Refinement of Ferrite Grain Size near the Ultrafine Range by Multipass, Thermomechanical Compression

Plane-strain compression testing was carried out on a Nb-Ti-V microalloyed steel, in a GLEEBLE3500 simulator using a different amount of roughing, intermediate, and finishing deformation over the temperature range of 1373?K to 1073?K (1100?°C to 800?°C). A decrease in soaking temperature from 1473?K to 1273?K (1200?°C to 1000?°C) offered marginal refinement in the ferrite (??) grain size from 7.8 to 6.6???m. Heavy deformation using multiple passes between A _e3 and A _r3 with true strain of 0.8 to 1.2 effectively refined the ?? grain size (4.1 to 3.2???m) close to the ultrafine size by dynamic-strain-induced austenite (??) ?? ferrite (??) transformation (DSIT). The intensities of microstructural banding, pearlite fraction in the microstructure (13?pct), and fraction of the harmful ??cube?? texture component (5?pct) were reduced with the increase in finishing deformation. Simultaneously, the fractions of high-angle (>15?deg misorientation) boundaries (75 to 80?pct), beneficial gamma-fiber (ND//??111??) texture components, along with {332}??133?? and {554}??225?? components were increased. Grain refinement and the formation of small Fe₃C particles (50- to 600-nm size) increased the hardness of the deformed samples (184 to 192?HV). For the same deformation temperature [1103?K (830?°C)], the difference in ??-grain sizes obtained after single-pass (2.7???m) and multipass compression (3.2???m) can be explained in view of the static- and dynamic-strain-induced ?? ?? ?? transformation, strain partitioning between ?? and ??, dynamic recovery and dynamic recrystallization of the deformed ??, and ??-grain growth during interpass intervals.     

Influence of annealing treatment on the formation of nano/submicron grain size AISI 301 Austenitic stainless steels

Nano/submicron austenitic stainless steels have attracted increasing attention over the past few years due to fine structural control for tailoring engineering properties. At the nano/submicron grain scales, grain boundary strengthening can be significant, while ductility remains attractive. To achieve a nano/submicron grain size, metastable austenitic stainless steels are heavily cold-worked, and annealed to convert the deformation-induced martensite formed during cold rolling into austenite. The amount of reverted austenite is a function of annealing temperature. In this work, an AISI 301 metastable austenitic stainless steel is 90 pct cold-rolled and subsequently annealed at temperatures varying from 600 °C to 900 °C for a dwelling time of 30 minutes. The effects of annealing on the microstructure, average austenite grain size, martensite-to-austenite ratio, and carbide formation are determined. Analysis of the as-cold-rolled microstructure reveals that a 90 pct cold reduction produces a combination of lath type and dislocation cell-type martensitic structure. For the annealed samples, the average austenite grain size increases from 0.28 μm at 600 °C to 5.85 μm at 900 °C. On the other hand, the amount of reverted austenite exhibits a maximum at 750 °C, where austenite grains with an average grain size of 1.7 μm compose approximately 95 pct of the microstructure. Annealing temperatures above 750 °C show an increase in the amount of martensite. Upon annealing, (Fe, Cr, Mo)₂₃C₆ carbides form within the grains and at the grain boundaries.     

Phase Equilibria of Sn-Co-Cu Ternary System

Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys?? development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523?K, 1073?K, and 1273?K (250?°C, 800?°C, and 1000?°C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn₃Co₂Cu₈, was found. The solubilities of Cu in the ??-CoSn₃ and CoSn₂ phases at 523?K (250?°C) are 4.2 and 1.6?at. pct, respectively, while the Cu solubility in the ??-Co₃Sn₂ phase is as high as 20.0?at. pct. The Cu solubility increases with temperature and is around 30.0?at. pct in the ??-Co₃Sn_2?at 1073?K (800?°C). The Co solubility in the ??-Cu₆Sn₅ phase is also significant and is 15.5?at. pct at 523?K (250?°C).     

In Situ Observation of Phase Transformation and Structure Evolution of a 12?pct Cr Ferritic Stainless Steel

This work focuses on an in situ observation of phase transformation of a 12?pct Cr ferritic stainless steel using high-temperature laser scanning confocal microscopy. ?????????? phase transformation temperatures are determined to be approximately 1073?K and 1423?K (800?°C and 1150?°C), respectively. The onset of phase transformation is found to occur at grain boundaries. When the temperature is beyond 1518?K (1245?°C), the grain growth rate suddenly becomes very high, and the grain growth is related to the self-organizing of adjacent grains. ?????? phase transformation has been mostly restrained when cooling rates are in the range of 22.4?K/s to 13.3?K/s (22.4?°C/s to 13.3?°C/s) except for at grain boundaries. Martensitic phase transformation, rather than ?????? phase transformation, occurs when the cooling rates are in the range of 8.5?K/s to 2.2?K/s (8.5?°C/s to 2.2?°C/s). The starting temperature of martensitic phase transformation is approximately 697?K to 728?K (424?°C to 455?°C) for specimens heated to 1373?K (1100?°C) (i.e., ?? phase field), which is 50?K to 100?K (50?°C to 100?°C) higher than that of specimens heated to 1723?K (1450?°C) (i.e., ?? phase field). Many bulges remain on the surfaces of the specimen heated to 1723?K (1450?°C), and their formation mechanism is analyzed.     

Role of Tungsten in the Tempered Martensite Embrittlement of a Modified 9 Pct Cr Steel

The effect of tempering on the mechanical properties and fracture behavior of two 3 pct Co-modified 9 pct Cr steels with 2 and 3 wt pct W was examined. Both steels were ductile in tension tests and tough under impact tests in high-temperature tempered conditions. At T ≤ 923 K (650 °C), the addition of 1 wt pct W led to low toughness and pronounced embrittlement. The 9Cr2W steel was tough after low-temperature tempering up to 723 K (450 °C). At 798 K (525 °C), the decomposition of retained austenite induced the formation of discontinuous and continuous films of M₂₃C₆ carbides along boundaries in the 9Cr2W and the 9Cr3W steels, respectively, which led to tempered martensite embrittlement (TME). In the 9Cr2W steel, the discontinuous boundary films played a role of crack initiation sites, and the absorption energy was 24 J cm^?2. In the 9Cr3W steel, continuous films provided a fracture path along the boundaries of prior austenite grains (PAG) and interlath boundaries in addition that caused the drop of impact energy to 6 J cm^?2. Tempering at 1023 K (750 °C) completely eliminated TME by spheroidization and the growth of M₂₃C₆ carbides, and both steels exhibited high values of adsorbed energy of ≥230 J cm^?2. The addition of 1 wt pct W extended the temperature domain of TME up to 923 K (650 °C) through the formation of W segregations at boundaries that hindered the spheroidization of M₂₃C₆ carbides.     

Mechanical Properties of β–Ti-35Nb-2.5Sn Alloy Synthesized by Mechanical Alloying and Pulsed Current Activated Sintering

A developed Ti-35?pct Nb-2.5?pct Sn (wt pct) alloy was synthesized by mechanical alloying using high-energy ball-milled powders, and the powder consolidation was done by pulsed current activated sintering (PCAS). The starting powder materials were mixed for 24 hours and then milled by high-energy ball milling (HEBM) for 1, 4, and 12 hours. The bulk solid samples were fabricated by PCAS at 1073?K to 1373?K (800 °C to 1100 °C) for a short time, followed by rapid cooling to 773?K (500 °C). The relative density of the sintered samples was about 93?pct. The Ti was completely transformed from ?? to ??-Ti phase after milling for 12 hours in powder state, and the specimen sintered at 1546?K (1273 °C) was almost transformed to ??-Ti phase. The homogeneity of the sintered specimen increased with increasing milling time and sintering temperature, as did its hardness, reaching 400?HV after 12 hours of milling. The Young??s modulus was almost constant for all sintered Ti-35?pct Nb-2.5?pct Sn specimens at different milling times. The Young??s modulus was low (63.55 to 65.3 GPa) compared to that of the standard alloy of Ti-6Al-4V (100 GPa). The wear resistance of the sintered specimen increased with increasing milling time. The 12-hour milled powder exhibited the best wear resistance.     

Surface Hardening of Powder Injection Molded 316L Stainless Steels Through Low-Temperature Carburization

The surface hardness of powder injection molded (PIM) 316L is generally low due to the inherited austenitic structure and large grains induced during high-temperature sintering. To increase the surface hardness and the wear resistance, low-temperature carburization (LTC) was applied to PIM 316L. With carburization at 773 K (500 °C) for 24 hours, the resulting hardness at the surface increases from 160 to 810 HV due to the “colossal” supersaturation of interstitial carbon and M₅C₂ carbide, and the corrosion resistance is not deteriorated. The carburized depth is about 40 μm, and the carbon content in this layer is about 3.25 wt pct or 13.5 at. pct, which causes lattice expansion of the austenite. When the carburization temperature increases to 823 K (550 °C), or the carburization time increases to 72 hours, chromium carbides are observed and the corrosion resistance is impaired. One distinct advantage of applying LTC to PIM 316L is that no acid cleaning process is required, unlike for wrought counterparts, because of the clean surface of the sintered materials.     

Improving the Mechanical Properties of Fe-Nb-(Ni-Mn) Dendrite-Ultrafine Eutectic Composites via Controlling the Primary Phase Features

Tuning of microstructure by addition of austenite stabilizers effectively enhances the mechanical properties in Fe-Nb-(Ni-Mn) dendrite-ultrafine eutectic composites. The Fe₉₃Nb₇ alloy displays the improved plasticity up to 10?pct due to the introduction of a ductile ??-Fe dendrite into the ultrafine eutectic matrix. Meanwhile, the Fe₇₈Nb₇Ni₁₀Mn₅ alloy, which forms an in-situ martensitic ????-Fe dendritic phase reinforced ultrafine eutectic composite exhibits excellent combination of a high fracture strength of 1.6?GPa and a large plastic strain of 11?pct. The investigations reveal that the characteristics of the modulated primary dendrites in the dendrite-ultrafine eutectic composites play an important role in manipulating the generation and propagation of shear bands, thus resulting in the improved mechanical properties and plastic deformation behavior.     

Microstructure,Mechanical and Abrasive Wear Behavior of 8.0 wt pct Cr White Iron Subjected to Continuous and Cyclic Annealing Treatment

Continuous annealing treatment (austenitization for 4 hours followed by furnace cooling) and cyclic annealing treatment (four cycles of austenitization, each of 0.66 hours duration followed by forced air cooling) of 8.0 wt pct Cr white iron samples are undertaken at 1173 K, 1223 K, 1273 K, 1323 K, and 1373 K (900 °C, 950 °C, 1000 °C, 1050 °C, and 1100 °C) as steps of destabilizing the as-cast structure. Continuous annealing results in precipitation of secondary carbides on a matrix containing mainly pearlite, while cyclic annealing treatment causes similar precipitation of secondary carbides on a matrix containing martensite plus retained austenite. On continuous annealing, the hardness falls below the as-cast value (HV 556), while after cyclic annealing treatment there is about 70 pct increase in hardness, i.e., up to HV 960. Decrease in hardness with increasing annealing temperature is quite common after both heat treatments. The as-cast notched impact toughness (4.0 J) is nearly doubled by increasing to 7.0 J after both continuous and cyclic annealing treatment at 1173 K and 1223 K (900 °C and 950 °C). Cyclic annealing treatment gives rise to a maximum notched impact toughness of 10.0 J at 1373 K (1100 °C). Abrasive wear resistance after continuous annealing treatment degrades exhibiting wear loss greater than that of the as-cast alloy. In contrast, samples with cyclic annealing treatment show reasonably good wear resistance, thereby superseding the wear performance of Ni-Hard IV.

     

Retained Austenite Decomposition and Carbide Formation During Tempering a Hot-Work Tool Steel X38CrMoV5-1 Studied by Dilatometry and Atom Probe Tomography

The microstructural development of a hot-work tool steel X38CrMoV5-1 during continuous heating to tempering temperature has been investigated with the focus on the decomposition of retained austenite (Stage II) and carbide formation (Stages III and IV). Investigations have been carried out after heating to 673.15?K, 773.15?K, 883.15?K (400?°C, 500?°C, 610?°C) and after a dwell time of 600?seconds at 883.15?K (610?°C). Dilatometry and atom probe tomography were used to identify tempering reactions. A distinctive reaction takes place between 723.15?K and 823.15?K (450?°C and 550?°C) which is determined to be the formation of M₃C from transition carbides. Stage II could be evidenced with the atom probe results and indirectly with dilatometry, indicating the formation of new martensite during cooling. Retained austenite decomposition starts with the precipitation of alloy carbides formed from nanometric interlath retained austenite films which are laminary arranged and cause a reduction of the carbon content within the retained austenite. Preceding enrichment of substitutes at the matrix/carbide interface in the early stages of Cr₇C₃ alloy carbide formation could be visualised on the basis of coarse M₃C carbides within the matrix. Atom probe tomography has been found to be very useful to complement dilatational experiments in order to characterise and identify microstructural changes.     

Retained Austenite Transformation during Heat Treatment of a 5 Wt Pct Cr Cold Work Tool Steel

Retained austenite transformation was studied for a 5 wt pct Cr cold work tool steel tempered at 798 K and 873 K (525 °C and 600 °C) followed by cooling to room temperature. Tempering cycles with variations in holding times were conducted to observe the mechanisms involved. Phase transformations were studied with dilatometry, and the resulting microstructures were characterized with X-ray diffraction and scanning electron microscopy. Tempering treatments at 798 K (525 °C) resulted in retained austenite transformation to martensite on cooling. The martensite start (M _s ) and martensite finish (M _f ) temperatures increased with longer holding times at tempering temperature. At the same time, the lattice parameter of retained austenite decreased. Calculations from the M _s temperatures and lattice parameters suggested that there was a decrease in carbon content of retained austenite as a result of precipitation of carbides prior to transformation. This was in agreement with the resulting microstructure and the contraction of the specimen during tempering, as observed by dilatometry. Tempering at 873 K (600 °C) resulted in precipitation of carbides in retained austenite followed by transformation to ferrite and carbides. This was further supported by the initial contraction and later expansion of the dilatometry specimen, the resulting microstructure, and the absence of any phase transformation on cooling from the tempering treatment. It was concluded that there are two mechanisms of retained austenite transformation occurring depending on tempering temperature and time. This was found useful in understanding the standard tempering treatment, and suggestions regarding alternative tempering treatments are discussed.     

Nanoscale Analyses of High-Nickel Concentration Martensitic High-Strength Steels

Austenite reversion in martensitic steels is known to improve fracture toughness. This research focuses on characterizing mechanical properties and the microstructure of low-carbon, high-nickel steels containing 4.5 and 10 wt pct Ni after a QLT-type austenite reversion heat treatment: first, martensite is formed by quenching (Q) from a temperature in the single-phase austenite field, then austenite is precipitated by annealing in the upper part of the intercritical region in a lamellarization step (L), followed by a tempering (T) step at lower temperatures. For the 10 wt pct Ni steel, the tensile strength after the QLT heat treatment is 910 MPa (132 ksi) at 293 K (20 °C), and the Charpy V-notch impact toughness is 144 J (106 ft-lb) at 188.8 K (?84.4 °C, ?120 °F). For the 4.5 wt pct Ni steel, the tensile strength is 731 MPa (106 ksi) at 293 K (20 °C) and the impact toughness is 209 J (154 ft-lb) at 188.8 K (?84.4 °C, ?120 °F). Light optical microscopy, scanning electron and transmission electron microscopies, synchrotron X-ray diffraction, and local-electrode atom-probe tomography (APT) are utilized to determine the morphologies, volume fractions, and local chemical compositions of the precipitated phases with sub-nanometer spatial resolution. The austenite lamellae are up to 200 nm in thickness, and up to several micrometers in length. In addition to the expected partitioning of Ni to austenite, APT reveals a substantial segregation of Ni at the austenite/martensite interface with concentration maxima of 10 and 23 wt pct Ni for the austenite lamellae in the 4.5 and 10 wt pct Ni steels, respectively. Copper-rich and M₂C-type metal carbide precipitates were detected both at the austenite/martensite interface and within the bulk of the austenite lamellae. Thermodynamic phase stability, equilibrium compositions, and volume fractions are discussed in the context of Thermo-Calc calculations.     

Characterization of the Martensitic Transformation in NiPtAl Alloy Using Digital Holographic Imaging

Surface reliefs due to phase transformations in a 56.8Ni-5.6Pt-37.6Al at. pct alloy were characterized in situ using digital holographic imaging during thermal cycling from room temperature up to 405 K (132 °C). The 3D images of the surface revealed that the austenite plates formed during heating are exactly the same for each cycle, which is not the case for the martensite plates formed during cooling. The martensite start temperature was found to vary by up to ~ 20 K from one grain to another within the same specimen. The absence of Ni₃Al γ′ precipitates, due to the relatively high Al content, results in the propagation of the martensitic transformation over grains up to a millimeter in size. Bright-field optical imaging showed the formation of large martensite plates in some grains, with cracks perpendicular to these plates, upon cycling. Cracks were also observed at grain boundaries and could be related to the height variations across the grain boundaries.     

Mechanism of Secondary Hardening in Rapid Tempering of Dual-Phase Steel

Dual-phase steel with ferrite-martensite-bainite microstructure exhibited secondary hardening in the subcritical heat affected zone during fiber laser welding. Rapid isothermal tempering conducted in a Gleeble simulator also indicated occurrence of secondary hardening at 773 K (500 °C), as confirmed by plotting the tempered hardness against the Holloman–Jaffe parameter. Isothermally tempered specimens were characterized by analytic transmission electron microscopy and high-angle annular dark-field imaging. The cementite (Fe₃C) and TiC located in the bainite phase of DP steel decomposed upon rapid tempering to form needle-shaped Mo₂C (aspect ratio ranging from 10 to 25) and plate-shaped M₄C₃ carbides giving rise to secondary hardening. Precipitation of these thermodynamically stable and coherent carbides promoted the hardening phenomenon. However, complex carbides were only seen in the tempered bainite and were not detected in the tempered martensite. The martensite phase decomposed into ferrite and spherical Fe₃C, and interlath-retained austenite decomposed into ferrite and elongated carbide.     

Phase Transformation and Shape Memory Effect of Ti(Pt, Ir)

The martensitic transformation and shape memory effect of Ti₅₀(Pt, Ir)₅₀ with 5?C37.5 at. pct Ir were investigated using differential thermal analysis (DTA), high-temperature X-ray diffraction (HT-XRD), and compression tests. The austenite finish temperature, A _f, increased with increasing Ir content from 1331?K (1058?°C) in Ti-50 at. pct Pt to 1491?K (1218?°C) in Ti-12.5Pt-37.5Ir. The structure of the parent and martensite phases was identified as B2 and B19 in all tested alloys. A large strain recovery rate was obtained in Ti₅₀(Pt, Ir)₅₀ with 10 to 30 at. pct Ir. The highest shape recovery ratio was 57?pct in Ti-25Pt-25Ir after deformation at 1123?K (850?°C), followed by heating to above A _f. Using HT-XRD, the dependence of lattice parameter change on Ir content and temperature was investigated. The volume change during phase transformation from B2 to B19 was estimated using the lattice parameter of the B2 and B19 phases. Strain recovery is discussed along with volume change and lattice parameter change.     

Interdiffusion in the Mg-Al System and Intrinsic Diffusion in β-Mg2Al3

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96?pct) and Al (99.999?pct). Diffusion anneals were carried out at 573?K, 623?K and 673?K (300?°C, 350?°C and 400?°C) for 720, 360, and 240?hours, respectively. Optical and scanning electron microscopes were used to identify the formation of the intermetallic phases, ??-Mg₁₇Al₁₂, and ??-Mg₂Al₃, as well as the absence of the ??-Mg₂₃Al₃₀ in the diffusion couples. The thicknesses of the ??-Mg₁₇Al₁₂ and ??-Mg₂Al₃ phases were measured and the parabolic growth constants were calculated to determine the activation energies for growth. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, ??-Mg₁₇Al₁₂, ??-Mg₂Al₃, and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Integrated and average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the ??-Mg₂Al₃ phase, followed by ??-Mg₁₇Al₁₂, Al-solid solution, and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann??s analysis (e.g., marker plane) were determined for the ~ Mg-62 at. pct Al in the ??-Mg₂Al₃ phase. Activation energies and the pre-exponential factors for the interdiffusion and intrinsic diffusion coefficients were calculated for the temperature range examined. The ??-Mg₂Al₃ phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the ??-Mg₂Al₃ phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared with the available self-diffusion and impurity diffusion data from the literature. Thermodynamic factor, tracer diffusion coefficients, and atomic mobilities at the marker plane composition were approximated using the available literature values of Mg activity in the ??-Mg₂Al₃ phase.     

Effects of the Treating Time on Microstructure and Erosion Corrosion Behavior of Salt-Bath-Nitrided 17-4PH Stainless Steel

The effects of salt-bath nitriding time on the microstructure, microhardness, and erosion-corrosion behavior of nitrided 17-4PH stainless steel at 703 K (430 °C) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and erosion-corrosion testing. The experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly process condition dependent. When 17-4PH stainless steel was subjected to complex salt-bathing nitriding, the main phase of the nitrided layer was expanded martensite (α`), expanded austenite (S), CrN, Fe₄N, and Fe₂N. The thickness of nitrided layers increased with the treating time. The salt-bath nitriding improves effectively the surface hardness. The maximum values measured from the treated surface are observed to be 1100 HV_0.1 for 40 hours approximately, which is about 3.5 times as hard as the untreated material (309 HV_0.1). Low-temperature nitriding can improve the erosion-corrosion resistance against two-phase flow. The sample nitrided for 4 hours has the best corrosion resistance.     

Retained carbide distribution in intercritically austenitized 52100 steel

Two 52100 steels, one containing 0.009 pct P, the other 0.023 pct P, were homogenized at 1150 °C, slowly cooled to form proeutectoid carbides and pearlite, partially spheroidized, austenitized at 850 °C for one hour, oil quenched, and tempered at 200 °C. Light microscopy and transmission electron microscopy of carbon extraction replicas showed that cementite particles were retained as three different morphologies in the fine-grained austenite formed during the 850 °C intercritical austenitizing treatment. The morphologies are characterized as follows: (1) closely spaced intragranular carbides most of which are less than 0.25 μm in diameter, (2) carbides about 1 μm in diameter, located on austenite grain boundaries, and (3) branched proeutectoid carbides arranged in networks corresponding to the coarse, 130 μm diameter austenite grains formed during homogenizing. The major effect of high phosphorus content was to retard the spheroidization of the retained carbides.     

Orientation relationships among M23C6, M6C,and austenite in an Fe-Mn-Al-Mo-C alloy

Both M₂₃C₆ and M_i6C carbides were observed to precipitate within the austenite phase in an Fe-24.6 pct Mn-6.6 pct Al-3.1 pct Mo-1.0 pct alloy after being quenched from 1200 °C and aged at 700 °C. By means of transmission electron microscopy and diffraction techniques, the orientation relationships among M₂₃C₆, M₆C, and the austenite phase were determined as follows: {fx567-1} The present result of the orientation relationship between M₆C and the austenite phase is in disagreement with that reported by Maziasz^[14] for M₆C in an austenitic stainless steel.     

Carbide Precipitation During Tempering of a Tool Steel Subjected to Deep Cryogenic Treatment

Using transmission electron microscopy, Mössbauer spectroscopy, and measurements of hardness, the carbide precipitation during tempering of steel X153CrMoV12 containing (mass pct) 1.55C, 11.90Cr, 0.70V, and 0.86Mo is studied after three treatments: quenching at RT and deep cryogenic treatment, DCT, at 77 K or 123 K (?196 °C or ?150 °C). In contrast to some previous studies, no fine carbide precipitation after long-time holding at cryogenic temperatures is detected. After quenching at room temperature, RT, the transient ε(ε′) carbide is precipitated between 373 K and 473 K (100 °C and 200 °C) and transformed to cementite starting from 573 K (300 °C). In case of DCT at 123 K (?150 °C), only fine cementite particles are detected after tempering at 373 K (200 °C) with their delayed coarsening at higher temperatures. Dissolution of cementite and precipitation of alloying element carbides proceed at 773 K (500 °C) after quenching at RT, although some undissolved cementite plates can also be observed. After DCT at 123 K (?150 °C), the transient ε(ε′) carbide is not precipitated during tempering, which is attributed to the intensive isothermal martensitic transformation accompanied by plastic deformation. In this case, cementite is the only carbide phase precipitated in the temperature range of 573 K to 773 K (300 °C to 500 °C). If DCT is carried out at 77 K (?196 °C), the ε(ε′) carbide is found after tempering at 373 K to 473 K (100 °C to 200 °C). Coarse cementite particles and the absence of alloying element carbides constitute a feature of steel subjected to DCT and tempering at 773 K (500 °C). As a result, a decreased secondary hardness is obtained in comparison with the steel quenched at RT. According to Mössbauer studies, the structure after DCT and tempering at 773 K (500 °C) is characterized by the decreased fraction of the retained austenite and clustering of alloying elements in the α solid solution. It is suggested that a competition between the strain-induced transformation of the retained austenite and carbide precipitation during the wear can control the life of steel tools.