Effect Of Rolling Temperature Research Articles

Influence of Rolling Temperatures on Interface Microstructure and Mechanical Properties of Multi-Pass Rolling TA1/Q235B Explosive Welded Sheets

The effect of rolling temperatures on the interface microstructure and mechanical properties is investigated using 2-mm-thick TA1/Q235B composite sheets, which were prepared after nine passes of hot rolling of explosive welded plates. The results show that the vortex region and the transition layer exist in the interface at the explosive welded plate, while only the transition layer exists in the interface after hot rolling. The transition layer is composed of α-Ti, TiC, Fe, and FeTi, and the thickness increases with the increasing rolling temperature. The microhardness of the explosive welded plate is higher than that of the hot-rolling sheet, and the microhardness of interface are higher than that of matrix metals. The interface shear strength and tensile elongation of the hot-rolled sheet increase with the increasing hot rolling temperature, while the ultimate tensile strength (UTS), yield strength (YS) and Young modulus decrease with the increase of hot rolling temperature. The shear strength of sheets is related to the interfacial compounds, and the tensile strength is mainly affected by the grain morphology of the matrix.

Effect of rolling temperature on microstructure and mechanical properties of Ti/steel clad plates fabricated by cold spraying and hot-rolling

The effect of rolling temperature on the interfacial microstructure and mechanical properties of Ti/steel clad plates, fabricated by a newly designed method (cold spraying and hot-rolling), was studied. For this purpose, three rolling temperatures (i.e. 850, 950, 1050 °C) were selected to completely understand the bonding mechanism at Ti/steel interface. The type of interfacial compounds and thickness of the diffusion layers were found to be the main factors controlling the mechanical properties of the Ti/steel clad plates. Results showed that the Ti/steel clad plate rolled at 850 °C exhibited metallurgical bonding due to the formation of a 250 nm thick TiC diffusion layer at the interface, and resulted in the best elongation. In contrast, the sample rolled at 950 °C developed a 400 nm thick diffusion layer which was composed of TiC and FeTi compounds, leading to the best tensile strength. When the rolling temperature was increased to 1050 °C, the thickness of the diffusion layer (composed of coarse TiC and FeTi phases) was sharply increased to 4 μm, and the sample displayed poor tensile strength and elongation.

Effect of rolling temperatures on mechanical and fracture behavior of AA 3003 alloy and pure Cu

Ultrafine-grained materials have an enormous scope of structural and functional applications owing to their higher mechanical properties compared to that of coarse-grained materials. The influence of room temperature and cryogenic temperature rolling of AA 3003 alloy and pure Cu on its mechanical properties and fracture behavior has been investigated in the present study. Both the materials are rolled to a thickness of 2 mm and 1 mm with a true plastic strain of 0.40 and 1.09, respectively. The deformed samples are characterized by tensile test, hardness test, and X-ray diffraction analysis. It has been observed that tensile strength and hardness of cryorolled (CYR) samples are higher than cold rolled (CR) samples and it is due to the fact that rolling at an extremely low temperature (− 196 °C) suppresses the dynamic recovery and hence mobility of dislocations becomes difficult as a result dislocation density increases. In CYR, low stacking fault energy material (Cu) has higher tendency to increase strength and work hardened compared to higher stacking fault energy materials (AA 3003) without much loss of ductility. SEM pictorial view of fractography revealed that CYR samples have mix mode of failure compared to CR samples. The dimple size is gradually decreased with increasing plastic strain and that is due to severe strain hardening and grain refinement.

Preparation of high-strength Co−Cr−Mo alloy rods via hot-caliber rolling

Co−Cr−Mo alloys have various remarkable properties, and their use has been extended in biomedical applications in recent times. In this study, small-diameter Co−Cr−Mo alloy rods, which can be used in spinal instrumentation surgery, were prepared using a developed manufacturing system that enables hot-caliber rolling immediately after the induction heating of a rod workpiece. The effects of rolling temperature (850−1150 °C) and the amount of deformation (up to 0.45 in equivalent strain) on the microstructure, mechanical properties, and cytocompatibility of the rods were examined to determine the processing−microstructure−property relationship and to optimize the processing parameters. The microstructural evolution, which was found to be associated with grain refinement due to the simultaneous dynamic recrystallization (DRX) and accumulation of lattice defects during hot-caliber rolling, significantly strengthened the alloy and maintained the ductility. Bi-directional deformation during hot-caliber rolling at higher rolling temperatures enhanced the DRX, thus realizing uniformly distributed fine grains without preferential orientations, which resulted in the homogeneous mechanical properties of the obtained rods. Consequently, an enhanced strength−ductility combination, which was superior to those obtained in the existing literature, was achieved. Moreover, the cytocompatibility experiments using human MG-63 osteoblast-like cells at various intervals (3, 6, and 10 days) revealed a limited detrimental influence on the cell proliferation and cell migration on the sample hot-rolled at 1150 °C. The developed manufacturing system can be employed for the fabrication of high-strength Co−Cr−Mo alloy rods with high durability, and it can be implemented in low-profile systems for spinal instrumentation surgery.

Preparation of High-Strength Co-Cr-Mo Alloy Rods Via Hot-Caliber Rolling

Co-Cr-Mo alloys have various remarkable properties and in recent times their use has been extended in biomedical applications in recent times. In this study, small-diameter Co-Cr-Mo alloy rods, which can be used in spinal instrumentation surgery, were prepared using a developed manufacturing system that enables hot-caliber rolling immediately after the induction heating of a rod workpiece. The effects of rolling temperature (850-1150 °C) and the amount of deformation (up to 0.45 in equivalent strain) on the microstructure, mechanical properties, and cytocompatibility of the rods were examined to determine the processing-microstructure-property relationship and to optimize the processing parameters. The microstructural evolution, which was found to be associated with grain refinement due to the simultaneous dynamic recrystallization (DRX) and accumulation of lattice defects during hot-caliber rolling, significantly strengthened the alloy and maintained the ductility. Bi-directional deformation during hot-caliber rolling at higher rolling temperatures enhanced the DRX, thus realizing uniformly distributed fine grains without preferential orientations, which resulted in the homogeneous mechanical properties of the obtained rods. Consequently, an enhanced strength-ductility combination, which was superior to those obtained in the existing literature, was achieved. Moreover, the cytocompatibility experiments using human MG-63 osteoblast-like cells at various intervals (3, 6, and 10 days) revealed a limited detrimental influence on the cell proliferation and cell migration on the sample hot-rolled at 1150 °C. The developed manufacturing system can be employed for the fabrication of high-strength Co-Cr-Mo alloy rods with high durability, and it can be implemented in low-profile systems for spinal instrumentation surgery.

Effects of Rolling Temperature on the Microstructure and Mechanical Properties of a High‐Mn Austenitic Steel for Cryogenic Applications

The effects of rolling temperature on the microstructure and mechanical properties of a high‐Mn austenitic steel is investigated. It is observed that the grain size decreases with the decrease in rolling temperature, resulting in an increase in yield strength (YS) and an increase in ultimate tensile strength (UTS). Mechanical twinning is found to be less active in fine‐grained specimen, leading to the decrease in uniform and total elongations and impact toughness. The existence of dislocations and nanoscale mechanical twins in the initial microstructure contributes to the high YS, and the active mechanical twinning during deformation maintains excellent ductility and impact toughness. The thick twins (generally thicker than 300 nm and formed during hot rolling) play a supplementary role in increasing the instantaneous strain hardening during the late stage of tensile deformation.

Effect of rolling temperature on deformation behavior and mechanical properties of Mg-8Li-1Al-0.6Y-0.6Ce alloy

The effect of rolling temperature on deformation behavior and mechanical properties of Mg-8Li-1Al-0.6Y-0.6Ce (LA81-0.6Y-0.6Ce) alloy were studied. As the temperature increases, the grain size of β-Li phase decreases first and then increases. When the temperature is 250 °C, the as-rolled sheets have the optimal mechanical properties with the ultimate tensile strength of 219 MPa and the elongation of 35% due to grain refinement strengthening and dislocations strengthening. With the increase of temperature, the dynamic recrystallization mechanism of α-Mg phases is transformed from continuous dynamic recrystallization (CDRX) to discontinuous dynamic recrystallization (DDRX), while that of β-Li phases is always DDRX without transformation.

Densification Mechanism for the Precursor of AFS under Different Rolling Temperatures.

The effect of rolling temperature on the precursor of aluminum foam sandwich (AFS) prepared by powder metallurgy through Pack Rolling method is investigated in this work. The cross-section along rolling direction of the precursors was observed. It was found that periodic corrugated morphology with micro-cracks on the composite interface as well as cracks and micro-holes among core powder particles emerged abundantly at room temperature rolling. These defects degraded with increasing rolling temperature and completely disappeared when the rolling temperature reached 400 °C. Combining with foaming ability of these precursors, the densification mechanism of core powders was discussed. Powder particles deformed with difficulty at low rolling temperature; the gap between them cannot be effectively filled through their plastic deformation. Fracture occurred in powder core layer during co-extension with the outer panel and was partly embedded by it, resulting in corrugated composite morphology at the interface. The precursors of high density and excellent bonding interface were prepared at the rolling temperature of 400 °C. A more suitable foaming condition was determined.

Microstructure Evolution and Mechanical Properties of a Powder Metallurgy Ti‐22Al‐25Nb Alloy Processed through Isothermal Rolling and Solution and Aging Treatment

Isothermal rolling is conducted at 1050 °C (α2 + B2 phase region) and 1100 °C (B2 phase region) for a spark plasma sintering (SPS)‐processed Ti‐22Al‐25Nb alloy. The effects of rolling temperature, pass, reduction per pass, and solution and aging on microstructure evolution, phase transformation, and tensile property at ambient temperature are systematically investigated. The results show that as the alloy is rolled at 1050 °C for 1 pass (P), the optimal tensile strength (TS) and the yield strength (YS) are 964.78 and 935.16 MPa, respectively, and the elongation (δ) reaches 23.65%. Then, followed by a subsequent solution and aging at 940 °C/30 min/water quenching (WQ) + 760 °C/24 h/air cooling (AC), it exhibits a decrease in mechanical properties. Moreover, a mixed fracture mechanism dominated by ductile fracture is shown for the as‐rolled alloy. However, after a solution and aging, it is transformed to a mixed fracture mechanism dominated by brittle fracture, which attributes to the void aggregation and the development of the discontinuous brittle α2 precipitates along B2 matrix grains during the solution and aging treatment. Finally, fracture models of the as‐rolled alloy and the solution and aging‐treated alloy are established.

Effect of Rolling Temperature on the Microstructure and Mechanical Properties of AZ31 Alloy Sheet Processed through Variable-Plane Rolling

AZ31 magnesium alloy sheet was produced through variable-plane rolling (VPRing) under different temperatures, and a conventional rolled AZ31 alloy was investigated for comparison. A basal texture was formed during these two processes. The texture intensity was closely related to dynamic recrystallization and deformation mechanism. Four types of twins appeared, namely {10-12} extension twins, {10-13} and {10-11} contraction twins and {10-11}-{10-12} double twins. High rolling temperature and rolling plane alteration were beneficial for activating {10-11}-{10-12} double twins. The tensile strengths revealed a declining trend with elevated rolling temperatures. The AZ31 alloy rolled at 573 K showed advantageous combination with a high yield strength of 286 MPa and compromised elongation of 5%. The mechanical anisotropy of VPRed AZ31 sheet decreased with nearly similar yield strengths along the roll direction (RD), transverse direction and 45° away from the RD. The VPRing process improved the rollability and strength of Mg alloy and reduced its mechanical anisotropy.

Effect of microstructure evolution on mechanical properties of a TiZrAlB alloy rolled by different processes

For the development of structural titanium alloys with excellent mechanical properties, the effect of rolling temperature and cooling rate on phase composition, microstructure evolution, and mechanical properties in a full-α TiZrAlB alloy were investigated. Optical microscopy, scanning electron microscopy, transmission electron microscopy, and statistical analysis, were employed to further understand and control the processing-structure-property relationships. The experimental results of specimens rolled at a temperature range from the α to β phase region demonstrated a significant grain refinement trend as the rolling temperature increased, and the work hardening effect was stronger in specimens rolled at the α+β double phase region than those rolled in the single phase region. The high density of the original β grain boundaries also enhanced the mechanical properties when the specimens were rolled at temperatures around/above the β-transus temperature. The highest strength (σ0.2 = 1121 MPa and σb = 1387 MPa) with a failure elongation of 6.1% was obtained in 840 °C-rolling water-quenched specimens, however, the furnace cooling led to worsened mechanical properties. In sum, the variation in the mechanical properties of the series of rolled alloys was mainly ascribed to the microstructure evolution under the different rolling processes.

Effect of Rolling Temperature on the Microstructural Characteristics of High-Speed-Rolled Mg Alloy with Initial Non-Basal Texture

In this study, the effects of rolling temperature on the microstructural characteristics of a highspeed-rolled Mg alloy with a non-basal texture were investigated. To this end, commercial AZ31 alloy samples in which the basal poles of most grains were tilted at an angle of 45° from the normal direction (ND) to the transverse direction were hot-rolled with a rolling reduction of 80% at a rolling speed of 470 m/min at various temperatures (300 °C, 350 °C, and 400 °C). With increasing rolling temperature, the area fraction of dynamically recrystallized (DRXed) grains increased and the internal strain energy accumulated in the rolled material decreased. This is attributed to the occurrence of homogeneous nucleation throughout the material at higher temperatures. When the rolling temperature increased from 300 °C to 350 °C, the area fraction of coarse unDRXed grains decreased, but the size of the relatively fine DRXed grains increased. Consequently, the average grain size of the rolled material remained nearly unchanged. However, when the rolling temperature increased from 350 °C to 400 °C, the size of the DRXed grains increased considerably owing to enhanced grain growth behavior. This increase led to an increase in the average grain size of the rolled material. The basal poles of the high-speed-rolled materials were mainly tilted 25° - 29° from the ND. This indicates that application of single-pass high-speed rolling causes the non-basal texture of the initial material to transform into a basal texture similar to the typical texture of rolled Mg alloys. Key words: Mg alloy, high-speed rolling, rolling temperature, texture, dynamic recrystallization, microstructure

Bond characteristics of Al/Mg clad materials produced by vacuum roll bonding

The A1050/AZ31 clad materials were produced by vacuum roll bonding. The effects of rolling temperature and reduction rate on the interface of A1050/AZ31 clad materials were investigated, and the fracture behaviors of A1050/AZ31 interface were studied. A very thin intermetallic compound layer was formed at the A1050/AZ31 interface at rolling temperature of 350°C and reduction rate of 25%. Therefore the A1050/AZ31 interface mainly was ductile fracture, and the average tensile strength of A1050/AZ31 interface reached the maximum (43MPa). When the rolling temperature was 450°C and the reduction rate was 25%, the fracture occurred on the brittle intermetallic compound Al3Mg2 layer (thickness 7.68μm) and Al12Mg17 layer (thickness 1.95μm), mainly on Al3Mg2 layer, and the average tensile strength of A1050/AZ31 interface reached the minimum (0.61MPa).

Effect of rolling temperature on the microstructure and mechanical properties of 6201 Al alloy

Abstract An 6201Al alloy was rolled at room temperature (RT), liquid nitrogen and alcohol mixed temperature (LAT) and liquid nitrogen temperature (LNT). The effect of the rolling temperature on microstructure and mechanical properties was investigated by means of hardness measurements, tensile tests, optical microscopy (OM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Microstructural observations reveal that the dislocation tangles and dislocation density increased with decreasing rolling temperature. The dislocation accumulation was enhanced, and the formation of dislocation tangles and cells occurred during deformation under low rolling temperature. The substructures of the rolled sample at LAT and LNT are similar, consisting of dislocation cells, high dislocation density with networks, dislocation array, dislocation tangles and subgrains. Compared with rolled samples at RT and LAT, the rolled samples at LNT presented strengthened hardness and strength. The improvement of mechanical properties contributes to the fine substructures and accumulation of higher dislocation density during low temperature rolling. In addition, with decreasing rolling temperature, the average dimple size decreased.

Influence of rolling temperature on microstructural evolution and mechanical behavior of AZ31 alloy with accumulative roll bonding

The effect of rolling temperature on AZ31 alloy with accumulative roll bonding (ARB) had been investigated. The results showed that dynamic recrystallization occurs and forming shear bands in the direction of shear stress, exhibit the shape that width decreases from the surface to the inside when ARB at 450 °C. Strength was increased result by strain hardening after ARB process, with compromise of elongation was attributable to the internal crack. Microhardness was enhanced after ARB, while decreasing with the increase rolling temperature. Because of the formation of shear band, microhardness of outer plate was lower than inner plate. Interface bonding strength was increased by improving ARB temperature. Interface bonding is a process in which dynamic recrystallization occurs on both sides of the interface, fine recrystallized grains constantly swallowed and replace the original grains until the interface is annihilated. Crack initiation in shear band and extends along the shear band.

Influence of Rolling Temperature on the Mechanical Properties and Microstructure of Variable-Plane-Rolled Mg-3Al-1Zn Alloy

AZ31 magnesium alloy was produced via variable-plane rolling (VPR) under different temperatures. The effects of rolling temperature on the microstructure, texture and mechanical properties were investigated. A double-peak basal texture was formed during VPR treatment. Dynamic recrystallization (DRX) was observed during the VPR treatment, and it can reduce the texture intensity owing to the coalescence of sub-grains. Four types of twins were observed in the VPR treatment: {10-12} extension twins, {10-13}, {10-11} contraction twins and {10-11}-{10-12} double twins. The suitable temperature of AZ31 magnesium alloy for VPR treatment is determined as 623 K through experiments with tensile yield strength of 240 MPa, compressive yield strength of 162 MPa and elongation of 13%. Owing to the important impact of temperature on mechanical properties, the alloy was further VPRed with a decrease in temperature pass-by-pass. The high temperature of 623 K at the initial passes randomized the texture, which led to notably high ductility.

Threshold Deformation and Mechanical Properties of Al/Al Laminated-Metal Material with Inner Grooves Fabricated by Hot Rolling

1100 Al/1100 Al laminated-metal material with inner grooves (LMWGs) were fabricated by hot roll bonding. Threshold deformation (the minimum rolling reduction in a single rolling pass that is required for metal bonding) and the mechanical properties of hot-roll-bonded LMWG and cold-roll-bonded LMWG were investigated and compared. The effects of rolling temperature and rolling reduction on the bond strength of the hot-roll-bonded LMWG were also studied. It was observed that the threshold deformation of the hot-roll-bonded LMWG decreased with increasing rolling temperature from 300 to 450 °C. However, the threshold deformations of the LMWGs rolled at 400-450 °C were smaller than those of the LMWGs rolled at room temperature, while the latter were smaller than those of the LMWGs rolled at 300-350 °C. The bond strength, ultimate tensile strength, and yield strength of the hot-roll-bonded LMWG increased with increasing rolling temperature from 300 to 450 °C. The effects of the rolling reduction were slight. When the rolling temperature and rolling reduction were 450 °C and 55%, respectively, the average bond strength reached a maximum value of 89.42 MPa.

Effect of Rolling Temperature on Microstructure and Mechanical Properties of a Nb-Mo Microalloyed Medium Mn Steel

Warm rolling of medium Mn steel is a promising technology to meet the needs of vehicle weight reduction and energy conservation while ensuring the safety for passengers. In this study, a novel Nb-Mo microalloyed 6.6Mn steel was subjected to a series of warm rolling tests at temperatures ranging from 630 to 690 oC, based on the thermodynamic-based prediction of inter-critical annealing using a Thermo-Calc software. As a comparison, a conventional multi-stage thermo- mechanical process involving hot rolling, cold rolling and inter-critical annealing was carried out as well. The optimal rolling temperature parameters for warm rolling was explored through tensile tests and the detailed microstructural characterization. The experimental results show that the microstructure and mechanical characteristics strongly depended on the warm rolling temperature. A better combination of UTS and TE products (~32.0 GPa·%) was achieved in the 660oC-warm-rolled specimen, which is much higher than 12.3 GPa·% for the hot formed 22MnB5 steel and is also comparable to 38.3 GPa·% for the annealed cold-rolled specimens.

Effect of Rolling Temperature on the Microstructure and Mechanical Properties of Mg-2Zn-0.4Y Alloy Subjected to Large Strain Rolling

Large strain rolling (LSR) has been conducted on the Mg-2Zn-0.4Y alloy. After the 1st rolling process at 250, 300, 350, and 400 °C, the alloy demonstrates a fully recrystallized microstructure. The grain size increases from 6, 8, 12, to 17 μm with an increasing rolling temperature. After the 2nd rolling process at 300 °C, twinning and shear bands were introduced. During the 3rd rolling process at 350 °C, dynamic recrystallization (DRX) was observed and resulted in a more uniform microstructure. DRX occurred because of temperature increase and large dislocation density induced by LSR. For the room temperature tensile tests, the plates rolled at 300 and 350 °C in the 1st rolling process demonstrate higher strength and lower elongation due to twinning. The one rolled at 400 °C in the 1st rolling process, shows the most uniform rolling microstructure and the best combination of strength and elongation at room temperature.

Effect of Rolling Temperature on Microstructure Evolution and Mechanical Properties of AISI316LN Austenitic Stainless Steel.

The impacts of rolling temperature on phase transformations and mechanical properties were investigated for AISI 316LN austenitic stainless steel subjected to rolling at cryogenic and room temperatures. The microstructure evolution and the mechanical properties were investigated by means of optical, scanning, and transmission electron microscopy, an X-ray diffractometer, microhardness tester, and tensile testing system. Results showed that strain-induced martensitic transformation occurred at both deformation temperatures, and the martensite volume fraction increased with the deformation. Compared with room temperature rolling, cryorolling substantially enhanced the martensite transformation rate. At 50% deformation, it yielded the same fraction as the room temperature counterpart at 90% strain, while at 70%, it totally transformed the austenite to martensite. The strength and hardness of the stainless steel increased remarkably with the deformation, but the corresponding elongation decreased dramatically. Meanwhile, the tensile fracture morphology changed from a typical ductile rupture to a mixture of ductile and quasi-cleavage fracture. The phase transformation and deformation mechanisms differed at two temperatures, with the martensite deformation contributing to the former, and austenite deformation to the latter. Orientations between the transformed martensite and its parent phase followed the K–S (Kurdjumov–Sachs) relationship.