Anisotropic Mechanical Properties Research Articles

The synergic effects of heat treatment and building direction on the microstructure and anisotropic mechanical properties of laser powder bed fusion Corrax maraging stainless steel

An anisotropic microstructure and mechanical properties are big challenges in the development of various laser powder bed fusion (LPBF) alloys. This study investigated the roles of heat treatment and building direction (BD) on the microstructure and anisotropic mechanical properties of LPBF Corrax maraging stainless steel. The effects of solution treatment (ST) and integrated solution-aging treatment (SAT) were clarified. The results show that the grain size of martensite, amount of austenite, and features of grain boundaries were slightly varied with the building direction due to the thermal history. In the as-built state, the weak <111>α′||BD, <1 1‾ 0>α′||X, and <001>α′||BD textures could be found. After the SAT process, the <1 1‾ 0>α′||X texture was slightly intensified due to the coarsening of large columnar grains. However, the texture of the SAT sample was still weak.Furthermore, the building direction and heat treatment did not lead to obvious anisotropic tensile properties or change the ductile fracture mode. The weak texture and pores in LPBF Corrax did not dominate the tensile properties. Irrespective of sample state, the horizontally-built samples exhibited comparable strengths and slightly higher elongation than the vertically-built ones did. In the as-built condition, this phenomenon can be mainly attributed to the transformation-induced plasticity effect. In the ST and SAT conditions, smaller grain sizes of martensite and higher high-angle grain boundary ratios in the horizontally-built samples provided more resistance to crack propagation. LPBF Corrax maraging stainless steel exhibited superior tensile performances and low anisotropic tensile properties, which are very beneficial to the stability of the material during service.

Integrating machine learning and response surface methodology for analyzing anisotropic mechanical properties of biocomposites

ABSTRACT This study enhances the anisotropic mechanical properties of banana fiber-epoxy composites by optimizing fiber loading, orientation, and treatment using Response Surface Methodology (RSM) and Artificial Neural Network (ANN). RSM suggests optimal values: fiber loading at 33 wt%, NaOH treatment at 6.8 wt%, and fiber orientation at 15 degrees. This material has exceptional mechanical characteristics, including a maximum tensile strength (TLS) of 31.72 MPa, a maximum flexural strength (FLS) of 42.86 MPa, and a maximum impact strength (IPS) of 38.56 kJm-2. ANN effectively predicts strengths with high R2 scores of 0.969, 0.984, and 0.954 for tensile, flexural, and impact strengths. Incorporating batch normalization and dropout layers enhances robustness. The study concludes that NaOH treatment and fiber orientation significantly impact the composite’s anisotropy.

Eliminating Mg-RE alloy the anisotropy of mechanical properties after wire arc additive manufacturing via Al refinement

The effects of adding 1.5% Al on the microstructure and mechanical properties of Mg-4Y-3Nd (WN43) alloy prepared by wire arc additive manufacturing (WAAM) were investigated. The addition of Al inhibits the formation of eutectic, promotes the formation of Al2RE phases, resulting in the formation of fine equiaxed grains (34 ± 1.1 μm). Consequently, the anisotropy of mechanical properties decreased significantly, and the mechanical properties were improved. The tensile strength, yield strength, and elongation of the alloy were measured as 244 MPa, 142 MPa, and 17.9%, respectively. These findings suggest that Al shows promise as an effective grain refiner for WAAM-produced magnesium rare-earth alloys.

A Novel Quasi-Planar Two-dimensional Carbon Sulfide with Negative Poisson's ratio and Dirac fermions.

In the present study, a novel and unconventional two-dimensional (2D) material with Dirac electronic features hasbeen designed using sulflower with the help of density functional theory methods and first principles calculations.This 2D material comprises of hetero atoms (C, S) and belongs to the tetragonal lattice with P4/nmm space group. Scrutiny of the results show that the 2D sheet exhibits a nanoporous wave-like geometrical structure. Quantummolecular dynamics simulations and phonon mode analysis emphasize the dynamical and thermal stability. Thenovel 2D sheet is an auxetic material with an anisotropy in the in-plane mechanical properties. Both compositionand geometrical features are completely different from the necessary conditions for the formation of Dirac conesin graphene. However, the presence of semi-metallic nature, linear band dispersion relation, massive fermions andmassless Dirac fermions are observed in the novel 2D sheet. The massless Dirac fermions exhibit highly isotropicFermi velocities (vf = 0.71 × 106 m/s) along all crystallographic directions. The zero-band gap semi metallic featuresof the novel 2D sheet are perturbative to the electric field and external strain.

Systematic Study of the Nanostructures of Exfoliated Polymer Nanocomposites.

High-performance bioinspired materials have shown rapid development over the last decade. Examples are brick-and-mortar hierarchical structures, which are often achieved via solvent evaporation. Although good properties are claimed, most systems are composed of stacked or intercalated platelets. Exfoliation is a crucial step to give ultimate anisotropic properties, e.g., thermal, mechanical, and barrier properties. We propose a general framework for all the various types of micro-scale structures that should be distinguished for 2D filler nanocomposites. In particular, the exfoliated state is systematically explored by the immobilization of montmorillonite platelets via (gelatin) hydrogelation. Scattering techniques were used to evaluate this strategy at the level of the particle dispersion and the regularity of spatial arrangement. The gelatin/montmorillonite exfoliated nanostructures are fully controlled by the filler volume fraction since the observed gallery d-spacings perfectly fall onto the predicted values. Surprisingly, X-ray analysis also revealed short- and quasi long-range arrangement of the montmorillonite clay at high loading.

Laser powder bed fusion (LPBF) of commercially pure titanium and alloy development for the LPBF process.

Laser powder bed fusion (LPBF) of titanium or titanium alloys allows fabrication of geometrically more complex and, possibly, individualized implants or osteosynthesis products and could thus improve the outcome of medical treatments considerably. However, insufficient LPBF process parameters can result in substantial porosity, decreasing mechanical properties and requiring post-treatment. Furthermore, texturized parts with anisotropic properties are usually obtained after LPBF processing, limiting their usage in medical applications. The present study addresses both: first, a design of experiments is used in order to establish a set of optimized process parameters and a process window for LPBF printing of small commercially pure (CP) titanium parts with minimized volume porosity. Afterward, the first results on the development of a biocompatible titanium alloy designed for LPBF processing of medical implants with improved solidification and more isotropic properties are presented on the basis of conventionally melted alloys. This development was performed on the basis of Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au, a near-α alloy presented by the authors for medical applications and conventional manufacturing, with yttrium and boron additions as additional growth restriction solutes. In terms of LPBF processing of CP titanium grade 1 powder, a high relative density of approximately 99.9% was obtained in the as-printed state of the volume of a small cubical sample by using optimized laser power, scanning speed, and hatch distance in combination with a rotating scanning pattern. Moreover, tensile specimens processed with these volume settings and tested in the as-printed milled state exhibited a high average yield and ultimate tensile strength of approximately 663 and 747N/mm2, respectively, combined with a high average ductility of approximately 24%. X-ray diffraction results suggest anisotropic mechanical properties, which are, however, less pronounced in terms of the tested specimens. Regarding alloy development, the results show that yttrium additions lead to a considerable microstructure refinement but have to be limited due to the occurrence of a large amount of precipitations and a supposed higher propensity for the formation of long columnar prior β-grains. However, phase/texture and microstructure analyses indicate that Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au-0.1B-0.1Y is a promising candidate to achieve lower anisotropy during LPBF processing, but further investigations on LPBF printing and Y2O3 formation are necessary.

Microstructure and Anisotropy of Mechanical Properties of Al-3Li-1Cu-0.4Mg-0.1Er-0.1Zr Alloys Prepared by Normal Rolling and Cross-Rolling

The influence of normal rolling and cross-rolling on the microstructure, mechanical properties, and anisotropy of Al-3Li-1Cu-0.4Mg-0.1Er-0.1Zr alloy was investigated. With an increase in the rolling reduction amount, both the strength and plasticity of the alloy are enhanced. Among them, the alloy in the normal rolling state with a deformation amount of 90% exhibits the best properties, with a tensile strength of 362 MPa and an elongation of 19.1% along the rolling direction. During the rolling process, the intergranular Cu-containing phase in the alloy is continuously broken and dissolved, leading to a decrease in both size and quantity, turning from continuous distribution along grain boundaries to a granular distribution. Moreover, a large quantity of the Al3Li phase and Al3(Er, Zr, Li) core–shell composite phase are precipitated in the alloy. Recrystallization occurs mainly through the particle stimulated nucleation (PSN) mechanism. Cross-rolling eliminates the brass-type texture &lt;111&gt; produced by normal rolling and enhances the brass R-type texture {111}&lt;112&gt;. The index of plane anisotropy (IPA) of the strength decreases from 10.1% for normal rolling to 5.5% for cross-rolling, and the IPA of elongation decreases from 12.8% to 3.3%. Cross-rolling provides an effective method to reduce the anisotropy of Al-Li alloys.

Effect of Heat Treatment on the Anisotropic Mechanical Properties of AlSi10Mg Fabricated by Selective Laser Melting

Effect of Heat Treatment on the Anisotropic Mechanical Properties of AlSi10Mg Fabricated by Selective Laser Melting

Anisotropic mechanical properties and deformation mechanisms of nanotwinned Ni and Ni alloys with extremely fine twin boundary spacings

Introducing nanotwins with extremely fine twin boundary spacing (TBSs ≤ 10 nm) in metals with high stacking fault energy (SFE) has posed a longstanding challenge, hindering an in-depth understanding of their strengthening mechanisms. Here, we synthesized a series of columnar-grained nanotwinned structures with extremely fine TBSs in Ni and Ni alloys with high SFEs, and systematically investigated their mechanical responses under various loading directions relative to the coherent twin boundaries (CTBs). Under the loading directions of 90° and 0°, contrary to the softening effect observed in nanotwinned metals with equiaxed grains, continuous strengthening was found to extend to the finest TBS of 1.9 nm in the columnar-grained nanotwinned Ni and Ni alloy. This resulted in an ultra-high strength of 4.46 and 3.80 GPa, respectively. Combined experimental and simulational studies were employed to investigate the mechanism for continuous strengthening. As the TBS decreased to a critical value (3–5 nm), the strengthening mechanism was revealed to transform from CTB obstructing dislocations to the dislocation starvation-dominated mechanism, which led to a shift in deformation behavior from homogeneous to localized plasticity. Distinct from the detwinning-induced softening effect, the dislocation-starvation mechanism resulted in continuous strengthening, with the yield strength following a power-law function concerning TBS. Additionally, our results illustrate that nanotwins deformed via significant detwinning at the loading direction of 45°, leading to strengthening that primarily depends mainly on the column width rather than TBS.

Modelling columnar-to-equiaxed transition during fusion-based metal additive manufacturing

During fusion-based metal additive manufacturing, there is an inherent directionality in heat transfer, which leads to columnar grain growth. This may result in cracking and anisotropic mechanical properties in many alloy systems. Therefore, it is important to study the conditions under which columnar-to-equiaxed transition in grain structure occurs. The grain morphology is determined by several factors such as process conditions, local alloy composition, and number density of nucleating sites. In the present work, a model for simulating columnar-to-equiaxed transition is formulated, considering nucleating site size distribution, rapid solidification and constitutional undercooling in multicomponent alloys. Furthermore, the model is coupled with multicomponent Calphad-based thermodynamic and diffusion mobility descriptions. It is demonstrated that including the above aspects is important in accurately predicting the columnar-to-equiaxed transition by comparing with experimental data for an additively manufactured TiB2-reinforced AlSi10Mg alloy. The framework developed in this work may be used to predict columnar-to-equiaxed transition in additively manufactured technical alloys consisting of multiple elements.

A design and optimisation framework for cold spray additive manufacturing of lightweight aerospace structural components

Cold spray additive manufacturing (CSAM) is a solid-state deposition process with the potential to produce near-net shape components with complex geometry at a high fabrication rate, making it an attractive alternative to more widely established additive manufacturing (AM) processes. However, CSAM is still in its early stages and requires numerous advancements. The current literature highlights the lack of a design framework for fabricating structural components that encompasses the advantages and constraints of CSAM. This work proposes such a framework to guide product and process engineers, with its novel aspects including (i) accounting for different spray trajectories and their effect on anisotropic mechanical properties, (ii) accounting for the primary constraint for toolpath planning (maximum overhang angle ‘MOA’), and (iii) virtual development and optimisation of a real-world structural component with complex geometry. To exemplify this framework, tensile properties under two spray trajectories were determined experimentally for a common lightweight metal (titanium) supplemented with a ceramic to form a metal matrix composite with improved strength and hardness. Optimisation of the design was conducted via finite element analysis and topology optimisation (TO). Two different TO processes were conducted, namely (i) minimising the strain energy of the structure and reducing the weight by 60% (best stiffness-to-weight ratio) and (ii) minimising the weight by targeting a maximum factor of safety (FoS) value of 1.2. The final design was fabricated via CSAM with relatively little raw material wastage and reasonably close geometric accuracy. Fabrication defects were, however, noticed after making a demonstration component and mitigation measures are discussed within the context of the design framework proposed here.

Mechanical properties, microstructural characteristics and heat treatment effects of WAAM stainless-steel plate material

Wire and arc additive manufacturing (WAAM) is a technology that enables the in-situ manufacturing of large-scale components efficiently for the construction industry. However, uncertainties persist regarding the characteristics of WAAM materials, such as anisotropic mechanical properties and their correlation with metallographic structure and fracture morphology, printing paths, and heat treatment. More experimental data is also required to establish design methods for the application of WAAM stainless steel in construction. To bridge these knowledge gaps, a comprehensive series of tensile tests was therefore conducted on WAAM stainless steel. Four deposition plates were fabricated using WAAM technique with different printing paths, and tensile coupons were extracted in three directions from each plate. Tensile tests were conducted to evaluate the mechanical properties of the material. Optical microscopy (OM) and scanning electron microscopy (SEM) were then employed to examine the metallographic structure of the material and the fracture morphology of the coupons. The results showed that the WAAM material had good yield and ultimate strengths but slightly lower ductility than conventional stainless steel. Anisotropy was observed in some but not all printing paths, and Young's modulus, ultimate strain and fracture strain exhibited the highest values in the 45° specimens. The grain size of the plate was influenced by its printing path. Mechanical properties were associated with the metallographic structure and fracture morphology. Compared to the heat-treated counterpart, the non-heat-treated material exhibited higher yield and ultimate strengths but lower ductility.

Anisotropy in microstructure and mechanical properties of additively manufactured Ni-based GH4099 alloy

Additively manufactured Ni-based superalloys exhibit strong anisotropy due to microstructural differences resulting from their unique fabrication method. This study systematically investagiated the microstructure and mechanical properties of Ni-based GH4099 alloy fabricated by Selective Laser Melting (SLM) with subsequent heat treatment (HT). The causes of anisotropy in the deformation mechanism of alloys at room temperature and high temperatures are discussed. The results indicate that epitaxial grain growth occurs along the building direction, and after SLM, entangled dislocations gather at the cell boundaries. After HT, high-density dislocations are eliminated, while most grains remain in the as-deposited form. At room temperature, the deformation mechanism of the alloy remains consistent. Cracks generate and propagate inside grains, while grain boundaries provide a more substantial barrier for dislocations. Therefore, the difference in mechanical anisotropy depends on the difference in grain morphology in the build direction and perpendicular to the build direction. At high temperatures, fracture failure occurs at grain boundaries. The growth of carbides at high temperatures leads to the weakening of grain boundaries. The alloy exhibits different deformation mechanisms when loaded along the short and long axes of the grain. Only dislocations are activated when loaded along the short axis of the grain. Stacking faults and deformation twins provide higher plastic-deformation ability when loaded along the long axis of the grains. Moreover, dislocations also activate, however the dislocation density is lower compared to loaded along the short axis.

Investigation on the crystal plasticity of α phase Ti-6Al-4V based on nano-indentation simulation and experiment

Ti-6Al-4V parts are usually hypothesized as isotropic mechanical properties during micro-machining operation. However, the crystal anisotropic mechanical property is an influential factor in the machining of crystals with different sizes and orientations. The hypothesis causes distinct variation in predicting machining force, and consequently the surface integrity cannot be exactly predicted in the micro-machining. Actually, Ti-6Al-4V parts are pseudo isotropy composed of grains with different orientations, elastic modulus, and hardness. Simultaneously, the initiation mode of plastic slip system varies with the grain orientation when the crystal is subjected to an applied load. It is challengeable to evaluate the effect of crystal orientation on its macroscopic properties, either by traditional experimental methods or macroscopic finite element analysis. Nano-indentation provides one novel method to investigate the plastic deformation of selected grains with specific orientations to characterize their mechanical response properties. This research aims to investigate the plastic behavior of α phase Ti-6Al-4V with different orientation grains by means of nano-indentation experiment and crystal plastic finite element method. In the study, single crystals of α phase are classified into “hard grains” (θ < 30°), “soft grains” (θ > 60°) and “normal grains” (30° < θ < 60°) by defining the crystal inclination angle (θ). The elastic modulus and hardness of hard grains are 9% and 28% larger than those of soft grains, respectively. This difference in mechanical properties depends on the slip system that dominates the plastic deformation behavior. The plastic deformation of soft grains is dominated by prismatic slip (48%), while hard grains are accommodated to plastic deformation by basal slip (51%). The average total cumulative shear strain of the soft grains is double that of the hard grains at a maximum load of 10 mN. Meanwhile, the sensitivity analysis is performed to evaluate the effects of the three sets of < a > slip systems and the two sets of < c + a > slip systems on plastic deformation with different grain orientations. The research contributes to the understanding of the plastic deformation mechanism in micro-machining and the exactly predicting the surface integrity generated from micro-machining.

Evaluating the influence of non-glide strain on prismatic dislocation in Mg using density functional theory calculations and the Peierls–Nabarro model

Mg and Mg alloys frequently exhibit anisotropic mechanical properties. Various high strength Mg alloys have been developed recently. Since the effect of non-glide stress on slip deformation can be prominent under a large strain or stress, it is crucial to examine the effect of non-glide stress/strain on dislocation motion. Mg easily undergoes 〈a〉 dislocation at ambient temperature; hence, in this study, the generalized stacking fault (GSF) energy of 〈a〉 dislocation on prismatic {101¯0} planes under non-glide strains was examined using the density function theory. To comprehend how dislocation behaves under various conditions, the relation between GSF energy and Peierls stress based on the discrete Peierls–Nabarro model was established, and screw and edge dislocation behaviors in the prismatic plane were discussed to obtain deeper understanding. While the dislocation core width decreases with compression and increases with tension, the Peierls stress increases greatly with compression and reduces slightly with the application of tension.

DFT Insights into MAX Phase Borides Hf2AB [A = S, Se, Te] in Comparison with MAX Phase Carbides Hf2AC [A = S, Se, Te

In this work, density functional theory (DFT)-based calculations were performed to compute the physical properties (structural stability, mechanical behavior, and electronic, thermodynamic, and optical properties) of synthesized MAX phases Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, and Hf2TeB and the as-yet-undiscovered MAX carbide phase Hf2TeC. Calculations of formation energy, phonon dispersion curves, and elastic constants confirmed the stability of the aforementioned compounds, including the predicted Hf2TeC. The obtained values of lattice parameters, elastic constants, and elastic moduli of Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, and Hf2TeB showed fair agreement with earlier studies, whereas the values of the aforementioned parameters for the predicted Hf2TeC exhibit a good consequence of B replacement by C. The anisotropic mechanical properties are exhibited by the considered MAX phases. The metallic nature and its anisotropic behavior were revealed by the electronic band structure and density of states. The analysis of the thermal properties-Debye temperature, melting temperature, minimum thermal conductivity, and Grüneisen parameter-confirmed that the carbide phases were more suited than the boride phases considered herein. The MAX phase's response to incoming photons further demonstrated that they were metallic. Their suitability for use as coating materials to prevent solar heating was demonstrated by the reflectivity spectra. Additionally, this study demonstrated the impact of B replacing C in the MAX phases.

An anisotropic conductive hydrogel for strain sensing and breath detection

Conductive hydrogels, with their excellent conductivity and flexibility, are highly suitable for use as strain sensors. However, they often exhibit weak mechanical properties and isotropy, which can limit their application potential. Moreover, the incorporation of self-powering capabilities within hydrogels would provide a significant advantage for sensor applications. In this study, we utilized hydrophilic delignified wood as a scaffold and impregnated it with FeCl3 solution to fabricate conductive wood. Subsequently, a precursor solution of polyvinyl alcohol (PVA), chitosan (CS), and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) was prepared by heating and mixing. The conductive wood was then fully infiltrated with the precursor solution and transformed into a conductive wood-based hydrogel (CWH) using a freeze-thaw method. The aligned fibers in the conductive wood scaffold imparted anisotropic mechanical and electrical properties to the hydrogel, with a fracture stress anisotropy ratio of 47.5 (ratio of values parallel to the fiber direction to values perpendicular to the fiber direction) and an electrical conductivity anisotropy ratio of 1.55. The hydrogel remained soft after bonding with the wood scaffold, preserving its potential as a sensor. Experimental results demonstrated that the CWH sensor exhibited stable strain sensitivity (gauge factor of 0.2805 with R²=0.998 in the range of 0∼90°), enabling the monitoring of human joint bending and capturing facial smiles. The CWH also exhibited excellent resistance to expansion while maintaining high water content (79.4%), making it more suitable for use in humid environments compared to traditional hydrogels. Furthermore, we assembled the CWH into a humidity-driven generator and conducted power generation tests, revealing its promising power generation potential. The voltage significantly increased when exposed to humid air (from 6.2 mV to 66.1 mV). Lastly, we integrated the humidity-driven generator with a mask to create a breath detector, which was connected to an electrochemical workstation for testing. The test curve demonstrated the successful capture of orderly breathing activities from volunteers. The combination of these advantages positions CWH for a wide range of applications, including wearable flexible strain sensors, breath detection, bioelectrodes, and green energy generation devices.

Two-dimensional anisotropic monolayers NbOX2 (X = Cl, Br, I): Promising candidates for photocatalytic water splitting with high solar-to-hydrogen efficiency

Motivated by the recent experimental synthesis of two-dimensional (2D) NbOI2 which possesses a moderate bandgap and outstanding absorption of sunlight, using the first-principles calculations, we conduct a thorough study of the geometric configuration, electronic structures, and photocatalytic properties for NbOX2 (X = Cl, Br, I) monolayers. These NbOX2 monolayers have been demonstrated to be dynamically, thermally, and mechanically stable. The significant anisotropic mechanical properties of NbOX2 monolayers are reflected by the calculated Young's modulus and Poisson's ratio. Our results indicate that these NbOX2 materials unfold semiconductor characters with indirect bandgaps of 1.886, 1.909, and 1.813 eV, respectively. Among these monolayers, it is found that the NbOBr2 system exhibits a favorable photocatalytic activity in an acidic condition (pH = 0), and the NbOI2 monolayer can act as a potential photocatalyst for spontaneous photocatalytic water splitting under a neutral environment (pH = 7). Furthermore, the response of bandgap and band edge positions of NbOX2 monolayers to the exerting in-plane strain (–6% to 6%) are investigated. These NbOX2 monolayers also show strong light absorption from the visible to ultraviolet region and anisotropic high carrier transport. Particularly, the high solar-to-hydrogen efficiency of the NbOCl2 (1% tensile strain), NbOBr2, and NbOI2 monolayers are predicted to be 14.11% (pH = 0), 16.34% (pH = 0), and 17.05% (pH = 7), respectively. Therefore, we expect the NbOX2 monolayers to be promising candidates for highly efficient photocatalytic water splitting.

Use of Digital Image Correlation in Predicting Mechanical Properties of Parts Made by Additive Manufacturing

Abstract The publication is focused on the anisotropic properties of products of additive manufacturing using a Fused Filament Fabrication technology (FFF). Five different materials used in technical practice were tested. These materials are PLA (polylactic acid), PETG/CF (polyethylene terephthalate-glycol with carbon fibre, composite material), PETG (polyethylene terephthalate-glycol), ABS (acrylonitrile butadiene styrene), and ASA (acrylic styrene acrylonitrile). Mechanical properties are verified by tensile testing according to ASTM D638. Testing is complemented by a digital image correlation method to locate the areas with the highest load transfer. The results have shown clear anisotropic properties of the test specimens. Anisotropic mechanical properties were also confirmed by digital image correlation (DIC).

Thickness-Dependent Microstructure and its Effect on Anisotropic Mechanical Properties of Duplex Stainless Steel 2205 Multi-pass Welded Joints

Thickness-Dependent Microstructure and its Effect on Anisotropic Mechanical Properties of Duplex Stainless Steel 2205 Multi-pass Welded Joints