Excellent Combination Of Strength Research Articles

Interfacial reaction induced mechanical behaviors in graphene reinforced Nb/Nb5Si3 composites

Fabricating high-toughness Nb/Nb5Si3 composites without sacrificing their strength is a challenge. Here, a novel and promising strategy is suggested for developing the graphene reinforced Nb/Nb5Si3 composites with high performance by adjusting the nano-sized Nb4C3 interfacial phase, and their mechanical behaviors including toughening and strengthening mechanisms were reported for the first time. The generated nano-Nb4C3 interfacial phase is tightly bonded with the graphene and matrix, which reduces the interfacial stress concentration and improves the interfacial bonding strength because of the improvement of interfacial compatibility. The high interfacial bonding strength caused by the nano-Nb4C3 can effectively promote crack deflection and bridging, and consume the more propagating energy of cracks, thus increasing the toughness. The primary strengthening mechanism in this composite is the load transfer, which is influenced by the nano-Nb4C3 interfacial phase. An appropriate amount of nano-Nb4C3 interfacial phase is crucial for achieving a good strength-toughness balance in this composite. The excellent combination of strength and toughness demonstrates that the strategy used in this work can make this composite stand out from the dilemma of strength toughness inversion. This work paves a new path for breaking the inverted relationship between the strength and toughness in graphene/metal matrix composites.

Construction of three-dimensional network morphology titanium matrix composites via adding nano B4C: As-built and heat-treated scenarios

This study examines the role of nano B4C addition in improving the mechanical properties of Ti-6Al-4V (Ti64) alloys fabricated by laser melting deposition under as-built and heat-treated conditions. However, the enrichment of reinforcing phases generated by in situ production at grain boundaries causes a serious reduction in ductility, limiting the development of high-performance titanium matrix composites. To avoid this deficiency, the fabricated titanium matrix composites (TMCs) were subjected to three different heat treatment programmers, namely, subtransus heat treatment, supertransus heat treatment and triple heat treatment. The effects of B4C addition and heat treatment on microstructure, texture and mechanical properties were systematically investigated. The results show that TiB and TiC, synthesized in situ, promote the precipitation of α-Ti with a non-Burgess orientation relationship, and weakening the texture intensity of α-Ti. The ultimate tensile strength of the in situ synthesized (TiB + TiC) reinforced Ti64 composites is 1168 MPa, which is 35.5% higher than the ultimate tensile strength of the Ti64 alloys. However, this effect resulted in a decrease in elongation at break to 2.5%. An excellent combination of strength and fracture strain of 1060 MPa and 9.3 %, respectively, was simultaneously achieved for the heat-treated TMCs. The excellent ductility is mainly attributed to the microstructure consisting of primary equiaxed-α, ultrafine αs lamellar and retained β phase has been obtained after triple heat treatment. This finding offers significant guidance for the additive manufacturing of TMCs microstructures in order to attain the desired mechanical properties.

A strong fracture-resistant high-entropy alloy with nano-bridged honeycomb microstructure intrinsically toughened by 3D-printing

Strengthening materials via conventional “top-down” processes generally involves restricting dislocation movement by precipitation or grain refinement, which invariably restricts the movement of dislocations away from, or towards, a crack tip, thereby severely compromising their fracture resistance. In the present study, a high-entropy alloy Al0.5CrCoFeNi is produced by the laser powder-bed fusion process, a “bottom-up” additive manufacturing process similar to how nature builds structures, with the microstructure resembling a nano-bridged honeycomb structure consisting of a face-centered cubic (fcc) matrix and an interwoven hexagonal net of an ordered body-centered cubic B2 phase. While the B2 phase, combined with high-dislocation density and solid-solution strengthening, provides strength to the material, the nano-bridges of dislocations connecting the fcc cells, i.e., the channels between the B2 phase on the cell boundaries, provide highways for dislocation movement away from the crack tip. Consequently, the nature-inspired microstructure imparts the material with an excellent combination of strength and toughness.

Designing eutectic medium-entropy alloys CoFeNiTax with outstanding mechanical properties

The eutectic medium-entropy alloys CoFeNiTax (x = 0.4, 0.5, 0.6) were designed successfully based on binary eutectic systems and thermodynamics calculations in this study. With the increase of Ta content, the solidified microstructures evolved from hypoeutectic to full eutectic and finally to hypereutectic. The primary phases in the hypoeutectic and hypereutectic were FCC solid solution and C14-Laves phase, respectively. The solidified microstructures were coarsened and spheroidized by the heat treatment, and a high-density of needle-like Laves phase precipitated in the FCC phase of the CoFeNiTa0.4. The crystallographic orientation relationship between the precipitated phase and matrix phase was [2‾ 42‾ 3]Laves//[011]FCC, and the crystal plane (1 1‾ 1)FCC was almost parallel to (0 1‾ 12)Laves, just with a mismatch angle of about 6°. The compressive strength and fracture strain of the heat-treated alloys were within 2232∼2465 MPa and 22.5–32.8 %, respectively, being superior to most high-entropy alloys. The excellent combination of strength and toughness was attributed to the synergistic effects of various strengthening-toughening mechanisms, including the second-phase strengthening, the solid solution strengthening, the interface strengthening and toughening, and the twinning toughening.

Excellent combination of strength and elongation of TZM alloys achieved by c-ZrO2 and single cross rolling

In this study, new TZM-xZrO2 (x = 0, 0.5, 1, 1.5) (wt%) alloys were designed by powder metallurgy solid-solid mixing method combined with single cross rolling. The results show that c-ZrO2 in TZM alloys was mainly spherical, and the average size of c-ZrO2 particle increases gradually from 1.28 μm to 1.71 μm with the increase of its content. c-ZrO2 can effectively refine the molybdenum grain and adsorb the free brittle element O in grain boundaries in the form of TiO2 layer. The interface was composed of three phase: c-ZrO2, Y2O3 and TiO2, with the presence of [0−11] c-ZrO2 ǁ [−11−2] Y2O3 ǁ [−10−3] TiO2 crystal relationship. The rolled plates mainly exist 〈100〉//ND and 〈111〉//ND two kinds of grain orientation, the addition of c-ZrO2 particles promote <100>//ND orientation ratio, thus weakening the texture strength (maximum pole density value from 8.34 to 5.39), conducive to the improvement of plasticity. When the c-ZrO2 content was 0.5 wt%, the best performance was achieved, with good strength and elongation (ultimate tensile strength: 958 MPa; Elongation: 17.3%), showing excellent strength and elongation product (16.6 GPa·%), 31% higher than TZM alloy, better than most reported molybdenum alloys. With the further increase of c-ZrO2 content, the particles gradually coarsened, the hindering effect on dislocations was weakened, and it was easy to become the nucleation site of main cracks, resulting in the decrease of strength and plasticity. Fine grain strengthening and dislocation strengthening were important factors to improve the strength. The excellent ductility was mainly due to the deflection mechanism of microcracks and the blocking effect of grain boundary enrichment on crack propagation.

Conch-shell-inspired porcelain ceramic tile/Kevlar fabric composites with excellent combination of strength, toughness and shock resistance

For various engineering applications in public, ceramics with exceptional strength, toughness and shock resistance are imminently required, but traditional ceramics struggle to meet these demands due to their fragility. Inspired by the shape of natural conch shells, this work offers a simple hot press approach to fabricate layered porcelain ceramic tile/Kevlar fabric composites, yielding excellent mechanical properties and the capacity for non-catastrophic failure. It was concluded that composites? excellent mechanical performance is attributed to the resin/fabric content. The composite with the resin/fabric content of 45.5 vol.% had an outstanding combination of high strength (310.5 ? 6.2MPa) and excellent fracture toughness (6.83 ? 0.09MPa?m1/2), whereas the sample with 36.4 vol.% resin/fabric content had the maximal impact energy of 2.04 ? 0.09 J, which is much better than those of traditional ceramics. The strong resistance to fracture is a result of the proper interfacial bonding and the presence of elastic component, which enables toughening mechanisms such as crack deflection, fibre pull-out and interfacial debonding. This finding provides useful guidance for replacing lowperformance ceramics in engineering applications with cost-effective ceramic composites.

Enhanced combination of strength and electrical conductivity properties with CrB2 reinforced Cu matrix composites fabricated by powder metallurgy

Generally, the severe aggregation of the strengthening phase in the metal matrix obviously weakened the strengthening efficiency. Herein, to eliminate the agglomeration phenomenon of CrB2 particle with a high-volume fraction and thus improve the mechanical properties, CrB2/Cu composites were fabricated by ball milling, hot pressure sintering and hot extrusion. And then the effects of milling time length and CrB2 aggregation state on mechanical and electrical properties were systemically studied. Moreover, the content of CrB2 particles on the mechanical and the relevant strengthening and conductive mechanisms were discussed. Microstructure results show that an increase in milling time reduced the agglomeration of CrB2 particles and enlarge the limit dispersion content from 3 to 8 vol%. Remarkably, the mechanical properties of CrB2/Cu composites increased with increasing ball milling time, while the electrical conductivity slowly declined. It is also found that the fabricated composites have higher strength than pure Cu. When the ball milling time is 20 h, an excellent combination of strength (622 MPa), elongation (12.6%), and electrical conductivity (70.56%IACS) is obtained from 5 vol% CrB2 particles, which can be attributed to the effect of uniform dispersion of CrB2 particles. Based on the experimental results, it is determined that refinement strengthening and dislocation strengthening are the main strengthening mechanisms, respectively.

Effects of annealing treatment on microstructure and mechanical properties of laser melting-deposited VCoNi medium-entropy alloy

Additive manufacturing (AM) is a promising approach to producing high- or medium-entropy alloys (HEAs or MEAs) with excellent properties. However, some undesirable microstructural defects and unstable precipitated phases were formed owing to the repeated heating and cooling steps and the rapid solidification nature of the AM process. Annealing treatment after AM fabrication is often beneficial for adjusting the comprehensive mechanical properties and stabilizing the microstructures. In this study, a VCoNi MEA single wall sample was fabricated successfully via laser melting deposition (LMD), and the effects of post-annealing treatments on the microstructures and mechanical properties were explored. The grain size and σ-phase particle size increase and the σ-phase particles undergo fragmentation, spheroidization, and coarsening during annealing. As the annealing time increases, the tensile strain increases, but the tensile strength decreases. An excellent combination of strength and ductility can be obtained after annealing for 1.5 h (The yield strength, ultimate tensile strength, and tensile strain are 741.2 MPa, 1287.8 MPa, and 30.5 %, respectively). HDI hardening is the most important strengthening mechanism in this work. The decrease in tensile stress after the annealing treatment is mainly attributed to the decrease of heterogeneity of microstructure, and the increase in tensile strain after the annealing treatment is mainly attributed to the decrease of the pores and the spheroidization of the rod-like σ-phase particles. This work provides practical insight into adjusting the microstructure and comprehensive mechanical properties of HEAs and MEAs for AM.

Corrosion behaviors and passive film properties of a newly developed cost-effective AlCrFeNi eutectic high entropy alloy in different corrosive solutions

Eutectic high entropy alloys (EHEAs) are of great interest among the scientific community because of their excellent combination of strength and ductility. The mechanical properties of various EHEAs were extensively studied in previous studies; however, investigations on corrosion behaviors and passive film properties of EHEAs in different corrosive solutions were relatively few. In this work, the corrosion behaviors and film properties of a newly developed cost-effective AlCrFe1.5Ni2.6 EHEA in solutions of 3.5 wt% NaCl, 0.5 M H2SO4 and 0.5 M HCl were investigated by combining electrochemical measurements and surface characterization techniques; furthermore, the results were compared with those obtained in AlCoCrFeNi2.1 EHEA. The results showed that AlCrFe1.5Ni2.6 EHEA exhibited better corrosion resistance abilities in three different corrosive solutions compared to AlCoCrFeNi2.1 EHEA, which was due to the higher fraction of the corrosion resistant FCC phase in the alloy and a more compact and protective passive film with a higher oxides/hydroxides ratio formed on the surface. The present work will provide guidance for designing EHEAs with a combination of excellent mechanical properties and good corrosion resistance abilities.

Modeling the Precipitation of Aluminum Nitride Inclusions during Solidification of High‐Aluminum Steels

High‐aluminum advanced high‐strength steels have received increasing interest due to their excellent combination of strength and ductility. The control of nonmetallic inclusions in steel is among the most important issue for the production of high‐aluminum steel. This study proposes a model for the evolution of size distributions of AlN inclusions during solidification of steel based on the Kampmann–Wagner numerical model and microsegregation calculation. Both homogeneous (pure AlN) and heterogeneous precipitations (AlN+oxide or MnS) are described using homogeneous nucleation and free growth models of Greer et al. respectively. The model is applied to calculate the size distributions of AlN in high‐Al (up to 5%) Fe–Cr–Al steels and high‐ and medium‐manganese steels and validated by the experimental data in the literature. The model correctly describes the influence of cooling rates on the precipitation of AlN in Fe–Cr–Al steels and high‐manganese steels, and the sizes of AlN are reduced and the number densities of AlN inclusions are increased by increasing the cooling rate. The effects of nitrogen and aluminum concentration in medium‐manganese steel on inclusion precipitation are investigated by the model calculation. The increases in nitrogen and aluminum concentration facilitate the homogeneous precipitation of AlN inclusions.

Effect of Mo Content on Friction and Wear Properties of Fe-Mn-Al-C Alloys Under Different Working Conditions

For this study, Fe-25Mn-9Al-8Cr-1C-xMo alloys (x = 0, 0.1, 0.2, 0.3, 0.4 wt%) were prepared by mechanical alloying combined with vacuum hot-pressing sintering. The corresponding microstructure, mechanical properties, and friction and wear properties under different working conditions (dry friction, oil lubrication and sulfur-containing boundary lubrication) of materials were studied. The results show that the Fe-25Mn-9Al-8Cr-1C alloy is mainly composed of the austenite phase, Cr7C3 phase, and a small amount of a-Al2O3 phase. After adding Mo element, the Fe2MoC phase appears. With the increase of Mo content, the tensile strength and elongation of the alloys increase first and then decrease. In particular, when the Mo content is 0.3 wt%, an excellent combination of strength and toughness is obtained. The product of strength and elongation of the Fe-25Mn-9Al-8Cr-1C-0.3Mo alloy reaches a maximum value of 3.69 GPa·%, which is improved by 158.04% compared with the matrix alloys. With the increase of Mo content, the average friction coefficient and volume wear rate of the alloys show a trend of first decreasing and then increasing under different working conditions. Also, the average friction coefficient and volume wear rate of the alloy with 0.3 wt% Mo reach a minimum value, especially under the condition of sulfur-containing boundary lubrication. The average friction coefficient and volume wear rate of Fe-25Mn-9Al-8Cr-1C-0.3Mo alloy are 0.051 and 0.222 × 10−4 mm3·N−1·m−1, respectively, which are 40.69% and 46.38% lower than those of the matrix alloys.

Achieving an Excellent Strength and Ductility Balance in Additive Manufactured Ti-6Al-4V Alloy through Multi-Step High-to-Low-Temperature Heat Treatment.

Selective laser melting (SLM) can effectively replace traditional processing methods to prepare parts with arbitrary complex shapes through layer-by-layer accumulation. However, SLM Ti-6Al-4V alloy typically exhibits low ductility and significant mechanical properties anisotropy due to the presence of acicular α' martensite and columnar prior β grains. Post-heat treatment is frequently used to obtain superior mechanical properties by decomposing acicular α' martensite into an equilibrium α + β phase. In this study, the microstructure and tensile properties of SLM Ti-6Al-4V alloy before and after various heat treatments were systematically investigated. The microstructure of the as-fabricated Ti-6Al-4V sample was composed of columnar prior β grains and acicular α' martensite, which led to high strength (~1400 MPa) but low ductility (~5%) as well as significantly tensile anisotropy. The single heat treatment samples with lamellar α + β microstructure exhibited improved elongation to 6.8-13.1% with a sacrifice of strength of 100-200 MPa, while the tensile anisotropy was weakened. A trimodal microstructure was achieved through multi-step high-to-low-temperature (HLT) heat treatment, resulting in an excellent combination of strength (~1090 MPa) and ductility (~17%), while the tensile anisotropy was almost eliminated. The comprehensive mechanical properties of the HLT samples were superior to that of the conventional manufactured Ti-6Al-4V alloy.

High temperature self-lubricating Ti-Mo-Ag composites with exceptional high mechanical strength and wear resistance

Titanium alloys are of keen interest as lightweight structural materials for aerospace and automotive industries. However, a longstanding problem for these materials is their poor tribological performances. Herein, we designed and fabricated a multiphase Ti-Mo-Ag composite (TMA) with heterogeneous triple-phase precipitation (TPP) structure by spark plasma sintering. A lamellar α-phase (αL) precipitates from the β-phase under furnace cooling conditions and maintains a Burgers orientation relationship (BOR) with β-matrix. An active eutectic transition also occurs in the titanium matrix, resulting in TiAg phase. The intersecting acicular TiAg and lamellar αL cut β grains into fine blocks and the primary equiaxed α phase also provides many interfaces with β phase, which together effectively impede dislocation movement and increase strength. Compared with other titanium composites, TMA with TPP microstructure gets an excellent combination of strength (yield strength 1205 MPa) and toughness (fracture strain 27%). Furthermore, the TPP structure endows TMA with strong cracking resistance, which aids in reducing abrasive debris at high temperatures during sliding and obtaining a low wear rate. Simultaneously, Ag particles distributed at grain boundaries will easily diffuse to the wear surface, in situ forming the necessary lubricating phase Ag2MoO4 with Mo-rich matrix debris via oxidation. TMA possesses excellent tribological properties with especially low wear rate of 8.0 × 10−6 mm3N−1m−1 and friction coefficient (CoF) of merely 0.20 at 600 °C. Unlike other self-lubricating composites with high volume fraction of soft ceramic lubricants, which inevitably sacrifice their mechanical strength and ductility, the composite TMA possesses well-balanced strength, toughness and self-lubricating properties. It holds important implications to design other metal matrix self-lubricating composites (MMSCs) used for load-bearing moving parts.

Effect of rolling reduction on the microstructure, texture, and mechanical behavior of AZ91 alloy

In this study, the effect of rolling reduction on the microstructure, crystallographic texture, and mechanical properties of the AZ91 alloy is studied. Optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and tensile and hardness tests were used. The homogenization process significantly increased the grain size of the as-cast sample. The results showed that {101¯2}⟨101¯1⟩ extension twinning during rolling leads to rotation of {0001}∥RD initial orientation toward {0001}‖ND basal texture. During asymmetric hot rolling up to 15%, the intensity of {0002} basal texture increased to 10 multiples of random distribution. After 15% deformation, the average grain size decreased due to the occurrence of dynamic recrystallization. It was found that by increasing the rolling reduction up to 15%, the hardness and tensile strength greatly increased owing to an increase in the fraction of twins and the intensity of basal texture. The occurrence of the CDRX mechanism and the formation of strong basal texture resulted in an excellent combination of strength and ductility for the 15% rolled sample. The as-homogenized and 8% rolled samples had the maximum and minimum inhomogeneity factor (IF), respectively. The fracture surfaces indicated that the mixture of ductile and brittle fracture is the main failure mode.

Excellent combination of strength, conductivity and ductility realized in a dilute Cu-Cr-Zr alloy by coherent nanoprecipitates

Here, by a proper design of chemical composition to provide a guarantee of excellent conductivity and high enough strength, a new dilute Cu-Cr-Zr alloy is developed. The alloy, after two-stage heavy cold rolling and subsequent aging, consists of high-density coherent or semi-coherent nanoprecipitates and exhibits a yield strength of over 600 MPa, uniform elongation about 9.0%, and conductivity about 90% IACS.

Ultrastrong High‐Ductility Ni35Co35Fe10Al10Ti8B2 High‐Entropy Alloy Strengthened with Super‐High Concentration L12 Precipitates

L12 phase hardening alloys with excellent mechanical properties are of great significance for structural applications. However, low volume fractions of L12 precipitates in conventional alloys (nearly lower than 60%) tend to limit their practical usage, while the strengths of the alloys generally increase with L12 precipitation contents. Herein, a novel high‐entropy alloy (HEA) Ni35Co35Fe10Al8Ti10B2 with ultrahigh concentration L12 precipitates is successfully designed aided by the calculation of phase diagrams (CALPHAD). The volume fraction of L12 precipitates in this HEA is up to 75% and outperforms that of most of traditional superalloys. The novel L12‐strengthened Ni35Co35Fe10Al8Ti10B2 has an ultrahigh tensile yield strength of ≈1.45 GPa, ultimate tensile strength of ≈1.9 GPa, and great ductility of ≈23% at room temperature. The desirable strength–ductility combination is superior to most of conventional superalloys and reported HEAs, mainly due to the presence of ultrahigh concentration L12 precipitates that act as dislocation obstacles and the formation of numerous stacking faults and deformation twining. This work is expected to provide guidance for developing new high‐performance HEAs with an excellent combination of strength and ductility.

Single material FDM printed nacre-like composite structure with high fracture resistance: Utilizing interface as soft phase

Nacre is known for its excellent combination of strength and toughness, which is believed to be due to its complex internal structure composed of hard mineral and soft organic matter. Here, a novel strategy for fused deposition modeling (FDM) printing of nacre-like structure is presented, in which the inherent interface between filaments is considered as the soft phase and the filament as the hard phase. The nacre-like specimens with different geometric parameters are prepared and investigated by fracture test and impact test. The results show that the fracture behavior of the nacre-like specimens is controlled by the overlap ratio and the aspect ratio. The impact strength of the nacre-like specimen with a single material is up to six times that of the injection molded one. The impact resistance originates from the generation of crack deflection. The strategy of exploiting the inherently weak interface of FDM printed materials provides a novel approach to the structural design of 3D printed composites.

Experimental Analysis of the Stability of Retained Austenite in a Low‐Alloy 42CrSi Steel after Different Quenching and Partitioning Heat Treatments

Quenching and partitioning (Q&amp;P) steels are characterized by an excellent combination of strength and ductility, opening up great potentials for advanced lightweight components. The Q&amp;P treatment results in microstructures with a martensitic matrix being responsible for increased strength whereas interstitially enriched metastable retained austenite (RA) contributes to excellent ductility. Herein, a comprehensive experimental characterization of microstructure evolution and austenite stability is carried out on a 42CrSi steel being subjected to different Q&amp;P treatments. The microstructure of both conditions is characterized by scanning electron microscopy as well as X‐ray diffraction (XRD) phase analysis. Besides macroscopic standard tensile tests, RA evolution under tensile loading is investigated by in situ XRD using synchrotron and laboratory methods. As a result of different quenching temperatures, the two conditions considered are characterized by different RA contents and morphologies, resulting in different strain hardening behaviors as well as strength and ductility values under tensile loading. In situ synchrotron measurements show differences in the transformation kinetics being rationalized by the different morphologies of the RA. Eventually, the evolution of the phase specific stresses can be explained by the well‐known Masing model.

Effect of Forming and Heat Treatment Parameters on the Mechanical Properties of Medium Manganese Steel with 5% Mn.

Medium manganese steels fall into the category of modern third-generation high-strength steels. Thanks to their alloying, they use a number of strengthening mechanisms, such as the TRIP and TWIP effects, to achieve their mechanical properties. The excellent combination of strength and ductility also makes them suitable for safety components in car shells, such as side reinforcements. Medium manganese steel with 0.2% C, 5% Mn, and 3% Al was used for the experimental program. Sheets with a thickness of 1.8 mm without surface treatment were formed in a press hardening tool. Side reinforcements require various mechanical properties in different parts. The change in mechanical properties was tested on the produced profiles. The changes in the tested regions were produced by local heating to an intercritical region. These results were compared with classically annealed specimens in a furnace. In the case of tool hardening, strength limits were over 1450 MPa with a ductility of about 15%.

The Effect of Annealing Temperature and Temper‐Rolling on Microstructure, Mechanical Properties, and Lüders Strain of Fe–0.25C–5.9Mn–1.0Al–1.57Si Medium Mn Steel

This study investigates the effect of austenite reverted transformation (ART) annealing temperature and temper‐rolling on the microstructure, mechanical properties, and deformation behaviors of cold‐rolled Fe–0.25C–5.9Mn–1.0Al–1.57Si transformation‐induced plasticity (TRIP) steel. The cold‐rolled steel annealed at 700 °C demonstrates excellent mechanical properties. The ultimate tensile strength, total elongation, and product of strength and elongation are observed as 1212 MPa, 31.8%, and 38.6 GPa%, respectively. The excellent combination of strength and ductility is related to the discontinuous TRIP effect; still, an inhomogeneous deformation is observed during tensile deformation, known as the Lüders strain. Temper‐rolling is used for the ART‐annealed specimens at 700 and 720 °C, and yield point elongation decreases when temper‐rolling reduction increases. When the temper‐rolling reduction increases by 8%, the yield point elongation of the specimen annealed at 700 °C is noted at 1%, while the specimen annealed at 720 °C exhibits continuous yielding. The strain‐induced martensite transformation and increased dislocation density in the ferritic matrix improve the early‐stage strain hardening rate, thus suppressing the Lüders band's formation.