Papers by Keyword: Cryogenic Treatment

Abstract: This study investigates the effect of deep cryogenic treatment on the tribological and electrochemical performance of X46Cr13 martensitic stainless steel, with a particular emphasis on the synergistic interaction between wear and corrosion and its microstructural origins. The material was subjected to conventional quenching and tempering and compared with heat treatment routes incorporating cryogenic processing. Hardness measurements, wear tests, and electrochemical characterization by Tafel polarization were combined with quantitative microstructural analysis. Cryogenic treatment induces a pronounced microstructural refinement through the transformation of retained austenite into martensite and the enhanced precipitation of fine chromium-rich carbides, predominantly M₂₃C₆ and M₇C₃. This process results in an increased carbide number density and a reduced average carbide area, leading to a more homogeneous carbide distribution within the martensitic matrix. The refined carbide population contributes to increased hardness and significantly improved wear resistance by effectively hindering plastic deformation and abrasive damage. Simultaneously, the stabilization of the martensitic matrix and the modified carbide–matrix interface promote the formation of a more uniform and stable passive film, improving corrosion resistance. The combined improvement in wear and corrosion behavior reduces the degradation rate under coupled mechanical and electrochemical loading, demonstrating a clear tribocorrosion synergy controlled by carbide characteristics. These findings highlight cryogenic treatment as an effective strategy for tailoring the microstructure of martensitic stainless steels to enhance their performance in aggressive and mechanically demanding environments.

Abstract: The tool steel materials are expensive this is the reason why the lifetime increase is a goal of the production technology. The tool life is determined by the various complex mechanical, thermal, chemical, and tribological properties. Tools properties depend on the chemical composition and their microstructure. The microstructure depends on the chemical composition, the production process, the heat treatment and surface treatment technologies. The goal of this research was to increase the service lifetime of the casting mould tool. It was prepared and investigated four kinds of test specimens. The first kind of specimen was made from conventional steel (W302). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. The quenching was followed with three times tempering processes (570°C, 580°C, 560°C) in 2 bar N₂ gas. The second kind of test specimen was made from Unimax electro-slag remelted steel (ESR). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. After quenching the process continues with three times tempering (610°C, 620°C, 600°C). The third kind of test specimen Unimax a electro-slag remelted steel (ESR), to which firstly an austenitization (1020°C) was made, quenched in nitrogen gas with 9bar and then cooled in liquid nitrogen till minus 150°C. After cryogenic treatment, the process continues with three times tempering (610°C, 620°C, 600°C). The fourth kind of specimen was made by the same process as the second and after it a PVD coating process was made to coat the surface by a TiBN layer. It investigated the hardness and wear resistance of all heat-treated and surface-coated steel specimens. The comparative wear resistance testing was investigated by a ball cratering tester. The rank of the tested specimen was the next: the lowest wear resistance measured in the case of the heat-treated W302, the middle in the case of cryogenic heat-treated Unimax and the highest wear resistance earned in the case of the PVD-coated Unimax. The results of the investigations proved that the Unimax tool steel service lifetime can increase better than the conventional tool steel by heat treatment and surface treatment. The practice certified that the surface-treated Unimax tools' service lifetime is much longer than the conventional ones.

Abstract: To meet the engineering applications, mechanical and physical properties of materials especially steels and their alloys are improved through thermal treatments. This research aimed to augment the impact toughness of EN-31 steel by picking the combinations of different levels of Charpy impact test control variables and thermal treatments built in three-level (L9) Orthogonal Arrays (OAs). For this reason, the experimental runs were conducted to examine the influence of varying V-notch angles (30°, 45° and 60°), heights of the hammer (1370 mm, 1570 mm, and 1755 mm), temperatures (-196°C, -50°C, and 28°C), and heat treatments (hardening followed by cryogenic treatment and low-temperature tempering - HCTLTT, hardening followed by cryogenic treatment and medium-temperature tempering - HCTMTT, and hardening followed by cryogenic treatment and high-temperature tempering - HCTHTT) on the impact toughness of EN-31 Steel specimens. Several patterns of thermal treatment sequences were executed with an aim to modify the material properties. Cryogenic treatment (CT) was conducted through a cryocan at 77K. The hardness of specimens were measured by employing a Brinell hardness tester. The results reported that height of the hammer and thermal treatments enhanced the toughness and hardness of the specimens most significantly.

Abstract: In recent years, the emphasis has shifted toward more precious minerals and composite structures to produce thinner, cheaper, more suitable materials for specific applications. The primary purpose of this study would be to determine how any walnut fillers perform in a vulgare biocomposite. The nanocomposite was created employing the most economical manual lay-up method. To accomplish the legitimate goal, the following descriptions have been levied: At different levels, (i) volume ratios of luffa thread, (ii) weight ratios of walnut powder, as well as (iii) freezing processing durations, all are accessible. The multilayer aggregates are in a freezing room set to 77 degrees Celsius. Tension and elastic modulus were tested mechanically. The morphological properties of powdered particles were detected using a scanning electron microscope. The mechanical integrity of 10% walnut shell powder, 40% luffa fabric, as well as 15-minute freezing treatments, surpasses 5 and 15% walnut shell granules.

Abstract: The effect of cryogenic treatment (CT) on the microstructure and mechanical properties of the as-extruded Mg–3.5Zn–0.6Gd alloy was investigated. The results showed that W-phase newly appeared in cryogenic treatment samples but without notable second phase amount increasing. There was also no remarkable grain refinement. But the amount of twins reduced greatly, the strong basal texture {0001} rotated and increased. The intensity of plane (0002) diffraction peak was weakened along with planes ( 1 0-1 0 ) ( 1 0-1 1 ) being enhanced in X-ray diffraction pattern. The change in mechanical properties was not obvious. The mechanism of the microstructure evolution is discussed as well.

Abstract: Feasibility of utilizing cryogenic technology to improve the shearability of Al2024-T351 alloy is experimentally investigated by carrying out a single grit scratch-grinding test. A single grit brazed diamond grinding tool is developed for the study. Al2024-T351 work specimens are treated with liquid nitrogen for 6 hours before the scratch test. Although there was no significant change in the tensile strength of the material, the surface experiences change in the microhardness. It helps in arresting the side flow and ploughing of the material during high speed scratch grinding. The scratched grooves on cryo-treated samples, compare to those of untreated specimens, shows signs of cleaner shear-cuts, superior finish and produces less grinding force during grinding

Abstract: An investigation has been made to improve the properties of the friction stir welded (FSW) 6061-T6 aluminum alloys. A cryogenic thermal treatment is developed for the joints during welding and its effects on mechanical and metallurgical properties, and precipitates are evaluated at various welding parameters. The friction stir welded joints with cryogenic treatment attained the better properties than the without cryogenic treatment. The improvement of properties was attributed to the refinement of grain size and to the introduction of a reduction in the softening region of the welded joints. Under cryogenic cooling rates, joints were experienced to the low temperature environments and faster cooling rates, which are contributed to enhance the hardness of the stir zone and heat affected zone regions and the formation of fine grain structure in the stir zone. The results indicated that the formation of finer grains of less than 5 µm in the stir zone, which is smaller than the joints of without cryogenic treatment. Subsequently, mechanical properties drastically improved and the joints achieved a maximum joint efficiency of 74% of the base material

Abstract: The growing pressure on tool performance and durability increases demands on the materials used and on the choice of optimal heat treatment. The properties of tool steels produced by conventional and powder metallurgy (1.2379, Vanadis 23) were compared after different heat treatment modes. Cryogenic treatment was performed in several batches for 4 hours at-90°C or-196°C. Cryogenic treatment was inserted between quenching and tempering. Mechanical properties were evaluated by hardness tests and three-point bending strength and wear resistance by Pin-on-disk tests. Metallographic analysis was performed using light and electron microscopy. On the basis of the results obtained both materials were subject to selected heat treatment and experimental forming tools produced which were used in operation. During operation the wear of the tools (shape change and volume loss) was assessed. Results of the laboratory tests were then compared with operation tests.

Abstract: Maraging steels belong to the class of steels that are found to have a unique combination of ultra-high strength and good fracture toughness, due to which they find uses in critical applications such as aircraft forgings, pressure vessels, missile casings, hydraulic hoses etc. Several studies on the effect of cryogenic treatment on various grades of Tool steels & Maraging steels have shown significant improvements in mechanical properties and dimensional stability.DMLS (Direct Metal Laser Sintering), an additive manufacturing technology, is increasingly becoming popular to build intricate high quality functional parts & rapid prototypes. DMLS technology uses a high intensity laser to build components layer by layer, directly from CAD data without the need for tooling. It is possible to build internal features and passages that are not possible in conventional manufacturing routes. Maraging Steel is used extensively to build functional parts by DMLS process especially for Tool and Die applications. However, very few findings have been reported on the effect of cryogenic treatment on the mechanical properties of Maraging steel built through this route. In this study, effect of cryogenic treatment on Maraging Steel grade 300 built by DMLS process is discussed. Test specimens were built in horizontal and vertical directions to see the effect of build direction on the properties. Half the specimens were given standard DMLS precipitation hardening heat treatment and the rest were given cryogenic treatment in addition to routine thermal treatment. Mechanical properties such as - tensile, impact properties , hardness, & density between the two sets of treatments are reported and discussed. Metallurgical structures are compared and findings are also reported.

Abstract: In this study, the effect of Shallow Cryogenic Treatment (SCT) on the wear behavior of copper beryllium alloy was investigated. The material is subjected to shallow cryogenic treatment to – 80 °C and wear study was conducted on a pin on disc apparatus. The Shallow Cryogenic treated and untreated copper beryllium alloy pins were used against hardened AISI 4140 steel disc. The micro-structural examination was carried out using optical microscope. The hardness was measured using Rockwell hardness tester. The wear track was studied using optical microscope. Microstructure study indicated that the grains of shallow cryogenic treated samples are finer than that of untreated sample. Hardness of the cryogenic treated sample is higher than that of the untreated sample. The wear resistance of cryogenic treated copper beryllium alloy has improved compared with untreated sample.