Large Uniform Elongation Research Articles

Evading the strength-ductility trade-off dilemma in high-entropy alloy by lamellar structure

Constructing lamellar structures in high-entropy alloys (HEAs) is an effective strategy for addressing the inherent trade-off between strength and ductility. However, conventional processing methods often struggle to achieve precise control over the microstructures and mechanical properties of the lamellar structures. Here, we employ laser remelting technology to successfully fabricate a lamellar structure within an HEA. The lamellar HEA shows an excellent yield strength of ∼547 MPa with a large uniform elongation of ∼41 %. Such enhanced strength-plasticity synergy is mainly attributed to the hetero-deformation of lamellar structures.

Effect of martensite hardness on mechanical properties and stress/strain-partitioning behavior in ferrite + martensite dual-phase steels

Low-carbon dual-phase (DP) steels composed of ferrite and martensite are widely used in automotive industries due to their good combination of strength and ductility and remarkable strain-hardening ability. Such exceptional mechanical properties of DP steels arise from microstructural deformation heterogeneity due to the different deformation roles of soft ferrite and hard martensite. The present study investigated mechanical properties and local deformation behavior of DP steels having different martensite hardness (strength) using digital image correlation (DIC) technique and in-situ X-ray diffraction (XRD) experiment during tensile deformation. The martensite hardness was reduced by tempering treatment, and its mechanical properties were compared with the as-quenched DP specimen by tensile testing. The tempered DP specimen exhibited reduced strength but enhanced ductility, especially in post-uniform elongation, compared to the as-quenched DP specimen. DIC-strain analysis indicated that the tempering effectively inhibited strain localization, allowing a greater contribution of martensite to plastic deformation. On the other hand, the in-situ XRD analysis revealed that the tempering significantly restricted the stress-increasing potential of martensite. Our results suggest that martensite, acting as a hard domain, plays a significant role in enhancing strain-hardening ability and achieving large uniform elongation due to its high stress-increasing potential. However, the presence of hard martensite also imposes restrictions on post-uniform elongation due to the strong strain localization induced in microstructures.

An order-disorder core-shell strategy for enhanced work-hardening capability and ductility in nanostructured alloys

Nanocrystalline metallic materials have the merit of high strength but usually suffer from poor ductility and rapid grain coarsening, limiting their practical application. Here, we introduce a core-shell nanostructure in a multicomponent alloy to address these challenges simultaneously, achieving a high tensile strength of 2.65 GPa, a large uniform elongation of 17%, and a high thermal stability of 1173 K. Our strategy relies on an ordered superlattice structure that excels in dislocation accumulation, encased by a ≈3 nm disordered face-centered-cubic nanolayer acting as dislocation sources. The ordered superlattice with high anti-phase boundary energy retards dislocation motions, promoting their interaction and storage within the nanograins. The disordered interfacial nanolayer promotes dislocation emission and effectively accommodates the plastic strain at grain boundaries, preventing intergranular cracking. Consequently, the order-disorder core-shell nanostructure exhibits enhanced work-hardening capability and large ductility. Moreover, such core-shell nanostructure exhibits high coarsening resistance at elevated temperatures, enabling it high thermal stability. Such a design strategy holds promise for developing high-performance materials.

Microstructural origins of enhanced work hardening and ductility in laser powder-bed fusion 3D-printed AlCoCrFeNi2.1 eutectic high-entropy alloys

Limited tensile ductility usually restricts the practical applications of new classes of high-strength materials in many industrial fields. Therefore, in-depth understanding of the work hardening behavior and its underlying plastic deformation mechanism are critical for the newly developed high-entropy alloys (HEAs). In this work, a geometric atomistic model of face-centered cubic (FCC)/ordered body-centered cubic (BCC (B2)) interfaces and the evolution of dislocation substructures have been investigated to explore the microstructural origins of work hardening responses for two additively manufactured AlCoCrFeNi2.1 eutectic high-entropy alloys (EHEAs) with the respective lamellar and cellular microstructures. Unlike the lamellar interphase interfaces with the most classical Kurdjumov-Sachs (KS) FCC-BCC relationship of {111}FCC∥{110}B2〈011〉FCC∥〈111〉B2, the Nishiyama-Wassermann (NW) relationship, namely {111}FCC∥{110}B2〈011〉FCC∥〈001〉B2, is observed to be dominant on the cellular interphase interfaces. Furthermore, our intermittent high-resolution transmission electron microscopy (HR-TEM) results directly show that the deformation of lamellar AlCoCrFeNi2.1 alloy first proceeds with massive stacking faults (SFs) and then dislocation walls developed across phases interfaces, due to the effective dislocation transfer capability of lamellar boundaries. The large uniform elongation of the cellular AlCoCrFeNi2.1 alloy is attributed to the stable and progressive strain-hardening mechanism that is stemmed from the activated multiple slip systems, deformation-induced SF networks, and the associated Lomer-Cottrell locks in the middle and later stages of plastic deformation. Moreover, the nano-bridging of FCC cells in the 3D-printed microstructure provides unique channels for dislocation movement, which offsets the “blocking effect” of cellular boundaries and thus suppresses the pre-mature fracture.

Enhanced strength-ductility synergy in pure Cu through the design of alternating coarse-grained and nanostructured layers

Heterogeneous micro/nano laminated structure (HM/NLS) design has emerged as a promising strategy for circumventing the strength-ductility trade-offs in nanostructured metals. However, most of reported HM/NLSed metals are mainly prepared from two dissimilar metals, which make it challenging to fully understand the deformation mechanisms of HM/NLS due to the complicated coupling of microstructural and compositional difference between component layers. Here, a series of HM/NLSs, consisting of alternating coarse-grained (CGed) and nanostructured (NSed) layers with varied thickness ratio (RCGed/NSed) of CGed layers to NSed layers, have been designed and introduced into pure Cu, which aim to exclude the influence of compositional difference between component layers and investigate the effect of microstructural difference on the deformational behavior of HM/NLSed metals independently. The effects of RCGed/NSed on the mechanical property of HM/NLSed Cu were investigated and an optimized strength-ductility synergy was achieve when RCGed/NSed = 2:3. Loading-unloading-reloading tests and in situ EBSD characterization reveal that the huge microstructural discrepancy between the neighboring CGed and NSed layers promotes dislocations accumulation and produces strong back stress strengthening during plastic deformation, thereby achieving a high yield strength ∼296 MPa and large uniform elongation of ∼18%. The results of this work will provide a viable approach for fabricating high-performance HM/NLSed metals and deepen the understanding of the underlying deformation mechanisms of HM/NLSed metals.

Simultaneous improvement of strength and ductility in a P-doped CrCoNi medium-entropy alloy

A newly developed P-doped CrCoNi medium-entropy alloy (MEA) provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA, even superior tensile ductility to the other-element-doped CrCoNi MEAs at similar yield strength levels. P segregation at grain boundaries (GBs) and dissolution inside grain interiors, together with the related lower stacking fault energy (SFE) are found in the P-doped CrCoNi MEA. Higher hetero-deformation-induced (HDI) hardening rate is observed in the P-doped CrCoNi MEA due to the grain-to-grain plastic deformation and the dynamic structural refinement by high-density stacking fault-walls (SFWs). The enhanced yield strength in the P-doped CoCrNi MEA can be attributed to the strong substitutional solid-solution strengthening by severer lattice distortion and the GB strengthening by phosphorus segregation at GBs. During the tensile deformation, the multiple SFW frames inundated with massive multi-orientational tiny planar stacking faults (SFs) between them, rather than deformation twins, are observed to induce dynamic structural refinement for forming parallelepiped domains in the P-doped CoCrNi MEA, due to the lower SFE and even lower atomically-local SFE. These nano-sized domains with domain boundary spacing at tens of nanometers can block dislocation movement for strengthening on one hand, and can accumulate defects in the interiors of domains for exceptionally high hardening rate on the other hand.

Dual nanoprecipitation and nanoscale chemical heterogeneity in a secondary hardening steel for ultrahigh strength and large uniform elongation

Nanoprecipitates and nanoscale retained austenite (RA) with suitable stability play crucial roles in determining the yield strength (YS) and ductility of ultrahigh strength steels (UHSSs). However, owing to the kinetics incompatibility between nanoprecipitation and austenite reversion, it is highly challenging to simultaneously introduce high-density nanoprecipitates and optimized RA in UHSSs. In this work, through the combination of austenite reversion treatment (ART) and subsequent flash austenitizing (FA), nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging process. This chemical heterogeneity involved the enrichment of Mn and Ni in the austenite phase. The resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn) and (Mo,Cr)2C and nanoscale austenite stabilized via Mn and Ni enrichment. The hard martensitic matrix strengthened by high-density dual-nanoprecipitates constrains the plastic deformation of soft RA with a relatively low fraction of ∼15 %, and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity (TRIP) effect. As a result, the newly-developed UHSS exhibits an ultrahigh YS of ∼ 1.7 GPa, an ultimate tensile strength (UTS) of ∼1.8 GPa, a large uniform elongation (UE) of ∼8.5 %, and a total elongation (TE) of ∼13 %. The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.

Investigations of microstructure and tensile properties of neutron irradiated 6061 aluminum alloys

Effects of neutron irradiation on the microstructure and mechanical properties of CMRR (China Mianyang Research Reactor) structural material pure aluminum and 6061 alloy were studied by scanning/transmission electron microscopy (S/TEM) and tensile tests. The fast neutron (E > 0.1 MeV) fluences of 1.09–2.89 × 1022 n•cm−2 produced damage doses of 1.6–4.2 displacements per atom (dpa). Voids and faulted 1/3<111> dislocation loops were observed in both pure aluminum and 6061 alloy. In particular, voids tended to preferentially aggregate on coarse Cu-rich and fine Mg2Si precipitates which contributes to the higher irradiation tolerance in terms of void formation for 6061 alloy, suggesting that the uniformly distributed precipitates can act as trapping sites for defect clusters during irradiation and thus promote recombination. The size and density of Mg2Si precipitates showed a slight increase and Cu-rich precipitates emerged in 6061 alloy after neutron irradiation. Moreover, radiation-induced segregation was also detected along the grain boundaries. After tensile testing, the pure aluminum showed a lower yield strength and larger uniform elongation than 6061 alloy, where a moderate uniform elongation was still reserved after irradiation to 4.2dpa. The severely reduced ductility in 6061 alloy is supposed to be caused by the transmutation product silicon which contributes to the increase of dispersed multiple precipitates after irradiation. Our results indicate that precipitates especially Mg2Si play a decisive role in void suppression, but are not suitable in diminishing the radiation hardening.

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.

Laser additive manufacturing of strong and ductile Al-12Si alloy under static magnetic field

Rapid cooling and solidification during laser additive manufacturing (LAM) can produce ultra-fine microstructure with higher strength. However, the non-uniform cell/grain structure can easily result in early stress concentration and fracture during deformation, which remains a major challenge for the LAM field. Using Al-12Si as the model alloy, we employed the external static magnetic field (SMF) to modulate the laser powder bed fusion process (L-PBF), demonstrating a uniform microstructure with a refined cell structure. The mechanical properties show that the SMF can produce a combination of high tensile strength of 451.4 ± 0.5 MPa and large uniform elongation of 10.4% ± 0.79%, which are superior to those of previously-reported Al-Si alloys with post-treatment or element alloying. The mechanism analysis based on multi-scale simulation reveals the determining role of SMF in rapid solidification, and this method is applicable to the microstructure control of other metallic materials during LAM.

Trifunctional nanoprecipitates ductilize and toughen a strong laminated metastable titanium alloy

Metastability-engineering, e.g., transformation-induced plasticity (TRIP), can enhance the ductility of alloys, however it often comes at the expense of relatively low yield strength. Here, using a metastable Ti-1Al-8.5Mo-2.8Cr-2.7Zr (wt.%) alloy as a model material, we fabricate a heterogeneous laminated structure decorated by multiple-morphological α-nanoprecipitates. The hard α nanoprecipitate in our alloy acts not only as a strengthener to the material, but also as a local stress raiser to activate TRIP in the soft matrix for great uniform elongation and as a promoter to trigger interfacial delamination toughening for superior fracture resistance. By elaborately manipulating the activation sequence of lamellar-thickness-dependent deformation mechanisms in Ti-1Al-8.5Mo-2.8Cr-2.7Zr alloys, the yield strength of the present submicron-laminated alloy is twice that of equiaxed-coarse grained alloys with the same composition, yet without sacrificing the large uniform elongation. The desired mechanical properties enabled by this strategy combining the laminated metastable structure and trifunctional nanoprecipitates provide new insights into designing ultra-strong and ductile materials with great toughness.

Effect of B2 ordering on the tensile mechanical properties of refractory AlxNb40Ti40V20−x medium-entropy alloys

Most of refractory high/medium-entropy alloys show promising compressive mechanical properties at elevated temperatures. However, scarce tensile testing data hinder the estimation of the applicability of these alloys for potential high-temperature service. It is also unclear how an ordered structure, which improves high-temperature compressive strength, will affect the tensile performance. This work demonstrated that the effect of B2 ordering on the tensile mechanical properties of new refractory AlxNb40Ti40V20−x (x = 0; 15; 20 at%) medium-entropy alloys was manifold, and it depended on the chemical composition. In an Al15Nb40Ti40V5 alloy having a weak degree of B2 ordering, large uniform room-temperature elongation and moderate high-temperature strength, comparable with a bcc Nb40Ti40V20 alloy, were found. An Al20Nb40Ti40 alloy with the high degree of B2 ordering was brittle at room-temperature and sensitive to testing environment at elevated temperatures. Meantime, it softened notably slower up to 0.4 Tm, albeit losing strength at> 0.4 Tm faster than the bcc Nb40Ti40V20 or weakly B2-ordered Al15Nb40Ti40V5 alloys. Factors responsible for the resulted mechanical properties were thoroughly discussed.

Influences of grain size on the deformation behavior of a twinning-induced plasticity metastable β titanium alloy

The influences of grain size on the deformation behavior of a metastable β-type Ti–12Mo (wt%) alloy has been investigated by using uniaxial tensile testing, scanning electron microscopy and electron backscatter diffraction. The results reveal that the twinning-induced plasticity (TWIP) effect mediated by {332}<113>β twins occurs in this alloy when its mean grain size (d0) ranges from 49 to 104 µm, leading to pronounced work hardening behavior and a large uniform elongation (> 25%). Furthermore, there is a Hall-Petch relationship between the yield strength and d0 for this d0 range, with a Hall-Petch coefficient higher than that expected for pure slip deformation. However, when this alloy is in a state with heterogeneous grain structures and smaller grain sizes (d0 ∼ 30 µm), only a very limited volume fraction (< 1.8%) of {332}<113>β twins occurs and these twins prefer to nucleate in large grains (> ∼40 µm), but they can propagate into rather small grains (< ∼25 µm). In such a state, the Ti−12Mo alloy has a high yield strength (1025 MPa) but does not exhibit any sign of work hardening, i.e., the TWIP effect is absent. Based on the α"-assisted {332}<113>β twinning mechanism, the effects of grain size on the {332}<113>β twinning and yield strength are discussed in terms of its role in affecting the stress-induced β→α" martensitic transformation.

Ultrahigh yield strength and large uniform elongation achieved in ultrafine-grained titanium containing nitrogen

In this study, we systematically investigated the influences of nitrogen content and grain size on the tensile properties and deformation behaviors of titanium at room temperature. By high-pressure torsion and annealing, we obtained ultrafine-grained (UFG) Ti-0.3 wt%N alloy with a fully recrystallized microstructure, which combined an unprecedented synergy of ultrahigh yield strength (1.04 GPa) and large uniform elongation (10%). The hardening and strain-hardening mechanisms of Ti-0.3 wt%N alloy were comprehensively studied via deformation substructure observation and first-principles calculations. It is revealed that the contributions of nitrogen to the excellent strength/ductility balance in UFG Ti-0.3 wt%N were twofold. On one hand, nitrogen atoms inside the grains strongly impeded the motion of <a> dislocations on prismatic plane due to the shuffling of nitrogen from octahedral to hexahedral site, giving rise to a six-fold increase in the friction stress relative to pure Ti. Moreover, the greatly reduced stacking fault energy difference between prismatic and pyramidal planes in Ti-0.3 wt%N alloy facilitated an easier activation of <c+a> dislocations, which contributed to an enhanced strain-hardening rate. On the other hand, some nitrogen atoms segregated near the grain boundaries, a phenomenon discovered in α-titanium for the first time. These segregated nitrogen atoms served as an additional contributor to the high yield strength of UFG Ti-0.3 wt%N, by raising the barrier against dislocation slip transfer between grains. Our experimental and theoretical calculation work provide insights for the design of affordable high strength titanium without a large sacrifice of ductility, shedding lights on a more widespread use of this high strength to weight ratio material.

Strong yet ductile nanolamellar high-entropy alloys by additive manufacturing.

Additive manufacturing produces net-shaped components layer by layer for engineering applications1-7. The additive manufacture of metal alloys by laser powder bed fusion (L-PBF) involves large temperature gradients and rapid cooling2,6, which enables microstructural refinement at the nanoscale to achieve high strength. However, high-strength nanostructured alloys produced by laser additive manufacturing often have limited ductility3. Here we use L-PBF to print dual-phase nanolamellar high-entropy alloys (HEAs) of AlCoCrFeNi2.1 that exhibit a combination of a high yield strength of about 1.3 gigapascals and a large uniform elongation of about 14 percent, which surpasses those of other state-of-the-art additively manufactured metal alloys. The high yield strength stems from the strong strengthening effects of the dual-phase structures that consist of alternating face-centred cubic and body-centred cubic nanolamellae; the body-centred cubic nanolamellae exhibit higher strengths and higher hardening rates than the face-centred cubic nanolamellae. The large tensile ductility arises owing to the high work-hardening capability of the as-printed hierarchical microstructures in the form of dual-phase nanolamellae embedded in microscale eutectic colonies, which have nearly random orientations to promote isotropic mechanical properties. The mechanistic insights into the deformation behaviour of additively manufactured HEAs have broad implications for the development of hierarchical, dual- and multi-phase, nanostructured alloys with exceptional mechanical properties.

An Evaluation of the Mechanical Properties, Microstructures, and Strengthening Mechanisms of Pure Mg Processed by High‐Pressure Torsion at Different Temperatures

Pure Mg samples are processed by high‐pressure torsion (HPT) for up to ten turns at temperatures of 293 and 423 K. The microstructures of these samples are significantly refined and bimodal structures are obtained after 10 turns of HPT processing at both 293 and 423 K. Tensile experiments are conducted at room temperature to reveal the mechanical properties of pure Mg subjected to HPT processing at different temperatures. The yield strength increases with increasing numbers of turns after processing at 293 K whereas the yield strength shows almost no variation with increasing numbers of turns at 423 K. Pure Mg processed at 423 K exhibits a higher strain hardening ability and a larger uniform elongation than after processing at 293 K. Calculations show that the grain size, bimodal structure, and dislocation density are the main factors affecting both the yield strength of the material and the work hardening behavior.

Deformation behaviour of novel medium carbon bainitic steels with different retained austenite characteristics designed by the sparse mixed regression model

A new concept for the alloy design of advanced structural steels was figured out with the experimental elaboration of deformation behaviour in two novel medium carbon bainitic steels proposed sparse mixed regression model. Fe-0.53C-1.55Si-0.48Mn-0.59Cr-0.05Ni (wt%, Steel-A) and Fe-0.64C-1.74Si-2.11Mn-0.2Cr-0.15Ni (Steel-B) were studied. These steels were austempered to get bainite structure with retained austenite of different fraction and morphology. The chemical composition and heat treatment conditions were designed by sparse mixed regression modelling. In the Steel-A, the retained austenite fraction is 0.07 and it is in film form. In the Steel-B, the retained austenite fraction is 0.37 and most of them are in blocky form. Both the samples showed high tensile strength (>1.6 GPa) and good elongation (>12%). The Steel-A showed poor uniform elongation, but large post-uniform elongation. In the Steel-A, the retained austenite is stable during deformation, so inherent ductility of bainitic ferrite matrix largely contributed to higher post-uniform elongation. On the other hand, in Steel-B, the occurrence of deformation-induced martensitic transformation leads to large uniform elongation, through increasing the work hardening rate and delaying the onset of plastic instability.

In situ observation of the effect of the twin boundary orientation on the mechanical properties of single crystalline Ni

The construction of twin boundaries (TBs) in materials is a remarkable way of promoting their strength and ductility. However, the effects of TB orientation on the mechanical properties have not been reported experimentally so far. Using a state-of-the-art in situ tensile stage equipped in a transmission electron microscope, uniaxial tensile tests were performed on three single-crystalline Ni samples with TB parallel and perpendicular to the tensile direction and no TB. The results showed that the uniform tensile elongation strongly depends on TB, 120% for the perpendicular TB sample, 99% for the parallel TB sample, and only 55% for the no TB sample. In addition, dislocation interaction before reaching the perpendicular CTB contribute to cross-slip and dynamic formation of dislocation jogs, thereby improving strain hardening and resulting in a large uniform tensile elongation.

Creep behavior of zirconia ceramics under a strong DC field

The tensile creep of 3 mol% Y2O3 stabilized tetragonal ZrO2 ceramics under a DC field was systematically investigated. The results show that the deformation mechanism of the material strongly depends on the current density and the applied stress. Exceptionally large uniform elongation can be obtained only when the creep is dominated by dislocation accommodated grain-boundary sliding. A maximum uniform elongation of ∼300% is achieved at a strain rate close to 10−3 s−1. At an even higher strain rate of about 10−2 s−1, uniform elongation is still near 100%. The current results suggest that high strain rate superplasticity can be induced by applying a strong electric field at proper stress and current density.

Reduction effect of final-pass heavy reduction rolling on the texture development, tensile property and stretch formability of ZWK100 alloy plates

• ZWK100 alloy sheets with initial casting structures was fabricated by final-pass heavy reduction rolling (FHRR) up to 70% single reduction after single-pass rough rolling, and subsequent annealing causes a symmetrical ‘oblique-line split’ texture instead of the traditional ‘TD split’ texture. • The high rollability for 70% reduction was ascribed to the significant activity of the prismatic 〈 a〉 slip facilitated by the off-basal textures formed after rough rolling • The ‘oblique-line split’ texture was correlated with the preferred growth of grains with [ 1 ¯ 2 1 ¯ 1 ] - [ 1 ¯ 2 1 ¯ 2 ] //RD during annealing. • The FHRR-annealed ZWK100 sheets reveal quasi-planar isotropy in mechanical properties ( Δr 2 ∼0.1), large uniform-elongation of ∼35% and excellent stretch formability of 8.1. Obviously planar anisotropy due to ‘TD split’ orthotropic texture (TD indicates Transverse direction) always exist in the Rare-earth (RE) or Ca containing Mg alloy sheets, which is likely caused by the low-reduction rolling (and annealing) as revealed in our previous research. In this work, the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling (FHRR) at 500 °C with different reductions (30%-70%) after rough rolling, aiming to investigate the reduction effect on the microstructure and texture formation. The results show that FHRR with higher reductions above 50% is in favor of shear banding formation but has little effect on the as-deformed texture components, and the excellent formability with single-pass reduction up to 70% is mainly ascribed to the activation of prismatic 〈 a〉 slip. FHRR with reduction above 50% and annealing can generate uniform grain structures of ∼10 μm and symmetrical ‘oblique-line split’ texture in (0001) pole figures, with basal poles tilting by about 50° from ND (Normal direction) towards some oblique-line of TD and RD (Rolling direction) as well as uniform distribution of counter lines as an annular shape, resulting in excellent elongation to failure of ∼50% and ultra-low planar anisotropy Δ r 2 of ∼0.1 and high stretch formability (Erichsen value: 8.1). The formation ‘oblique-line split’ texture in (0001) pole figures is mainly correlated with the preferred growth tendency of grains with [ 21 1 ¯ 1 ] - [ 12 1 ¯ 2 ] //RD, which was suggested to relate to the high mobility of some special boundaries such as 40°-45° [ 10 1 ¯ 0 ] (∑14). The influences of starting textures on the mechanical properties, planar anisotropy and related deformation modes, as well as their correlations with the stretch formability were comparatively investigated with the ‘TD split’ orthotropic texture as a counterpoint.