Evolution of microstructure and texture during annealing of Al-2.5%Mg-0.2%Sc severely deformed by a combination of accumulative roll bonding (ARB) and conventional rolling

Evolution of microstructure and texture during heavy cold-rolling and annealing of Al-2.5%Mg-0.2%Sc alloy was investigated. For this purpose recrystallized sheets of 1mm thickness having finely dispersed precipitates were processed to 3 cycles of ARB (equivalent strain, εeq=2.4) followed by conventional rolling to a final thickness of 200μm resulting in total equivalent strain of 4.0. Evolution of ultrafine microstructure and strong copper or pure metal type texture were observed during deformation. During annealing very stable microstructure was observed up to 400°C but further annealing resulted in formation of a layered microstructure with deformed layer sandwiched between recrystallized layers. Formation of strong cube texture is not observed in the recrystallized layers. Isothermal annealing for longer time at 500°C leads to abnormal growth of Q orientation ({013}) within the deformed layer

Effect of Strain Path Change during Cold Rolling On the Evolution of Deformation and Recrystallization Textures of High Purity Nickel

The effect of strain path change during cold rolling and subsequent annealing on the evolution of microstructure, texture and hardness properties of high purity nickel (~99.7%, average size ~ 36 μm) has been studied in the present work. Strain path change is achieved by employing two different rolling routes, namely, straight cold rolling (SCR) and cross cold rolling (CCR) in the present investigation. The rolling direction is kept constant throughout the deformation process in SCR route but during CCR processing the rolling direction (RD) and the transverse direction (TD) are mutually interchanged in every consecutive pass by rotating the sample around the normal direction (ND). Nickel sheets were deformed up to 90% reduction in thickness using the above two processing routes

Strain-path controlled microstructure, texture and hardness evolution in cryo-deformed AlCoCrFeNi2.1 eutectic high entropy alloy

In the present work, the effect of strain-path on the microstructure, texture and hardness properties of AlCoCrFeNi2.1 eutectic high entropy alloy was investigated. The EHEA was first cryo-rolled at 77K upto 90% thickness reduction using three different cross-rolling routes namely unidirectional cryo-rolling (UCR), multistep cross-rolling (MSCR) and two-step cross-rolling (TSCR(45º)) followed by annealing at three different temperatures. The UCR processed material showed heterogeneous microstructure as compared to MSCR and TSCR(45º)) processed materials. The deformation texture of L12/FCC in MSCR processed material agrees quite well the texture of cryo-rolled FCC materials whereas the texture of both the phases in TSCR(45º) processed material appears relatively weak. Upon recrystallization at 800ºC, the UCR processed material showed a rather novel heterogeneous microstructure whereas MSCR and TSCR(45º)) processed materials indicate ultra-fine micro-duplex structure. At higher annealing temperature, the micro-duplex structures remain stable in all the three processed materials. The annealing texture of L12/FCC phase showed presence of strong α-fibre (ND//) whereas B2 phase revealed intense ND-fibre (ND//) which is usual recrystallization texture found in BCC material. The UCR processed material showed much higher hardness as compared to MSCR and TSCR(45º)) processed materials which is attributed to its novel heterogeneous microstructure. Hence, it can be concluded that strain-path results in significant influence in controlling microstructure, texture and hardness properties of EHEA

Effect of Change in Strain Path during Cold Rolling on the Evolution of Microstructure, Texture and Hardness Properties of Different Aluminum Alloys

The effect of strain path change during heavy cold rolling on the development of texture, microstructure and hardness properties is investigated in different aluminum alloys. For this purpose 99.99% aluminum (4N-Al) and Al-2.5%Mg alloy was deformed up to 90% reduction in thickness by two different rolling routes, namely, unidirectional cold rolling (UCR) and cross cold rolling (CCR). In the CCR route the specimens are rotated by 90° around the normal direction (ND) so that the transverse direction (TD) of the previous pass became the rolling direction (RD) of the present pass. The evolution of microstructure, texture was subsequently studied by X-ray and electron back scatter diffraction (XRD and EBSD, respectively). Evolution of a lamellar type deformation microstructure is observed in all materials irrespective of the processing route. The UCR processed 4N-Al shows much pronounced dynamic recovery as compared to the CCR processed materials the reasons for which need to be investigated further. In sharp contrast, the CCR processing does not affect the microstructural development of Al-Mg alloy significantly as established by the values of the various structural parameters of differently processed heavily deformed materials. This seems to originate from the much restricted dynamic recovery in Al-Mg alloy due to the presence of Mg as solute

Evolution of microstructure and crystallographic texture in severely cold rolled high entropy equiatomic CoCrFeMnNi alloy during annealing

An equiatomic FCC CoCrFeMnNi high entropy alloy (HEA) was heavily cold rolled up to 9 0 % reduction in thickness followed by isochronal annealing for 1 hour at temperatures ranging between 70 0ºC to 1 1 00ºC. A strong brass texture was observed in the cold - roll ed condition indicating the low stacking fault energy of the material. A fine stable microstructure was observed during annealing at low temperatures. The recrystallization texture was characterized by the presence of deformation texture components, in pa rticula r, the α -fiber (ND//), S ({123} ) and the typical brass recrystallization texture component ({236} ). Annealing twins were shown to have important effect on the formation of annealing texture

Effect of severe cold-rolling and annealing on microstructure and mechanical properties of AlCoCrFeNi2.1 eutectic high entropy alloy

The possibility of microstructural refinement and improvement of mechanical properties by severe cold-rolling was investigated in an AlCoCrFeNi2.1 lamellar eutectic high entropy alloy (EHEA). The as-cast alloy revealed fine scale eutectic mixture of L1(2) (ordered FCC) and B2 (ordered BCC) phases. During severe cold-rolling up to 90% reduction in thickness the B2 phase maintained the ordered structure, while the L1(2) phase showed the evolution of a nanocrystalline structure and progressive disordering. Annealing of the severely cold-rolled material resulted in the formation of duplex microstructures composed of two different phases with equiaxed morphologies and significant resistance to grain growth up to 1200 degrees C. Annealing at 1000 degrees C resulted in an optimum strength-ductility balance with the tensile strength of 1175 MPa and the total elongation of 23%. The present results showed that severe cold-rolling and annealing can impart very attractive mechanical properties in complex EHEAs

Superplastic-like flow in a fine-grained equiatomic CoCrFeMnNi high-entropy alloy

A CoCrFeMnNi high-entropy alloy (HEA) showed elongation to failure similar to 320% at T = 1023 K and a strain rate. epsilon = 10(-4) s(-1). Strain hardening and texture weakening occurred at low. e, whereas flow softening and texture strengthening were observed at high. epsilon (> 3 x 10(-2) s(-1)) experiments. The strain rate sensitivity (m) decreased from 0.5 to similar to 0.25 with increasing. epsilon. Deformation with m similar to 0.5 and deformation-enhanced grain growth at low. e indicated superplasticity associated with grain boundary sliding. The grain boundary diffusion coefficient diminished by a factor of similar to 4 in the HEA. Concurrent nucleation, growth and cavity interlinkage caused premature failure compared with conventional superplastic alloys

Strain-path controlled microstructure, texture and hardness evolution in cryo-deformed AlCoCrFeNi 2.1 eutectic high entropy alloy

The effect of strain path on microstructure, texture and hardness properties of AlCoCrFeNi2.1 eutectic high entropy alloy containing ordered FCC (L12) and ordered BCC (B2) was investigated. The EHEA was cryo-rolled using UCR, MSCR (during which the samples were rotated by 90° around the ND between each pass) and TSCR(45°) (in which the samples were deformed by unidirectional rolling to half of the total strain and then diagonally rolled for rest half of the strain). The UCR processed material showed a rather heterogeneous microstructure. The textures of the L12/FCC and B2 phases in the MSCR processed material agreed with the cross-rolling texture of the corresponding single phase materials, while the texture of the two phases in the TSCR(45°) processed materials appeared rather weak. Upon annealing at 800 °C, the UCR processed materials showed a novel heterogeneous microstructure, while the MSCR and TSCR(45°) processed materials revealed microduplex structure. The heterogeneous microstructure was replaced by the usual microduplex structure at higher annealing temperatures. The annealing texture of the L12/FCC phase showed the presence of α-fiber (ND//) components while the B2 phase showed strong ND-fiber (ND//) components. The UCR processed material with novel heterogeneous microstructure showed much greater hardness as compared to the MSCR and TSCR(45°) processed materials. The present results indicate that strain path exerted significant influence in controlling microstructure, texture and hardness properties of EHEA

Evolution of Microstructure and Texture during Warm Rolling Of a Duplex Steel

The effect of warm rolling on the evolution of microstructure and texture in a duplex stainless steel (DSS) was investigated. For this purpose, a DSS steel was warm rolled up to 90 pct reduction in thickness at 498 K, 698 K, and 898 K (225 °C, 425 °C, and 625 °C). The microstructure with an alternate arrangement of deformed ferrite and austenite bands was observed after warm rolling; however, the microstructure after 90 pct warm rolling at 498 K and 898 K (225 °C and 625 °C) was more lamellar and uniform as compared to the rather fragmented and inhomogeneous structure observed after 90 pct warm rolling at 698 K (425 °C). The texture of ferrite in warm-rolled DSS was characterized by the presence of the RD (〈011〉//RD) and ND (〈111〉//ND) fibers. However, the texture of ferrite in DSS warm rolled at 698 K (425 °C) was distinctly different having much higher fraction of the RD-fiber components than that of the ND-fiber components. The texture and microstructural differences in ferrite in DSS warm rolled at different temperatures could be explained by the interaction of carbon atoms with dislocations. In contrast, the austenite in DSS warm rolled at different temperatures consistently showed pure metal- or copper-type deformation texture which was attributed to the increase in stacking fault energy at the warm-rolling temperatures. It was concluded that the evolution of microstructure and texture of the two constituent phases in DSS was greatly affected by the temperature of warm rolling, but not significantly by the presence of the other phas

Annealing-Mediated Microduplex Structure and Texture Evolution in Severely Cold-Rolled Nanolamellar Pearlite: A Perspective on the Effect of Starting Inter-lamellar Spacing

The effect of inter-lamellar (IL) spacing on the microstructure and texture of severely cold-rolled and annealed pearlite was studied. For this purpose, the behavior of fine IL spacing starting material (FILSM) (~ 190 nm) was compared with a coarser IL spacing starting material (CILSM) (~ 275 nm). The materials were severely cold-rolled to 95 pct reduction in thickness and annealed at 973 K (700 °C) for different time intervals. Despite similarities in microstructural evolution featured by progressive alignment of the pearlitic colonies along the rolling direction (RD), bending and kink morphologies, fragmentation of cementite, and deformation-induced nanoscale structure, the FILSM showed a smaller nanoscale IL spacing (~ 45 nm) than CILSM (~ 60 nm) after severe cold-rolling. Both FILSM and CILSM showed similar deformation texture featured by the presence of typical ND (// [removed]) and RD (// [removed]) fibers. Annealing of the severely cold-rolled materials resulted in an ultrafine microduplex structure. However, annealed FILSM consistently showed lower ferrite and spheroidized cementite sizes than those in the annealed CILSM. Irrespective of the starting IL spacing, continuous recrystallization was found to be the softening mechanism, which was amply corroborated by the texture evolution during annealing. Therefore, although the starting IL spacing considerably affected the microstructure, the texture evolution remained largely unaffected. The tensile behavior of the microduplex structured FILSM was further analyzed considering Hall–Petch (H–P) and Orowan–Ashby (O–A) strengthening mechanisms