Papers by Keyword: Solution Treatment

Abstract: Ti-6Al-7Nb is commonly used as orthopedic implant, especially for total hip arthroplasty application, due to its excellency in biocompatibility and surface feature. This study investigates the effects of varying solution treatment temperatures on the mechanical properties and corrosion resistance of the biomedical Ti-6Al-7Nb alloy fabricated using centrifugal investment casting. Solution treatment was performed at 850°C, 970°C, and 1050°C, and the results were evaluated through tensile tests, hardness measurements, microstructural observations, and potentiodynamic polarization tests. The treatment at 970°C produced the optimal combination of mechanical strength and corrosion resistance, achieving a tensile strength of 690 MPa and the lowest corrosion rate of 0.00826 mmpy. The superior performance at 970°C is attributed to the formation of fine α precipitates in the microstructure. These findings highlight the effectiveness of suitable solution treatment temperature in enhancing Ti-6Al-7Nb’s properties for potential use in biomedical applications.

Abstract: Welding induces various effects, including the generation of residual stress, deformation, alterations in shape, and changes in mechanical properties, particularly the hardness of the material in the welded zone due to the melting of the base material during the welding process. These factors can contribute to a reduction in product strength. This research aims to investigate the influence of solution treatment (ST) temperature on the hardness properties of aluminum 6061 with TIG welded joints. The study involves TIG welding to create joints, followed by a solution heat treatment process, during which the welded product is heated in a furnace at temperatures of 450, 475, and 500 °C, with a fixed holding time of one hour for each condition. Following the heat treatment, hardness tests are conducted to evaluate the condition of the TIG welded joints as influenced by the solution treatment temperature. The results demonstrate a significant effect of the solution treatment temperature on the hardness of the AA6061 alloy in the TIG welded joints. The highest hardness value, 80 HRE, is observed in the weld metal area of the ST 475 °C sample, while the lowest value, 37.17 HRE, is recorded in the base metal area of the ST 450 °C sample.

Abstract: The influence of Erbium (Er) addition and thermal treatments on the microstructure and hardness of Al-0.5 wt.%Mg-1.0 wt.%Si alloy has been studied. Chemical composition of the alloys was measured by optical emission spectrometry (OES) and x-ray fluorescence (XRF). Microstructural evolution of as-cast, solution-treated, and aged samples were characterized by scanning electron microscope (SEM). The phase identification and elemental distribution were obtained from energy dispersive spectroscopy (EDS). From the microstructure, it was confirmed that solutionization at 570 ͦ C for 15 hours dissolved the Mg₂Si and Er-rich intermetallics. However, some Fe-rich intermetallics remained after the solution heat treatment. Er addition had a role on the modification of β-AlFeSi and improved the hardness. Er-modified Al-Mg-Si alloy gave a significant improvement in mechanical properties. Therefore, Er is one of the candidate elements that could provide an opportunity for a high-strength Al-Mg-Si alloy.

Abstract: The dissolution of the second phase during solution treatment was of great importance for achieving preferential properties via aging treatment for Aluminum-Lithium (Al-Li) alloys. The microstructure characteristics of an extruded Al-Li alloy and its second phase dissolution during solution treatment were studied, while related electrical conductivity and tensile properties after ageing were tested for verification. The results indicated that as the alloy solution was treated from 500°C to 520°C with a soaking time of 1.5h, the Cu-rich phase dissolved into the matrix continuously. The statistics of remained phase area fraction ascertained no obvious decrement from 510°C to 520°C and only Fe-containing phase with large size was detected. Meanwhile, tensile properties under the same aging regime declared a higher strength was obtained at 510°C. As the solution time varied from 0.5h to 5h at 510°C, the Cu-rich phase was detected in a soaking time of 0.5h while disappeared after 1.5h and only the Fe-containing phase was observed. Correspondingly, electrical conductivity exhibited a moderate growth while tensile strength obviously increased from 0.5h to 1.5h and then maintained a platform, which revealed a preferential solution regime of 510°C/1.5h. This gives a reference for the second phase dissolution during solution treatments and furtherly obtaining preferential solution regimes.

Abstract: The main alloying elements have a decisive influence on the type and quantity of the second phase of the Al-Zn-Mg-Cu alloy, and even on the dissolution of the second phase during solution treatment. The effect of Zn/Mg ratio on second phase dissolution during solution treatment of Al-Zn-Mg-Cu alloys was investigated by means of differential scanning calorimetry (DSC), scanning electron microscope (SEM) and electrical conductivity testing. The results showed that Mg (Zn,Cu,Al)₂ phase and Fe-rich phase existed in the as-deformed alloys. In addition, a small amount of Al₂CuMg phase was found in the low and medium Zn/Mg ratio alloy. The number of Mg (Zn,Cu,Al)₂ phases as the major second phase in the alloys was inversely proportional to the Zn/Mg ratio. Mg (Zn,Cu,Al)₂ phase essentially dissolved into the matrix after solution treatment at 465°C/2h. Increasing the solution temperature and time were both beneficial to the dissolution of the Al₂CuMg phase. With the increase of the solution temperature from 465°C to 475°C, the conductivity of the alloy showed a decreasing trend initially and then increased. As the solution time increased at 470°C, the electrical conductivity of the low-Zn/Mg ratio alloy decreased and then increased due to the more secondary phase. After the second phase was fully dissolved in the alloy, the electrical conductivity gradually increased with the increase of the solution time.

Abstract: The study on solution treated Fe-40Ni-24Cr Ni-based alloy on the isothermal oxidation has been investigated. The solution treatment process has been done at two temperatures, which are 1100°C and 1200°C. The alloys were soaking for 3 hours, followed by rapid cooling using water cooled. The solution treated Fe-40Ni-24Cr Ni-based alloy were experienced an isothermal oxidation test at 700°C for 500 hours exposure time. The effect of Nb alloying element on the oxide growth behavior has been characterized in termed of plan and cross sectional view using scanning electron microscope with energy dispersive x-ray spectrometer. As a results, good protective oxide scale has formed on the fine grain solution treated sample with homogeneous and dense oxide structure. On the other hand, coarse grain solution treated sample demonstrated an oxide exfoliation after 500 hours exposure around the overgrown Nb-rich oxide precipitate area, hence indicating poor oxidation protection.

Abstract: In this research, a 800H Ni-based alloy was experienced a solution treatment procedure at two different temperatures. The solution-treated alloys were undergo a high-temperature oxidation under isothermal conditions at 500°C for 500 hours in laboratory air. The alloy was characterized using OES, XRD, SEM and FESEM equipped with an EDX spectrometer. It was found that the solution-treated alloy at 950°C produced a small grain size, and alloy treated at 1100°C produced a large grain size. The XRD results show that various oxides phases were detected. The oxidation kinetics followed the parabolic rate law indicating the oxide was formed based on diffusion-controlled oxide growth rate. The alloys with small grain sizes exhibited a lower oxidation rate, hence have excellent oxidation resistance. This is due to the accessibility of the high ion diffusion route through the grain boundaries of small-grained alloy and thus permits the speedy establishment of the initial oxide layer. Uniform oxide scale formed on a small-grained oxidized sample with visible overgrow discrete oxide particle comprised of Ti-rich oxide. The large-grained oxidized sample indicates evidence of oxide exfoliation indicating poor oxidation protection.

Abstract: In the present work, the possibility of using solution treatment to improve the cavitation erosion resistance of the duplex stainless steel surfacing layers was discussed. The effect of solution treatment on cavitation erosion resistance of duplex stainless steels was investigated. The results showed that the solution treatment can adjust the ratio of ferrite to austenite, reduce the precipitation content, and make the incubation period longer, leading to an increase in the cavitation erosion resistance of the duplex stainless steel surfacing layers. The sample treated at 900°C and water quenching was shown to have the best resistance to the absorption of the energy produced by cavitation erosion, and hence the best cavitation erosion resistance.

Abstract: Second phase dissolution of Al-Zn-Mg-Cu alloys during solution treatment was closely associated with the content of main alloying elements. In present work, the phase characteristics of several Al-Zn-Mg-Cu alloys with various main alloying contents were investigated, and the second phase dissolution of these alloys during solution treatment was analyzed. The results showed that the extrusion alloys possessed abundant second phases, mainly including Mg(Zn,Cu,Al)₂ phase and Fe-rich particles. The DSC analysis proved that the larger endothermic peak corresponded to the alloy with larger main alloying content, and the XRD spectrogram also backed up the advantage of Mg(Zn,Cu,Al)₂ phase. After solution treated at 450°C, the residual phases remained in the alloys and the quantity of them were positively correlated with the main alloying content. With the increase of solution temperature, the electrical conductivity of the alloys showed a decremental trend, while the alloys with relatively low main alloying contents exhibited an inversion at the solution temperature of 475°C. The SEM observation demonstrated that no Mg(Zn,Cu,Al)₂ phase was observed in the alloys with relatively low main alloying contents while seldom still remained in the alloy with high main alloying content after solution treated at 470°C. After solution treated at 475°C, Mg(Zn,Cu,Al)₂ phase completely dissolved into the matrix for the alloy with high main alloying content. The statistics of residual phase quantity also proved this.

Abstract: In this experiment, Al-Cu-Mg-Ag alloy was used as material and solution temperature was used as variable to investigate its effect on the corrosion properties of the alloy and Hardness test, metallographic observation, electrochemical test, intergranular corrosion and exfoliation corrosion test were carried out on three groups of samples. The results show that the intergranular corrosion resistance of the alloy decreases with the increase of solution treatment temperature, and the sample treated at 505 °C has the best performance. This is mainly because grain boundary structure plays a role in increasing PFZ and expanding corrosion channels. The exfoliation corrosion resistance of Al-Cu-Mg-Ag alloy increases first and then decreases, and the sample treated at 515 °C has the best performance. This is due to the dual effects of grain boundary structure and grain morphology. On the one hand, the solution treatment temperature increases, which widens the precipitation-free zone and reduces the electrochemical corrosion resistance of the alloy. On the other hand, the increase of recrystallized grains decreases the cohesion of corrosion products and enhances the electrochemical corrosion resistance of the alloy.