Effect Of Homogenization Heat Treatment Research Articles

The Effect of Homogenization Heat Treatment on 316L Stainless Steel Cast Billet.

This investigation aims to analyze the effect of homogenization heat treatment at 1240 °C for 2 and 6 h on the hardness, distribution, morphology, and chemical composition of the δ-ferrite and sigma phases in 316L stainless steel cast billet. A field emission scanning electron microscope, combined with electron back-scattered diffraction, a field emission electron probe microanalyzer with a wavelength dispersive spectrometer, and a Vickers microhardness tester are applied to identify various phase evolutions in the cast billet. The morphology of the δ-ferrite and sigma phases in the austenite matrix of the 316L cast billet are strongly related to the subsequent hot and cold wire drawings. The homogenization heat treatment is expected to provide a driving force to form spheroid interdendritic δ-ferrite and to minimize the amount of the brittle sigma intermetallic compound in the austenite matrix. The homogenization heat treatment at 1240 °C effectively spheroidized all δ-ferrites into blunt ones in the cast billet. The transformation of δ-ferrite into sigma is dominated by temperature and cooling rate. The fast air cooling after homogenization between 1240 and 850 °C retards the precipitation of the sigma in the δ-ferrite. There are two δ-ferrite transformation mechanisms in this experiment. The direct transformation of the δ-ferrite into sigma is observed in the as-cast 316L stainless steel billet. In contrast, the eutectoid transformation of the δ-ferrite into the sigma and austenite dominates the 316L cast billet homogenized at 1240 °C, with a slow furnace cooling rate.

Effect of homogenization heat treatment on the mechanical properties of AlMgSi alloys with different Cr content

Effect of homogenization heat treatment on the mechanical properties of AlMgSi alloys with different Cr content

Effect of homogenization heat treatment on the microstructure of AZ91 magnesium alloy at different temperatures and ageing times

Magnesium (Mg) alloys are promising biodegradable implant materials. If successful, they do not require a second surgiabscal operation for their removal. These alloys possessed microstructure, which contained alpha (α-Mg) phase, eutectic (α + β) phase and intermetallic or beta (β-Mg17Al12) phase. The bio-corrosion rate of any intermetallic alloy is related to its β phase volume fraction (VF). However, this β phase contributes galvanic corrosion which hinders the clinical application of Mg alloys. Thus, this study is focused to reduce the VF of the β phase and select the appropriate temperature for Mg homogenization heat treatment (HHT). HHT was carried out on Mg AZ91 alloy samples by using a high-temperature rotary furnace at 350 °C for 10 h, 370 °C for 10 h, 390 °C for 5 h and10h, 410 °C for 5 h and10h and 430 °C for 5 and 10 h. The influence of varying temperature with time was investigated on the microstructure and microhardness of Mg AZ91 alloy by using a field emission scanning electron microscope equipped with an energy-dispersive spectroscope and image Digimizer. The results revealed that the higher the HHT or the longer the homogenization heat dwelling time, the more the homogenous distribution of the large β phase over the microstructure, hence containing little or without a β phase. The microhardness increased with an increase in temperature and ageing time with the peak hardness at 410 °C and 430 °C for 10 h.

Effect of Homogenization Heat Treatment on Elongation Anisotropy in Cold-Rolled and Annealed Al–Si Alloy Sheets Fabricated from Vertical-Type High-Speed Twin-Roll Cast Strips

Effect of Homogenization Heat Treatment on Elongation Anisotropy in Cold-Rolled and Annealed Al–Si Alloy Sheets Fabricated from Vertical-Type High-Speed Twin-Roll Cast Strips

An investigation of microstructure and mechanical properties of as-cast Zn–22Al alloy during homogenizing and equal channel angular pressing

In this study, the effect of homogenization heat treatment and equal channel angular pressing process (ECAP) on microstructure and mechanical properties were explored in Zn–22Al alloy. It was observed that homogenization caused a significant part of the structure to transform to equiaxed grains from an initially lamellar structure. Also, with increasing time of homogenization, a homogeneous structure with no coarse phases were created. Average grain sizes of 48, 2.5, 1.2 and 1.1 μm were respectively achieved after homogenization for 4, 8, 12 and 24 h at 375 °C followed by water quenching. By removal of the lamellar structure during homogenization, improved superplastic behavior was observed. By increasing the time of homogenization, a decrease in microhardness took place which can be due to the loss of hard dendritic phases in the microstructure. On the other hand, grain size of 0.44 μm was achieved after 8 passes of ambient temperature ECAP process which was found to be quite effective in forming the ultra-fine grained (UFG) and equiaxed microstructure leading to further improvement in superplastic behavior. By increasing the number of ECAP passes, the failure elongation increased. On the other hand, the microhardness curve showed a work softening which is associated with the dynamic recovery/recrystallization of η phase after ECAP process.

The Effect of Homogenization Heat Treatment on the Texture Evolution in U-10Mo Alloy

The Effect of Homogenization Heat Treatment on the Texture Evolution in U-10Mo Alloy

Effect of Precipitation Hardening on Corrosion Resistance of Cu-4.5 wt.%Ti

Cu-Ti alloys are one of the main candidates to act as a substitute for Cu-Be alloys due to their more environmentally friendly nature. Cu-Ti alloys are age hardenable alloys, and their treatments can modify their microstructure, causing the formation of various Cu-Ti intermetallic that can strongly influence both the mechanical and corrosion properties. In this work, the effect of homogenization heat treatment at 1173 K followed by aging at 723 K for different times (0–24 h) on the microstructure, corrosion and mechanical properties of Cu-4.5 wt.%Ti alloy was investigated. Moreover, the corrosion mechanism based on the different kinetics for the formation of the protective oxide layer was studied. The microstructure and phase analyses were analyzed with SEM and XRD. The mechanical properties were investigated by microhardness test, whereas the corrosion properties were studied by potentiodynamic anodic polarization and potentiostatic tests in artificial sweat. The results showed that the cast sample had the highest corrosion resistance, and the mechanical properties decrease with the homogenization treatment and increase after the combination of homogenization and aging. A corrosion mechanism correlated to the amount and type of intermetallic material was proposed.

Effect of homogenization heat treatments on the cast structure and tensile properties of nickel-base superalloy ATI 718Plus in the presence of boron and zirconium additions

The effect of homogenization heat treatment on cast structure, hardness, and tensile properties of the nickel-based superalloy 718plus in the presence of boron and zirconium additives were investigated. For this purpose, five alloys with different contents of boron (0.00–0.016wt%) and zirconium (0.0–0.1wt%) were cast by double vacuum process VIM/VAR and then were homogenized at 1075–1175°C for 5–25h. Microstructural investigation by OM and SEM and phase analysis by XRD were done and then hardness and high temperature tensile tests were performed on the homogenized alloys. The results show that the amount of the Laves phase is reduced by increases in time and temperature of homogenization. It was also found that increases in duration of homogenization at 1075°C results in improving strength and ductility, while duration increase at 1175°C is accompanied with degradation of them, which caused the reduction of needle-like delta phase on grain boundaries. Boron and zirconium had negative effects on the strength and ductility of the alloy by increasing the amount of Laves in the cast structure. By increasing these elements in alloy composition, more time is needed in order to fully eliminate the Laves by homogenization treatment.

The Effect of Homogenization Heat Treatment on Thermal Expansion Coefficient and Dimensional Stability of Low Thermal Expansion Cast Irons

In this paper, the effect of homogenization heat treatment on α value [coefficient of thermal expansion (10−6 K−1)] of low thermal expansion cast irons was studied. In addition, constrained thermal cyclic tests were conducted to evaluate the dimensional stability of the low thermal expansion cast irons with various heat treatment conditions. The results indicate that when the alloys were homogenized at a relatively low temperature, e.g., 1023 K (750 °C), the elimination of Ni segregation was not very effective, but the C concentration in the matrix was moderately reduced. On the other hand, if the alloys were homogenized at a relatively high temperature, e.g., 1473 K (1200 °C), opposite results were obtained. Consequently, not much improvement (reduction) in α value was achieved in both cases. Therefore, a compound homogenization heat treatment procedure was designed, namely 1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ, in which a relatively high homogenization temperature of 1473 K (1200 °C) can effectively eliminate the Ni segregation, and a subsequent holding stage at 1023.15 K (750 °C) can reduce the C content in the matrix. As a result, very low α values of around (1 to 2) × 10−6 K−1 were obtained. Regarding the constrained thermal cyclic testing in 303 K to 473 K (30 °C to 200 °C), the results indicate that regardless of heat treatment condition, low thermal expansion cast irons exhibit exceedingly higher dimensional stability than either the regular ductile cast iron or the 304 stainless steel. Furthermore, positive correlation exists between the α303.15 K to 473.15 K value and the amount of shape change after the thermal cyclic testing. Among the alloys investigated, Heat I-T3B (1473 K (1200 °C)/4 hours/FC/1023 K (750 °C)/2 hours/WQ) exhibits the lowest α303 K to 473 K value (1.72 × 10−6 K−1), and hence has the least shape change (7.41 μm) or the best dimensional stability.

Effect of homogenization heat treatment on toughness and wear resistance of plastic mold steel

Abstract In this study, the effect of homogenization treatment on the microstructure, toughness and wear resistance of plastic mold steel was investigated. Homogenization heat treatment was performed at 1150 °C for 3 hours. All specimens were austenitized at 850 °C for 1 hour, quenched in oil and tempered at different temperatures. Wear tests were carried out using a pin-on-disc tribometer under dry sliding conditions. Charpy V notch impact tests were performed to determine the toughness properties. Microstructure, fracture and worn surfaces were investigated by scanning electron microscope. The results show that heat treatment conditions have an effect on the microstructure and mechanical properties of materials. It was determined that homogenization heat treatment causes more homogeneous structure, in particular, it has a positive effect on the toughness properties and wear resistance of the materials which were tempered at low temperatures.

Hot workability analysis of AZ61 Mg alloys with processing maps

The hot working behaviors of as-cast and homogenized AZ61 magnesium alloys were investigated using processing maps in this study. Compression tests were conducted in the temperature range of 250–450°C and in the strain rate range of 1×10−3–1s−1 to establish the processing maps. The effect of homogenization heat treatment on hot workability was analyzed. The map for as-cast material exhibited a single domain of dynamic recrystallization that occurs in the temperature range of 300–450°C and in the strain rate range of 1×10−3–1×10−2s−1. Homogenization heat treatment improved hot workability by expanding the workability domain and by significantly reducing the flow instability regime. Variations in power dissipation efficiency were related to the degree of dynamic recrystallization and the grain size in the workability domains for both as-cast and homogenized materials. The efficiency values generated by as-cast AZ61 were higher overall compared with those produced by homogenized AZ61 in the workability domains. The rate-controlling mechanism was dependent on the strain due to microstructural evolution.

Ｉｎｃｏｎｅｌ ７１８鋳造合金の溶接性に関する研究 ３ ＨＡＺ割れ感受性に及ぼす均質化熱処理の影響

The purpose of this study is to clarify the effect of homogenization heat treatment on HAZ cracking susceptibility of cast alloy 718. Homogenization heat treatment was conducted at 1368 K and 1378 K with varying holding time. HAZ cracking susceptibility was evaluated using Longitudinal -Varestraint test at three different strain levels. The test results showed that the number and length of cracks decreased by homogenization heat treatment. HAZ cracking susceptibility was found to be most improved at the heat treatment condition of 1378 K×10.8 ks. According to the isothermal liqaution test, grain boundary liquation was suppressed in heat treated samples. Microscopic observation indicated that the number and size of Laves cluster on the grain boundary decreased by homogenization heat treatment. On the basis of these results, the improvement of HAZ cracking susceptibility by homogenization heat treatment was considered to be attributed to mainly the reduction of Laves cluster on the grain boundary.

Effect of homogenization heat treatment on the microstructure and heat- affected zone microfissuring in welded cast alloy 718

The effect of homogenization temperature on microfissuring in the heat-affected zones of electronwelded cast INCONEL 718 has been studied. The material was homogenized at various temperatures in the range of 1037 ° to 1163 ° and air-cooled. The homogenized material was then electron-beam welded by the bead-on-plate welding technique. The microstructures and microfissuring in the heat-affected zone (HAZ) were evaluated by analytical scanning electron microscopy (SEM). The grain boundary segregation of various elements was evaluated by secondary ion mass spectroscopy (SIMS). It was observed that the total crack length (TCL) of microfissures first decreases with homogenization temperature and then increases, with a minimum occurring in the specimen heat treated at 1163 °. This trend coincides with the variation in segregation of B at grain boundaries with homogenization temperature and has been explained by equilibrium and nonequilibrium segregation of B to grain boundaries during the homogenization heat treatment. No other element was observed to segregate at the grain boundaries. The variation in volume fraction of phases like δ-Ni3Nb, MC carbide, and Laves phases does not follow the same trend as that observed for TCL and B segregation at the grain boundaries. Therefore, microfissuring in HAZ of welded cast INCONEL 718 is attributed to the segregation of B at the grain boundaries.