Brass Component Research Articles

Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling

ABSTRACTThe microstructure/texture evolution and strengthening of 316 L-type and 304 L-type austenitic stainless steels during cold rolling were studied. The cold rolling was accompanied by the deformation twinning and micro-shear banding followed by the strain-induced martensitic transformation, leading to nanocrystalline microstructures consisting of flattened austenite and martensite grains. The fraction of ultrafine grains can be expressed by a modified Johnson-Mehl-Avrami-Kolmogorov equation, while inverse exponential function holds as a first approximation between the mean grain size (austenite or martensite) and the total strain. The deformation austenite was characterised by the texture components of Brass, {011}<211>, Goss, {011}<100>, and S, {123}<634>, whereas the deformation martensite exhibited a strong {223}<110> texture component along with remarkable γ-fibre, <111>∥ND, with a maximum at {111}<211>. The grain refinement during cold rolling led to substantial strengthening, which could be expressed by a summation of the austenite and martensite strengthening contributions.

Microstructure analysis and low-cycle fatigue behavior of spray-formed Al–Li alloy 2195 extruded plate

Microstructure and low-cycle fatigue behavior of spray-formed Al–Li alloy 2195 extruded plate were investigated in this work. The spray-formed alloy after hot extrusion experiment was treated with solid solution treatment and artificial aging. Microstructure analysis indicated the aged plate was dominated by elongated unrecrystallized grains, and had a rolling-type texture along extrusion direction with the highest intensity at Brass component. The existence of T1 phase strengthened the alloy crucially, but δ′ phase was basically absent. Then, the fully-reversed strain-controlled low-cycle fatigue tests were conducted at total strain amplitudes ranging from 0.4% to 1.0% for samples along two orthogonal directions. The stress-strain hysteresis loops were acquired, and the cyclic stress response curves were derived. At low strain amplitudes (0.4–0.5%), the initial cyclic hardening was slight and followed by a cyclic stability, while at higher strain amplitudes (0.6–1.0%), the alloy merely presented a continuously increasing cycle hardening behavior. Moreover, the fatigue life model based on the total strain energy was built and found to be suitable to predict life. Finally, the fatigue fractography observation showed that the fatigue source is relatively concentrated and the fracture surface had typical fatigue striations at 0.5% strain amplitude, while multiple cracks originated on the sample surface and the final fracture zone showed a ductile characteristic at 1.0%. The deformed microstructure near fracture surfaces were observed, and it was found that the cyclic hardening and stability were closely associated with the interaction between moving dislocations and obstacles including (sub)grain boundaries and secondary phase particles against them.

Effect of annealing on the microstructure and texture of cold rolled CrCoNi medium-entropy alloy

The microstructure, texture and mechanical properties of medium-entropy ternary CrCoNi alloy after cold rolling and annealing were investigated. The cold rolled material shows a heavily fragmented microstructure coexisting with fine scale shear bands. The deformation texture is a ɑ-fibre with a spread between the Goss and Brass component. This type of texture during cold rolling is direct evidence of a low stacking fault energy of the CrCoNi alloy. Annealing at 700 °C yields a fully recrystallized ultrafine grained microstructure with a large fraction of annealing twins. Annealing twins play a significant role in the evolution of the annealing texture. They lead to the emergence of new orientations which have first order twin relationship (60° <111> rotation) with the ɑ-fibre rolling texture components. Typical brass recrystallization texture BR {236} <385> component does not develop during recrystallization unlike in other low SFE alloys such as brass, Ag and Cu alloys. New prominent twin related orientations are retained with increasing annealing temperature due to the hindrance of preferential growth of certain crystallographic orientations. Tensile tests show that this alloy exhibits ultra-high strength and good ductility.

Analysis of the Crystallographic Microtexture of a UNS S32205 and a UNS S32304 Duplex Stainless Steels After Cold Rolling and Heat Treatment

Samples of duplex stainless steel 32205 (standard duplex) and 32304 (lean duplex) were investigated in the as-received state, cold rolling (with thickness reduction of 64 % and 62 % respectively) and after annealing at 1055oC for 20 s soaking. Crystallographic microtexture was obtained via Electron BackScatter Diffraction (EBSD) technique. The results showed that the crystallographic microtexture of ferrite phase in the as-received, cold rolled and annealed condition were more intense in alpha fiber= // RD and tetha fiber. The austenite microtexture was shown to be, for all conditions, mainly composed by Brass component.

Deformation and annealing behaviour of dual phase TWIP steel from the perspective of residual stress, faults, microstructures and mechanical properties

The present study aims to examine the deformation and annealing behaviour of Fe–0.07C–20Mn–2.6Si–1.6Al TWIP steel in the viewpoint of microstructural characterisation, fault analysis, triaxial residual stress measurement and mechanism of twin formation. 50% cold deformation results in improvement of hardness and tensile strength (428 HV and 1419 MPa, respectively), whereas annealing at 900 °C of the same leads to improvement in ductility (61%) with the decrease in strength (873 MPa). The residual stress is maximum and compressive in nature in deformed sample which has been diminishing after annealing. Hot rolled and hot rolled-solution treated samples develop dual phase microstructure along with annealing twins, whereas fine nano twins and high dislocation density with dual phase microstructure are apparent after 50% cold deformation. The presence of Shockley partial dislocation, overlapping of stacking faults, Lomer-Cottrell lock, intrinsic and extrinsic stacking faults affect the mechanical properties as obstacles of dislocation movements or assisting twin formation. Goss and Brass components of texture are dominating after rolling, whereas annealing results in weakening of rolling texture components. The nucleation mechanism of twin has been consistent with the pole mechanism along with the deviation process. Hence the present work amplifies the present understanding of deformation and annealing behaviour on low carbon dual phase TWIP steel from different characterisation perspectives.

Role of cube texture on toughness variation of electric resistance welded steel

ABSTRACTProperties changes of an X52 microalloyed steel processed by a full-scale industrial electric resistant welding (ERW) equipment was studied. Lack of proper toughness level in the weld zone was investigated. Results show that the low toughness value could only be satisfactorily addressed after a two-stage annealing process. {100} pole figures for each processing step revealed a completely random texture for the initial plate. However, after the ERW process, a textured structure with the main components of brass, S and copper was obtained. Texture components were substantially weakened after the second stage of annealing and instead a cube texture was developed which could explain satisfactory level of toughness for the ERW pipe after conducting the two-step annealing process.

Effect of cold-rolling on microstructure, texture and mechanical properties of an equiatomic FeCrCuMnNi high entropy alloy

In the present study, the effect of cold-rolling on the microstructural evolution, texture development and mechanical properties of an equiatomic FeCrCuMnNi dual phase high entropy alloy (HEA) was investigated. The homogenized HEA was cold-rolled at different strain levels. The material properties were evaluated by employing XRD, SEM-EBSD, tensile, and hardness tests. No phase transformations were observed during rolling. The FCC phase exhibited high local deformation if compared to the BCC one. As a consequence, a marked elongation along the rolling direction was revealed for the FCC phase. A strong texture variation as well as the formation of Brass and shear texture components were observed in the alloy for different deformation levels. By increasing the deformation, the material's strength increased; the elongation decreased due to formation of new grain boundaries and to the increasing in the dislocation density. Rolling led to the modification of the fracture mechanisms, revealing a shift from a ductile behavior to a partially brittle one.

Asymmetric cross rolling (ACR): A novel technique for enhancement of Goss/Brass texture ratio in Al-Cu-Mg alloy

The present work focused on the effect of asymmetric cross rolling (ACR) process as a novel technique on microstructure and texture evolution of Al-Cu-Mg alloys. The microstructural observation and bulk texture from RD–TD plane of the initial and deformed samples were characterized by optical microscopy (OM) and X-ray diffraction (XRD). It was found that the deformed Al-Cu-Mg alloy consisted of strong Goss, Rotated Goss, Goss-Brass, and α-fiber textures. Usually, straight rolling leads to a significant strengthening of the Brass component with increasing strain in the Al-Cu-Mg alloy, but for asymmetrically cross rolled samples, the Goss orientation was stable after 40% deformation. Results showed that the ACR process was effective to intensify (up to 1.51 after 30% thickness reduction) the low Goss/Brass texture ratio often existing in the rolled Al-Cu-Mg alloy. During 30% ACR, the dynamic recrystallization (DRX) occurred, which led to increasing the intensity of Goss and Cube components and the fraction of extra high angle grain boundaries (EHAGBs).

Development of Goss texture in Al–0.3%Cu annealed after heavy rolling

The evolution of the microstructure and texture during annealing has been studied in the center layer of 95% cold rolled Al–0.3%Cu with a large initial grain size. The cold-rolled condition is characterized by a strong Brass texture component and a deformed microstructure comprising lamellar structures intersected by a large number of shear bands. Recrystallization and precipitation take place during annealing at 200 °C, and a strong Goss texture develops. In the beginning of recrystallization, Goss oriented grains nucleate preferentially at the shear bands. At a later stage of recrystallization, new Goss nuclei can appear in regions where lamellae of the dominant Brass component are interspersed with Goss-oriented subgrains. When recrystallization is almost complete, recrystallized Goss-oriented grains grow into grains of other orientations, which results in a rapid increase in the average grain size of Goss-oriented grains and strengthening of the Goss texture. As a result, new low angle boundaries are formed between Goss-oriented grains in this strongly textured material.

Microstructure and texture development of 7075 alloy during homogenisation

The microstructure evolution of Al–Zn–Mg–Cu alloy during homogenisation was studied by optical microscope, field emission scanning electron microscope, energy dispersive X-ray Spectroscopy, differential scanning calorimetry and X-ray diffraction in detailed. It has been found that primary cast structure consisted of primary α (Al), lamellar eutectic structure η Mg(Zn, Cu, Al)2 and a small amount of θ (Al2Cu) phase. A transformation of primary eutectic phase from η Mg(Zn, Cu, Al)2 to S (Al2CuMg) was observed after 6 h of homogenisation treatment. The volume fraction of dendrite network structure and intermetallic phase was decreased with increase in holding time and finally disappeared after 96 h of homogenisation, which is consistent with the results of homogenisation kinetic analysis. Crystallographic texture of this alloy after casting and 96 h of homogenisation was also studied. It was found that casting process led the development of strong Goss, Brass, P and CuT components, while after homogenisation Cube, S and Copper components became predominant. Mechanical tests revealed higher hardness, yield strength and tensile strength for cast materials compared to homogenised alloys due to the presence of coarse micro-segregation of MgZn2 phase. The significant improvement of ductility was observed after 96-h homogenisation, which was attributed to dissolution of second phase particles and grain coarsening. Fracture surfaces of the cast samples indicated the presence of shrinkage porosity and consequently failure occurred in the interdendritic regions or grain boundaries with brittle mode, while homogenised alloys failed under ductile mode as evident by the presence of fine dimple surfaces.

Effect of accumulative roll bonding process on textural evolution and its comparison with normal rolled AA7005 aluminum alloy

In the present work, texture evolution of AA7005 aluminum alloy during the accumulative roll bonding and conventionally rolled was investigated by X-ray diffraction. It was found that the dominant texture components of both samples were Brass, Copper, Rotated Cube and Goss components, but the ARB texture evolution was quicker and displayed complex features. When the number of ARB cycle increased, the intensity of texture components decreased at the second and third pass, then enhanced at the fourth pass, and finally decreased. During the ARB process there was a texture transition at the second and third pass from Brass and S to Rotated Cube components due to the shear texture which formed on the surface region and moved to the center during the next pass. The enhancement of texture intensity at the fourth pass might be attributed to the formation of nano shear bands. The texture intensity decreasing at final cycle was correlated to redundant shear strain and continuous recrystallization during the high ARB passes.

Deformation Behavior and Evolution of Microstructure and Texture During Hot Compression of AISI 304LN Stainless Steel

Deformation behavior of hot-rolled AISI 304 LN austenitic stainless steel was studied by hot axisymmetric compression tests at 1173 K, 1273 K, and 1373 K (900 °C, 1000 °C, and 1100 °C) at strain rates of 0.01, 0.1, and 1 s−1. The flow curves were examined to understand the deformation characteristics. The influence of Zener–Holloman parameter was analyzed using appropriate constitutive models. The activation energy for deformation was found to be 473 kJ/mol. Quantitative microstructural analysis was carried out using Electron backscattered diffraction. Compression at 1173 K (900 °C) at all true strain rates gave rise to partially dynamic recrystallized microstructure with strong α-fiber texture. The deformation texture is characterized by the formation of Brass component, and partial dynamic recrystallization (DRX) led to the development of Goss, S, and ube components. Necklace structure of small equiaxed recrystallized grains could be observed surrounding the large, elongated deformed grains. Compressions at 1273 K and 1373 K (1000 °C and 1100 °C) resulted in fully recrystallized microstructure consisting of mostly Σ3 and Σ9 coincidence site lattice high-angle boundaries. Compression at 1273 K (1000 °C) leads to the formation of low-intensity diffused α-fiber. DRX was confirmed by the presence of Goss, S, Cube, and rotated Cube components. Compression performed at 1373 K (1100 °C) resulted in nearly random texture with traces of α-fiber and prominent Cube/rotated Cube components. The microstructures of the 1173 K (900 °C)-compressed samples were partitioned using grain size and misorientation criteria to quantify DRX.

Effect of Scandium addition on evolution of microstructure, texture and mechanical properties of thermo-mechanically processed Al-Li alloy AA2195

In the present study, influence of Scandium (Sc) content (0.025 and 0.25 wt%) on microstructure, texture and mechanical properties of a thermo-mechanically processed AA2195 alloy has been investigated. Addition of Sc to AA2195 alloy results in grain refinement and enhanced precipitation kinetics. TEM analysis revealed the presence of Al3(Sc,Zr) dispersoids in the Sc containing AA2195 alloys. Solution treatment and peak aging of the Sc containing alloys revealed partially recrystallized microstructure. Texture of Sc containing alloys displayed weaker Brass component compared to the Sc free material. A clear improvement in hardness and strength was observed which could be attributed to grain refinement as well as the presence of fine Al3(Sc,Zr) dispersoids. Ductility decreased slightly on Sc addition and there was an associated change in fracture mode as a result of Sc addition.

Strain partitioning and texture evolution during cold rolling of AISI 201 austenitic stainless steel

Strain partitioning and texture evolution of AISI 201 austenitic stainless steel were investigated upon cold rolling up to a true strain of ε = 0.92. ε-martensite formation is the main work hardening mechanism at low strains (ε = 0.11). With increasing strain, the volume fraction of α’-martensite increases with a sigmoidal-like behavior. Remaining untransformed austenite is intensely fragmented by mechanical microtwins. The in-grain misorientation increases for all phases up ε = 0.51 and then levels off for further strain. Strain partitions evenly between austenite and α’-martensite during cold rolling. X-ray texture measurements revealed that austenite develops Goss, Brass and S texture components up to the largest investigated strain. The presence of Brass component at the highest deformation seems to be assisted by mechanical twinning. The texture components of α’-martensite belong to the α- and γ- fibers. Texture evolution of ε-martensite was followed by electron backscatter diffraction data and results show that texture evolves up to ε = 0.51 and remains nearly unchanged at larger strains, similarly as observed for austenite and α’-martensite.

Texture transformations near the bonding zones of the three-layer Al/Ti/Al explosively welded clads

Al/Ti/Al explosively welded clads were analyzed by electron backscatter diffraction. Particular attention was drawn to texture evolution across the Al/Ti/Al interfaces. Significant changes in texture within the joined metals were conducted with the place of detonation of explosive material. The so-called base (lower) Al clad is characterized by a typical rolling texture exhibiting copper and brass components, while the flyer (upper) clad, located closer to the detonation wave front, transformed to a shear texture with rotated cube and {111} 〈110〉 components. The shear deformation also changes substantially the texture of Ti producing a much higher twin density. The observed changes unveil the effect of explosion on the microstructure of the joined metals and are discussed with respect to deformation mode and further annealing process.

Effect of strain path on microstructure and texture formation in cold-rolled and annealed FCC equiatomic CoCrFeMnNi high entropy alloy

The effect of strain path on microstructure and texture formation in an equiatomic CoCrFeMnNi high entropy alloy was investigated. For this purpose, the alloy was cold-rolled to 90% reduction in thickness (total equivalent strain (εeq) ∼2.65) using unidirectional cold-rolling (UCR) and different cross-rolling routes. In the MSCCR route, the samples were rotated by 90° around the ND in between each pass. In the TSCCR(90°) and TSCCR(45°) routes, the samples were deformed by unidirectional rolling to half of the εeq (∼1.3) in the first step and the rest half of the strain (εeq ∼1.3) was imparted after rotation around the ND by 90° and 45°, respectively. The development of deformation microstructures in all the processing routes were characterized by fine lamellar type structure intercepted by inclined shear bands. The TSCCR(45°) processed material appeared to be most prone to shear band formation. The UCR processed material showed brass type texture, while the textures of different cross-rolled materials were featured by different rotated brass components. Upon annealing, the UCR processed material showed the lowest grain size while the highest grain size was observed in the TSCCR(45°) processed material. This indicated greater available nucleation sites in the UCR processed material as compared to the TSCCR(45°) processed material. The differences in annealed grain size was presumably higher due to substructure destabilization and misorientation build-up diminishing the number of potential nuclei in the TSCCR(45°) processed material. The annealing textures of the differently processed materials were featured by the presence of α-fiber (ND//<110>) and absence of preferential nucleation and growth.

Investigation of the Origin of Coarse-Grained Bainite in X70 Pipeline Steels by EBSD Technique

Structural inhomogeneities that occurred in pipeline steels during controlled rolling and were identified as elongated regions of coarse-grained bainite were found to promote a tendency for brittle fracture of these steels. In particular, it was shown by tint etching, with subsequent analysis in polarized light with the light-optical microscope, that their volume fraction exhibited a perfect correspondence with the failure behavior. The aim of the present investigation was to comprehensively characterize the microstructure and the local texture of these regions using the EBSD technique and thereby clarify their origin. It was shown that, whereas the local texture of fine-grained regions corresponded well to the macroscopic texture of the steel band, the local texture of the structural inhomogeneities corresponds to certain minor components of the macroscopic texture. The grains of the parent austenite, from which these inhomogeneities have been produced, had orientations concentrated close to the brass component of austenite rolling texture. Hot deformation of the austenite leads to a strong variant selection (predominant realization of certain lattice orientations among plausible orientations of α-phase) during phase transformation of these grains, that result in a significant increase of the bainite packet size. Formation of bainite in the upper temperature range of bainite transformation, in its turn, leads to such a variant pairing that low-angle boundaries are formed predominantly both inside and between the packets. This further enlarges the effective grain size and correspondingly enhances the deteriorative effect of the structural inhomogeneity.

Texture/Microstructural Evolution and Mechanical Properties of a Hot and Cold Rolled Al-Mg-Si-Cu Alloy

The evolutions of texture, microstructure as well as mechanical properties of an Al-Mg-Si-Cu alloy during hot and cold rolling were investigated by TEM, EBSD and X-ray diffraction in this study. The results revealed that formation of sub-grain boundaries and //RD fiber texture after hot rolling is beneficial to the increase of the elongation of the alloy. The shear texture of //RD fiber and γ-fiber occupies a dominant role during the hot rolling process, while the main texture during the cold rolling process is the rolling texture of β-fiber. β-fiber and τ-fiber texture components are identified as two main types of texture components during cold rolling, and the Brass component {011} is transformed into Goss component {011} with the increase of the deformation.

Fracture analysis and embrittlement phenomena of machined brass components

Fracture analysis and metallographic characterization is performed in selected machinable brass components, for use in hydraulic installations. Evidence of brittle fracture was mainly indicated by the presence of intergranular failure and limited plasticity areas. Multiple cracking was observed at the most highly stressed areas, such as the crests of the threads, the cross section transitions and thinnest wall locations. Fractographic analysis performed using Field Emission SEM, suggested the occurrence of embrittling phenomena, probably attributed to overheating and subsequent Pb-phase grain boundary segregation. Metallographic cross section investigation rather supported the failure hypothesis, implying that hot shortness is the plausible cause of ductility trough and brittle failure.

Evolution of Recrystallization Textures in Cold-Rolled Commercially Pure Aluminum

The evolution of recrystallization texture in commercially pure aluminum sheet cold-rolled by 90% reduction in thickness was measured by Juul Jensen et al. The cold-rolling texture consisted of the Goss {110}&lt;001&gt;, Brass {110}&lt;112&gt;, S {123}&lt;634&gt;, and copper {112}&lt;111&gt; components. When the cold-rolled aluminum sheet was annealed at temperatures between 253 and 341°C for times between 5 min and 20 h., the cube {001}&lt;100&gt; component evolved. The evolution of the cube texture cannot be explained by either the oriented nucleation theory by Burgers and Louwerse or the oriented growth theory by Barrett. The cube texture evolution originates from the Copper component by the strain-energy-release-maximization (SERM) theory by Lee. Once the Cube oriented, dislocation free nuclei evolve, they are in the best position to grow at the expense of neighboring deformed high energy grains of the Goss, Brass, S, and Copper orientations, and the volume fractions of the Goss, Brass, S, and copper components would decrease. However, the volume fraction of the Goss component increased a little at annealing temperatures of 253 and 278°C, at variance with expectation. Low stacking-fault-energy alloys with the brass {110}&lt;112&gt; rolling texture evolve the {236}&lt;385&gt; texture after recrystallization, whereas high stacking-fault-energy alloys with the brass rolling texture evolve the Goss texture after recrystallization by the SERM theory, resulting in the increase of the volume fraction of the Goss texture.