Continuous Grain Research Articles

Creep-fatigue interaction in a bimodal 12Cr-ODS steel

The present study reports on the creep-fatigue (CF) behavior of a ferritic bimodal 12Cr-ODS steel. The tests were performed in air at 550°C and 650°C by introducing hold-time at peak tensile, peak compressive and both peak tensile as well as compressive strains of ±0.5%. The symmetrical loops under pure fatigue/continuous cycling (CC) became asymmetrical upon introducing hold-time at either peak tensile or peak compressive strain. On the contrary, hold-time on both sides had no influence regarding symmetry but exhibited minor variation in peak stresses. For the investigated hold-time durations, the increase in hold-time period had a negligible effect on peak stresses. Due to stress relaxation during hold-time, elastic strain gets partially converted into inelastic strain which is relatively lower at 650°C than at 550°C. This eventually led to lower mean stresses; and finally, a relatively lower reduction in lifetime at 650°C than at 550°C. In comparison to similar CC conditions, CF loading resulted in an expeditious and prominent microstructural evolution, which assists in accumulating additional inelastic strain. Nevertheless, microstructural evolution appeared independent of the nature of the applied hold-time waveform which became pronounced with increase in temperature. The dislocation arrangements varied from grain to grain and even within the grains as a consequence of different grains sizes, orientations, and oxide particle distributions. Furthermore, in comparison to CC, an extensive W-enriched Laves phase precipitation/coarsening in the form of continuous or semi-continuous grain boundary networks was realized under CF loading. The damage studies revealed a single surface initiated transgranular crack under CC and multiple surface initiated transgranular cracks under CF loading. The transgranular crack path under CC possessed an intergranular tendency under CF loading which is obviously associated with the lower cyclic life.

Effect of in-situ Al2Y particles on the as-cast/as-rolled microstructure and mechanical properties of AZ31 alloy

The Al2Y particle reinforced AZ31 alloy was prepared by adding Al and Y elements into AZ31 melt. The average dimension of these particles increased from 6.4µm to 14.2µm with the increase of Y and Al contents. TEM analysis proved the good interfacial bonding between the Al2Y particle and the matrix. The Al2Y particles resulted in the continuous grain refinement in the as-cast AZ31+xAl2Y (x=2, 4, 6wt%) alloys. The as-rolled grains of Al2Y containing AZ31 alloys were also obviously refined compared with the as-rolled AZ31 alloy, which is attributed to the particle stimulated nucleation (PSN) during the hot rolling process. The as-cast/as-rolled mechanical properties were determined by the combination effects of the grain size and the Al2Y particles. Finer grains and small Al2Y particles contributed to the simultaneous improvement in strength and elongation. Furthermore, the texture of as-rolled AZ31 alloy was also weakened with Al2Y addition.

Long-term N fertilization and conservation tillage practices conserve surface but not profile SOC stocks under semi-arid irrigated corn

No tillage (NT) and N fertilization can increase surface soil organic C (SOC) stocks, but these gains are frequently not observed through the soil profile and could be subject to loss through subsequent tillage events. We evaluated a long-term irrigated continuous corn no-tillage (NT) and N rate study near Fort Collins, CO that was split into continuous NT or strip till (ST) treatments after five years. We measured grain and residue yields yearly, and SOC and particulate organic matter C (POM-C) at baseline, 5 yrs and 11yrs later. Continuous NT depressed grain yields (10%) but not stover yields compared to ST. Continuous NT and increasing N fertilization rate increased surface (0–7.5cm) SOC stocks 10 and 13%, respectively, compared to baseline. Seven years of ST completely negated initial surface (0–7.5cm) SOC gain under NT and was only partially explained by POM-C loss (8–25%). All treatments lost between 14 and 19MgCha−1 in the soil profile (0–120cm) compared to baseline with no N or tillage effects. Soil C cycling appears to be rapid in this irrigated system, requiring greater C inputs to maintain SOC stocks. Effective conservation practices will need to balance crop yield, surface erosion protection, and profile-wide SOC stock losses.

Brazing Inconel 600 Using the VZ-2150 Filler for Plate Heat Exchanger

The purpose of this investigation is focused on brazing Inconel 600 alloy using the nickel-based VZ-2150 filler foil for advanced plate heat exchanger application. Based on SEM microstructural observations and WDS chemical analysis results, both the amount and shape of precipitates in the brazed joint are changed with brazing parameters. With increasing the brazing temperature and/or time results in depletion of the boron from the joint into the grain boundary of base metal. The amount of boride in the joint is greatly decreased, and continuous grain boundary boride will dominate the entire brazed joint. However, the continuous grain boundary boride cannot be completely eliminated by increasing the brazing temperature and/or time.

Grain Sorghum Water Use Efficiency and Yield Are Impacted by Tillage Management Systems, Stubble Height, and Crop Rotation

Core Ideas Tillage, stubble management, and crop rotation are important management decisions for maximizing productivity and profitability in semi‐arid environments. Under poor rainfall distribution conditions of sandy loam, most positive effects of tillage‐stubble management were partially moderated by a significant rotation × tillage‐stubble interaction. Under above‐average rainfall conditions of clay loam, yield characteristics were influenced by neither rotation nor tillage‐stubble management. Conservation tillage combined with stubble management resulted in greater WUE than conventional tillage with no residue management at one out of two locations. Successful crop production in semiarid environments of the Southern High Plains depends on critical management practices such as tillage, stubble management, and crop rotation that maximize the use efficiency of limited resources. An experiment was conducted at two locations in 2010, after the first year of rainfed crop rotation (continuous grain sorghum [Sorghum bicolor (L.) Moench] or cowpea [Vigna unquiculata (L.) Walp.]–sorghum), tillage (conventional, strip‐till, or no‐till) and stubble height (short and tall in strip‐ or no‐till) had been imposed, to evaluate the effects of these management factors on early growth, yield characteristics, and water use efficiency of grain sorghum. Based on the results, the influence of tillage‐stubble management on yield and water use characteristics varied with soil type and seasonal rainfall pattern. Under poor rainfall distribution conditions of Tucumcari sandy loam, the most positive effects of tillage‐stubble management were partially moderated by a significant rotation × tillage‐stubble interaction. Under above‐average rainfall conditions at the Clovis site, which has clay loam soils, yield characteristics were influenced by neither rotation nor tillage‐stubble management. However, at Clovis, conservation tillage (no‐till and strip‐till) in combination with stubble management (short and tall) resulted in greater WUE than conventional tillage with no residue management (P < 0.05). A long‐term study is needed to make recommendations on the adoption of suitable conservation tillage and stubble management strategies in this region; however, the results of this work are encouraging and indicate potential benefits of conservation tillage and stubble management in semiarid environments.

Using UAS optical imagery and SfM photogrammetry to characterize the surface grain size of gravel bars in a braided river (Vénéon River, French Alps)

This paper explores the potential of unmanned aerial system (UAS) optical aerial imagery to characterize grain roughness and size distribution in a braided, gravel-bed river (Vénéon River, French Alps). With this aim in view, a Wolman field campaign (19 samples) and five UAS surveys were conducted over the Vénéon braided channel during summer 2015. The UAS consisted of a small quadcopter carrying a GoPro camera. Structure-from-Motion (SfM) photogrammetry was used to extract dense and accurate three-dimensional point clouds. Roughness descriptors (roughness heights, standard deviation of elevation) were computed from the SfM point clouds and were correlated with the median grain size of the Wolman samples. A strong relationship was found between UAS-SfM-derived grain roughness and Wolman grain size. The procedure employed has potential for the rapid and continuous characterization of grain size distribution in exposed bars of gravel-bed rivers. The workflow described in this paper has been successfully used to produce spatially continuous grain size information on exposed gravel bars and to explore textural changes following flow events.

Effects of REFe2 on microstructure and magnetic properties of Nd-Ce-Fe-B sintered magnets

Ce substitution level in Nd-Fe-B magnets has been significantly increased via the binary main phase (BMP) approach, i.e. sintering the mixture of Ce-free and Ce-containing RE2Fe14B (RE, rare earth) powders. REFe2 phase that forms in the high Ce-containing Nd-Ce-Fe-B magnets has been considered to be harmful to magnetic performance due to its soft magnetism. In this work, we found that REFe2 phase with lower melting point than the 2:14:1 phase plays positive role on optimizing the microstructure and retaining magnetic performance of the Nd-Ce-Fe-B BMP magnets. The wettability of 2:14:1 phase can be improved by sintering above the melting point of REFe2 phase, which promotes densification of the magnet and the formation of continuous and smooth grain boundary (GB) phases. This contributes to the weakened short-range exchange coupling between adjacent grains, hence ensures superior magnetic performance of BMP magnets to the single main phase (SMP) ones with the same average composition. As a result, magnetic properties of Br = 12.4 kG, Hcj = 9.0 kOe and (BH)max = 36.7 MGOe can be obtained even when 45 wt % Ce substitutes for Nd in the BMP magnets.

Coercivity enhancement of Ce-Fe-B sintered magnets by low-melting point intergranular additive

Ce-Fe-B sintered magnets with enhanced coercivity were prepared by the powder metallurgy method. The mechanism of the coercivity enhancement in Ce-Fe-B sintered magnets with the low-melting point intergranular additive was discussed in details. It was speculated that the low coercivity of Ce-Fe-B sintered magnet was related to the irregular sharps and relatively low magneto-anisotropy field of the matrix phase. After introducing a 20 wt.% Nd-based intergranular additive, the coercivity markedly increased from 108 Oe to 2560 Oe due to the formation of thin and continuous grain boundary layers and the surface modification of the matrix phase grains. Additionally, the formation of the high anisotropy field (Nd,Ce)2Fe14B shell was beneficial to the increase of the coercivity as well. This work suggested that adding low-melting point intergranular additives was effective to fabricate the practical Ce-Fe-B sintered magnets.

Selective laser melting of TiB2/H13 steel nanocomposites: Influence of hot isostatic pressing post-treatment

A TiB2/H13 steel nanocomposite powder was produced by high-energy ball milling and used to fabricate components by selective laser melting (SLM), an additive manufacturing process. Hot isostatic pressing (HIP) post-treatment was applied to improve the final density of the SLM-fabricated component, and the results were compared with those of an untreated component. The microstructure of the as-built nanocomposite comprised of fine equiaxed grains with TiB2 particles homogenously dispersed in the H13 steel grains and grain boundaries. Relative to the unreinforced base metal, the hardness of the SLM-processed nanocomposite was found to be slightly higher, but friction and wear rate significantly decreased. The HIP post-treatment effectively eliminated major pores in the nanocomposites. In addition, the post-treatment transformed the continuous grains into intermittent grains with crystalline clusters. A further increase in the average hardness values with large standard deviations was observed after HIP treatment because of the competition between the high-temperature annealing effect and the improvement in density. A slight increase in the wear rate after the post-treatment was observed as a result of the grain coarsening and agglomeration of the TiB2 nanoparticles in the H13 matrix.

Improvement of the magnetic property, thermal stability and corrosion resistance of the sintered Nd-Fe-B magnets with Dy80Al20 addition

To improve the coercivity and thermal stability of the Nd-Fe-B sintered magnets simultaneously, the Dy80Al20 (at%) powders with low melting point were introduced into the Nd-Fe-B magnets. Additionally, the magnetic properties, microstructure and thermal stability of the sintered magnets with different amounts of Dy80Al20 were investigated. By adding a small amount of Dy80Al20, the coercivity was significantly increased from 12.72 to 21.75kOe. As indicated by the microstructure analysis, a well-developed core-shell structure was formed in the magnets with the addition of Dy80Al20. The improvement of magnetic properties could be attributed to the refined and uniform matrix phase, continuous grain boundaries and a (Nd, Dy)2Fe14B hardening shell surrounding the matrix phase grains. With the addition of 0–4wt% Dy80Al20 powder, the reversible temperature coefficients of remanence (α) and coercivity (β) of the magnets could be improved from −0.117 to −0.108%/°C and −0.74 to −0.66%/°C in the range of 20–100°C, respectively. Additionally, the irreversible loss of magnetic flux (hirr) decreased sharply as Dy80Al20 powder was added. The results of temperature-dependent magnetic properties suggest that, the thermal stability of the magnets was effectively improved with the intergranular addition of Dy80Al20 alloy. Also, the corrosion resistance was found to be improved through small addition of Dy80Al20 powders This was partly due to the stability enhancement of the (Pr, Nd)-rich intergranular phase by Dy80Al20.

Boundary structure modification and magnetic properties of Nd-Fe-B sintered magnets by co-doping with Dy2O3/S powders

In this paper, the effect of Dy2O3/S co-doping on the magnetic properties and microstructure was studied in Nd-Fe-B sintered magnets. With S co-doping, the coercivity increased due to grain boundary modification and Dy selective introduction. Continuous grain boundary phases were formed in the co-doped magnets with smaller grain size. The average grain size after a doping of 0.2wt% S is 7.25µm, which is approximately 2.37µm smaller than that of the S-free sintered magnets(9.62µm). The coercivity of the Dy2O3/0.2wt% S co-doped magnets could be increased from 20.9 to 22.8kOe with changing the remanence and the maximum magnetic energy product slightly. S precipitates in the Nd-rich phases were hexagonal Nd2O2S phase. Dy avoided the Nd2O2S phase in the triple junction region, resulting in more available Dy atoms diffusing into the Nd2Fe14B phase grains to enhance the anisotropy field. Dy-saving was achieved by forming Nd2O2S phase in the Dy2O3/S co-doped magnets.

Crystalline Intermediates and Their Transformation Kinetics during the Formation of Methylammonium Lead Halide Perovskite Thin Films

The morphology of methylammonium lead halide perovskite thin films significantly affects the performance of opto-electronic devices that comprise them. Using X-ray diffraction studies, we elucidated the mechanisms of thin-film formation to complete the complex picture of structural development of perovskites under an inert atmosphere. The presence of excess methylammonium iodide during perovskite crystallization leads to the formation of layered intermediates and low-dimensional perovskites; these intermediates are correlated with the formation of large and continuous grains in the final films. When the precursors are present in stoichiometric equivalence, initial stages of crystallization instead involve the formation of solvates; the fully crystallized films have poor surface coverage and comprise needle-like structures. The activation energy of crystallization in films with stoichiometric excess methylammonium iodide is higher than that for films comprising stoichiometrically equivalent precursors; the...

Comparative studies of the dielectric properties of (1−x)BiFeO3-xNi0.8Zn0.2Fe2O4 (x=0.0, 0.2, 0.5, 0.8, 1.0) multiferroic nanocomposite with their single phase BiFeO3 and Ni0.8Zn0.2Fe2O4

BiFeO3 (BFO) and nickel zinc ferrite Ni0.8Zn0.2Fe2O4 (NZFO) were prepared by sol gel and auto combustion route respectively. Stoichiometric proportions were mixed to obtain the multiferroic nanocomposites having the compositional formula (1−x)BiFeO3-x Ni0.8Zn0.2Fe2O4 (x=0.0, 0.2, 0.5, 0.8, 1.0). The phases were confirmed by XRD analyses. SEM micrographs showed the agglomerated nature of the particles with continuous grain growth in all directions. Elemental compositions were confirmed from EDAX studies. FTIR studies showed the stretching and bending vibrations of the various bonds present in the samples. The dielectric properties such as dielectric constant, ε′ and dielectric loss tangent, tanδ were studied for the spinel, perovskite and nanocomposite ferrites. Experimental result shows an increasing trend in the value of dielectric constant in going from spinel to perovskite phase. The frequency dependence of tanδ showed minimum loss for x=0.5 nanocomposite. Possible mechanisms explaining the above results were being discussed.

Macro-micro modeling and simulation for the morphological evolution of the solidification structures in the entire weld

The heat and mass transfer and the morphological evolution of the various weld solidification structures for the entire weld were simulated through the macro-micro modeling which combined the welding process and the solidification structures in the weld pool. The weld profiles were calculated for different welding conditions, and the effects of the welding parameters on the solidification conditions were analyzed along the trailing pool boundary. The formation mechanism of the axial columnar structure and the equiaxed grains in the weld were studied by the developed model. The results indicate that the temperature gradient G, solidification rate Rw, and the ratio G/Rw along the trailing pool boundary are related with the location in the weld and the welding parameters. If there does not exist heterogeneous nuclei in the weld pool, the axial columnar structure forms in the central region of the weld at low welding speeds owing to the anisotropic kinetics of the dendritic structure. When the heterogeneous nucleation occurs in the weld pool, the weld structure is directly determined by the competitive growth between the columnar and new nucleated grains. At low welding speeds, the preferential orientations of the survival grains get closer to the welding direction with the decrease of the distance to the weld centerline. With the increase of the welding speed and welding current, more grains form in the weld pool, and the new nucleated grains also become more competitive. The columnar grains from the fusion line are blocked by the equiaxed grains. The continuous equiaxed grain zone forms in the weld, and the columnar to equiaxed transition (CET) occurs.

Evaluation of water-limited cropping systems in a semi-arid climate using DSSAT-CSM

Water is the major factor limiting crop production in western Kansas due to declining groundwater levels in the Ogallala aquifer resulting from withdrawals for irrigation exceeding recharge rates coupled with erratic semi-arid rainfall. Study objectives were to assess yield and water productivity of water limited cropping systems in western Kansas using DSSAT-CSM (Decision Support System for Agrotechnology Transfer Cropping Systems Model). The cropping systems evaluated included continuous (corn, wheat, and grain sorghum) and rotation (corn-wheat, corn-wheat-grain sorghum, and corn-wheat-grain sorghum-corn). Results showed that the model adequately reproduced measured days to flowering and maturity as well as yield and aboveground biomass of all three crops. Crop rotation improved water productivity of corn. Under deficit irrigation, corn in rotation produced higher yields, crop water productivity, and irrigation water use efficiency compared to continuous corn, implying that crop rotation is a better option under limited well capacities. Under full irrigation, yield and water productivity of continuous wheat were lower than wheat in rotation. In contrast, continuous wheat yields under deficit irrigation were better than under crop rotation. Deficit irrigation substantially improved irrigation water use efficiency of grain sorghum under both continuous and crop rotations. Long–term average grain sorghum yields under rotation were higher than those of continuous grain sorghum. Indicating grain sorghum should be grown in rotation under deficit irrigation. This research did not simulate the impacts of pests, weeds and diseases, hail and freeze damage on crop yield. However, the study identifies cropping systems that are more likely to produce highest water productivity under semi-arid climate similar to that in western Kansas.

Improvement in coercivity, thermal stability, and corrosion resistance of sintered Nd–Fe–B magnets with Dy80Ga20 intergranular addition**Project supported by the Ministry of Science and Technology of China (Grant Nos. 2014DFB50130 and 2011CB612304) and the National Natural Science Foundation of China (Grant Nos. 51172168 and 51072139).

To investigate the coercivity, corrosion resistance, and thermal stability of Nd–Fe–B magnets, their properties were investigated at room and high temperature before and after doping with Dy80Ga20 (at.%) powder. The coercivity of the magnets increased from the undoped value of 12.72 kOe to a doped value of 21.44 kOe. A micro-structural analysis indicates that a well-developed core-shell structure forms in the magnets doped with Dy80Ga20 powder. The improvement in magnetic properties is believed to be related to the refined and uniform matrix grains, continuous grain boundaries, and a hardened (Nd, Dy)2Fe14B shell surrounding the matrix grains. Additionally, the doped magnets exhibit an obvious improvement in thermal stability. For the magnets with added Dy80Ga20 powder, the temperature coefficients of remanence (α) and coercivity (β) increased to −0.106% °C−1 and −0.60% °C−1 over the range 20–100 °C, compared to temperature coefficients of −0.117% °C−1 (α) and −0.74% °C−1 (β) in the regular magnets without Dy80Ga20 powder. The irreversible loss of magnetic flux (Hirr) was investigated at different temperatures. After being exposed to 150 °C for 2 h, the Hirr of magnets with 4 wt.% Dy80Ga20 decreased by ∼95% compared to that of the undoped magnets. The enhanced temperature coefficients and Hirr indicate improved thermal stability in the doped Nd–Fe–B magnets. The intergranular addition of Dy80Ga20 also improved the corrosion resistance of the magnets because of the enhanced intergranular phase. In a corrosive atmosphere for 96 h, the mass loss of the sintered magnets with 4 wt.% Dy80Ga20 was 2.68 mg/cm2, less than 10% of that suffered by the undoped magnets (28.1 mg/cm2).

Low temperature formation of highly resistive ZnO films using nonequilibrium N2/O2 plasma generated near atmospheric pressure

Low temperature chemical vapor deposition of ZnO thin films was demonstrated using β-diketonate complexes [Bis-2,4octanedionato zinc: Zn(OD)2] and nonequilibrium N2/O2 plasma generated near atmospheric pressure. ZnO films grown at the substrate temperature of 200°C and at the O2 concentration in the N2/O2 mixture gas (O2%) of 0.2, 3.8 and 20% exhibited excellent (0001) preferred orientation on glass substrates, high transmittance of above 85% in the visible region and smooth surface structure with the continuous columnar grains. Electrical measurement revealed that our ZnO films were highly resistive with the specific resistivity exceeding 106Ωcm at room temperature, which is not easily obtained by the conventional high-vacuum processes without intentional acceptor doping. Thermally stimulated current measurement detected two peaks from highly resistive ZnO film grown at the O2% of 0.2%, which correspond to the carrier emission from deep trap levels with the activation energies of 170 and 610meV. The former was assigned as zinc vacancy (VZn) or nitrogen substituting oxygen site (NO), and the latter was assigned as VZn or oxygen interstitial (Oi). The carrier compensation by these deep acceptor levels seems to be the origin of high resistivity.

Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

The influence of grain growth inhibitors and powder size on the microstructure and mechanical properties of ultrafine and nanostructured cemented carbides was researched. Three different WC powders, with an addition of different type and content of grain growth inhibitors GGIs, VC and Cr3C2 and with dBET grain sizes in the range from 95 to 150 nm were selected as starting powders. Four different mixtures with 6 and 9 wt. % Co were prepared. The consolidated samples are characterized by different microstructural and mechanical properties with respect to the characteristics of starting powders. Increased sintering temperatures led to microstructural irregularities in the form of a discontinuous WC growth, carbide agglomerates and abnormal grain growth as a consequence of coalescence via grain boundary elimination. The addition of 0.45% Cr3C2 contributed to microstructure homogeneity, reduced discontinuous and continuous grain growth, and increased Vickers hardness by approximately 70 HV and fracture toughness by approximately 0.15 MN/m3/2. The reduction of the starting powder to a real nanosize of 95 nm resulted in lower densities, and significant hardness increase, with a simultaneously small increase in fracture toughness. The consolidation of real nanopowders (dBET < 100 nm) solely by conventional sintering in hydrogen without isostatic pressing is not preferred.

Effect of system of lamb rearing and season on early post-partum fertility of ewes and growth performance of lambs in Katahdin sheep.

The effect of season (S), lamb rearing system (RT) and grain supplementation (GS) on post-partum fertility in Katahdin ewes and growth in Katahdin lambs was evaluated. Katahdin ewes were bred to lamb in fall (n=36) or spring (n=56) and at approximately 2.5months post-partum were randomly assigned to be permanently separated or to continue to suckle their lambs for an additional 3months. All ewes were joined with rams following treatment to synchronize oestrus. Weaned (W, n=84) and continuously suckled lambs (CSK, n=88) were fed forage only (n=84; hay and pasture for fall- and spring-born lambs respectively) or were supplemented (n=88; 18% crude protein ration adlibitum) and all weighed biweekly. Ewes rebred in the fall had a shorter ram introduction to lambing interval (p<0.05), higher prolificacy (p=0.001) and higher lambing rates (p=0.02); however, the proportion of ewes lambing was not affected by season. The first service lambing rate was lower in ewes continuously suckling lambs in the spring, but not in the fall breeding season (S×RT, p=0.03). Lambs that continuously suckled their dams and were supplemented grew quicker and gained more (p<0.001) than their weaned and unsupplemented counterparts. The effect of CSK on growth rate of lambs was greater in the spring (RT×S; p=0.05), and the effect of supplementation on growth rate of lambs was greater in the fall (GS×S; p<0.0001). In conclusion, Katahdin lambs achieved higher weight gains from continuous suckling and grain supplementation. Moreover, Katahdin ewes are capable of early rebreeding post-partum while suckling their lambs, which makes them suited for use in accelerated lambing programmes.

Microstructure and anisotropic tensile behavior of laser additive manufactured TC21 titanium alloy

In the present work, two types of part with different geometries were fabricated by laser additive manufacturing (LAM) process under the same processing parameters. Tensile samples perpendicular to (horizontal) and parallel to (vertical) the build direction were produced after heat treated under different conditions. The results showed that the samples exhibit similar columnar β grains, but very different α phase characterizations. The tensile properties show significant anisotropic. The sample containing finest α laths shows highest ultimate tensile strength and yield strength. And the strength decreased with the increase of α laths width. The total elongation of the samples does not show regularity relationship with the strength. The horizontal samples show inferior ductility and brittle fracture due to the columnar β grain morphology and the presence of continuous grain boundary α layers. The coarse grain boundary α layers after double heat treatment further reduced the ductility. The vertical samples exhibit better ductility due to lack of continuous grain boundary α layers which perpendicular to the tensile load. The Vickers hardness test shows that the vertical samples were strengthened while the horizontal samples were little strengthened after tensile test.