Proper Heat Treatment Research Articles

Evidence for austenite to non-modulated martensite transformation crystallography and variant organization in Ni-Mn-Ga-Co ferromagnetic shape memory alloys

Knowledge of transformation crystallography and variant organization of product phase was a prerequisite for tuning microstructure and enhancing functionalities in materials with displacive structure-transformation. However, the transformation orientation relationship (OR) between parent austenite and non-modulated (NM) martensite in traditional NiMnGa ferromagnetic shape memory alloy was not yet well-determined via direct experimental results, thus leading to ambiguity in understanding the self-accommodated configuration. In this work, by generating a microstructure with coexisting austenite and NM martensite through minor Co substitution and proper heat treatment, the transformation OR was unambiguously determined to be the N-W relation with {111}A//{101}NM and <2¯11>A//<101¯>NM on the basis of accurate EBSD orientation measurements. Analysis on deformation gradient matrix constructed from the N-W OR revealed that, the internal nano-twined structure allowed a maximum profit for eliminating the overall latticed deformation caused by transformation, overweighing the “sandwich” micro-variant pair structure. Such strain accommodation mechanisms consequently contributed to the resultant self-accommodated hierarchically twinned structure of martensite. Moreover, it was found that the prior austenite grain boundaries (PAGBs) provided dominated nucleation sites for NM martensite variants, where the preferential variant selection at PAGBs mainly depended on the inclination angle between the PAGB and matching close-packed direction (<2¯11>A//<101¯>NM) of variants. The present study provided comprehensive information on transformation crystallography and displacive characters of austenite to NM martensite transformation, which was useful for the efforts in property optimization and theoretical simulation.

Effects of post-heat treatment on anisotropic mechanical properties of laser additively manufactured IN718

In this presented work, the effects of different heat treatments on the anisotropic mechanical properties of Inconel 718 (IN718) fabricated by laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) were comparatively investigated. Samples prepared in build direction (BD) and transverse direction (TD) for tensile and creep tests were heat-treated with Solution + double aging (SA) and Homogenization + solution + double aging (HSA) procedures, separately. Experimental results indicate that both SA-treated LPBF-IN718 and LDED-IN718 show strong anisotropy in tensile and creep properties. TD samples have higher tensile strength and relatively better creep performance. After HSA treatment, LPBF-IN718 samples still show strong anisotropic tensile and creep properties. In contrast, anisotropy in mechanical properties of LDED-IN718 samples is mitigated significantly. The columnar grains in as-built LDED-IN718 recrystallized after HSA treatment, resulting in similar tensile and creep properties in both directions. The difference in residual stresses of LPBF-IN718 and LDED-IN718 is the main reason that causes the totally different conditions after HSA treatment. This work can provide a deeper understanding of the difference in anisotropic mechanical properties of LPBF-IN718 and LDED-IN718, which may guide the design of proper heat treatment of laser additively manufactured nickel-based superalloy potentially.

Effect of post-heat treatment on Ti2AlNb-based alloy fabricated by twin-wire alternating dual-electron beam additive manufacturing technology

Thanks to its excellent high-temperature performance and moderate density, Ti2AlNb-based alloy is considered to be a new generation of high-temperature structural material in the aerospace field. However, its application is restricted currently due to the limitations of traditional processing methods. Recently, our group first successfully prepared this alloy with an unconventional approach named wire-based in-situ additive manufacturing (AM) technology, and great mechanical performance has been obtained. The unbalanced thermal process of AM easily causes inconsistent or undesired microstructures, as well as mechanical properties. Therefore, in this study, we further carried out post-heat treatment research on the as-printed sample so as to optimize its mechanical performance. Results show that the α2-phase will precipitate from the as-deposited samples (B2/β+O) after solution treatment(ST), while all precipitates were dissolved to the B2/β-matrix when the solution temperature was 1100 °C. The aging treatment(AT) promoted a great number of O-phases precipitated and led to an increase in its proportion. With the increase in aging temperature, the tensile strength decreased (995 to 821 MPa) gradually coupling the increase of fracture strain (1.65% to 2.12%), while the aging duration time did not show an obvious effect on its performance. In addition, after proper heat treatment, the high temperature (650 °C) tensile strength of the samples was as high as 818 and 792 MPa. This research not only promotes the development of Ti2AlNb-based alloy fabricated through in-situ AM, but also facilitates its further application in the aerospace field.

Tunable Raman Gain in Transparent Nanostructured Glass-Ceramic Based on Ba2NaNb5O15 †.

Stimulated Raman scattering in transparent glass-ceramics (TGCs) based on bulk nucleating phase Ba2NaNb5O15 were investigated with the aim to explore the influence of micro- and nanoscale structural transformations on Raman gain. Nanostructured TGCs were synthesized, starting with 8BaO·15Na2O·27Nb2O5·50SiO2 (BaNaNS) glass, by proper nucleation and crystallization heat treatments. TGCs are composed of nanocrystals that are 10-15 nm in size, uniformly distributed in the residual glass matrix, with a crystallinity degree ranging from 30 up to 50% for samples subjected to different heat treatments. A significant Raman gain improvement for both BaNaNS glass and TGCs with respect to SiO2 glass is demonstrated, which can be clearly related to the nanostructuring process. These findings show that the nonlinear optical functionalities of TGC materials can be modulated by controlling the structural transformations at the nanoscale rather than microscale.

Influence of pre-heat treatment on glass structure and chemical strengthening of aluminosilicate glass

We consider a commercial aluminosilicate glass as an example case to obtain an understanding of the correlations between heat treatment and characteristics of chemical strengthening. Different heat treatments are performed prior to an ionic exchange process, and their effects on the chemical strengthening are investigated. It is verified that pre-heating treatment is influential, increasing the generated compressive stress by ∼10%, whereas depth of the compressive layer is observed to be remained identical regardless of heat treatment. These behaviors are able to be connected with structural evolutions observed through a Raman analysis, revealing that 4- and 3-membered ring structures are increased with proper heat-treatment. This indicates that the glass structure tends to be densified on a medium range scale by forming a smaller ring structure, which influences the stuffing effect of chemical strengthening. The stress profile of aluminosilicate glasses can be additionally engineered via heat-treatment conducted before the ionic exchange process.

Corrosion resistance improvement of multi-principal element alloy by tailored structure with heterogeneous grains

The Co40Cr20Ni30Al5Ti5 multi-principal element alloy (MPEA) with heterogeneous grain structure (HGS) and nano L12 precipitates is successfully designed by cold rolling and proper heat treatment. The HGS alloy exhibits excellent corrosion resistance and passivation performance, originated from high-density grain boundaries in fine grains and abundant defects in deformed grains, which encourages surface to form a thicker and more efficient passive layer to inhibit the initial pitting corrosion. This finding indicates that the developed MPEA with HGS can possess an excellent combination of corrosion resistance and mechanical properties, providing highly positive factors for future applications.

Microstructural evolution and dynamic recrystallization mechanism of a heavily-alloyed Ni-based superalloy during hot extrusion

Direct hot forging of heavily-alloyed Ni-based superalloy castings usually ends up with severe cracking due to serious macro-segregation. To address this issue, we propose to use hot extrusion as the replacement technology to process this kind of superalloys. An advanced cast and wrought Ni-based superalloy, GH4151, was thus subjected to hot extrusion. It was found that the cast GH4151 ingot can be successfully processed by hot extrusion without cracking. Extensive twinning happened and played a crucial role in accommodating large and sudden macroscopic plastic deformation during hot extrusion. Dynamic recrystallization happened through twinning and grain boundary bulging, leading to significant grain refinement. Along the radial direction, the central region shows a relatively larger grain size than the outer region, which is believed to be associated with the less extent of recrystallization in the central region. Despite a certain microstructural scatter, the hot-extruded GH4151 demonstrates superior tensile strengths and stress rupture properties as compared with a number of the state-of-the-art disc superalloys. With proper heat treatment, the microstructure was further refined and the strengths were further enhanced. The present study indicates that hot extrusion is capable of processing heavily-alloyed Ni-based superalloys and producing desired microstructure that allows for acquisition of excellent mechanical properties.

Structural and Electrochemical Properties of Li2O-V2O5-B2O3-Bi2O3 Glass and Glass-Ceramic Cathodes for Lithium-Ion Batteries.

In this study, 20Li2O-60V2O5-(20 - x)B2O3-xBi2O3 (x = 5, 7.5, 10 mol%) glass materials have been prepared by the melt-quenching method, and the structure and morphology of the glass materials have been characterized by XRD, FTIR, Raman, and FE-SEM. The results show that the disordered network of the glass is mainly composed of structural motifs, such as VO4, BO3, BiO3, and BiO6. The electrochemical properties of the glass cathode material have been investigated by the galvanostatic charge-discharge method and cyclic voltammetry, and the results show that with the increases of Bi2O3 molar content, the amount of the VO4 group increases, and the network structure of the glass becomes more stable. To further enhance the electrochemical properties, glass-ceramic materials have been obtained by heat treatment, and the effect of the heat treatment temperature on the structure and electrochemical properties of the glass has been studied. The results show that the initial discharge capacity of the glass-ceramic cathode obtained by heat treatment at 280 °C at a current density of 50 mA·g-1 is 333.4 mAh·g-1. In addition, after several cycles of charging and discharging at a high current density of 1000 mA·g-1 and then 10 cycles at 50 mA·g-1, its discharge capacity remains at approximately 300 mAh·g-1 with a capacity retention rate of approximately 90.0%. The results indicate that a proper heat treatment temperature is crucial to improving the electrochemical properties of glass materials. This study provides an approach for the development of new glass cathode materials for lithium-ion batteries.

AISI 420 Paslanmaz Çeliğin MQL ve Kriyojenik Yöntemlerle Tornalanmasında CNC Torna Tezgahında İşleme Titreşim Stabilizasyonunun İyileştirilmesi

It is common to find annealed and tempered stainless steels on the market for raw materials. The choice of proper heat treatment settings is one of the most influential aspects in determining the corrosion resistance of annealed materials. The degradation of materials as a result of wear and corrosion is a problem that leads to very considerable economic losses nowadays. By applying lubrication and cooling to the material's surface during operation, the destructive effects of wear and corrosion on the material may be reduced. This study investigates the influence that different machining and lubrication/cooling environments have on vibrational stabilization-based acceleration as well as power consumption during the turning of AISI 420 stainless steel under dry, minimum quantity lubrication (MQL), and cryogenic settings. In all of the turning trials, the cutting speed and the depth of cut were maintained at the same levels. When the data were analyzed, a change from the dry environment to the MQL condition resulted in a drop of 7.04% and 5.2% in power consumption and acceleration, respectively, while a change from the MQL test settings to cryogenic cooling conditions resulted in a decrease of 2.02% and 14.3% in power consumption and acceleration, respectively.

Effect of a multi-phase structure on the damping response of a novel high entropy alloy

• Dynamic behavior of a multi-phase high entropy alloy is investigated in a wide temperature range. • Effects of processing and the resulting phase constitution on the damping response is underlined. • The storage modulus and the internal friction values of the annealed alloys are improved. In this study, dynamic behavior of a novel multi-phase high entropy alloy (HEA) was investigated. Thermo-mechanical processes containing an 80% reduction in room temperature rolling followed by annealing at 750°C and 850°C were applied to modify the microstructure and the resulting damping properties of the HEA. Annealing at 750°C introduced the BCC phase, while at 850°C, the sigma phase was precluded in the microstructure, leading to over 1 GPa strength with decent ductility in the latter condition. The storage modulus and the internal friction values of the annealed alloys are noticeably improved, indicating that proper heat treatments could enhance both the mechanical response and the damping performance of this HEA.

Luminescence properties and thermal stability of Sm3+-doped Na2O–Y2O3–SiO2–P2O5 transparent glass-ceramics containing Na3YSi2O7 crystals

Sm3+-doped Na2O–Y2O3–SiO2–P2O5 precursor glasses were prepared by melting cooling and quenching methods. The optimal doping concentration of Sm3+ ions was determined by fluorescence spectrum. The thermodynamic parameters of precursor glass were determined by the DSC test. The transparent glass-ceramics containing Na3YSi2O7 crystals were obtained by proper heat treatment. The types and microstructures of Na3YSi2O7 crystals were characterized by XRD and SEM. The highest emission peak in the emission spectrum represents the transition of Sm3+: 6H5/2 → 4F7/2. Moreover, the emission intensity of the glass-ceramic is 3 times higher than the original. According to the calculation results of CIE chromaticity coordinates, the luminescence of the glass-ceramics and precursor glass were located in the orange light region. The high thermal stability of the glass-ceramic was discussed through the variable temperature fluorescence test. The thermal quenching activation energy was determined to be 0.27 eV. The results indicate that the transparent glass-ceramics containing Na3YSi2O7 crystals have potential applications in orange LED components.

Microstructural evolution, mechanical properties and corrosion resistance of CoCrFeNiW0.5 high entropy alloys with various annealing heat treatment

High entropy alloys (HEAs) with excellent mechanical properties and corrosion resistance show promising potential for use in many fields including marine environment. In order to make a good tradeoff between the mechanical properties and corrosion resistance, the microstructure of HEA is adjusted by proper heat treatment. Herein, the non-equiatomic CoCrFeNiW 0.5 HEA with dual FCC and μ phase was prepared by using an electromagnetic levitation melting method, and the microstructure, mechanical properties and corrosion resistance of these alloys with annealing temperature range from 600 to 1200 °C for 3 h have been investigated. After annealing at 1000 °C, a large number of needle-like μ phase precipitates was firstly observed in the matrix, the volume fraction of the μ phase is 26.64 %, which is about twice as higher as under the as-cast conditions (13.35 %). This alloy exhibited the highest compression yield strength of 1253.9 MPa with a considerable fracture strain of 40.8 % and the highest Vickers hardness value of 369.6 HV. The decomposition of μ phase precipitates was observed when annealing temperature up to 1200 °C, which lead to the mechanical properties of the alloy decreased slightly. All the alloys were found to show excellent corrosion resistance in 3.5 wt% NaCl solution, and corrosion occurs preferentially on the FCC matrix and phase boundaries, the increase of μ phase volume fraction result in more severe galvanic corrosion of alloys. Our results offer insights into analyzing the evolution of both mechanical properties and corrosion resistance of HEAs caused by heat treatment. • Heat treatment between 600 and 1200 °C lead to the change of μ phase precipitates. • CoCrFeNiW 0.5 HEA exhibited the highest compression yield strength of 1253.9 MPa with a fracture strain of 40.8 %. • The potential difference between FCC and μ phase intensifies the corrosion. • Phase volume ratio can influence the mechanical properties and corrosion resistance.

Development of a Novel Welding Technique With Reduced Heat-Input by Employing Double-Pulsed Gas Metal Arc Welding for Aerospace Grade 18% Ni Maraging Steel

Abstract Eighteen percent Ni maraging steels are high performance Fe–Ni martensite-based alloys with ultra-high strength and good toughness. They find applications in strategic sectors, joining of thick sections often coming into picture. Welding of thick section involves a longer processing time, more passes, and a higher heat-input. Double-pulsed gas metal arc welding (DP-GMAW) is an emerging welding technique, well suited for joining thick sections. DP-GMAW is capable of controlling the solidification parameters, weld pool geometry, and cooling rate at a reduced heat-input. The major concern regarding the welding of maraging steel is the formation of the reverted austenite (RA) phase in the fusion zone (FZ). The formation of RA deteriorates the mechanical performance of welded joints. The presence of RA can be supressed by the usage of suitable welding techniques and proper post-weld heat treatments (PWHTs). DP-GMAW process was employed to carry out the welding; studies on the joints produced are reported in this research paper. The studies also included the effect of various PWHTs on the metallurgical and mechanical properties of the maraging steel weldments. The research used three distinct PWHTs: direct aging (DA), solutionizing + aging (SA), and homogenizing + solutionizing + aging (HSA). The FZ microstructures under DA and SA conditions show that there is RA at the cell boundaries. However, there was no evidence of RA in FZ following HSA. The energy dispersive spectra (EDS) analysis of the as-welded FZ showed segregation along the grain boundaries (GBs). This led to the premature formation of RA upon subsequent aging. The SA treatments proved inadequate to totally eliminate RA in the microstructure. On the other hand, the HSA treatments were effective in evening out concentration differences and preventing formation of RA. This study demonstrates that DP-GMAW combined with HSA treatment has the best mechanical properties.

A CoCrFeNiMnSi high entropy alloy showing a good combination of shape memory effect and mechanical properties

We realized a good combination of shape memory effect and mechanical properties in a hot-rolled Fe47.7Mn15.5Co9.8Cr10.8Ni5.1Si11.1 high entropy alloy (HEA) by Si alloying and proper heat treatment to guarantee a low density of annealing twin boundaries. Its maximal recovery strain of 5.7% reached the level that conventional FeMnSi-based and Co-based shape memory alloys (SMAs) showing the same FCC to HCP martensitic transformation can realize. It showed a better combination of ultimate tensile strength and fracture strain than the reported CoCrFeNiMn-based HEAs with FCC matrix did. This result showed that to marry the shape memory effect with the excellent mechanical properties will be a promising direction for developing novel HEAs.

Isothermal Quenching of As-Cast Medium Carbon, High-Silicon AR Steel.

Medium carbon high-silicon abrasion resistant (AR) steel was examined by performing dilatometry, light optical microscopy (LOM), scanning electron microscopy (SEM), and hardness measurements after isothermal bainitization and modified martempering and compared to direct quenching technology. A commercial thermodynamic tool was used for hardness prediction and compared to the measured one and revealed a rather good agreement for direct quenching, as was the case for isothermal holdings near to the martensite start (Ms). The predicted martensite start temperatures were in good agreement with the experimental data, the experimental value was 321 °C, while the predicted values were 324 and 296 °C. However, a higher discrepancy appeared for isothermal holding much above the martensite transition in the bainite region resulting in lower measured hardness compared to the predictions related to the actual kinetics and complexity of the formed final volume percentages of phase constituents such as bainite, martensite, and rest austenite, later as a part of unfinished bainite transformation at studied temperature. The predicted hardness values for quenching, isothermal holding at 280, 300 and 350 °C were 50.6, 50.6, 49.4 and 49.4 HRC, while the measured values were 53.3, 48.3, 48 and 43 HRC, respectively. A very good agreement between the thermodynamic prediction was achieved by comparing the measured Ms concerning prior austenite grain size as one of the crucial parameters for setting a proper heat treatment strategy of various isothermal quenchings making thermodynamic predictions for low alloyed steels a powerful tool for optimizing the heat-treating operations.

(Fe,Mn)3AlCx κ-carbide formation and characterization in pack aluminization of Fe–29Mn–9Al–0.9C lightweight steel

The Fe–Mn–Al–C lightweight steel has been widely studied due to its higher strength-to-weight ratio and potential applications for automotive vehicles, energy, transportation and mining industries. In general, the strength and ductility of the Fe–Mn–Al–C lightweight steel can be improved by the formation of nano-sized (Fe,Mn)3AlCx κ-carbide precipitates by a proper heat treatment below 800 °C. In this work, a unique micrometer scale κ-carbide phase transformation phenomenon induced by the pack aluminization in the Fe–29Mn–9Al–0.9C lightweight steel was firstly reported.Extremely large columnar-like (Fe,Mn)3AlCx κ-carbide grains with average length of 18.1 μm embedded in the Fe3Al matrix were discovered in the interdiffusion zone of aluminization layer, which were totally different from these nanoscale κ-carbides precipitated in the austenitic steel matrix. The increased Al content in the pack aluminide coating/substrate interface reduced the chemical potential of carbon and became the driving force for carbon diffusion toward the coating/substrate interface. Therefore, due to the extremely low solubility of carbon in the Fe3Al phase and the inward diffusion of carbon atoms, very long columnar-like (Fe,Mn)3AlCx κ-carbide phases were thus produced in the interdiffusion zone. The average chemical concentration of the κ-carbide was 43.9Fe–27.3Mn–20.3Al–8.5 C (in at.%). The average hardness, elastic modulus and the lattice parameter of κ-carbide were 8.8 ± 0.3 GPa, 285 ± 10 GPa and 0.3764 nm, respectively. This study provided detailed chemical compositions, hardness and elastic modulus of (Fe,Mn)3AlCx κ-carbide phase for better understanding the carbide precipitation and strengthening mechanism of Fe–Mn–Al–C lightweight steel.

Development of novel ferritic steels strengthened by the Co16X6Si7-G phase: A theoretical and experimental study

This work aims to develop a novel Co16X6Si7-G (X = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re) phase strengthened ferritic steel with the help of first-principles calculations. Ddensity function theory calculation results demonstrated that the Co16X6Si7-G phase possesses the advantage of good thermodynamic stability and low misfit with the ferritic matrix. On the basis of calculation, we successfully prepared three model alloys, i.e., the Fe20Cr5Co2Si1Ti, Fe20Cr5Co2Si0.75Nb and Fe20Cr5Co2Si1.5Ta (wt.%), who make a good trade-off between strength, ductility and good oxidation/corrosion resistance. Our observation verified that the Co16X6Si7-G phase can precipitate within 1 h with proper heat treatment, showing a cube-on-cube orientation relationship with its parent matrix. The introduction of G phase precipitates amazingly increases the micro-hardness of model alloys by ∼ 160 HV after aging at 873 K. And the precipitates within the ferrite phase have not been observed to grow coarser even after 96 hrs aging treatment. Furthermore, excellent mechanical properties of ∼ 1.2 GPa tensile strength and ∼ 10 % total elongation have been achieved after 6 hrs aging time at 873 K. These findings indicate the Co16X6Si7-G phase would be a promising candidate as a strengthening medium and provide valuable insight into the screen of precipitates for the development of high-strength and ductile steels.

Damping performance and martensitic transformation of rapidly solidified Fe-17%Mn alloy

The rapid solidification of Fe-17%Mn alloy was performed to investigate the influence of cooling rate on its damping performance and martensitic transformation mechanism. A proper heat treatment was also carried out to clarify its coupled effects with rapid solidification. The stacking fault probability and martensitic transformation temperature were determined to demonstrate their relationship with the cooling rate and the heat treatment process. With the increase of cooling rate, the volume fraction of ε-martensite increased and the stacking fault probability of ε-martensite was enhanced. The formation of ε-martensite phase was remarkable for the increase of damping capacity and microhardness. It was found that rapid solidification was beneficial for the formation of ε-martensite and the improvement of damping capacity. This effect can be facilitated by the incorporation of the heat treatment process.

Simultaneously Improving Microstructures and Wear Properties of Ni60 Coating by Heat Treatment

Ni60 self-lubricated anti-wear composite coatings were successfully precipitated on the 35CrMoV substrate by laser cladding technology. The effects of heat treatment on the macro-morphology, microstructure, precipitated phase, microhardness, and wear properties of the composite coatings with different heat treatment temperatures (25 °C, 500 °C, 600 °C, and 700 °C for 1 h) were investigated systemically. The macro-morphology, microstructure, precipitated phases, and elements distribution of laser cladding layers were detected by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), respectively. The mechanical and tribological properties of the cladding layers were tested using a microscopic Vickers hardness tester and friction and wear tester, respectively. The results show that the main phases of Ni60 coatings are composed of γ-(Ni, Fe), Cr7C3, Cr23C6, CrB, CrFeB, and Cr2Ni3. In particular, the micro-structure and mechanical properties reach the best levels after heat treatment at 600 °C. The micro-hardness, average friction coefficient, and wear volume of the cladding layer are 771.4 to 915.8 HV1 and 0.434 and 2.9546 × 10−5 mm3, respectively. In conclusion, the micro-structure and mechanical properties of the cladding layer are greatly improved by the proper heat treatment temperature.

Improving the Strength of Prestressed Steel ASTM A633 Grade C by Combination of the Cr-Ti Alloying and Heat Treatment

Laboratory-scale experiments were carried out to improve the strength of prestressed steel by combination of the Cr-Ti alloying and heat treatment. A predetermined amount of the scrap and some ferrous alloys (such as FeMn, FeSi, FeCr and FeTi) was melted in the induction furnace to obtain the aimed compositions of the steel ASTM A633 grade C and the modified steel with Cr-Ti alloying. The molten steel was cast into the 45 mm ingot which was then hot forged into the 25 mm, subsequently prepared the tensile specimens that were heat-treated by quenching and tempering. After that, the hot forged and heat-treated specimens were subjected to the composition analysis, the tensile test and microstructural observation by optical and scanning electron microscopy. It has been concluded that the strengths of the prestressed steel strongly increased when the martensitic microstructure was obtained through the proper heat treatment. All the prepared steel exhibited high strength and adequate elongation, especially the UTS/YS of the Cr-Ti alloyed steel had increased from the value of 961/702 to 1611/1217 MPa and the elongation decreased from 15 to 10% corresponding to the deformed and heat-treated sample. These increasing strengths were attributed to the hardenability of the Cr element as well as the formation of the TiN precipitates which hindered the movement of the dislocation. The results suggested that further research must be conducted for the practical production of prestressed steel that is used in construction applications.