Studies on Microstructure and Properties by Mass Smelting for Directionally Solidified Superalloy

2016 ◽  
Vol 849 ◽  
pp. 508-512
Author(s):  
Yang Gao ◽  
Yong Ji Niu ◽  
Shi Feng Shi ◽  
Jian Jun Tian ◽  
Chao Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Solution Treatment ◽  
Smelting Process ◽  
Uniform Structure ◽  
Vacuum Furnace ◽  
Directionally Solidified ◽  
Factors Affecting ◽  
Reduction Of Area ◽  
High Temperature Tensile ◽  
The Impact

Large quantities of VIDP400 vacuum furnace smelting DZ417G oriented superalloys smelting process has been researched, analysis of the main factors affecting the organizational uniformity and stability, as well as the impact of high temperature tensile and lasting properties has been studied. The results showed that: At pulling rate of 4.5~8.5mm•min-1, after 1220°C solid solution treatment and 980°C aging system, the DZ417G superalloy had uniform chemical constitution with oxygen and nitrogen content of the alloy in sharply reduced to 13ppm. It can be got available treatment uniform structure with proper γ'phase size, with high-temperature tensile strength up to 750MPa, elongation of 17% reduction of area 22%. The lasting high temperature performance can reach to more than 100 hours.

High Temperature Tensile Behavior of Directionally Solidified MAR-M247 Superalloy

2014 ◽  
Vol 783-786 ◽  
pp. 1153-1158
Author(s):  
Hui Yun Bor ◽  
Chao Nan Wei ◽  
An Chou Yeh ◽  
Wei Bin He ◽  
Huei Sen Wang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Room Temperature ◽  
Solution Treatment ◽  
Standard Heat Treatment ◽  
Directionally Solidified ◽  
Gamma Prime ◽  
Elongation To Failure ◽  
Initial Fracture ◽  
High Temperature Tensile

In this study, two heat treatment schemes were proposed to study the high temperature mechanical behavior of directionally solidified MAR-M247 superalloy. Two withdraw rates, namely, 60 and 180 mm/h were used to produce directionally solidified MAR-M247 specimens by the Bridgeman type furnace. Standard heat treatment (HT1) procedures are solution treatment at 1230°C for 2 h/ArC, then first aging at 980°C for 5 h/AC and followed by second aging at 870°C for 20 h/AC. Modified heat treatment (HT2) is solution treatment at 1260°C for 3 h/ArC and first aging at 980°C for 6 h/AC, then the same second aging procedure. Uneven size, shape and fusion-alike of gamma prime precipitates are observed after full HT1 scheme, whereas even size but fine gamma prime precipitates are observed in HT2 specimen. All three tensile properties (elongation to failure, ultimate tensile strength and yield strength) of HT2 specimens are higher than these of HT1 specimens either at room temperature 25°C or at high temperature 982°C for both withdraw rates. Uneven distribution of the γ′ precipitates attributes to the initial fracture of HT1 specimens.

scholarly journals The Effect of the Cooling Rates on the Microstructure and High-Temperature Mechanical Properties of a Nickel-Based Single Crystal Superalloy

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4256
Author(s):  
Xiao-Yan Wang ◽  
Meng Li ◽  
Zhi-Xun Wen
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Single Crystal ◽  
Solution Treatment ◽  
Single Crystal Superalloy ◽  
Air Cooling ◽  
Strengthening Effect ◽  
Cooling Rates ◽  
High Temperature Mechanical Properties ◽  
High Temperature Tensile

The as-cast alloy of nickel-based single-crystal superalloy was used as the research object. After four hours of solution treatment at 1315 °C, four cooling rates (water cooling (WC), air cooling (AC) and furnace cooling (FC1/FC2)) were used to reduce the alloy to room temperature. Four different microstructures of nickel-based superalloy material were prepared. A high-temperature tensile test at 980 °C was carried out to study the influence of various rates on the formation of the material’s microstructure and to further obtain the influence of different microstructures on the high-temperature mechanical properties of the materials. The results show that an increase of cooling rate resulted in a larger γ′ phase nucleation rate, formation of a smaller γ′ phase and a greater number. When air cooling was used, the uniformity of the γ′ phase and the coherence relationship between the γ′ phase and the γ phase were the best. At the same time, the test alloy had the best high-temperature tensile properties, and the material showed a certain degree of plasticity. TEM test results showed that the test alloy mainly blocked dislocations from traveling in the material through the strengthening effect of γ′, and that AC had the strongest hindering effect on γ′ dislocation movement.

Heat Treatment Microstructures of a Directionally Solidified Nickel Base Superalloy under High Temperature Gradient

2014 ◽  
Vol 788 ◽  
pp. 519-524
Author(s):  
Wei Guo Zhang ◽  
Xue Mei Yi ◽  
Chu Ang Feng
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Temperature Gradient ◽  
Grain Boundary ◽  
Solution Treatment ◽  
Grain Boundary Sliding ◽  
Chinese Script ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
High Temperature Gradient

The heat treatment of a directionally solidified superalloy under high temperature gradient with different dendritic size was studied. The evolution rules of each phase in DZ125 alloy after heat treatment were analyzed. The results show that γ' phase presents cube and uniform distribution after heat treatment. Its size is about 0.4μm and its area ratio is about 65%. MC carbide transforms into MC(2) carbide with high concentration of Hf. The morphology of MC carbide changes from Chinese-script to block and its size reduces gradually with increasing solidification rate under directional solidification. There is bulk γ' phase around carbide. MC(2) carbide and γ' phase in the grain boundary form chain along grain boundary, and effectively retard grain boundary sliding. γ+γ' eutectic is basically eliminated by solution treatment and only a little γ+γ' eutectic exists around carbide.

scholarly journals Study on High-Temperature Mechanical Properties of Fe–Mn–C–Al TWIP/TRIP Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 821
Author(s):  
Guangkai Yang ◽  
Changling Zhuang ◽  
Changrong Li ◽  
Fangjie Lan ◽  
Hanjie Yao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Low Temperature ◽  
Tensile Fracture ◽  
Temperature Range ◽  
High Temperature Mechanical Properties ◽  
Ductility Trough ◽  
Different Temperatures ◽  
Reduction Of Area ◽  
High Temperature Tensile

In this study, high-temperature tensile tests were carried out on a Gleeble-3500 thermal simulator under a strain rate of ε = 1 × 10−3 s−1 in the temperature range of 600–1310 °C. The hot deformation process of Fe–15.3Mn–0.58C–2.3Al TWIP/TRIP at different temperatures was studied. In the whole tested temperature range, the reduction of area ranged from 47.3 to 89.4% and reached the maximum value of 89.4% at 1275 °C. Assuming that 60% reduction of area is relative ductility trough, the high-temperature ductility trough was from 1275 °C to the melting point temperature, the medium-temperature ductility trough was 1000–1250 °C, and the low-temperature ductility trough was around 600 °C. The phase transformation process of the steel was analyzed by Thermo-Calc thermodynamics software. It was found that ferrite transformation occurred at 646 °C, and the austenite was softened by a small amount of ferrite, resulting in the reduction of thermoplastic and formation of the low-temperature ductility trough. However, the small difference in thermoplasticity in the low-temperature ductility trough was attributed to the small amount of ferrite and the low transformation temperature of ferrite. The tensile fracture at different temperatures was characterized by means of optical microscopy and scanning electron microscopy. It was found that there were Al2O3, AlN, MnO, and MnS(Se) impurities in the fracture. The abnormal points of thermoplasticity showed that the inclusions had a significant effect on the high-temperature mechanical properties. The results of EBSD local orientation difference analysis showed that the temperature range with good plasticity was around 1275 °C. Under large deformation extent, the phase difference in the internal position of the grain was larger than that in the grain boundary. The defect density in the grain was large, and the high dislocation density was the main deformation mechanism in the high-temperature tensile process.

scholarly journals Tensile Deformation Behavior of Typical Porous Laminate Structure at Different Temperatures

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5369
Author(s):  
Ping Wang ◽  
Ye-Da Lian ◽  
Zhi-Xun Wen
Keyword(s):  
High Temperature ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Image Correlation ◽  
Test Material ◽  
Transgranular Fracture ◽  
Laminate Structure ◽  
Actual Structure ◽  
High Temperature Tensile ◽  
The Impact

In this study, the Ni-Cr-W superalloy GH3230 is used as the test material. According to the actual structure of the flame tube, a porous laminate structure specimen is designed. The structure consists of impact holes, overflow holes and pin fins. High-temperature tensile tests at 650 °C, 750 °C and 850 °C were carried out to study the high-temperature mechanical properties and fracture mechanism of the specimens of porous laminate structure, and the strain nephogram of the specimens were obtained by digital image correlation (DIC) technique. Due to the large number and dense arrangement of overflow holes, an obvious hole interference effect can be found from the strain nephogram. The stress concentration around the pore and the interference between the pores provide priority places and paths for the initiation and propagation of microcracks. The test found that the microcracks of the porous laminate structure first occurred around the hole, the overflow surface fractured first, after which the impact surface fractured. The strength of the alloy exhibits a significant temperature sensitivity to temperature. From 650 °C to 750 °C, the ultimate strength (σb) and yield strength (σ0.2) decrease slightly, but they decrease significantly at 850 °C. The microstructure of the fracture surface shows that all microcracks occur at the interface between the matrix and the carbides but that the fracture mode of the specimens gradually changes from intergranular fracture to transgranular fracture as the temperature increases. Due to the pinning effect of the intracrystalline diffusive solute atoms on the dislocations, the stress-strain curves of the high-temperature tensile tests at 650 °C and 750 °C showed zigzag characteristic fluctuations during the strengthening stage.

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