Heat Treatment Behavior Research Articles

Plastic deformation and heat treatment of Mg-Li alloys: a review

• Review on plastic deformation and heat treatment behavior of Mg-Li alloys. • Aging softening and strengthening mechanism of Mg-Li-Al alloys is summarized. • Research emphasis of Mg-Li alloys in the future is prospected. As the lightest structural metallic materials, Mg-Li alloys have a bright development prospect in the fields of aerospace, weapon equipment, electronic technology and transportation. In this paper, the research progress of deformation processing and heat treatment of Mg-Li alloys is reviewed, with particular emphasis on the factors affecting the plastic deformation, the effects of plastic deformation on microstructural evolution and mechanical properties, and the heat treatment behavior of Mg-Li alloys. The problems existing in the scale application of Mg-Li alloys are pointed out, and the research focus of Mg-Li alloys in the future are also prospected.

Solidification Structure and Heat Treatment Behavior of Multi-alloyed White Cast Iron with Extensive Molybdenum Content for Applying to Hot Work Rolls

Solidification Structure and Heat Treatment Behavior of Multi-alloyed White Cast Iron with Extensive Molybdenum Content for Applying to Hot Work Rolls

Heat treatment and tribological behaviour of hypo and hyper eutectic aluminium alloy

Hypoeutectic and Hypereutectic aluminium alloys are alloys with compositions below and beyond the eutectic points respectively where aluminium is the major constituent and silicon is the primary alloying element. The silicon content at eutectic point is 12.6% based on which it can be characterized as hypoeutectic and hypereutectic alloys. In the present study the amount of silicon varies between 10 and 16 wt%. Heat treatment enhances or alters the hardness and other mechanical properties of the alloy for better reliability of these alloys. Hence it is proposed to analyze the variation in mechanical, tribological properties and microstructural changes of heat-treated alloys. Tribology studies were conducted based on L9 orthogonal array for two factors: sliding distances and load. 3 levels for each factor were 1 km, 2 km, 3 km sliding distance and 10 N, 20 N and 30 N load and the responses analyzed were wear rate and Coefficient of Friction. The microstructure analysis reveals the grain boundaries and shows the aluminium and primary alloying elements in both the alloys for the heat-treated samples. Hardness test was done to observe the difference between the solution treated and raw samples. The results revealed that the microstructure analysis, hardness and tribological testing of solution heat-treated samples revealed that hypoeutectic alloys have greater hardness than hypereutectic alloys.

Heat Treatment Behaviour of In718 Superalloy Fabricated by Laser-Powder Bed Fusion

Heat Treatment Behaviour of In718 Superalloy Fabricated by Laser-Powder Bed Fusion

Determining the heat treatment behaviour of metal injection moulded and wrought alloy 718 using differential scanning calorimetry

The heat treatment behaviour of metal injection moulded (MIM) and wrought alloy 718 was investigated using DSC, microscopy and hardness measurements. Reheating solutionized samples in the DSC resulted in a distinct exothermic peak around 725 °C, which was attributed to γ" precipitation. This was followed by a broad endothermic region (~750-900 °C), which was attributed to the dissolution of γ' and γ" precipitates. No DSC peak was observed corresponding to γ' precipitation upon reheat. The endothermic dissolution region (750–900 °C) ended with an abrupt exothermic shoulder around 900 °C, which was attributed to the solvus of the γ'/γ" precipitates and an acceleration of δ phase precipitation. Ageing the samples at progressively higher temperatures and for longer times resulted in a decrease in the 725 °C exothermic γ" precipitation peak and a deepening of the 750–900 °C endothermic dissolution region. Also, samples with higher Al content exhibited a deeper dissolution trough and a small bump in the exothermic shoulder at the end of this trough (~880 °C), which were attributed to the higher levels of γ' observed in the FESEM for these samples. A shallow endothermic trough peaking between 1000 and 1045 °C was observed in samples treated below the δ phase solvus and was attributed to dissolution of the δ phase. Hardness measurements showed an increase in hardness with the amount of γ' and γ" precipitated as expected. Differences in heat treatment behaviour appeared to be driven largely by differences in chemical composition rather than by processing route (wrought vs. MIM). However, the MIM material had smaller, more evenly distributed carbides and additional oxides not present in the wrought material which acted to restrict grain growth in samples solutionized up to 1232 °C.

Fatigue response of additively manufactured Maraging Stainless Steel CX and effects of heat treatment and surface finishing

AbstractThis paper deals with the novel topic of the fatigue response of additively manufactured Maraging Stainless Steel CX. A two‐by‐two factorial plan was arranged, to experimentally assess the effects of heat treatment and machining on the fatigue strength in both finite and infinite life domains. The two factors were regarded as on–off, taking the untreated unmachined condition as a reference for comparisons. Cylindrical specimens with vertical build orientation were involved in the fatigue campaign under four‐point rotating bending. The results indicate that the fatigue strength may be remarkably incremented (up to five times) with respect to the as received conditions, especially thanks to surface smoothing and taking advantage of a very low porosity level. Heat treatment strengthening mechanisms were also interpreted in the light of optical and electron microscope observations. Fatigue enhancement arises from precipitate size increment throughout the conducted heat treatment, although the fracture mode turns to be more brittle.

Age hardening heat treatment behavior of as-cast Mg–Zn–Al alloys

Magnesium alloys have generated renewed interest as a light alloys; replacing some conventional structural materials for weight reduction in applications like aerospace, automotive and electronics industries. In interior components and powertrains, cast alloys are widely used and represent more than 99% of magnesium alloys used today, whereas only a few wrought products are used. Mostly in automotive applications, Mg-engine block can noticeably reduce the weight and consequently its fuel consumption and environmental impact. Due to solid-state precipitates, these alloys are strong in nature and are produced by an age-hardening heat treatment process. In the present work the age hardening behavior of the as cast Mg–Zn–Al alloys (ZA85 alloy) in the composition of 8 wt. %Zn, 5 wt. %Al has been investigated. Through the differential thermal analysis (DTA) studies, it has been found out that dissolution temperature of ternary eutectic precipitates is present in the alloy. Based on the DTA results, the as cast samples have been solutionised at 360 °C temperature for different intervals of time. Solutionising time has been optimized from the enthalpy values of un-dissolved precipitates. The solution treated samples have been then aged at temperature of 180° C for different time intervals. From the peak hardness values, the ageing conditions have been optimized.

Relationship between the microstructure and the heat treatment and creep behavior of Fe–33Ni–19Cr alloy

AbstractIn the present study, the relationship between heat treatment, grain size, and the creep rupture properties of Fe–33Ni–19Cr alloy was investigated. The microstructure analysis showed that Fe–33Ni–19Cr alloy consists of the austenite phase matrix and a small number of precipitates such as titanium nitride and titanium carbides. Fe–33Ni–19Cr alloy shows an increase in steady‐state creep rate with increased grain size from 94 to 381 μm, due to the grain boundary sliding mechanism. The result also exhibited that the alloy that was subjected to creep test failed in ductile mode and cavitation at the grain boundaries. The fracture surface shows a transgranular fracture but an intergranular fracture at the recrystallized grains at the fracture area. Taken together, the result exhibited that the Fe–33Ni–19Cr alloy subjected lower heat treatment temperature possess a smaller grain size, which led to better creep property along with more excellent service life during operation.

Fabrication of spherical WC-Co powders by radio frequency inductively coupled plasma and a consequent heat treatment

To obtain spherical cemented carbide powders suitable for the additive manufacturing process, granulated WC-Co powders made by spray drying were spheroidized by radio frequency inductively coupled plasma. The influence of powder feed rate on the sphericity of the obtained powders was investigated. Results show that spheroidization efficiency of near 100% was achieved at different applied feed rates. Applying plasma processing decreased the particle size, compacted the microstructure and caused obvious improvements in the apparent density and flowability. However, complete decomposition of WC and certain evaporation loss of Co were noted in these powders. The spheroidized powders consisted of W2C, C, Co3W3C, and contained higher Co at a higher applied feed rate. After conducting heat treatment at 950 °C for 3 h, the powder phase composition was regenerated as WC and Co. The heat-treated powders, due to their good sphericity, improved apparent density and flowability are suitable for the printing processes.

Mechanical Property and Heat Treatment Behaviour of Ti-Zr-Fe Alloys

The element of zirconium (Zr) belongs to the same group 4 as Ti in the periodic table. Therefore it possesses similar chemical properties. The Ti-Zr binary system forms a continuous solid solution for both high temperature β phase with the body centered cubic (BCC) structure and low temperature α phase with the hexagonal close-packed (HCP) structure throughout the entire range of composition. As is well known, on the other hand, the element of iron (Fe) is not only inevitable but also effective element in Ti.By incorporating Fe at the stage of alloy design, off-grade sponge titanium can be employed. Both elements seem to be effective in strengthening the titanium alloys. The purpose of this work was to prepare Ti-Zr-Fe alloys and then mechanical property and heat treatment behaviours were investigated as a fundamental research. Ti-x mass% Zr-1mass% Fe alloys (x=0, 5, 10) were melted in a laboratory-scale arc furnace under a high purity argon atmosphere from the sponge Ti, the sponge Zr and the Fe wire. The resulting ingots were hot forged and rolled at approximately 1120 K to obtain plates of approximately 2 mm in thickness. Well-mixed and homogeneous samples could be obtained, oxygen contaminations were less than 0.09 %. Solid solution of Zr into Ti was confirmed by the XRD peak shift in α phase. Vickers hardness and proof stress increased with Zr content. No remarkable changes could be observed in the microstructures after the solution treatment at 1173 K. However, Young’s modulus increased at x=10 by the treatment.

Influence of Substitution of Fe by Mo on Heat Treatment Behavior in Ti-Mo-Fe Alloys

In order to reduce the cost of β-type Ti alloys, the use of Fe as an alloying element has been studied. However, Fe is known to have a very high diffusion coefficient in β-Ti of about 2.6×10-12 m2/s at 1200 K, and its behavior during heat treatment is expected to be difficult to control. By contrast, Mo, which is also a β-stabilizing element, has a diffusion coefficient of only about 2.5×10-14 m2/s at 1200 K, i.e., roughly 100 times smaller than that of Fe1), 2). In this study, the effect of the partial substitution of Fe with Mo on the aging behavior of β-Ti alloys was investigated using X-ray diffraction, electric resistivity, and Vickers hardness measurements. Ti-Mo-Fe alloys were solution-treated by holding at 1173 K for 3.6 ks and then quenching in ice water. In the X-ray diffraction patterns for the resulting samples, only peaks associated with the β phase were identified. It was found that the electrical resistivity and Vickers hardness decreased with increasing Mo content. As the Mo-to-Fe ratio increased, the decrease in electrical resistivity and the increase in Vickers hardness occurred later during the isothermal aging process. This was due to a delay in isothermal ω-phase precipitation.

Design of friction stir welding for butt joining of aluminum to steel of dissimilar thickness: heat treatment and fracture behavior

A 5-mm-thick aluminum sheet (Al) was successfully welded by friction stir welding (FSW) to a 3-mm-thick carbon steel (St) in a butt configuration. For this purpose, a new joint design was used where a support plate was employed under the St part and an insert layer made of steel was used between the support plate and the Al part. A stationary shoulder was also considered in the joint design. After welding, an intermetallic compound (IMC) layer of FeAl with less than 3 μm thickness was obtained along the bond line. The joint was then tested in tensile loading conditions. An abrupt load drop was observed during the test, which was due to crack propagation from pre-existed cracks in the IMC layer. A cohesion zone model (CZM) was used to simulate the fracture behavior of the joints and obtain the fracture energy of the IMC layer. Based on the CZM results, the fracture energy of the as-welded and heat-treated joints was obtained as 0.2 and 0.13 N/mm, respectively. A comprehensive analysis of the joints showed that the irregularities and fragments of steel in the IMC layer delay the propagation of cracks. Consequently, a higher fracture energy is obtained with respect to the heat-treated joint, in which a continuous IMC layer exists.

Experimental study on heat treatment and mechanical behaviour of M50 NiL steel – A review

M50 NiL Steel is low carbon high alloy steel with good strength, toughness, better wear and corrosion resistance at elevated temperature, because of this properties it is widely used in aerospace industry. Detection methods such as SEM, XPS, AES and TEM, and potentio dynamic polarization are used to find out corrosion resistance of double element alternate implanted M50 NiL steel. Hot Compression tests are used to study the behaviour of M50 NiL Steel during deformation. Potentio dynamic curves and electrochemical impedance spectroscopy are used to evaluate the corrosion properties for untreated and carbon ion implanted steels. Development of latest method like LPC Technology to meet the client requirements in industry, where the furnace design and operation has very crucial importance because of its flexibility to perform standard vacuum heat treatment and carburizing cycles. Different treatments like solution and tempering, gives precipitation behaviours of carbides [(V, Cr)-rich MC, (Mo, Fe)-rich M2C, Fe-rich M3C and (Fe, Cr)-rich M7C3] in M50 NiL Carburized Steel after heat treatment. The wear resistance behaviour of nitrided steel pieces will be enhanced by plasma nitriding process, where ultra fine grains and smooth surface of nitrided layer, posses high wear resistance. The mechanical behaviour of M50 Nil steel under carburizing and nitriding (dual) treatments, at the temperatures from 890 °C to 900 °C is helpful and Microstructure analysis can be characterized by XRD and SEM, TEM Methods. The objective of the paper is to review the mechanical behaviour and heat treatment process for better performance of M50 NiL Steel under various heat treatments and ion implementation methods.

The Simultaneous Effect of Extrusion Ratio and Solution Heat Treatment on the Microstructure and Tensile Properties of Extruded Al-15%Mg<sub>2</sub>Si- 1.0%Gd Composite

The effect of extrusion ratios and solution heat treatment on microstructure and tensile properties of extruded Al-15%Mg2Si-1.0%Gd composite was investigated. The as-cast composite was hot extruded using three different dies and solution heat treated. After conducting heat treatment on extruded samples, microstructure alteration was examined using scanning electron microscope (SEM). Furthermore, mechanical properties of the composites were studied with tensile test. The results demonstrated that extruded and heat treated composite possesses higher strength and ductility compared to as-extruded composites. It was also found that the extrusion and heat treatment processes altered the morphology of primary Mg2Si particles as well as reduction in their size especially when the extrusion ratio increases. Fracture surface examination revealed a transition from ductile fracture in as-extruded samples to more ductile fracture in extruded and heat treated ones. This can be attributed to the change in size and morphology of primary Mg2Si particles as well as fragmentation of Gd intermetallic compounds.

Influence of rhenium and tungsten on the microstructure and performance of GH4169 alloy through heat treatment

The microstructure and performances of GH4169 nickel (Ni)-based alloy were studied after adding the elements rhenium (Re) and tungsten (W) and then conducting heat treatment. The alloy containing the element rhenium showed less δ phase after heat treatment. For both alloys containing the element tungsten and the GH4169 alloy without any element, the δ phase and rectangular carbide were all precipitated after the heat treatment. The creep rupture life of the alloy added with the element rhenium was higher than that of the alloy added with the element tungsten at a high temperature. When a mixture of 75% sodium sulfate (Na2SO4) and 25% sodium chloride (NaCl) was applied at 950°C under the same conditions, the thermal corrosion resistance of the nickel-based alloy containing rhenium was obviously better than that of the nickel-based alloy containing tungsten. The hot-corrosion resistance of the GH4169 alloy without adding any element was slightly better than that of the alloy with tungsten.

Effect of Tungsten Equivalent on Heat Treatment Behavior of Semi-multi-alloyed White Cast Iron for Abrasive Wear Resistance

In this research, the effect of tungsten equivalent (Weq) on hardness and volume fraction of retained austenite (Vγ) of heat-treated semi-multi-alloyed white cast irons was investigated. Cast irons with 5.0 to 6.6%Weq under 2%C, 3%Cr, 1%W and 5%V were prepared. After annealing, the test specimens were hardened from austenitizing temperatures at 1050 °C and 1100 °C by fan air cooling. The tempering was carried out between 400 and 600 °C. In as-hardened state, the hardness dropped progressively as the Weq rose. High austenitizing temperature provided low hardness. The Vγ increased continuously as the Weq increased, and more Vγ was obtained by hardening from 1100 °C. In tempered state, the hardness curves showed an evident secondary hardening due to the precipitation of secondary carbides and the transformation of retained austenite to martensite. The degree of secondary hardening increased with a rise of Weq value and austenitizing temperature. The maximum tempered hardness (HTmax) was obtained by tempering at 500 °C in all the specimens regardless of austenitizing temperature. The highest values of HTmax, 830 HV30, was obtained in the specimen with 5.0%Weq hardened from 1100 °C.

Laser Metal Deposition of Ti6Al4V—A Brief Review

Laser metal deposition (LMD) is one of the most important laser additive manufacturing processes. It can be used to produce functional coatings, to repair damaged parts and to manufacture metal components. Ti6Al4V is one of the most commonly used titanium alloys, since it features a good balance of the mechanical properties of strength and ductility. The LMD of Ti6Al4V is attracting more and more attention from both science and engineering. The interest in processing Ti6Al4V with LMD in industry, especially in aerospace and medical branches, has been increasing in the last few years. In this paper, the state of the art for LMD of Ti6Al4V is reviewed. In the first part, the basics for Ti6Al4V, including, for example, the development history, the material properties, the applications, the crystal structure, the heat treatment and the mechanical properties, are introduced. In the second part, the main emphasis is on state of the art for LMD of Ti6Al4V. Initially, the process parameters of the current state of the art in the last years and their effects are summarized. After that, the typical microstructure after LMD is discussed. Then, the conducted heat treatment methods and the achievable mechanical properties are presented. In the end, some of the existing, current challenges are mentioned, and the possible research directions for the future are proposed.

Heat treatment and its effect on mechanical and wear properties of Al6061/Gr/TiC hybrid MMCs

The objective of this investigation is to explore the mechanical and wear characteristics of heat-treated hybrid metal matrix composites (MMCs) comprising Al6061, 5 wt.% graphite and different fractions of Titanium Carbide. In this, composites of different configurations were prepared by employing liquid metallurgy technique. The accumulation of graphite was kept constant that is 5 wt.% while TiC was varied from 0% to 8 wt.% in a stage of 2% and are subjected to T6 heat treatment. At first, composites were exposed to solutionising heat treatment at 530°C for 8 h and followed by quenching in ice and water. Artificial ageing of quenched composites was performed for an interval of 4-10 h in a step of 2 h. The role of heat treatment and ageing behaviour of composites on mechanical and wear characteristics were investigated and compared with un-heat treated. The result shows superior hardness and wear properties of MMCs for T6 heat treatment.

Conducting heat treatment of the TiNiTa alloy and studying the mechanical properties depending on the heat treatment

In this work, a TiNiTa wire with a tantalum content of 10% (weight) was obtained, heat treatment of wire samples was carried out at various temperatures in a vacuum furnace, mechanical tests were carried out after heat treatment to determine the optimal heat treatment mode after the final drawing step to remove hardening and obtain the best complex mechanical properties for the use of wire in the manufacture of medical stents.

Investigation of Mechanical Properties of AISI 316 Stainless Steel by Carbonitriding Process

This project investigates on salt bath nitriding process in order to improve the wear behavior of the material. This process increases the hardness of the material. The specimens were nitrided at 580°c on three different timing hours such as 60 minutes, 90 minutes & 120 minutes. A pin on disc machine is used to conduct wear test, so that wear loss can be determined. The specimens are to be magnified by metallographic test like scanning electron microscope. The untreated specimen is used to compare with the nitrided specimen. The best specimen is chosen which determines the life of material & improves the better wear resistance. The hardness of untreated material and nitrided material are compared. The material AISI stainless steel has many unique properties but it lacks wear resistance and hardness because of which it has limited applications. By conducting heat treatment operation, the hardness of the material does not improve, but by conducting case hardening process the hardness of the outer case will be high compared to base metal. If the hardness and wear resistance of the material improves the material can be used in wide range of applications.