUENCH TEMPERED STEEL PLATE AS A CANDIDATE FOR BALLISTIC RESISTANCE MATERIAL

Ballistic resistant materials are materials containing right combination of hardness, strength, and toughness. The quench process produces high hardness and tensile strength but decreases toughness. The hardening process has been performed using an induction machine and a tempering process on a medium carbon steel plate. This work aimed to determine and analyze the effect of deep cryogenic treatment (DCT) on steel plates that have been quenched tempered. This research utilized steel plates of 130 x 130 x 8 mm size which has been quenched and then immersed in liquid nitrogen at a temperature of -196°C for 1, 5, 10, and 20 days. The micro Vickers hardness test specimen, tensile test and charpy impact test were made to determine the effect of immersion time. The test results and analysis showed that DCT had the ability to change microstructure, improve the hardness, tensile strength, and impact toughness. Furthermore, the maximum hardness was obtained during the immersion treatment of 20 days, which was 449.45 VHN and 1107.53 MPa, respectively. However, the highest toughness was obtained during the immersion of 10 days, which was 1,001 J/mm2. In order to get the optimal combination of ballistic characters, further ballistic testing is needed, both in simulation using the finite element method and ballistic experiment test.

Effect of Deep Cryogenic Treatment on Wear and Galling Properties of High-Speed Steels

New approaches to improving wear resistance with an affordable and noncomplex technology, such as deep cryogenic treatment, (DCT0), are receiving attention. The aim of this study is to investigate the effect of DCT on the friction and wear performance of high-speed steels. AISI M2, AISI M3:2 and AISI M35 were heat-treated under different conditions, and then investigated under dry sliding conditions. Tribological testing involved different contact conditions, prevailing wear mechanisms and loading conditions. The DCT effect on sliding wear resistance depends on HSS steel grade, as well as contact conditions and wear mode, whereas it improves the dynamic impact of the wear and galling resistance.

Investigation of Micromechanical Properties and Tribological Behavior of WE43 Magnesium Alloy after Deep Cryogenic Treatment Combined with Precipitation Hardening

This study investigated the micromechanical and tribological properties of WE43 alloy (Mg-Y-Nd-Zr) alloy subjected to cryogenic treatment and precipitation hardening. Microindentation tests were carried out in the range of load from 100 to 1000 mN. The introduction of deep cryogenic treatment (DCT) was shown to increase hardness and Young’s modulus, and reduce the total indentation work. As the load set during the tests increased, a gradual decrease in the measured values was observed, indicating a significant relationship between the indent size and the value of the measured parameters. Cryogenic treatment used in conjunction with precipitation hardening (after solutioning and after aging) reduces the tribological wear of the alloy. Tests have shown an almost twofold reduction in the area of the wear trace and in the volumetric wear of the alloy, as well as a more than twofold reduction in linear wear, with relatively small fluctuations in the coefficient of friction. Abrasion was the main mechanism of wear. Areas where microcutting, adhesion and plastic deformation occurred were also observed. The results indicate the significant effectiveness of the applied heat treatment in improving the service life of the WE43 alloy containing rare earth metals.