The Effects of Heat Treatments and Tungsten Additions on Microstructures and Tensile Properties of Powder Metallurgy Ti-48Al-2Nb-2Cr

2010 ◽  
Vol 638-642 ◽  
pp. 1406-1411 ◽  
Author(s):  
Dong Yi Seo ◽  
S. Bulmer ◽  
H. Saari ◽  
Peter Au
Keyword(s):  
Tensile Properties ◽  
Hot Isostatic Pressing ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Beta Phase ◽  
Mixed Mode Fracture ◽  
Controlled Cooling ◽  
Alloy Strength ◽  
Fully Lamellar ◽  
And Tungsten

The microstructures and tensile properties of a fully lamellar Ti-48Al-2Cr-2Nb, and two tungsten-modified versions, Ti-48Al-2Cr-2Nb-0.5W and Ti-48Al-2Cr-2Nb-1.0W (atomic percent) are investigated. Gas atomized powders are consolidated by hot isostatic pressing followed by solution treatment and aging. The microstructures are characterized by optical, scanning electron, and transmission electron microscopy and mechanical properties are characterized by room temperature tensile testing. The solution heat treatment, combined with controlled cooling, generates relatively fine, fully lamellar grains. Tungsten reduces the propensity for martensitic gamma formation during cooling, and slows down lamellar coarsening as well as the formation of equiaxed gamma phase during aging. The aging treatment stabilizes the microstructure and, in the tungsten-modified alloys, causes beta phase precipitation at lamellar interfaces and grain boundaries. Both aging and tungsten additions increase the alloy strength and reduce ductility. The fracture morphologies of the alloys are similar and exhibit mixed-mode fracture consisting of inter- and intra-granular cracking, as well as inter-lamellar cracking.

Mechanical Performance of a Cast A354 Aluminium Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 489-494 ◽  
Author(s):  
J.H. Sandoval ◽  
Adel M.A. Mohamed ◽  
S. Valtierra ◽  
F.H. Samuel
Keyword(s):  
Tensile Properties ◽  
Quality Index ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Test Results ◽  
Cast Aluminum ◽  
Treatment Conditions ◽  
Cast Aluminum Alloys

Cast aluminum alloys are an important group of materials which find wide application in the automotive industry. Insufficient studies have been carried out to date with regard to the mechanical performance of the aged A354 alloy. Therefore, the present work investigates the Quality index charts with the purpose of setting the limits of the tensile properties, as well as for comparing the mechanical behavior of cast alloy A354, to delineate the effect of the solution treatment applied. Tensile properties upon artificial aging in the temperature range of 155–350oC for times ranging from 2 to 100 hours are also investigated. The results showed that the use of quality index charts is a satisfactory method for presenting tensile test results and, for assessing the effect of solution and aging treatment conditions subjected to the modified and grain-refined A354 alloys. It is also observed that the quality index, Q, is more sensitive to variations in the tensile ductility than to tensile strength.

scholarly journals Effects of the γ″-Ni3Nb Phase on Mechanical Properties of Inconel 718 Superalloys with Different Heat Treatments

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 151
Author(s):  
Li-Shi-Bao Ling ◽  
Zheng Yin ◽  
Zhi Hu ◽  
Jin-Hui Liang ◽  
Zhi-Yong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Inconel 718 ◽  
Hot Isostatic Pressing ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Strengthening Mechanism ◽  
Morphological Observation ◽  
Isostatic Pressing ◽  
Direct Aging

The effects of the γ″-Ni3Nb phase on the mechanical properties of Inconel 718 superalloys, with standard heat treatment, hot isostatic pressing + solution treatment + aging, and hot isostatic pressing + direct aging, were characterized by morphological observation, X-ray diffraction, and tensile experiments. The results of the morphological observation revealed that many fine γ″ precipitates of ~26.49 ± 1.82 nm in mean size were formed in all samples. However, the relatively coarser γ″ precipitates formed in the grain boundaries were only observed in the sample treated with hot isostatic pressing + direct aging. The yield strengths of the hot isostatic pressing + direct aging sample at room temperature and at 650 °C both exhibited the maximum values about 993 ± 5.7 and 811 ± 12.6 MPa, respectively. The γ″ precipitate was considered to be the dominant strengthening phase in the sample according to the lattice misfits (ε) of γ/γ″. The strengthening mechanism of the samples can be explained as the coherency strain strengthening of fine γ″ precipitates. Moreover, due to the coarser γ″ precipitates in the grain boundaries, dislocation-cut ordered particle strengthening also occurred in the sample after hot isostatic pressing + direct aging treatment.

The Role of Interfacial Precipitates on Creep Behaviour of Power Metallurgy (PM) Ti-48Al-2Cr-2Nb+1W Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 496-499 ◽  
Author(s):  
Dong Yi Seo ◽  
Scott Bulmer ◽  
H. Saari ◽  
Han Liang Zhu ◽  
Peter Au
Keyword(s):  
Creep Resistance ◽  
Creep Behaviour ◽  
Hot Isostatic Pressing ◽  
Lamellar Microstructure ◽  
Primary Creep ◽  
Nominal Composition ◽  
Controlled Cooling ◽  
Creep Tests ◽  
Fully Lamellar

Pre-alloyed powders with a nominal composition of Ti-48Al-2Cr-2Nb+1W were consolidated by hot isostatic pressing (HIP). After the HIP process, a step cooled heat treatment (SCHT) with a carefully controlled cooling rate was applied to homogenize the HIP’ed microstructure and produce a fully lamellar microstructure. Following the SCHT, various isothermal aging at 950 °C and step aging processes form interfacial precipitates at the lamellar interfaces. The morphology, size, and distribution of the precipitates are dependent on the aging condition. Creep tests were carried out in air at 760 °C and 276 MPa to investigate the effect of interfacial precipitates. Primary creep resistance and creep life of the 8 and 144 hr aged conditions are improved substantially compared to the unaged condition due to the existence of the interfacial precipitates. However, the step aging process improves the creep resistance only slightly, probably because of the size and distribution differences of the interfacial precipitates compared to the 144 hr aged condition. Microstructure control is important since it has a substantial influence on creep behavior, especially primary creep resistance.

Effects of Heat Treatment on Microstructure and Mechanical Properties of Rolled AM50+xCa Magnesium Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 257-260 ◽  
Author(s):  
Jianguo Peng ◽  
Qu Dong Wang ◽  
Man Ping Liu ◽  
Yongjun Chen ◽  
Wen Jiang Ding ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Properties ◽  
Magnesium Alloys ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Secondary Phase ◽  
Solid Solution Treatment ◽  
Microstructure And Mechanical Properties

Effects of solution and aging treatment on microstructure and mechanical properties of rolled AM50+xCa alloys(x=0, 1, 2 wt. %) were studied. The results indicated that, with increasing solution time i, the secondary phase Mg17Al12 was dissolved into the Mg matrix and Al2Ca became thinner and shorter, then gradually broken and spheroidized.With an increase of aging time, Mg17Al12 precipitated from the Mg matrix in the form of particles and Al2Ca changed a little. After solution treatment, hardness and tensile properties of the alloy’s decreased. After the aging treatment, the alloy’s hardness increased first and decreased later while the tensile properties increased little. The solution and aging treatment can increase the ductility of AM50 and AM50+1Ca alloys. For AM50+2Ca alloy, the ductility increased after solid solution treatment and decreased after aging treatment.

scholarly journals Microstructure evolution-based design of thermal post-treatments for EBM-built Alloy 718

2020 ◽  
Vol 56 (8) ◽  
pp. 5250-5268
Author(s):  
Sneha Goel ◽  
Enrico Zaninelli ◽  
Johannes Gårdstam ◽  
Uta Klement ◽  
Shrikant Joshi
Keyword(s):  
Electron Beam Melting ◽  
Hot Isostatic Pressing ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Systematic Investigation ◽  
Alloy 718 ◽  
Treatment Procedure ◽  
Subsequent Aging ◽  
Economic Implications ◽  
Δ Phase

Abstract Alloy 718 samples were fabricated by electron beam melting (EBM) additive manufacturing process. The work focused on systematic investigation of response of the material to various thermal post-treatments, involving hot isostatic pressing (HIPing), solution treatment (ST) and two-step aging, to tailor post-treatment procedure for EBM-built Alloy 718. Results showed that HIPing at lowered temperature can be used for attaining desired defect closure while preserving grain size. Subjecting the material to ST, with or without prior HIPing, mainly caused precipitation of δ phase at the grain boundaries with prior HIPing decreasing the extent of δ phase precipitation. Moreover, results suggest that the utility of ST, with prior HIPing, could be dictated by the need to achieve a certain δ phase content, as the typically targeted homogenization after ST had already been achieved through HIPing. Detailed investigation of microstructural evolution during subsequent aging with and without prior HIPing showed that a significantly shortened aging treatment (‘4 + 1’ h), compared to the ‘standard’ long treatment (‘8 + 8’ h) traditionally developed for conventionally produced Alloy 718, might be realizable. These results can have significant techno-economic implications in designing tailored post-treatments for EBM-built Alloy 718. Graphical abstract

Effect of Cooling Rate on Tensile Properties of Ti-5Al-5Mo-5V-3Cr Alloy

2012 ◽  
Vol 567 ◽  
pp. 212-215
Author(s):  
Yan Yan Fu ◽  
Song Xiao Hui ◽  
Wen Jun Ye ◽  
Xu Jun Mi
Keyword(s):  
Tensile Properties ◽  
Cooling Rate ◽  
Room Temperature ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Air Cooling ◽  
Lower Strength ◽  
Α Phase ◽  
Water Quench ◽  
Strength And Ductility

The effects of cooling rate on the tensile properties of Ti-5Al-5Mo-5V-3Cr alloy with different microstructures were investigated at room temperature. The results indicate that as the cooling rates (water quench, air cooling and furnace cooling) get slower, the quantity and size of primary α phase of Widmanstatten microstructure and bi-modal microstructure increase, resulting in lower strength but higher ductility. The alloy from solution treatment at 820°C for 1 h followed by air cooling and aging treatment at 580°C for 4h is in good balance of strength and ductility.

scholarly journals Improving the Properties of Laser-Welded Al–Zn–Mg–Cu Alloy Joints by Aging and Double-Sided Ultrasonic Impact Compound Treatment

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2742
Author(s):  
Furong Chen ◽  
Chenghao Liu
Keyword(s):  
Plastic Deformation ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Welded Joints ◽  
Welded Joint ◽  
Weld Zone ◽  
Aging Treatment ◽  
Residual Tensile Stress ◽  
Impact Surface ◽  
Deformation Layer

To improve the loose structure and serious porosity of (Al–Zn–Mg–Cu) 7075 aluminum alloy laser-welded joints, aging treatment, double-sided ultrasonic impact treatment (DSUIT), and a combination of aging and DSUIT (A–DSUIT) were used to treat joints. In this experiment, the mechanism of A–DSUIT on the microstructure and properties of welded joints was analyzed. The microstructure of the welded joints was observed using optical microscopy, scanning electron microscopy, and electron backscatter diffraction (EBSD). The hardness and tensile properties of the welded components under the different processes were examined via Vickers hardness test and a universal tensile testing machine. The results showed that, after the aging treatment, the dendritic structure of the welded joints transformed into an equiaxed crystal structure. Moreover, the residual tensile stress generated in the welding process was weakened, and the hardness and tensile strength were significantly improved. After DSUIT, a plastic deformation layer of a certain thickness was generated from the surface downward, and the residual compressive stress was introduced to a certain depth of the joint. However, the weld zone unaffected by DSUIT still exhibited residual tensile stress. The inner microhardness of the joint surface improved; the impact surface hardness was the largest and gradually decreased inward to the weld zone base metal hardness, with a small improvement in the tensile strength. Compared with the single treatment process, the microstructural and mechanical properties of the welded joint after A–DSUIT were comprehensively improved. The microhardness and tensile strength of the welded joint reached 200 HV and 615 MPa, respectively, for an increase of 45.8% and 61.8%, respectively. Observation of the fractures of the tensile specimens under the different treatment processes showed that the fractures before the aging treatment were mainly ductile fractures while those after were mainly brittle fractures. After DSUIT of the welded joints, a clear and dense plastic deformation layer was observed in the fracture of the tensile specimens and effectively improved the tensile properties of the welded joints. Under the EBSD characterization, the larger the residual compressive stress near the ultrasonic impact surface, the smaller the grain diameter and misorientation angle, and the lower the texture strength. Finally, after A–DSUIT, the hardness and tensile properties improved the most.

Effect of Cold Machining Process on the Property and Microstructure of Ti-5Mo-5V-8Cr-3Al Strip

2014 ◽  
Vol 788 ◽  
pp. 134-137 ◽  
Author(s):  
Pei Tong Ni ◽  
Li Peng Zhou ◽  
Bao Liang Bai ◽  
Ming Chen Han ◽  
Mei Sheng Zhu
Keyword(s):  
Solution Treatment ◽  
Aging Treatment ◽  
High Strength ◽  
Machining Process ◽  
Beta Titanium Alloy ◽  
Cold Forming ◽  
Corrugated Shell ◽  
Beta Titanium ◽  
Gas Quenching ◽  
Metastable Beta

Metastable beta titanium alloy Ti-5Mo-5V-8Cr-3Al, with high-strength, favorite ductility and outstanding capacity of cold forming and welding, has been found the applications in sheet metal component, pressure vessel, corrugated shell and cold heading rivet at the temperature lower than 350°C. In the present paper, the effect of cold machining deformation rate and heat treatment process on the properties and microstructures of Ti-5Mo-5V-8Cr-3Al strip were investigated. The results revealed that excellent comprehensive mechanical properties could be achieved with the alloy by reasonable cold machining process and with solution treatment at 800°C followed by gas quenching. Upon a solution and aging treatment at 480°C, the alloy performed favorite plasticity and high ultimate tensile strength of 1250MPa.

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