Effect Of Hot Deformation Research Articles

Microstructure and Properties of Deformed AlSi7Mg Alloy

Herein, the effects of hot deformation on the mechanical properties and microstructure of AlSi7Mg alloys were investigated. The microstructure of the alloys with deformation were observed. It can be found that the Si grains of the deformed alloy undergo segregation; however, a suitable heat treatment can be employed to effectively eliminate the segregation. The alloy deformation was 40% at 300 °C, and the mechanical properties of the alloy increased significantly after the heat treatment; the AlFeSi phase was found at the inside of the Si grain and the boundary between eutectic Si and α-Al grains. The AlFeSi phase was found at the inner grain and grain boundaries, and the main strengthening mechanisms of the alloy were precipitation strengthening and deformation strengthening.

The pressure treatment effect on the high‑strength austempered ductile iron structure

This paper presents the results of a study on the effect of pressure treatment (direct hot extrusion) on the structure of graphite inclusions and the metallic matrix of high‑strength austempered ductile iron. Comparative analysis of the cooling processes of the cast high‑strength ductile iron billet without deformation and after deformation was carried out using simulation modeling methods. The results of the study on the effect of hot deformation (up to 950–970 ℃) on the fracture structure and mechanical properties of austempered high‑strength ductile iron billets are presented.

Effect of Hot Deformation and Heat Treatment on the Microstructure and Properties of Spray-Formed Al-Zn-Mg-Cu Alloys

Spray forming is a manufacturing process that enables the production of high-performance metallic materials with exceptional properties. Due to its rapid solidification nature, spray forming can produce materials that exhibit fine, uniform, and equiaxed microstructures, with low micro-segregation, high solubility, and excellent workability. Al-Zn-Mg-Cu alloys have been widely used in the aerospace field due to their excellent properties, i.e., high strength, low density, and outstanding machinability. The alloy manufactured by spray forming has a combination of better impact properties and higher specific strength, due to its higher cooling rate, higher solute concentration, and lower segregation. In this manuscript, the recent development of spray-formed Al-Zn-Mg-Cu alloys is briefly reviewed. The influence of hot working, i.e., hot extrusion, hot forging, and hot rolling, as well as different heat treatments on the property and microstructure of spray-formed Al-Zn-Mg-Cu alloys is introduced. The second phases and their influence on the microstructure and mechanical properties are summarized. Finally, the potential in high-temperature applications and future prospects of spray-formed aluminum alloys are discussed.

Effect of hot deformation on the dynamic precipitation and mechanical properties of AA2099 Al–Li alloy

Al-Li alloys, known for their exceptional performance, are increasingly preferred in the aerospace industry. In this study, Al-Li alloys were deformed by controlled temperature hot rolling with different reductions to investigate the microstructural evolution during the thermal deformation process and its impact on subsequent aging behavior. The relationship between microstructure and mechanical properties of the alloy was quantitatively investigated. The findings indicate that the T1 (Al2CuLi) phase mainly precipitates along the sub-grain boundaries, while a significant number of T1 cell nuclei form within the matrix. The hot rolling process obviously increases the aging kinetics of the T1 phase, resulting in a significant reduction in peak aging time (yield strength of 520 MPa achieved in just 10 h) and an increase in the volume fraction of precipitation. The contribution of T1 phase strengthening was estimated under peak aging conditions, and the results reveal that the sensitivity of the strengthening effect becomes less sensitive to variations in the volume fraction once a certain value is reached.

Effect of Hot Deformation on Microstructure and Porosity of Additively Manufactured 7050 Al Alloy

Wire arc additive manufacturing technology of 7050 aluminum alloy has a broad application prospect in aerospace field. But the lack of comprehensive properties caused by coarse columnar grains and pores becomes an important bottleneck. In this study, hot compression is conducted to simulate forging process to investigate the microstructure improvement of as‐deposited 7050 Al alloy by plastic deformation. The effect of temperature at 390–540 °C and deformation at 20%–60% on the microstructure and porosity is revealed. In the results, only slip deformation occurs at 420 °C and below. Local dynamic recrystallization occurs at columnar grain boundaries at 450 °C. Complete dynamic recrystallization occurs at 480 °C with the average grain size of about 60 μm. The microstructure overburns at 510 °C and above. The η eutectic phases are broken during deformation. The hot deformation accelerates the dissolution of η eutectic phases and the dissolution temperature of nano‐phases is 30 °C lower than solid solution. As the deformation amount increases from 20% to 60%, the deformation gradually extends from interlayer to inner of columnar grain layers. The spherical pores are first compressed to ellipsoid and then further compressed until completely closed. The pores are basically annihilated completely at 60% deformation with porosity of less than 0.1%.

Effect of hot deformation on quenching sensitivity and heterogeneous precipitation behavior of 7150 aluminum alloy

Effect of hot deformation on quenching sensitivity and heterogeneous precipitation behavior of 7150 aluminum alloy

Effects of Hot Deformation on the Evolution of Microstructure in Pearlitic Steel Wire Rod

Effects of Hot Deformation on the Evolution of Microstructure in Pearlitic Steel Wire Rod

Effects of hot deformation and in-situ ZrB2 particle on microstructure and tensile performance of AA7085 composite sheets

Effects of hot deformation and in-situ ZrB2 particle on microstructure and tensile performance of AA7085 composite sheets

Effect of hot deformation on microstructure, corrosion resistance, and pitting corrosion behavior of dual-phase Ti–Zr alloy

Dual-phase Ti–30Zr–5Al–3V alloy was subjected to hot deformation to investigate its effect on microstructure, corrosion resistance, and pitting behavior in acid corrosive medium by assessing the electrochemical behavior, immersion corrosion phenomenon, and passive film characteristics of alloys of different states. The hot deformation and water quenching process does not significantly change the concentration of α and β phases but significantly refines the microstructure, which reduces the compositional differences and, consequently, the galvanic corrosion strength between them, which is beneficial to the corrosion resistance. In addition, refinement increases the relative content of high-valent oxide and the thickness of the passive film, which reduce the concentration of oxygen vacancy, thereby decreasing the transfer rate of cation vacancies. Simultaneously, fewer oxygen vacancies also inhibit the formation of cation–anion-vacancy associations at the metal/film interface. Therefore, the pitting resistance is also improved.

The consequences of hot deformation and control cooling on the microstructure of medium carbon microalloyed steel − 38MnSiVS5 grade

Medium carbon micro-alloyed steels are mostly being utilized in the application where quenched and tempered steels are needed for cost-productive processing. However, the impact toughness of micro-alloyed steels is inferior to that of quenching & tempered steels, which resist their use in critical applications. Conventional techniques are used for hardness enhancement of micro-alloyed steels due to reduction in carbon percentage, the addition of relevant chemical constituent such as titanium to achieve the reduction in the amount of pearlite and controlling the microstructure during thermomechanical processing, subsequently after cooling and forging. In this research work, the effect of hot deformation and control cooling temperature on the microstructure of medium carbon micro-alloyed steel 38MnSiVS5 was studied. Different approaches were performed to improve the impact toughness and hardness and found out that forced air cooling of the micro-alloyed steel 38MnSiVS5 forgings resulted in the finest microstructure and exhibiting a higher hardness of 45.93 RC.

Effect of hot deformation and isothermal holding temperature on retained austenite characteristics in 3-5% Mn multiphase steels

Effect of hot deformation and isothermal holding temperature on retained austenite characteristics in 3-5% Mn multiphase steels

Effect of Thermal Simulation Process on Microstructure of Seismic Steel Bars.

Thermal deformation has a significant influence on the microstructure of high-strength antiseismic steel. The effect of hot deformation on the microstructure of experimental steel was studied by the Gleeble-3800 thermal simulator. The microstructure of the steel was characterized by the metallographic microscope, microhardness, tensile test, field emission scanning electron microscope, electron backscatter diffraction, and high-resolution transmission electron microscope. The results show that the core microstructure of the test steel is composed of polygonal ferrite and lamellar pearlite. The test steel is mainly ductile fracture. Tensile strength and hardness increase with the decrease of temperature. At 650 °C isothermal temperature, the ferrite distribution was uniform, the average grain size was 7.78 μm, the grain size grade reached 11, the pearlite lamellar spacing was 0.208 μm, and the tensile fracture was distributed with uniform equiaxed dimples. Polygonal ferrite grain boundaries have high density dislocations that can effectively block the initiation and propagation of cracks. However, there are some low dislocation boundaries and subgrain boundaries in ferrite grains. Precipitation strengthening is mainly provided by fine precipitates of V-rich carbonitride in experimental steel. The precipitates are round or narrow strips, about 70–100 nm in size, distributed along ferrite grain boundaries and matrix.

Effect of Hot Rolling on Microstructural Evolution and Wear Behaviors of G20CrNi2MoA Bearing Steel

Hot rolling can improve the mechanical properties after heat treatment by improving the microstructure. The effect of hot rolling (HR) deformation on the microstructural transformation of G20CrNi2MoA bearing steel in the subsequent CQT (carburizing-quenching and tempering) and RQT (reheating-quenching and tempering) processes was studied. The results indicate that the austenite grain size decreased by 20% after 45% hot rolling reduction, and the number of large-angle grain boundaries increased due to the recovery and recrystallization induced by hot deformation. The refinement effect of hot deformation on austenite grains was retained after dual austenitizing, and the large-angle grain boundaries and massive dislocation in the grains caused by hot deformation promoted the diffusion of carbon atoms during carburization, resulting in a higher surface carbon concentration. The refined grains and higher carbon concentration affected the volume fraction and size of undissolved carbides in RQT specimens. When the initial hot rolling reduction reached 45%, the average particle size of carbides decreased by 40%, and the area volume fraction increased by 37%. The Vickers hardness increased, but the friction coefficient and wear rate were significantly reduced with the increase in the initial hot rolling reduction. The main reasons for the improved wear resistance were fine grains, superior carbide distribution and high hardness.

Effectiveness of hot deformation and subsequent annealing for β grain refinement of Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy

High strength titanium alloys suffer from a limited combination of strength and ductility. Considering their microstructure, the coarse β grain is a detrimental factor. In the present study, the effects of hot deformation and annealing treatment on the β grain refinement of Ti–5Al–5Mo–5V–1Cr–1Fe (TC18) titanium alloy have been investigated by using electronic backscattered diffraction (EBSD) and transmission electric microscopy (TEM). Hot compression tests of TC18 alloy were performed between 1073 and 1223 K at strain rates of 0.01 and 0.10 s−1. Subsequent annealing treatments were conducted to investigate the effect of deformation microstructure on the recrystallization behavior of β grains. The results indicate that dynamic recovery (DRV) is the dominant restoration mechanism during hot deformation. Discontinuous dynamic recrystallization (dDRX) is significantly limited at a higher temperature in the β region, whereas continuous dynamic recrystallization (cDRX) of the β phase is observed at a higher strain rate in the (α + β) region. The final annealing microstructure is highly dependent on the deformation microstructure. Limited dDRX during hot deformation could not effectively refine the β grains. The refined and uniform β grains with an average grain size of 12 μm are achieved by combining hot deformation and subsequent annealing in the (α + β) region. This study provides a guide for the β grain refinement of high strength titanium alloys.

Effect of hot deformation on microstructure and quenching-induced precipitation behavior of Al-Zn-Mg-Cu alloy

The effect of hot deformation on microstructure and quenching-induced precipitation behavior of an Al-Zn-Mg-Cu alloy 7055 was investigated by electron backscattered diffraction (EBSD), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and scanning transmission electron microscope (STEM). In the solution heat treated and slowly-quenched alloy without hot deformation, there are equiaxed grains with low dislocation density, and there is major quenching-induced η (MgZn2) phase located at grain boundaries and on some Al3Zr dispersoids in the interior of grains and minor T(Al2Zn3Mg3) phase on Al3Zr dispersoids inside grains. While in the solution heat treated and slowly-quenched alloy after hot rolling, there are recrystallized grains and subgrains with higher dislocation density, and there is a larger amount of quenching-induced η and T phase on incoherent Al3Zr dispersoids inside recrystallized grains and at (sub) grain boundaries; moreover, quenching-induced S (Al2CuMg) phase and Zn-Cu rich Y phase are observed in the interior of subgrains. The precipitation behavior of these quenching-induced phases has been discussed primarily based on their chemical compositions, nucleation sites and different microstructure features in the solution heat treated alloy with and without hot deformation.

In Situ Investigation of the Bainitic Transformation from Deformed Austenite During Continuous Cooling in a Low Carbon Mn-Si-Cr-Mo Steel

The effects of hot deformation on the bainitic transformation of a low carbon steel during continuous cooling were comprehensively studied through in situ high-energy synchrotron X-ray diffraction, dilatometry, and ex situ microstructural characterizations. The obtained results indicated that the prior deformation of austenite at 950 °C accelerates the bainite formation at the early stages. During the ongoing of the transformation, both the overall kinetics of bainite and carbon enrichment of austenite are lower in deformed austenite. The bainitic microstructure developed from deformed austenite is more refined and presents the same retained austenite content at room temperature with slightly lower carbon content when compared with the undeformed sample. Besides, a significant higher dilatation strain was measured during the bainitic transformation in the deformed sample, which can be explained by the crystallographic texture in hot deformed austenite. The evolution of the peak broadening of the {220}γ and {211}α reflections during bainitic transformation are discussed in detail.

EBSD Study of the Effect of Hot Deformation on Low Carbon Bainitic Structure

The effect of deformation temperature (DT) and thickness reduction on the bainitic structure was investigated under various test conditions by using hot compression on a Gleeble-1500 thermo-mechanical simulation machine, and electron back scattering diffraction (EBSD) technique. In the case of the bainitic structure consisting of granular bainite (GB), lath bainite (LB) and a little ferrite (AF) under the given deformation conditions, DT and thickness reduction have remarkable effect on the transformation kinetics, starting temperature (B) of bainite fast transformation, and the type of bainitic structure. With the decreasing of DT from 810 °C to 730 °C, the starting temperature of transformation B increase from 585 °C to 595 °C. When the thickness reduction was 0 % and 20 %, the microstructure consists of GB, LB and a little AF, whereas as the thickness reduction increase to 40 %, large grain size of LB and GB disappear, and only AF and M/A remained. With the thickness reduction increases from 0 % to 40 %, the effective grain size decreases from 4 μm to 2 μm, and the fraction of HGB increases from 48 % to 57 %.

Effect of Hot Deformation on Impact Toughness of High Strength Steel

Effect of Hot Deformation on Impact Toughness of High Strength Steel

Effects of hot deformation and heat treatment on grain refinement for as-cast and spray formed SA508-3 steel

In order to identify quantitatively the different effects of hot deformation and heat treatment processes on the grain size of as-cast and spray formed SA508-3 steel, two kinds of billets were produced respectively. Samples were machined, forged and heat-treated in sequence under the same conditions for both billets. Then, the corresponding microstructures were observed and analysed for each process. The experimental results demonstrate that both hot deformation and heat treatment are beneficial to refine the grains of the as-cast and spray formed billets. Furthermore, the grains of spray formed samples are much finer and more uniform than that of as-cast ones. It indicates that the spray forming process is more competitive for grain refinement than the conventional casting. However, the existence of voids in the spray formed is detrimental for the mechanical properties, especially the elongation. Therefore, not only the spray forming process but also the hot deformation parameters should be further improved to densify the microstructures and guarantee the complete closure of voids.

Effects of hot deformation and heat treatment on grain refinement for as-cast and spray formed SA508-3 steel

Effects of hot deformation and heat treatment on grain refinement for as-cast and spray formed SA508-3 steel