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This paper presents the results of studies on texture formation in ferritic/martensitic steel 12Cr-2W subjected to equal channel angular pressing, warm rolling, and additional heat treatment. X-ray diffraction analysis, transmission electron microscopy, and electron backscatter diffraction were used to study the structure. An unusual texture transition H {001} → L {0 $$\overline{1}$$ 1} was observed for the first time during additional heat treatment of rolled ferritic/martensitic steel. A possibility of such texture transition is due to activation of twinning processes and increase of a number of boundaries with the coincidence site lattice relationships (the CSL boundaries).

Evolution of microstructure, texture, and hardness of the Al-Cu-Mg alloy was investigated by using scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and x-ray diffraction. Results have shown that the hardness and Brass texture intensity of the Al-Cu-Mg alloy can be enhanced during the annealing process at 240-385 °C. The hardness enhancement of the alloy can be attributed to the fine-grain strengthening; the enhancement of the Brass texture intensity of the alloy is related to the polygonization of the deformed grains with Brass orientation. In addition, the evolution path of the Brass texture evolving into recrystallization texture during annealing can be summarized as follows: Brass texture → Goss texture → R-Goss texture → Cube texture.

The microstructure evolution and impact toughness of the coarse grain heat-affected zone (CGHAZ) of TiNbV microalloyed steels were investigated by using a thermal simulation test. The samples were treated with various simulated welding thermal cycles. The phase constituents and grain sizes were analyzed by using electron backscatter diffraction analysis. The microstructure of the CGHAZ of the treated samples consisted of ferrite, acicular ferrite, pearlite, and bainite. The samples have a higher impact toughness under a lower welding heat input. This is because the microstructure of the CGHAZ is dominated by the higher volume fraction of the high-angle grain boundaries of acicular ferrites. The presence of bainite and coarsening grains are two key factors deteriorating the toughness of the CGHAZ of TiNbV microalloyed steels. The volume fraction of bainite sharply increased as the welding heat input increased, leading to a decrease in the impact toughness of the CGHAZ. For a higher welding heat input, both the severe coarsening of the grain size and a higher bainite content would result in poor impact toughness.

This paper studies the effects of solution and aging treatment on the microstructure and mechanical properties of TG6 titanium alloy systematically. The cooling methods of solution and aging are water cooling (WC) and air cooling (AC), respectively. Based on the metallographic, EBSD, and SEM analysis, it can be concluded that the solution temperature and aging time are pivotal to the microstructure and mechanical properties of TG6 titanium alloy. First, the content of the primary α phase (αp) gradually decreases as the solution temperature increases. Meanwhile, the secondary a phase (αs) precipitates from the β phase during the subsequent cooling process. Additionally, the aging time mainly affects the morphology of the αs phase. Second, the microstructure performs a better orientation during the heat treatment process. The mechanical hardness gradually increases with the solution temperature while the aging time has little effect on it. Both the tensile strength and plasticity decrease gradually as the solution temperature increases. 48 h is the best aging time. This study's relatively optimal heat treatment regime combines a solution temperature of 850 °C and an aging time of 48 h.

Microstructures and mechanical properties of tensile-strained 316L stainless steel are investigated using x-ray diffraction, electron backscatter diffraction, transmission electron microscopy, and mechanical tests to elucidate the underlying mechanisms for the evolved anisotropic mechanical properties. The straining facilitates the formation of dislocations, twins and martensite, and the yield strength increases with the strain while the elongation and the impact toughness exhibit the opposite trend. Under the same strain, the yield strength tested at angles of 0°, 45° and 90° and the impact toughness tested at angles of 0° and 90° to the straining direction are successively decreased, and this anisotropy will enhance with the strain extent. The yield strength is increased due to the higher dislocation and second-phase (martensite) hardening. The microstructure, the yield strength and the impact toughness are correlated, proving the linkage between the orientation dependence of the mechanical properties.

Super duplex stainless steel specimens were subjected to controlled (in a deformation simulator) thermal and thermal plus deformation treatments. The objective was to relate the corrosion performance with hot (1000-1300°C) deformed microstructures. The microstructural evolutions were quantified with extensive microtextural characterization and measurements of phase-specific micro-hardness. The corrosion behavior was investigated by anodic polarization and phase-specific selective dissolution methods. Though the thermal treatment imposed an increasing degradation in corrosion performance with holding temperature, the associated deformation at that temperature brought a non-monotonic behavior. The best corrosion performance (or the lowest passivation current density) was noted in the specimen deformed at ~1100°C. This superior corrosion behavior was attributed to the grain size refinement in the austenite phase. Finally, a combination of transmission Kikuchi diffraction (TKD) plus transmission electron microscopy (TEM) clearly related the grain size refinement to discontinuous dynamic recrystallization. The overall corrosion behavior was shown to be determined by a balance between decreasing austenite fraction and dynamic recrystallization-induced grain size refinement of the austenite phase.

The influence mechanism of the localized corrosion initiation and expansion of the pearlite structure and the grain boundaries of low-alloy weathering steel S500AW was studied. The structure of the material was studied by means of metallographic microscope, XRD, SEM, TEM and EBSD spectrum. The surface potential between structures on the surface of low-alloy steel substrate was studied by SKPFM. The solution immersion experiment was used to study the material structure and grain boundary phenomena in corrosion initiation stage. The results showed that the existence of defects such as dislocations and high internal stress in the organization will lead to the preferential occurrence of corrosion. The ferrite inside the pearlite underwent corrosion process preferentially, while the surrounding ferrite underwent slow corrosion process. The MxCy precipitate at the grain boundary gradually fell off with this process to form pits. The presence of Cr in the precipitate would lead to the lack of Cr in the matrix, which would affect the corrosion resistance of the material.

Wire-arc additive manufacturing (WAAM) technique was adopted to fabricate bimetallic parts by depositing nickel aluminum bronze (NAB) in two different shapes (cylindrical rod and square bar) on a 316L stainless steel substrate. Crystallography and characteristics of the interfacial layer in both parts were investigated using energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and nanoindentation techniques. Within the first layer of the deposit, several rosette-like κI particles were formed in the cylinder-NAB, whereas it is not the case in the square-NAB. In both parts, a well metallurgically bonded interface without any pores and cracks with a thin (2 μm) intermetallic layer was formed along with the interface. This interface layer is a FeAl-based intermetallic in the cylinder-NAB part, whereas it is Fe3Al intermetallic phases in the square-NAB part, as confirmed by EDS and nanohardness analysis. Occasional liquation cracks and infiltration of NAB were observed on the austenitic grain boundaries in the heat-affected zone (HAZ) of 316L. The interface did not exhibit any strong texture orientation owing to the thermal gradient’s control, as NAB is more conductive than 316L. In this work, for both parts, the role of grain boundary misorientations across different grains of the interfacial layer and HAZ cracks and relative to the deposited NAB and stainless steel substrate was studied. The cylinder-NAB sample consisted of a higher fraction (75%) of low Σ3 coincident site lattice (CSL) boundaries compared to the square-NAB sample (55%). The findings were discussed in the context of the formation mechanism of the intermetallic layer.

In this paper, the microstructure characteristics and microhardness distribution of titanium alloy joints by narrow gap fiber laser welding were studied. High-quality welded joints in 40-mm-thick TA2 have been successfully manufactured using the laser multi-pass narrow gap welding process. The welds were found to be free of lack of fusion defects. The size of grains, microstructure, dislocations, Kernel average misorientation (KAM), texture and microhardness of joint in upper and middle were investigated by optical microscope (OM), transmission electron microscope (TEM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and microhardness Vicker. Results indicate that the upper joint has great different from middle joint on microstructure. In addition, the microhardness of the weld metal center is the highest, and the fusion zone is higher than the base metal and lower than the weld metal. The microhardness of the upper weld metal is higher than that of the middle weld metal. The strength of weld metal is not lower than that of the base metal, and impact toughness KV2 of joint is lower than that of base metal.

AZ31 magnesium alloy has poor plastic deformation ability at room temperature due to its hexagonal close-packed (HCP) structure. For traditional plastic forming processes, such as extrusion processes, they can improve the mechanical properties of AZ31 magnesium alloy within a certain range at room temperature. But the coordinated deformation of twin mechanism cannot be neglected during the plastic deformation process. The mechanical properties of AZ31 magnesium alloy exhibit tension–compression yield asymmetry (TCYA). These characteristics of AZ31 magnesium alloy have caused restrictions. As a short forming/preparing integrated process, CVCDE can increase the yield strength (YS) of AZ31 magnesium alloy while effectively improving the TCYA of AZ31 magnesium alloy. In this study, the uniaxial compression test is employed and the quantitative evaluation of the AZ31 magnesium alloy TCYA is carried out by means of the SDE coefficient. With the aid of scanning electron microscopes (SEM) and electron backscattered diffraction (EBSD), the test results indicate that the fracture morphology has changed significantly with the increase in CVCDE interim. The distribution of tear ridges in the fracture area tends to be uniform and the number of dimples increases significantly. The dimples also present a trend of deepening. From the twin distribution, the proportion of {10-12} tensile twins (TTWs) decreased after the AZ31 magnesium alloy processed by CVCDE. This is conducive to the YS in the compression process and the improvement of the TCYA can be obtained.

The microstructure observation, hardness test, texture analysis, and axial tensile test were conducted to clarify the effect of special solution treatment (at 980 °C for 1 hour with air cooling) on high-temperature mechanical properties of Inconel 718 (IN718) superalloy manufactured by selective laser melting (SLM). After solution treatment, the columnar and equiaxed grains with a diameter of 300 nm dissolved, which were formed due to the high cooling rate during the SLM procedure. Moreover, the strengthening γ′′ or δ phases precipitated at grain boundaries after solution treatment resulting in the increment of mechanical properties. Results of electron backscatter diffraction show that the solution treatment has a little effect on the texture, but can increase the fraction of high angle grain boundaries and Schmid factor by 15.6% and 1.5%, receptively. Varieties of mechanical properties at room and high temperature were explained with the characteristics of low-angle grain boundary, Schmidt factors, and grain size. Fractographic features analysis was used to reveal the high temperature deformation behavior, meanwhile, the stress-strain curves were fitted based on the Ramberg-Osgood equation. The differences between the tensile test fracture surfaces indicate that the solution treatment can change the shear strength limit of SLM IN718 superalloy.

Within this research, the multiscale microstructural evolution before and after the tensile test of a FeCo alloy is addressed. X-ray µ-computer tomography (CT), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM) are employed to determine the microstructure on different length scales. Microstructural evolution is studied by performing EBSD of the same area before and after the tensile test. As a result, $$\langle$$ ⟨ 001$$\rangle$$ ⟩ ||TD, $$\langle$$ ⟨ 011$$\rangle$$ ⟩ ||TD are hard orientations and $$\langle$$ ⟨ 111$$\rangle$$ ⟩ ||TD is soft orientations for deformation accommodation. It is not possible to predict the deformation of a single grain with the Taylor model. However, the Taylor model accurately predicts the orientation of all grains after deformation. {123}$$\langle$$ ⟨ 111$$\rangle$$ ⟩ is the most active slip system, and {112}$$\langle$$ ⟨ 111$$\rangle$$ ⟩ is the least active slip system. Both EBSD micrographs show grain subdivision after tensile testing. TEM images show the formation of dislocation cells. Correlative HRTEM images show unresolved lattice fringes at dislocation cell boundaries, whereas resolved lattice fringes are observed at dislocation cell interior. Since Schmid’s law is unable to predict the deformation behavior of grains, the boundary slip transmission accurately predicts the grain deformation behavior.

The use of lightweight arc-shaped products is one of the effective ways to realize the lightweight of material and structure. Staggered extrusion (SE) is a new method for short process forming of arc-shaped materials. Due to step-like stem, it has an important influence on extrusion flow behavior and microstructure. Herein, the AZ31 magnesium alloy microstructure evolution during the SE is focused on. By means of metallographic microstructure analysis and electron backscatter diffraction, the microstructure of bending products with staggered distance h of 16 mm and extrusion ratio of 11.11 was analyzed. The results show that with the change of stem structure, the order and amount of shear deformation change at each part, resulting in the difference of average grain size. Compared with the initial billet, the average grain size is refined from 68.38 to 17.15 μm. Complete dynamic recrystallization takes place to form fine and uniform grains. Basal texture {0001} tends to be perpendicular to the extrusion direction (ED) in regions A, B and C. The texture of region A in forward extrusion is shifted counterclockwise, and that of regions B and C in backward extrusion is shifted clockwise. However, the texture in the region D turns parallel to the ED, but there is a small deflection angle α. It provides scientific guidance for the shape control and precision manufacturing of high-quality arc-shaped products.

Wetting of ZrB2 substrate with NiCrBSiC self-fluxing alloy was studied by the sessile drop technique in a vacuum environment at 1100 °C. The structure and composition of the interface and the drop regions were investigated using scanning electron microscope, equipped with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). It was found that NiCrBSiC alloy wets the ZrB2 substrate forming a final contact angle of 42°. Dissolution of ZrB2 in the molten drop and formation of new phases, such as Zr2Ni21B6, CrB, Ni3Si, and Ni3B, have been found to occur both at the interface and in the drop regions in the ZrB2-NiCrBSiC system.

Rolling–sliding wear experiments of U75V rail steel were carried out on a GPM-40 friction and wear machine. The microstructure evolution and property change of the sample under rolling–sliding conditions were studied using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and hardness test. In the early wear stage, the wear mechanism of the sample surface is mainly oxidative wear, and the sample is in uniform wear stage. With the increase in cycle number, the surface wear mechanism changes to fatigue wear, the mass wearing quantity increases significantly, while the wear rate remains unchanged after increasing; thus, the sample is in the rapid wear stage. As the slip ratio increases, the mass wearing quantity and the wear rate increase. During the plastic deformation of U75V rail steel, cementite is bent, fractured, fragmented, and even dissolved, and the proportion of high-angle boundary (HAB) in ferrite gradually increases. The increase in slip ratio accelerates the microstructure refinement of U75V rail steel. As a result, the proportion of high-angle boundary increases obviously at the same distance from the surface, and the grain refinement becomes serious. The maximum hardness is located at the worn surface. With the increase in cycle number, the hardness of the worn surface increases rapidly at first, reaches the maximum, and then reaches saturation. The saturation hardness is about 850 HV, increasing by 1.38 times. The increase in slip ratio improves the hardening speed of U75V rail steel but exerts a minimal effect on the saturation hardness. Surface hardening results from the combination of dislocation strengthening, strengthening by grain size reduction, and solid solution strengthening.

Forming limit diagrams (FLDs) are widely used in sheet metal industries to assess formability. These are graphical representations of major and minor strains on a 2-D plot separating safe and unsafe regions. Limiting strains were measured by digital image correlation (DIC) technique. In the present work, microstructure evolution and forming behavior of family of interstitial free steels: interstitial free (IF) and interstitial free-high strength (IF-HS) grades have been investigated. Both experimental and finite element (FE) simulated FLDs indicated higher formability for IF steel. Microstructural developments affect forming limits and influence forming limit diagrams. Evolving microstructure during forming was studied by texture developments using x-ray diffraction (XRD) and in grain average misorientation developments using electron backscattered diffraction (EBSD) techniques as a function of strain and strain paths. Estimated microstructural parameters revealed that the enhanced formability of IF steel was due to the presence of strong γ-fiber (ND// ) recrystallization texture and corresponding absence of θ-fiber (ND// ). On the contrary, IF-HS steel showed the abundant θ-fiber component and hence decreased formability.

The high-temperature deformation behavior of the as-forged TC17 titanium alloy was studied based on the results of thermal compression simulation tests. Additionally, the effects of strain rate, temperature and true strain on the flow stress were analyzed using orthogonal experimentation and variance analysis. The results indicated that all deformation parameters exerted significant influence on flow stress, with temperature and strain having the largest and least influence, respectively. Thereafter, a constitutive equation based on modified nonlinear regression was proposed. The error analysis results showed that the flow stress of the as-forged TC17 alloy could be predicted by the obtained constitutive equation. The effect of deformation parameters on the microstructure was investigated by EBSD and TEM.

Widespread industrial adoption of metal additive manufacturing (AM) requires an in-depth understanding of microstructural evolution during AM. In this study, the effect of process parameters and feature thickness on the microstructures of 316L stainless steel components fabricated by laser powder bed fusion (LPBF) was examined. A standard benchmark geometry developed by the National Institute of Standards and Technology, which contained walls of 0.5, 2.5 and 5.0 mm in thickness, was used. Optical microscopy, finite element analysis, scanning electron microscopy and electron backscatter diffraction revealed dramatic microstructural differences in features of different thickness within the same component. The feature thickness influenced the cooling rate, which in turn impacted the melt pool size, solidification microstructure, grain morphology and density of geometrically necessary dislocations. The relationship between feature size and grain morphology was dependent on the energy input used during LPBF. Such behavior suggested that local manipulation of LPBF process parameters can be employed to achieve microstructural homogeneity within the as-printed stainless steel components.

Microstructure and microtexture of a dual-phase (DP) steel was investigated using the electron backscattered diffraction (EBSD) technique. A DP600 steel was produced by 60% cold-rolling a low carbon steel with an initial ferrite pearlite microstructure followed by intercritical annealing at 720°C for 1 h. Kernel average misorientation map of the DP600 steel showed that the density of geometrically necessary dislocations as well as the local misorientation is higher in the vicinity of ferrite–martensite interfaces compared to the middle of the ferrite grains. Microtexture analysis of the cold-rolled steel by EBSD revealed that a strong α fiber and weaker γ fiber texture forms after cold-rolling. After intercritical annealing, the intensity of the α fiber texture is significantly reduced, whereas that of the more desirable γ fiber texture is slightly increased. The maximum texture intensity in the DP600 steel was observed for (112)[110] component in the α fiber, and (111)[123] and (111)[112] components in the γ fiber.

To develop high-quality refractory metal targets, pure W and W/Re alloys (with Re contents of 1, 5 and 10 mass%) were fabricated via mechanical mixing, press forming and vacuum sintering. Properties such as relative density, grain size and orientation, and magnetron sputtering characteristics were investigated in the W/Re alloys. With increasing Re content, both the relative density and purity of the W-Re alloys increased, while the grain size decreased. The sizes of the grains in the W/10 mass% Re alloy target were mainly between 10 and 40 μm. The results of electron backscatter diffraction (EBSD) indicated that the grains in the W/Re alloys were randomly distributed and did not have a preferred orientation. The percentage of small-angle grain boundaries (

A comprehensive analysis and characterization of granular structure (GS) and granular bainite (GB) were conducted in a low-carbon alloy steel with the objective to elucidate the mechanisms that contributed to strength–ductility combination. Ferrite + martensite–austenite (M-A) islands were observed in both GS and GB, but a transformation mechanism produced a variation in the matrix and in the M-A size, distribution and morphology. The differences in the matrix and M-A islands were carefully studied by electron backscatter diffraction. Furthermore, tensile tests were interrupted at different strains to study the microstructure evolution during tensile straining and mechanical properties determined from samples tensile strained to fracture. It was observed that the specimen with GB exhibited higher tensile strength, ductility and strain hardening compared to GS. Dislocation strengthening of GB was more apparent than GS. The higher volume fraction and uniform distribution of M-A islands also contributed to the higher strength of GB. The improvement in ductility may partly be attributed to the sub-structural refinement. An increased presence of geometrically necessary dislocations array in GB also simultaneously enhanced strength and ductility. During deformation, GB exhibited a more uniform local strain distribution compared to GS because of superior plastic ability of M-A islands. Based on the experimental results and analysis, we propose models describing the different failure mechanism in GS and GB.

Single-point incremental forming (SPIF) was conducted on a 1-mm-thick commercially pure titanium grade 2 (Ti-G2) sheet metal in a CNC vertical milling unit. A hardened steel ball of 12 mm diameter was used as forming tool. Frustum cups were formed with varying spindle speeds between 300, 450, and 600 RPM. Other process parameters including the vertical step down and feed rate were kept as 0.2 mm and 300 mm/min, respectively. The metallurgical and mechanical properties of the formed material were investigated by cutting samples from the frustum cup walls. Electron-backscattered diffraction (EBSD) investigation revealed limited change in grain size with an increase in spindle speed. Dislocation density was measured by x-ray diffraction peak broadening analysis. The results indicate that an increase in spindle speed resulted in an increased dislocation density. The EBSD-based textural studies revealed a strong basal texture with near P and B type orientations visible at the maximum spindle speed. The tensile tests demonstrated a proportional increase in tensile strength with an increase in spindle speed along with a significant reduction in total ductility. The enhanced dislocation density and the formation of a strong basal texture were considered as the main drivers for the improvement in the tensile strength. A maximum tensile strength of nearly 550 MPa was obtained for samples extracted from the walls of the frustum cup at the maximum spindle speed of 600 RPM. This translates to an 80% enhancement of the tensile strength when compared to the base metal .

This paper presents the details on predicted and experimental microstructural evolution and high-temperature tensile behavior of a hot isostatically processed (HIPed) and heat-treated Ni-based superalloy EP741NP for aerospace applications. The phase prediction carried out using JMatPro® software from the composition of the alloy as a function of heat treatment has been found to agree with the results of characterization by scanning and transmission electron microscopy. Prediction has revealed the evolution of secondary and tertiary gamma prime (γ′) with phase fraction of ~46% during solutionization at 1483 K (1210 °C) for 8 h and ~12% during the course of aging treatment at 1144 K (871 °C) for 32 h, respectively. A uniform distribution of secondary γ′ with typical octocube morphology within a size range of 0.5–0.8 µm and a sparse distribution of tertiary γ′ of fine spherical particles with average size < 0.1 µm have been observed during study of microstructure. Electron backscattered diffraction (EBSD) studies showed epitaxial growth for γ′ phase within a grain with similar crystallographic orientation. Tensile tests conducted at room temperature and in the temperature range from 823 K to 1123 K (550 °C to 850 °C) have shown that yield strength (YS) and ultimate tensile strength (UTS) remain almost unchanged up to temperature 923 K (650 °C) due to microstructural stability of strengthening γ′ precipitate. Thereafter, it starts decreasing because tertiary precipitates cannot hinder grain boundary motion at high temperature, first because of their size and more importantly because they are usually dissolved back into the matrix at high temperature, which assist the annihilation and rearrangement of dislocations leading to reduction of dislocation density. Fractographic studies have revealed that the fracture mode is found to be mostly mixed in nature (both ductile and brittle fracture).

The double-sided electron beam welding (EBW) was proposed to overcome the severe deterioration of mechanical properties and electrical conductivity of Al/Cu bilayer laminated composite in the single-sided EBW process. The results show that the sound butt joint was obtained via the double-sided EBW. For the double-sided EBW joint, the microstructures in the Cu and Al side welds were similar. In the weld edge, it consisted of well-developed columnar structures. In the weld center, the fine equiaxed structures formed. The results of scanning electron microscopy with energy-dispersive spectroscopy, electron backscatter diffraction and x-ray diffraction indicated that the interface zone consisted of Al2Cu IMC and (Al2Cu+α-Al) eutectic structure. Moreover, the tensile strength of the double-sided EBW joint was 116.9 ± 5.3 MPa, and the fracture position was at the center of the joint, which was approximately 93% of the base material strength and far superior to the performance of single-sided joints with Modes I (57.5 ± 3.7 MPa) and II (66.7 ± 4.6 MPa). Furthermore, the electrical conductivity of the double-sided EBW joint was 56.8 ± 0.4 MS/m, which could reach 99.3% of the base material conductivity and was significantly higher than that of single-sided joints with Modes I (38.5 ± 2.1 MS/m) and II (44.3 ± 1.7 MS/m), ensuring the functionality of the joint after double-sided EBW.

The aim of this work was to characterize the microstructure-mechanical response relationships in UNS N08825/AISI 316L welds by means of electron backscatter diffraction analysis. Welding was conducted by ERNiCrMo-3 and ER308L filler wires. It was indicated that a significant increase in fractions of low Σ coincidence site lattice (CSL) boundaries occurred in UNS N08825 heat-affected zones (HAZs), whereas a small number of the boundaries formed in the AISI 316L HAZs and weld zones were of low ΣCSL types. Abnormal grain growth took place in the HAZs leading to changes in the initial texture components of the alloys. It was also demonstrated that the type of the used filler wire was a factor influencing the microtexture components formed within the HAZs. According to the results of mechanical tests, the weldment employing the ERNiCrMo-3 filler wire exhibited superior hardness, tensile strength, and elongation. Moreover, the occurrence of the abnormal grain growth in UNS N08825 HAZs had no negative effects on the tensile response of the weldments as a result of the activation of texture strengthening mechanism. Based on the obtained results, the ERNiCrMo-3 filler metal was recommended to fabricate the joint.

As the manufacturing sectors are leaning toward additive manufacturing, leaving the traditional methods behind. Wire arc additive manufacturing (WAAM) technique is the growing technique to fabricate the aerospace, defense, and automotive sector components. The major problem associated with the WAAM technique is establishing the process parameters to acquire the defect-free components. In this research work, an attempt has been carried out to establish a wire arc additively manufactured component using Inconel 625 filler. A successful attempt has been made to build the thick slab wall component using Inconel 625. The microstructure analysis was studied in both longitudinal and transverse direction to check the homogeneity. The transverse microstructure at the near substrate region has a cellular structure. The columnar structure is observed in the layer bands between the layers, and the topmost layer revealed equiaxed with a dendritic structure. The longitudinal microstructure varies from a columnar structure in the inter-pass boundaries to fine equiaxed structures between the passes, and at the end, it is an equiaxed structure. Microsegregation in the dendritic core and interdendritic regions was evaluated along with microhardness measurement. The microhardness values along the different layers were increased when taken from bottom to top. Similarly, it increases across the passes due to the formation of an equiaxed dendritic structure. The EBSD investigation was performed to evaluate the manufactured component’s grain size (25.48 ± 61.02 μm), and misorientation angle, low boundary rotation angle (2–5°) and high boundary rotation angle (15–180°). Further, the local dislocation sites were observed through KAM mapping.

The effect of cold rolling on the recrystallization texture and ridging of AISI 430 type ferritic stainless steel is investigated. For comparison, the steel was cold-rolled under different reductions, two-stage rolled, and cross-rolled, respectively, and the recrystallization texture was determined by EBSD and microstructure was characterized by SEM, and the uniaxial deformation was conducted on MTS electronic universal material testing machine. The results show that in the one-stage cold rolling and annealing process, γ-fiber texture component increases with the rolling reduction, and the maximum orientation density of which appears at {334} orientation with a slight deviation from {111} . The intensity of {100} texture decreases and the other main texture components remain unchangeable. After two-stage cold rolling, the recrystallization texture returns to the γ-fiber texture that is of the feature of the ordinary bcc metals, while cross-rolling results in a recrystallization texture of mainly {100} and {111} components. It is indicated that intermediate annealing obviously improves the deviation of orientation from γ-fiber texture, which is beneficial for the steel obtaining the typical texture of bcc metals. By one-stage cold rolling and annealing process, AISI 430 type ferritic stainless steel possesses a microstructure with the texture components of {100} , {211} , {111} and {111} , with clusters of {111} , {hkl} and {hkl} grains, which deteriorates the ridging resistance, while in the two-stage rolling and annealing process, the microstructure of dispersed oriented grains shows a much better surface ridging resistance.

The electron backscatter electron diffraction (EBSD) technique was applied to study the microstructure evolution and properties of the annealed cold rolling C71500 cupronickel alloy tube. The fixed reduction ratio of C71500 alloy tube was 23.71%. After rolling with different thickness reduction, the change process of grain, the evolution of texture, the characteristic distribution of grain boundary and the mechanical properties of the alloy tube were discussed systematically. The texture of cold rolling tube was obviously different from the drawing and sheet textures, and only the textures of RZ{111 type and R-cube{001} type could be observed after the two roller cold rolling process. After a certain amount of deformation, obvious accumulated orientation differences could be seen in the textures, which could create favourable conditions for the recrystallization nucleation. In the rolling process, the nonuniformity deformation of tube was caused by the inconsistency of stress state. With the increase reduction of tube wall, the tensile strength of the alloy increased from 405.13 to 574.65 MPa, the yield strength increased from 310.35 to 338.76 MPa, and the micro-Vickers hardness increased from 137.40 to 186.01.

The additively fabricated functionally gradient structures can be a potential replacement for conventionally manufactured structures via fusion welding techniques. A SS321/Inconel 625 functionally gradient material was processed by wire arc additive manufacturing (WAAM) process. The WAAM-formed SS321 comprises of equiaxed and columnar structures, while the Inconel 625 consists of dendritic structures. It can be concluded that a very narrow interface was formed between the additively manufactured SS321/Inconel 625 FGM without forming cracks or fissures. Energy-dispersive x-ray spectroscopy (EDS) element maps show a smooth transition of elements at the interface without much segregation while EDS point scan confirmed the presence of laves phase. The electron backscatter diffraction results at the interface region revealed continuous crystallographic growth with large elongated grains in the orientation. Tensile properties were better for SS321 and comparable for Inconel 625 than the wrought alloys, while the interface FGM sample failed on the SS321 side. The micro-hardness steadily changed from 226-195 HV and 272-236 HV in SS321 and Inconel 625, respectively. The WAAM process demonstrates that successful FGM components can be fabricated with multi-material and controlled properties.

Two-stage rolling process was adopted to study the texture and special grain boundary distribution of C71500 copper-nickel alloy tubes at different annealing temperatures. The effect of temperature on the texture of C71500 copper-nickel alloy tube was analyzed. The hardness analysis was used to study the recrystallization and low lattice reconstruction grain boundaries ratio at different temperatures. It was observed by electron backscattered diffraction that static recovery of the alloy tube occurs when the annealing temperature below 800 °C and it transforms into static recrystallization at 825 °C. The initial strain-induced grain boundary migration temperature of alloy tube is about 775 °C. The number of Copper{112} textures can be used to determine the ratio of the low coincidence site lattice (low ΣCSL) grain boundary. The optimal annealing process for C71500 alloy tube to obtain a high proportion of special grain boundaries is to keep the temperature at 800 °C for 15 min.

An Nb-Ti low carbon HSLA steel with the application of Coiled Tubing steel in petroleum industry, was subjected to hot rolling followed by the subsequent cooling procedures including cooling and coiling. The effect of cooling rate and coiling temperature on final microstructure and texture was investigated via optical microscopy, SEM, and EBSD analyses. It was found that rolling at 800 °C results in the appearance of elongated ferrites due to the activation of the deformation-induced ferrite transformation mechanism. Cooling from the finish rolling with different rates of 2.4 to 15 °C/s leads to the formation of polygonal ferrite and retained austenite. Higher cooling rate increases the retained austenite, decreases the ferrite grain size and improves the grain size homogeneity. Coiling at 600 °C results in coarser ferrite with the texture of γ fiber which is due to the recrystallization of ferrite. On the other hand, coiling at 500 °C intensifies the {332} $$\left\langle {113} \right\rangle$$ and {113} $$\left\langle {110} \right\rangle$$ components indicating deformed austenite transformed to ferrite.

The effect of grain size on adiabatic shear susceptibility of copper was investigated in this paper. Moreover, the results show that the critical time and critical strain corresponding to the stress collapse point decrease with the increase of grain size at the same strain rate, while the widths of adiabatic shear bands (ASBs) increase as grain size increases, indicating that the adiabatic shear susceptibility of copper increases with the increase of grain size. The electron backscatter diffraction (EBSD) experiment shows that the fraction of twin boundaries in large-grain copper is higher than that in small-grain copper before loading. Furthermore, the larger the grain size is, the easier twin will be produced in large-grain copper during deformation, which leads to the twin boundary ratio of large-grain copper will be further higher than that of small-grain copper. The higher fraction of twin boundaries makes large-grain copper have a stronger strain rate hardening effect and thermal softening effect than small-grain copper. Considering that their strain hardening effects are similar, the enhancement of thermal softening caused by the increase of twin boundary ratio exceeds the enhancement of strain hardening effect and strain rate hardening effect, indicating that large-grain copper has a higher adiabatic shear susceptibility.

Al-18%Si-4.5%Cu alloy was processed by route BC equal-channel angular pressing (ECAP) at a temperature of 400 °C. Electron backscattered diffraction (EBSD) was used to analyze the microstructure and microtexture during the ECAP process. The microstructural results showed three important effects: First, the particle-stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) had the main effect on the refinement of the aluminum matrix during the ECAP process. Second, after the third and fourth passes, due to redundant strain created by route BC, the heterogeneous microstructure was observed. Third, further ECAP passes led to further fragmenting and better distribution of the particles. The microtextural results showed that further ECAP passes led to strengthening the $$B/\overline{B}$$ component at the center and also strengthening the A*1 and A*2 components at the bottom of specimens. The microhardness results showed that the grain refinement strengthening and precipitation strengthening were the main strengthening mechanisms in the route BC-ECAPed Al-18%Si-4.5%Cu alloy.

The hot ring rolling of centrifugal casting 25Mn flange blank was conducted for achieving the grain and texture distribution in the whole thickness. Compared to the casting one, the mechanical properties of the hot-rolled flange are improved, and the tensile and impact fracture are dominated by the mixture of quasi-cleavage and ductile fractures. The homogeneous grain distribution with 30–38 μm in diameter is presented near the outer and inner layers, and the irregular grain is observed in the center-layer closely related to the lower recrystallization degree. The finer and uniform distribution grains with low-angle grain boundaries approximately 60% are found in the surface layers, which are caused by the HRR, resulting in the generation of many sub-grains. The misorientation changes within grains in the surface layers illustrate an increment in the refined grains. The textures are characterized by the Brass-R {111} component along //ND, Goss {110} , and Copper {112} components, which result in the excellent tensile and yield strengths but a relative low plasticity and toughness. Thus, it is feasible to fabricate 25Mn flange with sound microstructure and excellent mechanical properties hot-rolled directly from a centrifugal casting blank by controlling texture component along RD.

The present work investigates the influence of constrained groove pressing (CGP) on the microstructural evolution and mechanical properties of 304 austenitic stainless steel. CGP shows a significant improvement in mechanical properties such as tensile strength and micro-hardness. XRD analysis shows the transformation of austenite phase into deformation-induced martensite phase which is also confirmed by vibrating sample magnetometer. Finite element analysis employing Deform 3D software shows the average induced strain of 2.29, after two passes of CGP. Rietveld refinements on XRD patterns affirm the decrease in crystallite size, increase in microstrain and dislocation density. EBSD also shows the formation of substructures due to CGP. The ultimate tensile strength of solution-treated specimens enhances from 729 to 1058 MPa, and the value of micro-hardness increases from 238 to 477 VHN after two passes of CGP. The augmentation in mechanical properties is attributed to the synergic effect of increased dislocation density, martensitic transformation, substructure formation and reduced crystallite size.

The dynamic recrystallization behavior of a high-temperature titanium alloy Ti600 has been investigated by hot compression tests at the strain rates of 0.001-10 s−1 and temperatures of 950-1010 °C. The grain boundary migration during deformation has been analyzed, and a critical DRX dislocation density associated with material essence and grain boundary mobility has been proposed to identify the main softening mechanism of Ti600. Additionally, JMAK model has been employed to describe the dynamic recrystallization behavior, which is essential to concerned dynamic recrystallization with material and deformation parameters to investigate the dynamic recrystallization behavior of Ti600. The activation energy QSRX has been calculated as 91.18 kJ. Finally, processing map has been established, and the optimal process window has been present. And EBSD experiments at different temperatures and strain rates have been conducted to deeply study the grain boundary distribution and crystal orientation.

This paper focuses on microstructural and mechanical characterization of metallic thin-walled tube produced with additive manufacturing (AM), as a promising alternative technique for the manufacturing of tubes as a feedstock for stents micromachining. Tubes, with a wall thickness of 500 μm, were made of 316L stainless steel using selective laser melting. Its surface roughness, constituting phases, underlying microstructures and chemical composition were analyzed. The dependence of hardness and elastic modulus on the crystallographic orientation were investigated using electron backscatter diffraction and nanoindentation. Spherical nanoindentation was performed to extract the indentation stress–strain curve from the load–displacement data. The obtained results were compared with those for a commercial 316L stainless steel stent. Both tube and commercial stent samples were fully austenitic, and the as-fabricated surface finish for the tube was much rougher than the stent. Microstructural characterization revealed that the tube had a columnar and coarse grain microstructure, compared to equiaxed grains in the commercial stent. Berkovich nanoindentation suggested an effect for the grain orientation on the hardness and Young’s modulus. The stress–strain curves and the indentation yield strength for the tube and stent were similar. The work is an important step toward AM of patient-specific stents.

Additive manufacturing (AM) is able to generate parts of a quality comparable to those produced through conventional manufacturing, but most of the AM processes are associated with low build speeds, which reduce the overall productivity. This paper evaluates how increasing the powder layer thickness from 20 µm to 80 µm affects the build speed, microstructure and mechanical properties of stainless steel 316L parts that are produced using laser powder bed fusion. A detailed microstructure characterization was performed using scanning electron microscopy, electron backscatter diffraction, and x-ray powder diffraction in conjunction with tensile testing. The results suggest that parts can be fabricated four times faster with tensile strengths comparable to those obtained using standard process parameters. In either case, nominal relative density of > 99.9% is obtained but with the 80 µm layer thickness presenting some lack of fusion defects, which resulted in a reduced elongation to fracture. Still, acceptable yield strength and ultimate tensile strength values of 464 MPa and 605 MPa were obtained, and the average elongation to fracture was 44%, indicating that desirable properties can be achieved.

Inhomogeneous microstructural gradient of the friction stir welding (FSW) joint in T2 thick copper plates was studied in the present work. Microstructures along the thickness direction of the nugget zone (NZ) were systematically characterized via using electron back-scattering diffraction (EBSD) method. The corresponding mechanical properties of different layers in the NZ, involving tensile performance and microhardness, were examined as well. Through our characterization results of each layer in the NZ, it is found that a significant gradient microstructure is generated due to the temperature and strain gradient produced by FSW process. Refined equiaxed grains dominate the NZ’s lower areas, while coarse grains with a mass of twins occupy the upper regions. Along the thickness direction from the top to bottom, the mean grain size of the NZ gradually declines from 15.56 ± 8.79 to 5.74 ± 3.06 μm. Such refined microstructure in the lower layer of the NZ leads to the enhancement of mechanical properties of the specimens due to the Hall–Petch relationship. Particularly, the strength and hardness of the lowest layer are found to be comparable with the cold-rolled base metals. The result further uncovers the underlying mechanism about how the microstructural gradient forms on FSW and how it affects the mechanical performance of the weld joint. The work also inspires that, through controlling the heat input of the present FSW method, the gradient microstructure of NZ can be rationally adjusted to improve the welding quality.

The development of inhomogeneity in the microstructure, texture, and mechanical property in hot-rolled (API) 5L X70 pipeline steel after rough and finish thermomechanical control processing has been investigated by experimental measurements. Our investigations revealed that the rough rolling stage produced mostly large and coarse ferrite grains across the thickness, while the finish rolling stage led to a rather refined small-grained microstructure. EBSD investigations confirmed that after the rough rolling stage, recovered and deformed grains dominated the quarter and mid-thickness compared to the surface. Investigation of the finish rolled steel showed that in comparison with the quarter and mid-thickness sections of the plate, the surface section mostly consists of deformed grains. The texture components obtained from x-ray measurement showed that after rough and finish processing stages, the {001} , {110} , {123} , {112} , and {001} components were observed to be present. However, inhomogeneity of texture was observed at different depths of the rolled steel, such that in comparison with the surface, volume fractions of texture and intensities of the desired γ-fiber texture were seen to be highest at the mid- and quarter-thickness sections after both rolling stages. The room-temperature tensile stress–strain curves showed that the highest yield strength was observed for samples obtained from the near-surface section, while samples obtained from the mid-thickness section showed the highest elongation during tensile deformation. Overall, the final stage processing was observed to refine the final microstructure of the steel, thus improving the strength of the steel.

The microstructure and corrosion properties of the as-extruded Mg-Zn-Ca alloy with and without Ce addition are investigated. The microstructure was characterized by optical microscopy, scanning electron microscopy coupled with electron backscatter diffraction detector. Ce addition retarded dynamic recrystallization during deformation, which resulted in the formation of bimodal microstructure with finely dynamically recrystallized (DRXed) grains and coarsely unDRXed grains. Texture of the DRXed region was weakened after small addition of Ce, mainly attributing to particle stimulated nucleation. The strength enhancement for the Ce containing Mg-Zn-Ca alloy was attributed to the fine microstructure and strong texture. Corrosion results indicated that Ce addition deteriorated corrosion resistance in 3.5 wt.% NaCl solution of the as-extruded Mg-Zn-Ca alloy, which was related to the dispersed second phases, refined microstructure and weak basal texture in DRXed region.