Effects Of Deep Cryogenic Treatment Research Articles

The effects of deep cryogenic treatment on PVD-TiN coated AISI M2 high speed steel

In this study, the effect of deep cryogenic treatment (DCT) on PVD-TiN coated AISI M2 high speed steel was investigated. DCT has been cited to improve hardness, toughness, and wear resistance in martensitic steels. Despite these promising results, there is limited published work on the effects of DCT on hard coated steels, such as industrial cutting tools. Hence, the aim of this study is dedicated to providing experimental data on the effects of PVD-TiN coated AISI M2 high speed steel subjected to DCT. A combination of microstructural and mechanical techniques, such as optical and scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nanoindentation hardness and scratch testing have been applied to determine the changes observed. The result of the nanoindentation hardness showed that an improved result in terms of hardness and elastic modulus were obtained for DCT coated test samples with increases of 5.2 % and 14.8 % compared to conventionally prepared coated non-DCT samples. Upon further examination, it was interesting to note that there was a significant change of 14.8 % in the elastic modulus of the DCT coated samples as compared with the untreated samples. The reason for the difference could be attributed to the contribution of the substrate or changes in the substrate due to DCT.For adhesion testing, optical and SEM examination revealed that DCT coated samples exhibited promising results as the transverse cracks observed for the DCT coated samples appeared denser, more extensive, and could suggest good adhesion as when the mechanical work is applied, energy is better absorbed rather than coating flaking. A comparison of the critical failure points (Lc) revealed that DCT coated samples had Lc values 3.62 % high than the conventionally prepared samples, which could be attributed to the elastic modulus mismatch between the coating and substrate.

Regulating strength and ductility of additively manufactured Inconel 718 alloy via adding nano-TiC and deep cryogenic treatment

The morphology and size of Laves phases play a crucial role in influencing mechanical properties of the additively manufactured Inconel 718 alloy. The current study explores the effects of deep cryogenic treatment (DCT) and the addition of nano-TiC on the microstructure and tensile properties of Inconel 718 alloy manufactured through direct energy deposition (DED). It is found that the addition of 1.5 wt% nano-TiC is conducive to transforming long-striped Laves phases into granular shapes, and the reduced porosity and finer grains are obtained. Compared to the Inconel 718 alloy, the 1.5 wt% nano-TiC/Inconel 718 composite exhibits an enhancement in ultimate tensile strength by approximately 46.81 MPa. Through the thermodynamic simulations, the microstructural evolution induced by the addition of nano-TiC is discussed, which includes the suppression of Laves phases and precipitation of MC particles. Moreover, finer Laves phases and uniform distribution of dislocations are observed in the Inconel 718 alloy after DCT. Dynamic recrystallization occurs within the Inconel 718 alloy during the DCT process, and the grain refinement mechanism is facilitated by a high dislocation density. Consequently, the elongation increases by about 24.8 %, while the strength remains virtually unchanged. Furthermore, the synergistic effect of the addition of nano-TiC and the DCT on Inconel 718 is investigated, and the elongation of nano-TiC/Inconel 718 composite is increased by about 32.7 % with more uniform fracture dimples. This study provides guidance for DED-fabricated Ni-based alloys with excellent strength and ductility.

Effects of Deep Cryogenic Treatment on Friction and Wear of EN24 Steel Against Alumina Under Dry and Lubrication Conditions

As-received (AsRec) EN24 steel was treated with conventional heat treatment (ConHeatTreat) without tempering followed by deep cryogenic treatment (DeepCryoTreat) as a supplemental treatment to study its tribological behaviour against alumina without or with mineral oil (MO) under different normal loads of 1 N and 5 N. The ConHeatTreat of the AsRec-EN24 obtained an 218.5% improvement in its hardness as the supplemental DeepCryoTreat of the ConHeatTreat-EN24 resulted in a 11.7% further improvement in its hardness. As a result, the ConHeatTreat-EN24 had the 67.5% and 56.3% lower wear volumes for 1 N and 5 N under dry condition and the 53.6% lower wear volume for 5 N under MO lubrication condition compared to those of the AsRec-EN24, respectively. The DeepCryoTreat-EN24 had the 11.5% and 39.7% lower wear volumes for 1 N and 5 N under dry condition and the unmeasurable wear volume for 5 N under MO lubrication condition compared to those of the ConHeatTreat-EN24, respectively. It could be concluded that the supplemental DeepCryoTreat further improved the hardness and thereby the abrasive wear resistance of the ConHeatTreat-EN24 under both dry and lubrication conditions.

On the Effects of Deep Cryogenic Treatment on Wear Resistance, Hardness and Microstructure of the AISI D2 and D3 Tool Steel

The present study investigates the effect of cryogenic treatment on AISI D2 and D3 tool steels. This analysis is carried out for several heat treatment cycles that follow various tempering and cryoprocessing sequences that are not analysed erstwhile. Moreover, the effect of these heat treatment cycles on wear characteristics, hardness, and microstructural features of AISI D2 and D3 tool steel is also analysed. It is demonstrated that the cryogenic treatment significantly improves the wear resistance, hardness, and retained austenitic transformation of both types of material specimens under consideration. Furthermore, it is established that single tempering after cryogenic treatment is more effective than double tempering processes carried out in different sequences. It is also revealed that the double tempering sequencing involving cryoprocessing stalls the transformation of retained austenite, leading to higher wear and low hardness in the material

Effects of deep cryogenic treatment on microstructure, mechanical, and corrosion of ZK60 Mg alloy

This study aims to investigate the effects of deep cryogenic treatment combined with traditional heat treatment on the microstructural characteristics, mechanical properties, and corrosion performance of ZK60 magnesium alloy. Quasi-in-situ TEM testing also indicates that deep cryogenic treatment induces the formation of ultra-fine zinc-rich precipitates in the magnesium matrix. After solid solution treatment, materials with cryogenic treatment will retain significant internal stress, which promotes the subsequent precipitation of rod-like β′1 during aging. Microstructural analysis reveals that deep cryogenic treatment before solution treatment and artificial aging can significantly enhance the length and density of rod-like β′1 precipitates. The treated material shows improved strength while maintaining its original elongation rate. Due to the nanoscale precipitation-induced micro galvanic effect, the aged samples exhibit a higher corrosion rate. The abundance of micrometer-sized second phases in the untreated sample does not significantly accelerate the material's corrosion rate. The solution-treated samples show the weakest micro galvanic effect and the best corrosion resistance.

INVESTIGATION OF THE EFFECTS OF DEEP CRYOGENIC TREATMENT ON THE MICROSTRUCTURE, HARDNESS, STRENGTH AND WEAR RESISTANCE OF X17CrNi16-2 MARTENSITIC STAINLESS STEEL

This study investigates the effects of deep cryogenic treatment on the hardness, tensile strength, yield strength, and wear resistance of X17CrNi16-2 martensitic stainless steel. Steel samples were applied to deep cryogenic treatment at [Formula: see text]C for 12, 18 and 36[Formula: see text]h after conventional heat treatment. After these processes, the steel samples were examined microstructurally, and martensite structure and carbides were observed. Mechanical properties increased after the cryogenic treatment was applied at all soaking times. It has been observed that the cryogenic treatment soaking time is directly proportional to the improvement in mechanical properties. The highest mechanical properties were obtained after the cryogenic treatment was applied for 36[Formula: see text]h, which is the longest soaking time. Compared to the CHT sample, the DCT36 sample has a higher microhardness, tensile strength and yield strength of approximately 5.87%, 1.87% and 8.17%, respectively, and has 88% less wear rate.

Effects of Deep Cryogenic Treatment and Controlled Rolling on Microstructures and Mechanical Properties of an Ultra-High Strength Steel

The microstructure mechanisms and mechanical properties of 0.23C-1.96Si-1.94Cr-1.93 Mn-0.35 Mo ultra-high strength steel treated by the deep cryogenic treatment at −196 °C were investigated after the steel was hot rolled at different temperatures. Experimental results show that austenitizing zone rolling with a large reduction in a single pass can comprehensively enhance the mechanical properties due to the high volume of retained austenite and refined lath martensite and bainite. The high strain gradient was suppressed, and tensile strength, yield strength, impact toughness, and total elongation were 2221 MPa, 2017 MPa, 65.5 J, and 16.9%, respectively. In addition, the austenitizing zone rolling can promote the formation of film retained austenite more than dual phase zone rolling, and retained austenite was decreased with an increase in rolling pass in a total rolling reduction of 75%. It is demonstrated that deep cryogenic treatment after austenite zone rolling with a large reduction is the proper method to enhance strength and toughness via refinement strengthening and retained austenite. This work not only reveals that the effects of refinement strengthening and high strain gradients can be markedly improved by deep cryogenic treatment after austenitizing zone rolling with large reduction strategies, but also provides a realistic preparation technology for the exploitation of superior steel applications.

Effects of deep cryogenic treatment with different holding times on the mechanical properties of Al 7050-T7451 alloy friction stir welding

Abstract This study aimed to improve mechanical properties, which decreased in the weld area, with deep cryogenic treatment at different holding times. In the study, firstly, the formation of heat damaging the welding area was observed. The temperatures in the welding zone were measured on the shoulder with a thermal camera, on the material surface, and inside the material with a thermocouple. The effects of these temperatures during welding on the surface topography and mechanical properties were investigated. The effect of tempering heat treatment after deep cryogenic treatment applied for 6, 12, 18, and 24 h was investigated. It has been observed that tempering after cryogenic treatment applied to 7xxx series aluminum alloys reduces the hardness of the nugget zone but increases the hardness in the heat unaffected zone. In addition, it was observed that deep cryogenic treatment applied at different holding times positively affected the hardness, tensile strength, and % elongation in the weld area.

Effect of Deep Cryogenic Treatment on Wear Behavior of Cold Work Tool Steel

Shock resisting cold work tool steel is one of the most applicable steels for several applications such as cutting sheets, chisels, hammers, etc. It has been categorized according to its characteristic properties into different categories as hot and cold work tool steel. This work aims to study the effects of conventional and deep cryogenic treatment (DCT) on shock-resistant cold work tool steel. In this study, three alloys were cast and prepared with different carbides forming elements such as vanadium (V) and niobium (Nb). The samples were quenched in water at 900 ℃ followed by a tempering treatment at 200 ℃ for 30 min. After quenching in water, the other samples were subjected to DCT at −196 ℃ for a 5-h soaking time, followed by tempering at 200 ℃ for 30 min. To study the wear behavior of the three heats, pin-on-disc tests were used, where the sliding speed was kept constant at a value of 0.5 m/s. The normal applied loads during the wear test were 50 N and 100 N. In order to understand the wear behavior, wear tracks were studied by scanning electron microscopy, coefficient of friction and weight loss were evaluated. The results showed that the lowest average coefficient of friction was achieved by a sample of steel 3 with quenching + DCT at a load of 100 N of load by value of 0.33. A sample of steel 3 at load 50 N achieved the lowest weight loss by using DCT plus tempering. On the other hand, a sample of steel 3 achieved the lowest weight loss at 100 N by using quenching + DCT.

Effects of Deep Cryogenic Treatment and Controlled Rolling on Microstructures and Mechanical Properties Of An Ultra High Strength Steel

Effects of Deep Cryogenic Treatment and Controlled Rolling on Microstructures and Mechanical Properties Of An Ultra High Strength Steel

Investigation of the effects of deep cryogenic treatment on the structural and mechanic properties of polyoxymethylene copolymer (POM-C) materials

Polyoxymethylene is used as an engineering material in many fields such as aircraft, aviation, and automotive industries in today due to its thermal resistance and mechanical properties. In this study, it is aimed to investigate the effects on the mechanical and structural properties of polyoxymethylene copolymer (POM-C) materials, which are used in many different industrial applications, by applying cryogenic treatment. For this purpose, deep cryogenic treatment was applied to the prepared samples at −175°C for 6, 12, 18, and 24 h, and then tensile, abrasion, impact, and hardness tests were applied to the samples that were kept at room temperature. In order to understand the changes in micro and crystal structures, XRD (X-Ray Diffraction), SEM (Scanning Electron Microscope), and FTIR (Fourier Transform Infrared Radiation) analyzes were performed, and based on these analyzes, the differences in the structure of the POM-C material were compared. It was observed that there was no improvement in the tensile strength of the deep cryogenically treated samples, but an increase in hardness and impact strength was detected.

Beneficial effects of deep cryogenic treatment on mechanical properties of additively manufactured high entropy alloy: cyclic vs single cryogenic cooling

• Cyclic deep cryogenic treatment was utilized to homogenize the residual stress and tune the microstructure of a high entropy alloy fabricated by laser melting deposition, in order to improve its overall mechanical properties. • Cyclic deep cryogenic treatment can induce an increased compressive residual stress and introduce various types of reinforcing defect microstructures into a high entropy alloy, including dense dislocations, intersecting twins, transformed HCP phase and nanograins, thus effectively overcoming the strength-ductility trade-off. • Compared to single-step DCT, cyclic DCT can reduce the residual stress gradients in the LMD-built sample, relieving or removing the tensile residual stress at the top surface. • Transformation to HCP phase can occur during the cyclic DCT process due to the cyclic reverting of the thermal stress to a high level on each cryogenic cooling, which promotes twinning on secondary habit planes and more frequent faulting. Additively manufactured (AM) metallic materials commonly possess substantial tensile surface residual stress, which is detrimental to the load-bearing service behavior. Recently, we demonstrated that deep cryogenic treatment (DCT) is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy (HEA) samples fabricated by laser melting deposition (LMD), by introducing high compressive residual stress and deformation microstructures without destroying the AM shape. However, carrying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process, which are undesirable as the mechanical properties will not be homogeneous within the sample. In this work, we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated CoCrFeMnNi HEA, and improve tensile strength and ductility, compared with single-step DCT of the same cryogenic soaking duration. Under cyclic DCT, the thermal stress is re-elevated to a high value at each cryogenic cooling step, leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation, compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over time. The enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the DCT. The results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.

Research on influence of deep cryogenic treatment and ultrasonic rolling on improving surface integrity of Ti6Al4V alloy

The synergistic effects of deep cryogenic treatment (DCT) and the ultrasonic surface rolling process (USRP) on surface microstructure and properties of Ti6Al4V alloy were investigated. Surface roughness, surface topography, nano-hardness and residual stress were used to characterize the surface-modified layer. A plastic deformation layer with a deformation depth of 7.80 μm was formed in the DCT + USRP specimen. The content of the β phase in the surface of the DCT + USRP specimen was 3% less than that of USRP, making the surface hardness of the DCT + USRP specimen higher than that of USRP. Further, the surface roughness of the DCT + USRP specimen was lower. Especially, tension-tension fatigue tests showed that the fatigue life of the specimen after DCT + USRP treatment increased by 61.9% relative to the original specimen. The synergy mechanisms of surface quality, residual stress, microstructure and work hardening were analyzed in the DCT + USRP specimen.

Effect of deep cryogenic treatment on the microstructure and tensile property of Mg-9Gd-4Y–2Zn-0.5Zr alloy

The effects of deep cryogenic treatment (DCT) on the tensile property and microstructure of Mg-9Gd-4Y–2Zn-0.5Zr(wt.%) alloy were investigated by comparing the alloy treated by solution treatment, deep cryogenic treatment and aging treatment (ST + DCT + AT) and that treated by solution treatment and aging treatment (ST + AT). The lamellar 14H-type long-period stacking ordered (14H-LPSO) in grain was precipitated in the alloy treated by ST + AT. However, the particle and needle-like Mg5RE (RE = Gd, Y) phases instead of the lamellar 14H-LPSO were precipitated, and a high-density dislocation existed in the alloy treated by ST + DCT. The greater ultimate tensile strength (UTS) and yield strength (YS) of the alloy treated by ST + DCT + AT were obtained because of the precipitation of the Mg5RE phases. The trend, the UTS and YS firstly increased then decreased with the increasing of soaking time, is corresponding to the volume fraction increasing and size-coarsening of Mg5RE precipitates, respectively. The greater elongation (EL) was obtained after the short-time DCT for 0–2 h (DCT0h-DCT2h) and the smaller EL was obtained for the long soaking time (>DCT2h). The fracture mode of the samples is all quasi-cleavage fracture.

Microstructure and improved plasticity of (FeCoNi1.5CrCu)p/Al composites subject to adjusted deep cryogenic treatment (DCT)

This study aimed to reveal the effects of Deep Cryogenic Treatment (DCT) on the microstructure and mechanical properties of (FeCoNi1.5CrCu)p/Al composites. Precisely, the microwave sintering-prepared samples were soaked in liquid nitrogen to optimize the DCT parameter. The results demonstrated that the (111) and (200) crystal face indexes were induced by released internal stress during DCT to turn to (220). The preferential orientation plays a vital role in plasticity improvement. The compression experiments show that the plasticity of DCT 36 is greatly improved, reaching 142%, compared to the untreated sample. The macro performance shows that the cracks change from one-way to two-way propagation, and the fracture toughness of DCT 36 increased by 155.6% compared to untreated due to multi-system slip.

Effects of Deep Cryogenic Treatment on the Microstructure and Properties of Rolled Cu Foil.

The development of fifth-generation (5G) communication and wearable electronics generates higher requirements for the mechanical properties of copper foil. Higher mechanical properties and lower resistance are required for flexible copper-clad laminate and high-frequency and high-speed Cu foil. Deep cryogenic treatment (DCT), as a post-treatment method, has many advantages, such as low cost and ease of operation. However, less attention has been paid to the impact of DCT on rolled Cu foil. In this study, the effects of DCT on the microstructure and mechanical properties of rolled Cu foil were investigated. The results show that as the treatment time increased, the tensile strength and hardness first increased and then decreased, reaching a peak value of 394.06 MPa and 1.47 GPa at 12 h. The mechanical property improvement of rolled Cu foil was due to the grain refinement and the increase of dislocation density. The dislocation density of rolled Cu foil after a DCT time of 12 h was determined to have a peak value of 4.3798 × 1015 m−2. The dislocation density increased by 19% and the grain size decreased by 12% after 12 h DCT.

Effects of deep cryogenic treatment on the microstructure and mechanical properties of an ultrahigh-strength TRIP-aided bainitic steel

Deep cryogenic treatment (DCT) provides an effective and convenient pathway to improve the comprehensive mechanical properties of multiphase steels. However, the transformation characteristics of retained austenite (RA) during the DCT and its effect on the precipitation behavior and bainitic transformation at the subsequent tempering stage are still unclear. In the present work, DCT is applied to a 1500 MPa grade ultrahigh-strength bainitic steel subjected to quenching and austempering treatment (QAT). The same region before and after DCT is selected and characterized by electron backscatter diffraction (EBSD), and the observations show that blocky RA located at the boundaries of primary martensite and prior austenite undergoes martensitic transformation. Dilatometry and transmission electron microscopy (TEM) characterization methods were used to elucidate the effects of tempering temperature and DCT on the competitive relationship between bainitic transformation and nanoscale carbide precipitation during tempering. Compared with QAT steel, the yield strength of QAT-C-T steels is significantly enhanced by 199–292 MPa, depending on the tempering temperature, due to the precipitation of nanoscale carbides and the elimination of unstable RA. EBSD characterization of RA at different tensile strains reveals that large blocky RA at prior austenite grain boundaries and fine RA between the bainite laths transform to martensite during uniform deformation and the necking stage, respectively. The evolution of RA during DCT and tensile strain demonstrates the correlation of its thermal and mechanical stabilities. • Effects of DCT and tempering on structure-properties of bainitic steel are studied. • DCT eliminates 5.5% blocky RA distributed at PAGB as observing same region via EBSD. • DCT affects both carbide precipitation and bainitic transformation during tempering. • DCT increases yield strength by eliminating unstable RA and promoting precipitation. • Thermal and mechanical stabilities of RA are interdependent in bainitic steel.

Effects of deep cryogenic treatment for tungsten carbide‑iron cemented carbide

This study aims to clarify the effects of deep cryogenic treatment of WC–Fe cemented carbide. WC–10 wt% Fe cemented carbide is fabricated using spark plasma sintering method and is cryogenically exposed to liquid nitrogen (‐196 °C) at a 1, 6, 12, 24, and 48 h sequence. Depending on the deep cryogenic treatment duration, the phase constituent is related to martensitic transformation (γ-fcc to α-bcc), causing a carbide–binder alloy phase (Fe3W3C or Fe6W6C; η-phase) between the deformation of the lattice structure and segregation from the WC/Fe interface. The mechanical properties of WC–Fe subjected to deep cryogenic treatment show that the hardness strengthens until 6 h (21.33 GPa) and then weakens after continued deep cryogenic treatment from 12 h (18.28 GPa). However, subsequent deep cryogenic treatment for more than 24 h recovers their mechanical properties to those observed initially. The variation in properties indicates a relationship between the grain growth behavior of cemented carbide and the formation of secondary phases induced by dislocation motion for martensitic transformation.

Performance of Multilayer Coated and Cryo-Treated Uncoated Tools in Machining of AISI H13 Tool Steel—Part 1: Tungsten Carbide End Mills

This paper focused on the performance of tungsten carbide end mills in machining of AISI H13 hot work tool steel under dry and wet conditions. The tool performance was evaluated in terms of resultant cutting force (Fc), average surface roughness (Ra) and tool life. In the milling tests, four categories of end mills were used: untreated (U), cryo-treated (CT), cryo-treated and tempered uncoated (CTT) and TiAlN/TiN multilayer coated (MLC). The tests were performed at four cutting speeds (80, 100, 120, 140 m/min), three feeds (0.08, 0.12, 0.16 mm/rev) and a depth of cut (2 mm). The test results showed that the lowest values of Fc and Ra were obtained with the use of MLC end mills. However, the cryogenic treatment was also effective on decreasing Fc and Ra. In addition, while the CTT end mills provided a slight improvement in tool life under dry conditions, they showed a remarkable improvement of 126.1% in comparison with the untreated ones under wet conditions. Although the CTT end mills exhibited a superior performance to U and CT ones, the MLC end mills were much more resistant to abrasive wear. This study is organized into two parts (WC-Co and HSS) to observe the effects of deep cryogenic treatment on performance of two different tool materials and to compare cryo-treated end mills with multilayer coated ones. This part is related to the cryogenic treatment of tungsten carbide end mills, whereas part two is regarding cryo-treated HSS end mills.

Effects of deep cryogenic treatment on machinability, hardness and microstructure in dry turning process of tempered steels

This study investigated the effects of Deep Cryogenic Treatment (DCT) on machinability, hardness, and microstructure in dry turning process of AISI 4140 (48-51 HRc) tempered steels with ceramic cutting tools on the surface roughness (Ra). DCT process of steels has shown significant improvement in their mechanical properties. In this context, experiments were made with Taguchi L16 method and optimum values were determined. Three different values for each control factors as: different heat treated samples, cutting speeds (160, 200, 240, 280 m/min), feed rates (0.08, 0.12, 0.16, 0.20 mm/rev) were selected. As a result, the lowest Ra value was found to be 0.159 µm for the DCTT36 sample at a cutting speed of 240 m/min, a feed rate of 0.08 mm/rev. The optimum Ra value was the lowest for the DCTT36 sample compared to the other samples as 0.206 µm. The hardness values of the micro and macro were highest for the DCTT36 sample. Microstructural point of view Scanning Electron Microscopy (SEM) point of view, the DCCT36 sample showed that best results owing to its homogeneity. It was concluded that lower Ra values can be obtained with ceramic cutting tool in dry turning experiments according to the studies in the literature review. It is thought to be preferred as an alternative to cylindrical grinding process due to lower cost.