Uniform Elongation Research Articles

Hierarchical structured Zn-Cu-Li alloy with high strength and ductility and its deformation mechanisms

Although Zn-based alloys exhibit great potential as biodegradable implants due to their moderate degradation rate and acceptable biocompatibility, the mechanical property is insufficient to meet medical applications. In this study, a Zn-2Cu-0.8Li (wt%) alloy with both high strength and high ductility is developed via a unique hierarchical structure. The alloy is composed of a hard micron-sized β-LiZn4 matrix, a soft submicron η-Zn phase and dispersive ε-CuZn4 nanoprecipitates. The ε-CuZn4 nanoprecipitates grow along the specific direction and exhibit a coherent interface with the matrix. During the room-temperature tensile deformation, continuous dynamic recrystallization (CDRX) related to dislocation absorption and preferential misorientation increase near grain boundaries, as well as 〈c + a〉 dislocations, are observed. The excellent strength of the alloy is mainly attributed to the hard β-LiZn4 matrix with fine grains and the dispersive ε-CuZn4 coherent nanoprecipitates. Simultaneously, favorable ductility is ensured by the deformable matrix with fine grains, and further improved by the activated CDRX, 〈c + a〉 slip and soft submicron η-Zn phase. Owing to the unique hierarchical microstructure, Zn-2Cu-0.8Li alloy exhibits a yield strength of 426.2 MPa, ultimate tensile strength of 472.2 MPa, uniform elongation of 43.7% and fracture elongation of 63.7%, showing great prospects for broader biomedical applications. This research proposes a significant strategy for the design of Zn alloys with excellent combination of high strength and ductility.

Local control of microstructure and mechanical properties of high-strength steel in electric arc-based additive manufacturing

Additive manufacturing offers a significant potential for producing metallic parts with distinctly localised microstructures and mechanical properties, commonly known as functional grading. While functional grading is generally accomplished through compositional variations or in-situ thermo-mechanical treatments, variation of process parameters during additive manufacturing can offer a promising alternative approach. Focusing on the electric arc-based additive manufacturing process, this work focuses on the functional grading of high-strength steel (S690 grade) by adjusting the travel speed and inter-pass temperature. Through a combination of thermal simulations and experimental measurements on single bead-on-plate depositions, it is shown that the microstructure and the mechanical properties of parts can be controlled through the rational adjustment of process parameters. A rectangular block was fabricated to demonstrate functional grading using a constant wire feed rate and varying travel speed. The rectangular block consisted of a low heat input (LHI) region deposited between high heat input (HHI) zones. A graded microstructure was obtained with the HHI zones composed of a mixture of polygonal ferrite, acicular ferrite, and bainite, while the LHI region was primarily composed of martensite. The hardness and profilometry-based indentation plastometry measurements indicated that the LHI region exhibited higher hardness (32%) and strength (50%), but lower uniform elongation (80%), compared to the HHI zones. The present study demonstrates the potential to achieve functional grading by adjusting process parameters in electric arc-based additive manufacturing, providing opportunities for tailor-made properties in parts.

Improving strain hardening capacity of high-strength Ti–6Al–4V alloy by a dual harmonic structure

By TiH2/Al60V40 powder processing, in-situ dehydrogenation, and powder compact extrusion, we successfully fabricate a Ti–6Al–4V (wt.%) alloy with a dual harmonic structure. Such multilevel structural heterogeneity is attained by suppressing the stabilization effect of the residual hydrogen on β-Ti phase, through controlling the prior β grain sizes and interstitial element contents. It is demonstrated that this dual harmonic structure is beneficial in alleviating mechanical mismatch between hetero-domains and fully exploiting the hetero-deformation induced hardening, thereby leading to a high strain hardening rate and large uniform elongation. As a result, the material exhibits a better strength-ductility synergy (an ultimate tensile strength of 1338 MPa and a uniform elongation of 7.7%) than both the one-level harmonic and homogeneously structured materials. The present ‘tailoring structural heterogeneity through manipulating hydrogen-enabled eutectoid transformation’ strategy offers a different pathway to design and fabricate novel heterogeneously structured titanium alloys with a high strength-ductility synergy.

Strengthening mechanisms of a heterostructured pure aluminum with extraordinary mechanical properties

To achieve superior mechanical properties in metallic materials, one promising way is to make them into heterogeneous structures (HS). In this work, a novel HS including grain size and dislocation density is developed in commercial pure aluminum through cold-rolling and subsequent partial annealing processes. Tensile tests show that the HS specimen, annealed at 150 °C for 2 min with ~31.1% recrystallized grains, have a high yield strength of ~121 MPa and a good uniform elongation of ~8.5%. The yield strength increases by 10% and the ductility increases by 7 times compared with the as-rolled specimen, respectively. Detailed microstructure characterizations confirm that a significant strain gradient was generated near the interface between the hard zone and soft zone, in which the slip and plugging of geometrically necessary dislocations act as an important role in the abnormal hardening and strengthening phenomena of the HS specimen. To quantify the specific contribution of each strengthening mechanism, we compare the experimental measurements with the theoretical calculations and confirm that the multiple deformation modes are activated by the deformation stress. The hetero-deformation-induced hardening and strengthening effects are responsible for the superior mechanical properties of the heterostructured pure aluminum.

Analysis of the AISI 316 stainless steel sheet response to sub-zero deformation temperatures

Sheet forming carried out at sub-zero temperatures is gaining interest for deforming metal sheets to increase formability while avoiding the need for subsequent heat treatments after forming at elevated temperatures. This paper investigates the feasibility of conducting sub-zero deformation on AISI 316 stainless steel sheets at temperatures ranging from −100 °C to 700 °C at varying rolling directions. The mechanical and microstructural features were evaluated after deformation as well as the corrosion resistance. The obtained results showed that deformation at −50 °C induced a substantial increase of the uniform elongation and slightly higher hardness, but lower corrosion resistance, compared to testing at room temperature and at 300 °C and 700 °C.

Microstructural evolution and mechanical properties of multilayered ARB6/3/6 2N Al processed by accumulative roll bonding

The multilayered 2N (99.2% purity) Al sheets containing 3-cycle ARB processed layers (shorted as ARB3 layer) with low strain and 6-cycle ARB processed layers (shorted as ARB6 layer) with high strain were prepared by accumulative roll bonding (ARB) process. The multilayered 2N Al (referred as ARB6/3/6 Al) sheets were further annealed at various temperatures. The effect of annealing process on the microstructures and mechanical properties of the multilayered ARB6/3/6 Al were systematically studied and compared with a conventional ARB6 2N Al. Recrystallized grains and grains coarsening are more pronounced in ARB6 layers comparing with the ARB3 layers due to high total strain in ARB6 layers. The ultimate tensile strength and uniform elongation of ARB6/3/6 are 219 MPa and 2.4%, respectively. Both decreasing trends of normalized strength are almost similar in ARB6 Al and ARB6/3/6 Al after annealing, while the elongation in ARB6/3/6 Al recover more rapidly than ARB6 2N Al due to the suppression of the early necking.

Strengthening 5A02 Al alloy via gradient structures processed by severe torsional deformation

5A02 Al alloys with gradient structures were designed by controlling the number of torsional revolutions of 1, 2, 4, and 8. The results showed that the yield strength increased and the uniform elongation decreased with the increasing torsional revolution. Preferable comprehensive properties with yield strength of 196.7 ± 3.7 MPa and uniform elongation of 1.9 ± 0.2 % were obtained at the torsional revolution of 4. It is revealed that the increment in yield strength contributed by HDI stress, grain refinement and the introduction of dislocations, in which dislocation strengthening played the major role. The ductility came from HDI hardening and the strain hardening ability of the center region with low dislocation density. The finding provided a promising and cost-effective method to enhance mechanical properties of Al alloys by tailoring gradient structures.

Microstructural heterogeneity and exceptional mechanical properties in a wire-arc additively manufactured stainless steel

Wire arc additive manufacturing (WAAM), thanks to the utilization of the electric arc as an energy source and metal wire as feedstock, has become one of the most cost-effective industrial-scale additive manufacturing techniques. The present study investigates the origin of the superior room temperature mechanical properties of AISI 316L stainless steel fabricated using WAAM. The yield strength (450 MPa ± 20 MPa) and uniform elongation (41.2% ± 2.5%) of the specimens extracted from the printed part are well higher than those reported in the case of conventionally manufactured counterparts. The findings from microstructural and elemental analyses reveal that the achieved non-equilibrium microstructure falls into the categories of dual-phase, periodic layered, and harmonic hetero-structured materials. In this respect, the contribution of hetero-deformation induced (HDI) strengthening in overall strength is determined to be 61.3 ± 2.2% through the loading-unloading reloading test.

Designing gradient nanograined dual-phase structure in duplex stainless steel for superior strength-ductility synergy

Similar to other metallic materials, duplex stainless steel dramatically loses its advantage of high ductility as they are strengthened. Here, we produce a gradient nanograined dual-phase structure in the 2101 duplex stainless steel, thus facilitating a superior strength-ductility synergy: a yield strength of 1009.5 MPa being two times higher than that of the as-received sample, a total elongation of 23.4% and a uniform elongation of 5.9%. This novel structure is produced through a processing route of ultrasonic severe surface rolling and annealing, which realizes a superposition of gradient nanostructure and lamellar dual-phase structure with austenite and ferrite. During the tension deformation of gradient nanograined dual-phase structured duplex stainless steel, a significant accumulation of geometrically necessary dislocations occurs. These dislocations are formed to accommodate the deformation incompatibility caused by the layer-by-layer difference in strength and hardness of individual phase domains, as well as the inherent difference in properties between the austenite and ferrite domains. This results in a stronger hetero-deformation induced strengthening and hardening significantly contributing to superior mechanical properties. Our study provides a new avenue to develop advanced steels with high strength and ductility.

Strong yet strain-hardenable equiatomic CoCrFeMnNi high-entropy alloys by dynamic heterostructuring

Heterostructuring gives solutions to achieve better mechanical performance of metallic materials. For instance, partial static recrystallization by short-term annealing induces bimodal grain size distribution. Distinct from the well-studied ‘static heterostructuring’ by cold rolling followed by annealing, this study introduces ‘dynamic heterostructuring’ by hot rolling. Dynamic recrystallization (DRX) during the hot rolling as a softening mechanism leaves room for dislocation accumulation. With the expectations of enhanced strain hardening of the as-rolled materials with the aid of the DRX, we monitored tensile responses of the as-hot-rolled equiatomic CoCrFeMnNi high-entropy alloys (HEAs). Among the hot rolling temperatures from 800 ℃ to 900 ℃ with a thickness reduction ratio of 78.6% for the HEAs, the hot rolling at 850 °C results in a bimodal grain size distribution, i.e., partial DRX. It comprises relatively fine DRXed grains and coarse unrecrystallized grains: the latter is harder than the DRXed ones with relatively low dislocation density. The microstructural heterogeneity results in uniform elongation of ∼13% due to the accumulation of dislocations at the grain boundaries inside the soft DRXed grains. This endows the as-hot-rolled single-phase HEAs with strain hardenability without the aid of phase transformation, deformation twinning, or precipitates. In addition, the hot-rolled HEAs with high dislocation density have doubled yield stresses of those of conventionally cold-rolled and annealed counterparts. Considering the industrial benefits of the simplified thermo-mechanical control processes, this work extends the academic and practical value of DRX by dynamic heterostructuring through annealing-free hot rolling.

Experimental assessment on cyclic flexural behavior of UHPC beam reinforced with negative Poisson’s ratio (NPR) steel rebar

The objective of this study is to experimentally explore the implication of an innovative steel rebar with negative Poisson’s ratio effect (termed as NPR steel rebar) on ultra high performance concrete (UHPC) beam under cyclic loading. Distinctly from conventional steel rebar, NPR steel rebar employed in this research inherently owns high ultimate tensile strength of approximately 1100 MPa, high uniform elongation of around 40% and superior durability. Four reinforced UHPC beams are conducted and tested under monotonic/cyclic loading through the four-point bending method. The structural characteristics of all specimens are discussed via failure mode, hysteretic curve, envelop response, stiffness degradation, energy-dissipating capacity, and steel strain evolution and etc. The results show that reinforced UHPC beam longitudinally configured with NPR steel rebar is available to exhibit satisfactory and superior monotonic/cyclic flexural performance. Firstly, the final failure mode of reinforced UHPC beam with NPR steel rebar exhibits multiple (7–8) closely-spacing localized cracks distributing within the pure bending section whether under monotonic or cyclic loading. Additionally, the superior mechanical performance of NPR steel rebar endows reinforced UHPC beam with high flexural capacity, high deformability, excellent stiffness degradation control, and outstanding energy dissipation capacity under cyclic loading. In which, the flexural capacity of UHPC beams reinforced with NPR steel rebar have been upgraded approximately by 47.8%, 52.3% under monotonic and cyclic loading respectively, compared with that of UHPC beams reinforced with HRB 400 steel rebar, meanwhile, the comparison for the energy dissipation capacity is emphasized in stages. Finally, the deflection prediction method for UHPC beam reinforced with NPR steel rebar at normal service stage under monotonic/cyclic loading is proposed. The results of this study provide valuable information for attaining a preliminarily comprehensive understanding of the structural behavior of reinforced UHPC members with NPR steel rebar under monotonic/cyclic loading, and the proposed combination of UHPC and NPR steel rebar provides a new idea for seismic toughness design of anti-bending structural components as well.

Simultaneously increasing mechanical and corrosion properties in CoCrFeNiCu high entropy alloy via friction stir processing with an improved hemispherical convex tool

It generally shows the trade-off for the mechanical properties and corrosion resistance of high entropy alloys (HEAs). In this study, friction stir processing (FSP) with an improved hemispherical convex tool was applied to process the as-cast CoCrFeNiCu HEA, which simultaneously increased the mechanical properties and corrosion resistance of the HEA by a large degree. After FSP, the grains were significantly refined from 6 μm to ∼300 nm, with 91% of high angle grain boundaries and 18% of nanometer twins, leading to a remarkable increase in the yield strength from ∼194 MPa to ∼935 MPa. More importantly, the FSP HEA showed an excellent strength-ductility synergy with yield strength of ∼695 MPa and a uniform tensile elongation of ∼17.5% after annealing, which was mainly attributed to the comprehensive role of equiaxed ultrafine microstructure, second phase and the high fraction of annealing twins (27%). In addition, the FSP HEA showed higher corrosion resistance than the base material by electrochemical test, which was mainly attributed to the improvement of the self-corrosion potential and the stability of the passivation film caused by the mitigation of Cu segregation and grain refinement. This study provides a new way to simultaneously increase the mechanical properties and corrosion resistance in HEAs.

Cost-effective and facile route to ultrafine-microstructure high-entropy alloy for cryogenic applications

Industry applications of the current cryogenic high entropy alloys (HEAs) are limited by their prohibitive costs, relatively low yield strength and unknown corrosion resistance. Here, we present a cost-effective and facile approach to produce cryogenic HEAs with lower cost, exceptional mechanical properties and corrosion resistance. The key is to design a cost-effective Fe35Ni35Cr20Mo5Al5 HEA and introduce ultrafine microstructure (UFM), including ultrafine grains (∼693 nm), high density of annealing twins and nanoprecipitates, into the alloy by manipulating the concurrent precipitation and recrystallization at 940 °C within 2 min. The cost-effective UFM-HEA exhibits a temperature-dependent strain-hardening capacity and a superior strength-ductility synergy at 77 K with a yield strength of ∼1165 MPa, a tensile strength of ∼1412 MPa and a uniform elongation over 20%. The superior tensile properties at cryogenic temperature are attributed to the twining-dominated multiple deformation mechanisms and the integrated strengthening effects, including grain refinement strengthening, twin strengthening and second-phase strengthening. At the fracture strain of ∼20%, extensive microcracks formed within the nanoprecipitates without propagating into the face-cantered-cubic matrix, suggesting a high crack tolerance of the UFM-HEA at both room and cryogenic temperatures. Moreover, the UFM-HEA has a superior corrosion resistance compared to the 316L stainless steel due to the larger passivity region and higher charge transfer resistance. Such outstanding cryogenic mechanical properties and corrosion resistance together with the lower cost make the UFM-HEA superior to most cryogenic HEAs. This strategy not only sheds light on the development of new-generation cryogenic HEAs but also significantly enhances their industrial application potential.

Tensile instability and limit strain behavior of explosion-welded steel/Al plate considering interface defect characteristics

Explosion-welded steel/Al composite plate has advantages of excellent conductivity, heat conductivity, light weight, and corrosion resistance. While the elongation of explosion-welded steel/Al composite plate can not been predicted by the traditional damage fracture theory. Establishing a new prediction model to analyze the deformation behavior of steel/Al composite plate are necessary. First, the deformation behavior and interface microscopic characteristics of explosion-welded steel/Al composite plate were analyzed using uniaxial tensile tests and SEM experiments, the result showed that wave structure, brittle phase, and microcrack existed at the interface layer of composite plate, the uniform elongation and elongation of steel/Al composite plates basically deviate linearly from the mixing law. Second, simulation models were established to analyze the effect of interface wave structure, brittle phase, and interface microcracks on the instability and fracture behavior of explosion-welded steel/Al composite plate. The interface wave structure could enhance the elongation of the composite plate, while the uniform elongation of the composite plate decreased with the increasing of brittle phase and microcrack. When f0 = 0.985, the predicted tensile strength through simulation is 258.94 MPa, which only has a difference of 1.9 MPa from the experimental value, when the length of the crack increases from 0.03 mm to 0.2 mm, the uniform elongation of the composite plate decreases by 92.52%. Finally, M−K theory considering the characteristics of interface defects was established to predict the tensile instability behavior of steel/Al composite plates. The instability behavior of the composite plate considering interface defects could be accurately described using the modified M−K theory when the height of the interface groove of the composite plate was Δta/Δts=ha/hs and Δta+Δts=0.5mm.

Effects of layer thickness on deformation-induced martensite transformation and tensile behaviors in a multilayer laminate

Multilayer laminates with a 304 stainless steel as surface layers and with a low C steel and a medium-Mn steel as alternating central layers have been developed in the present study. The number of interfaces and the layer thickness have been varied, while maintaining the similar microstructures for each layer. The uniform elongation is observed to increase from 10.1% to 37.8%, and the product of strength and elongation is found to increase from 13.6 GPa·% to 36.8 GPa·% monotonically with decreasing layer thickness in multilayer laminates, while the yield stress remains almost constant. Firstly, deformation-induced martensite transformation is significantly promoted with decreasing layer thickness. Secondly, the more interfaces can induce the accumulation of higher density of geometrically necessary dislocations, resulting in better mechanical properties. Lastly, the main cracks nucleate and propagate at the interfaces of low C steel layers and medium Mn steel layers, thus the samples with smaller layer thickness have more interfaces and require more energy consumption during the micro-fracture process, resulting in better tensile performance.

Strength-ductility synergy and grain refinement mechanisms in a Co-Cr-Ni medium-entropy alloy with novel analogous harmonic structure

A novel strategy is implemented to enhance the strength-ductility synergy in the Co-Cr-Ni-based medium-entropy alloy (MEA) by designing analogous harmonic structures (AHS), where the soft face-centered cubic (FCC) matrix is surrounded by hard multiphase constitutes. The high yield strength of 1028 MPa and ultimate tensile strength of 1558 MPa coupled with considerable uniform elongation of 20% are achieved for the AHS-MEA. Upon uniaxial tension, a large number of the nanograins appear in the core near the interface meanwhile the hard σ precipitates are penetrated by the mobile dislocations in the shell. A finite-element based model is developed to elucidate the intrinsic mechanisms underlying microstructure evolution during plastic deformation. Similar to the equal channel angular pressing/extrusion and high pressure torsion, the coexistence of large tensile hydrostatic stresses and shear stresses plays a crucial role in the grain refinement. The study provides new insights into the nanocrystalline formation mechanism and excellent strength-ductility synergy.

Superior mechanical properties and microstructural evolution of powder metallurgy 2195 Al-Li alloy subjected to hot extrusion

In this paper, the microstructural evolution, precipitation behavior and mechanical properties of 2195 Al-Li alloys prepared by powder metallurgy (PM) combined with hot extrusion were investigated systematically. The results show that the deformation of PM 2195 Al-Li alloys during hot extrusion is dominated by the coupling of dynamic recovery with continuous dynamic recrystallization. The homogeneously distributed needle-like T1 phase is precipitated in the matrix after T6 treatment. The T6-treated sample exhibits a perfect combination of strength and ductility, that is, ultimate tensile strength of 662 MPa, yield strength of 617 MPa and uniform elongation of 6.6 %. The strengthening of heat-treated alloys originates from densification, work hardening, grain refinement and precipitation strengthening. It is noted that the precipitation strengthening of T1 phase is the dominant mechanism. Therefore, this work should suggest a strategy for developing novel Al-Li alloys with excellent mechanical properties.

Effect of through-thickness microstructure inhomogeneity on mechanical properties and strain hardening behavior in heavy-wall X70 pipeline steels

The ever-increasing demand for oil & gas exploration from land to subsea necessitates using higher-strength and high-ductility heavy-wall thickness pipes, which may increase the microstructural inhomogeneity along the steel plate sections, ultimately impacting the mechanical properties. In this work, the differences in microstructure and mechanical properties between the through-thickness layers of a heavy-wall ferrite/bainite (F/B) dual-phase (DP) X70 pipeline steel plate were studied. The results showed that the size of the ferrite grain and the volume fraction of bainite increased from the surface layer to the mid-thickness layer of the DP X70 pipeline steel plate. The surface and mid-thickness layers had a lower uniform elongation and higher strength and hardness. In comparison, the quarter layer had higher uniform elongation and lower strength and hardness. The refined grain size and the strong {001}<110> texture were responsible for enhanced in strength and hardness. The higher γ-fiber texture at the quarter layer favored the higher plasticity. The analysis results of strain-hardening behaviors based on the modified C-J model showed that the mid-thickness layer had a higher strain-hardening capacity at the beginning of the plastic strain, leading to deformation instability and reduced material plasticity. The surface layer maintained a high hardening exponent even at high plastic strains, which facilitated the deformation properties of the material. The results provide a basis for evaluating the influence of microstructural factors on the strength and plasticity of heavy-wall X70 pipeline steel and the coordination mechanism of micro deformation in DP steels.

A new grain refinement route for duplex stainless steels: Micro-duplex stainless steel matrix composites processed by laser powder bed fusion

The employment of grain refinement approaches is regarded as a favorable strategy to increase mechanical properties of duplex stainless steels (DSSs). In this work, a new grain refinement route was successfully developed via laser powder bed fusion (LPBF) of micro-duplex stainless steel (SS) matrix composites along with a subsequent quenching process. For as-built composites, TiCxNy nanoparticles were first formed in-situ via the introduction of submicron/micron-sized TiC particles with low cost into 2205 DSSs, and fine equiaxed high-temperature ferrite (δ-ferrite) grains were formed due to the ultra-high cooling rate of LPBF and heterogeneous nucleation sites provided by in-situ formed TiCxNy nanoparticles. The formation of TiCxNy nanoparticles inhibited the epitaxial growth of δ-ferrite grains, and no obvious textures were found in as-built composites. Subsequently, fine austenite grains were produced at grain boundaries of fine unrecrystallized δ-ferrite during quenching treatment of as-built composites, which enabled heat-treated composites to achieve an ensemble of outstanding ultimate tensile strength and uniform elongation. The δ-ferrite recrystallization was mainly inhibited by the existence of TiCxNy nanoparticles. This study can provide a groundwork for designing grain refinement methods to produce high-performance DSS parts with complex geometry based on LPBF technique.

Microstructure and mechanical properties of the laminated heterostructured material with 316L stainless steel/18Ni300 maraging steel fabricated by WAAM

Heterostructured materials (HMs) have attracted extensive interest due to their excellent properties, and additive manufacturing presents great potential in fabricating HMs. A laminated HM (LHM) was prepared by wire and arc additive manufacturing with alternating deposition of 316L stainless steel (SS) and 18Ni300 maraging steel (MS). The microstructure, chemical composition, texture and mechanical properties of the LHM thin walls were investigated and compared with those of the corresponding single-material thin walls. Remelting and mixing of the previously deposited layer caused deviations in the chemical composition in both regions. The 18Ni300 MS region microstructure was composed of austenite and martensite phases with the K-S orientation relationship, and the 316L SS region microstructure consisted of the austenite phase. All samples exhibited obvious austenite phase epitaxial growth, causing grains with the same orientation to pass through multiple deposited layers. The cubic texture in the as-fabricated 316L SS sample disappeared in the 316L SS region of the LHM samples. The Goss texture intensity in the 18Ni300 MS region decreased compared with that in the 18Ni300 MS thin walls, from 20.6 to 6.36. The 18Ni300 MS region microhardness of the LHM samples of 263 HV was lower than that of the 18Ni300 MS sample due to the lower-hardness austenite phase. The ultimate tensile strength of the LHM samples was 635.25 ± 31.1 MPa, which was between those of 316L SS and 18Ni300 MS. The uniform and total elongations of the LHM samples were 19.85 ± 3.6% and 29.2 ± 2.3%, which were higher than the mixing law-calculated values. The plasticity improvement was attributed to transformation-induced plasticity and stress state variation. In the initial plastic deformation stage, the 18Ni300 MS region underwent more plastic strain with a high dislocation density, causing the strain-induced martensitic transformation. The 316L SS region was strengthened with high strain, and its necking caused stress state conversion from uniaxial to multiaxial stress.