Influence of Ageing Treatments on Stress Rupture Properties of Ni3Al-Base Single-Crystal Alloy IC21 at 850°C

2013 ◽  
Vol 747-748 ◽  
pp. 659-664 ◽  
Author(s):  
Hui Li ◽  
Fu Lin Li ◽  
Shu Suo Li ◽  
Heng Zhang ◽  
Sheng Kai Gong
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Heat Treatments ◽  
Air Cooling ◽  
Single Crystal Alloy ◽  
Stress Rupture Properties ◽  
Microstructure Examination ◽  
Rupture Properties

The influence of three different ageing treatments (R1:1100/2h,air cooling+870/32h,air cooling, R2: 870/32h,air cooling and R3: 1060/2h,air cooling+870/32h,air cooling) on stress rupture properties of Ni3Al-base single-crystal alloy IC21 was investigated. The results indicate that ageing heat treatments have obvious effects on stress rupture properties of IC21 at 850/500Mpa. After R3 ageing treatment, IC21 alloy presents the longest rupture life and the smallest ellipticity and elongation compared to those after the other two ageing treatments. Microstructure examination shows that the mean size of γ precipitate is about 0.44μm after R3 ageing heat treatment (1060/2h, ac + 870/32h, ac). Transmission electron microscope (TEM) study on the rupture samples illustrates that after R1 and R2 ageing heat treatments, the density of stacking faults increases and the length is larger compared to that after R3 heat treatment. Meanwhile the shearings of γ precipitates are more severe. The appropriate γ phase size and γ channel width after R3 treatment promote homogenous deformation by <110>{111} slip in the matrix, and facilitate the formation of finer dislocation networks on the γ/γ interface, which can restrain the shearing of γ phase by dislocations.

Microstructure Evolution and Stress Rupture Properties of DD6 Single Crystal Superalloy after Overheating

2017 ◽  
Vol 898 ◽  
pp. 517-522 ◽  
Author(s):  
Shi Zhong Liu ◽  
Zhen Xue Shi ◽  
M. Han ◽  
Jia Rong Li
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Standard Heat Treatment ◽  
Stress Rupture Life ◽  
Matrix Channel ◽  
Standard Heat ◽  
Stress Rupture Properties ◽  
Rupture Properties

The second generation single crystal superalloy DD6 after standard heat treatment was respectively overheated at 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1320°C for 1h and air cooled. The effect of overheating on the microstructure and stress rupture properties at 980°C/250MPa of the alloy was investigated. The results showed that the size of γ′ phase was slightly increased overheating at 1100°C, 1150°C and 1200°C. The size of γ′ phase had a big increase and its size distribution was very uneven after overheating at 1250°C. The small part of γ′ phase has serrated γ′/γ phase surface as a result of un-completely solution and the irregular small γ′ phase was in the majority when overheated at 1300°C. While all the irregular small γ′ phase precipitated again after completely solution when overheated at 1320°C. There was no fine second γ′ phase in the γ matrix channel of the alloy after standard heat treatment and overheating at 1320°C. But the fine second γ′ phase precipitated in the γ matrix channel after overheating at every temperature of 1100 °C~1300°C. No obvious change of the stress rupture life was found after overheating at 1100°C, 1150°C, 1200°C and 1250°C. The stress rupture life considerably reduced after overheating at 1300°C, whereas slightly reduced after overheating at 1320°C. The appearance of the raft had almost no change after overheating at 1100°C. With increasing of overheating temperature from 1100°C to 1250°C, the length of raft became shorter and the width thickening. The γ phase formed the wavy raft after overheating at 1300°C and 1320°C and the thickness of latter was larger than that of the former. Finally, the relationship between the microstructural evolution and stress rupture properties of the alloy after overheating was discussed.

Microstructure and Mechanical Properties of In718 Alloy Produced with Twin-Scanning Atomizer

2007 ◽  
Vol 561-565 ◽  
pp. 415-418 ◽  
Author(s):  
Zheng Dong Li ◽  
Guo Qing Zhang ◽  
Zhou Li ◽  
Wen Yong Xu ◽  
Rui Ping Yao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Rupture Life ◽  
Stress Rupture ◽  
Spray Forming ◽  
Microstructure And Mechanical Properties ◽  
Stress Rupture Properties ◽  
Direct Aging ◽  
Rupture Properties

Sound billets were produced at BIAM with a twin-scanning spray forming facility. Microstructure and mechanical properties of In718 alloy produced with this technology were examined. Both tensile strength and stress rupture properties are excellent with the rupture life even doubled after received a direct aging heat treatment.

Effect of Heat Treatment on Microstructure and Mechanical Properties for a Ni3Al Base Single Crystal Alloy DDIC6

2007 ◽  
Vol 546-549 ◽  
pp. 1443-1446 ◽  
Author(s):  
Zhi Gang Kong ◽  
Lei Ji ◽  
Shu Suo Li ◽  
Ya Fang Han ◽  
Hui Bin Xu
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Constant Load ◽  
Heat Treatment Condition ◽  
Stress Rupture Life ◽  
Stress Rupture Property ◽  
Single Crystal Alloy ◽  
Proper Size

The effect of heat treatment on microstructures and stress rupture property of a Ni3Al base single crystal alloy DDIC6 was studied in the present investigate. The single crystal specimens were produced by screw selection crystal method. The heat treatment for the alloy was 1300°C/10h+1120°C/4h+870°C/32h and 1300°C/10h+870°C/32h.The microstructures were examined by SEM, TEM and X-ray EDS techniques. The stress rupture tests were carried out in air by constant load creep machines under 1100°C/130MPa with the specimens size of φ5×25 mm. The experimental results showed that the as-cast large size γ′ phases entirely dissolved after 1300°C/10h, and secondary fine γ′ phases precipitated by following aging at 1120°C and 870°C for certain periods of time. The stress rupture life under 1100°C/130MPa increased from 20~30hrs for as-cast condition to 60~100hrs for heat treatment condition. The improvement of the creep resistance of the alloy may attribute to the decrement of the elements segregation at dendrite and interdendritic areas, and the proper size and distribution of γ′ phases.

scholarly journals Influence of solution treatment on microstructure and stress rupture properties of K439 nickel-base superalloy

2018 ◽  
pp. 78-82
Author(s):  
Jin Xu ◽  
Mingjun Zhang ◽  
Xin Tang ◽  
Guangyu Yang ◽  
Jingyang Chen ◽  
...  
Keyword(s):  
Cast Alloy ◽  
Rupture Life ◽  
Dendritic Structure ◽  
Solution Treatment ◽  
Stress Rupture ◽  
Solution Temperature ◽  
Nickel Base Superalloy ◽  
Air Cooling ◽  
Stress Rupture Properties ◽  
Rupture Properties

The isochronal solution treatment (4h) in the 1080-1190°C range with air cooling are performed to investigate the effects of solution temperature on the microstructure and stress rupture properties of K439 alloy. The detailed as-cast and solution treated microstructures were analyzed through optical microscopy (OM), scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). The experimental results show that the as-cast alloy exhibited a typical dendritic structure with five phases of γ, γ´, γ/γ´, η and MC. After solution heat treated at 1080°C, although all of the γ´ particles in the dendritic cores were dissolved, there were still some of these precipitates in the interdendritic regions beside η phase. With the solution temperature increasing to 1150°C, all of the γ´ and η solutioned and a uniform microstructure was observed. Furthermore, increasing the temperature to 1210°C, a small amount of incipient melting occurred in the alloy. The stress rupture life of K439 alloy at 760°C/530MPa increased with the rising of solution temperature and reached to the top value under the solution temperature of 1150°C. The optimum solution treatment considered to be 1150 C/4 h followed by air cooling.

Influence of Withdrawal Rate on Tensile and Stress Rupture Properties of the Single Crystal Superalloy DD9

2013 ◽  
Vol 747-748 ◽  
pp. 625-628 ◽  
Author(s):  
Z.X. Shi ◽  
J.R. Li ◽  
Shi Zhong Liu
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Stress Rupture ◽  
Single Crystal Superalloy ◽  
Withdrawal Rate ◽  
Stress Rupture Life ◽  
The Third ◽  
Stress Orientation ◽  
Stress Rupture Properties ◽  
Rupture Properties

The third generation single crystal superalloy DD9 was processed with different withdrawal rates and the effect of withdrawal rate on the tensile and stress rupture properties of the alloy was investigated. The relation between the mechanical properties and microstructure of the alloy with different withdrawal rates was discussed. The results showed that the withdrawal rate had a little effect on the tensile properties at 25 of the alloy. The tensile strength at 980 and stress rupture life at 1120/140MPa of DD9 alloy all increased with the increasing of withdrawal rate. The γ precipitates of specimen tensile at 25 had a little extension in the stress orientation. The extension of γ precipitates in the stress orientation at 980 was much more than that at 25. The vertical γ matrix at 980 became thinner and horizontal γ matrix became thicker slightly. The γ precipitates of those had rafted in a direction transverse to the applied stress.

Stress Rupture Properties of the Second Generation Single Crystal Superalloy DD6 after High Temperature Exposure

2007 ◽  
Vol 546-549 ◽  
pp. 1249-1252 ◽  
Author(s):  
Hai Peng Jin ◽  
Jia Rong Li ◽  
Shi Zhong Liu
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Second Generation ◽  
Rupture Life ◽  
Stress Rupture ◽  
Single Crystal Superalloy ◽  
Stress Rupture Life ◽  
Stress Rupture Properties ◽  
Temperature Exposure ◽  
Rupture Properties

The effects of high temperature exposure simulating service conditions on stress rupture properties were studied for the second generation single crystal superalloy DD6. The specimens with [001] orientation were exposed in air at temperatures of 980°C and 1070°C for 100h to 1000h. They were then tested using conventional mechanical tests at 1070°C/140MPa to determine the effects of exposure on stress rupture properties. The analysis indicated that stress rupture life decreased with increasing exposure time. At the temperature of 980°C, the stress rupture life is more than 180h after exposure for 1000h. When the test temperature increased to 1070°C, the stress rupture life exceeds 100h after 800h exposure. The morphology of γ prime phase after exposure was observed by using scanning electron microscopy (SEM). Morphologies evaluations have shown that alloy DD6 exhibits excellent microstructure stability after exposure. TCP (Topologically Closed Packed) phases have not been observed. It has been also found that the morphology and size of γ prime affected stress rupture life of the alloy. The decrement in stress rupture life with increasing exposure is a result of γ prime rafting.

Influence of Cooling Method on the Microstructure and Stress Rupture Property of a Single Crystal Superalloy

2015 ◽  
Vol 816 ◽  
pp. 513-517 ◽  
Author(s):  
Zhen Xue Shi ◽  
Shi Zhong Liu ◽  
Xiao Guang Wang ◽  
Jia Rong Li
Keyword(s):  
Single Crystal ◽  
Cooling Rate ◽  
Stress Rupture ◽  
Single Crystal Superalloy ◽  
Air Cooling ◽  
Water Cooling ◽  
Stress Rupture Property ◽  
Cooling Method ◽  
Stress Rupture Properties ◽  
Rupture Properties

The single crystal superalloy with [001] orientation were prepared by screw selecting method in the directionally solidified furnace. Three different cooling method, water cooling (WC), air cooling (AC) and furnace cooling (FC) were used after same solution treatment. Then these specimens received same two-step aging treatment. Influence of solution cooling method on the microstructure and stress rupture properties of the alloy under the test condition of 980 °C and 300 MPa was investigated. The microstructures of the samples were examined by scanning electron microscope (SEM). The results showed that the solution cooling method of heat treatment played an important role in the microstructure and stress rupture properties of the alloy. The size of γ′ phase and the width of the γ matrix channel of the alloy increased with decreasing cooling rate. The stress rupture properties of the alloy increased at first and decreased afterwards with decreasing cooling rate. The alloy with air cooling (AC) has the best stress rupture properties. The γ′ phase changed into a perfect raft structure during the stress rupture process of the specimens with AC method. However, the γ′ phase changed into a very irregular raft microstructure in the specimens with the water cooling (WC) and furnace cooling (FC) method. The micro-cracks in the specimen with irregular raft make the initiation and interconnection easier than that in the specimen with regular raft. Therefore, the alloy with AC method has optimum microstructure and stress rupture property.

Effect of Long-Term Aging on the Microstructures and Stress Rupture Properties of a Ni-Based Single Crystal Superalloy at 980°C

2014 ◽  
Vol 788 ◽  
pp. 560-564 ◽  
Author(s):  
Jian Wei Xu ◽  
Li Li Cui ◽  
Hai Wen Wang
Keyword(s):  
Single Crystal ◽  
Rupture Life ◽  
Interface Reaction ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Phase Coarsening ◽  
Precipitated Phase ◽  
Stress Rupture Properties ◽  
Rupture Properties

The effect of aging time at 980°C on the microstructures and mechanic properties for a single crystal Ni-based superalloy was investigated in this paper. The results showed that γ’ size distribution portrayed a low growth rate and maintained well cubic during aging for 0~1000h at 980°C. However, γ’ phase was gradually coarsened directionally during the aging for 1000~2500h at 980°C, indicating that the γ’ phase coarsening was controlled by diffusion during aging for 0~1000h at 980°C. In addition, the γ’ phase coarsening was also susceptible to the interface reaction during aging for 1000~2500h at 980°C. Furthermore the precipitated phase was analyzed, and the results showed that only slightly Topologically Close-Packed (TCP) phase was precipitated after aging for 1500h at 980°C which indicates that the microstructures of alloy were stable during aging for up to 1500 hours. At the same time, stress rupture life decreased rapidly for 0~250h, but basically kept constant value when aged for 250~1500h, then decreased rapidly again aging for 1500~2000h.

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