Fatigue Properties of a Ni-Base Superalloy Treated by Laserolazing

1986 ◽  
Vol 80 ◽  
Author(s):  
Jiang Xiaoping ◽  
Hu Zhuang Qi ◽  
Shih Changxu ◽  
Zhu Guizeng ◽  
Meng Qinglin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Boundary Carbide ◽  
Post Heat Treatment ◽  
Before And After ◽  
Vibration Fatigue ◽  
Base Superalloy

AbstractFatigue properties of a wrought Ni-base superalloy treated by laserglazing and post heat treatments have been investigated. Tests have been run both by the rotating bend fatigue at 700°C and the vibration fatigue of turbine blades at room temperature. The results showed that the fatigue property of laserglazed specimens was obviously deteriorated because of resolution of γ′ phase and grain boundary carbide, interdendritic segregation of TiC and microcrack caused by thermal stress. However, suitable preheating and post heat treatment added before and after laserglazing can eliminate these defects and recover the fatigue life of this superalloy. Selected laser processing technology was applied to repairing blades rejected due to microcracks at trailing edge. The vibration fatigue life of blades repaired by laserglazing and post heat treatment was over two times as high as that of normal used blades with same service time.

Influence of Heat Treatment on Properties of Hot Isostatically Pressed Turbine Blade Superalloy IN738

2011 ◽  
Vol 264-265 ◽  
pp. 502-507 ◽  
Author(s):  
Saeed Farahany ◽  
M. Aghaie-Khafri ◽  
Ali Ourdjini ◽  
Mohd Hasbullah Idris
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Treatment Cycle ◽  
Post Heat Treatment ◽  
Cast Specimen ◽  
Temperature Heat ◽  
Before And After ◽  
Hip Process ◽  
Temperature Heat Treatment ◽  
Base Superalloy

Impact of heat treatment on hot isostatically pressed (HIP) Ni-base superalloy has been investigated before and after conducting HIP process. HIP was performed by applying a stress of 120 MPa at a temperature of 1200 °C for 2 hours under argon atmosphere followed by furnace cooling to room temperature. Heat treatment cycle was conducted on the samples according to GEB50A563. Microstructural observation demonstrated the deleterious change of  morphology after HIP process which causes to decrease of hardness and creep strength. However, pre heat treatment in compared with cast specimen show slight changes in microstructure but, post heat treatment can revert this change of  morphology completely and also increase the mechanical properties.

scholarly journals Effect of Post-Heat Treatment Cooling Conditions on Microstructures and Fatigue Properties of Cobalt Chromium Molybdenum Alloy Fabricated through Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1005
Author(s):  
Hla Htoot Wai Wai Cho ◽  
Atsushi Takaichi ◽  
Yuka Kajima ◽  
Hein Linn Htat ◽  
Nuttaphon Kittikundecha ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Post Heat Treatment ◽  
X Ray ◽  
Cooling Conditions ◽  
Cobalt Chromium Molybdenum

Although post-heat treatment can improve the fatigue life of selective laser melting (SLM)-fabricated cobalt chromium molybdenum (CoCrMo) alloys, the effect of cooling conditions on the fatigue properties of such alloys remains unclear. In this study, we fabricated SLM CoCrMo alloy specimens and, after heat-treating them, cooled them either via furnace-cooling (FC) or air-cooling (AC). Subsequently, we analyzed their microstructures using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, electron backscattered diffraction, confocal laser scanning microscopy, and X-ray diffraction. Tensile and Vickers hardness (HV) tests and axial-fatigue tests were also conducted to assess their mechanical and fatigue properties, respectively. The microstructures of all samples showed homogeneous equiaxed grains, with the grains and precipitates of the AC samples (grain size: 84.9 μm) smaller than those of the FC samples (grain size: 109.7 μm). The AC samples exhibited better ductility than the FC samples. However, we observed no significant differences in the 0.2% yield strength and HV tests. The S–N curve derived from the fatigue tests showed that the AC samples had greater fatigue life than the FC samples. Therefore, a high cooling rate during post-heat treatment is effective in reducing grain and precipitate sizes, resulting in improved ductility and fatigue life.

Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part I: Fatigue Tests on Full Scale Blades

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Xiaojun Yan ◽  
Xia Chen ◽  
Ruijie Sun ◽  
Ying Deng ◽  
Lianshan Lin ◽  
...  
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Directional Solidification ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Full Scale ◽  
Fatigue Properties ◽  
Casting Method ◽  
Property Variation ◽  
Conventional Casting

At present, directional solidification (DS) made blades are commonly used in high performance turbine for their better high temperature mechanical, especially in creep properties compared with the equiaxed grain (EG) blades made by conventional casting method. To predict DS blades' fatigue life accurately, one of the practical ways is to conduct tests on full-scale blades in a laboratory/bench environment. In this investigation, two types of full scale turbine blades, which are made from DZ22B by DS method and K403 by conventional casting method, respectively, were selected to conduct high temperature combined low and high cycle fatigue (CCF) tests on a special design test rig, to evaluate the increase of fatigue life benefitted from material change. Experimental results show that different from EG blades, DS blades' fracture section is not located on the position where the maximum stress point lies. By comparing fatigue test results of the two types of blade, it can be found that the fatigue properties among different regions of the DS blade are different, and its fatigue damage is not only related to the stress field, but also affected by different parts material's fatigue properties.

scholarly journals Effect of Post Heat-Treatment on the Microstructure, Tensile and Fatigue Properties of Al 3003 Alloy Manufactured by Strip Casting Process

2020 ◽  
Vol 58 (3) ◽  
pp. 151-161
Author(s):  
Min-Seok Baek ◽  
Kwangjun Euh ◽  
Chang-Yeol Jeong ◽  
Kee-Ahn Lee
Keyword(s):  
Heat Treatment ◽  
Fatigue Property ◽  
Casting Process ◽  
Cyclic Stress ◽  
Strip Casting ◽  
Solidification Structure ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Strip Cast ◽  
Strengthening Phases

Al 3003 alloy was manufactured by strip casting process, and the effect of post heat-treatment on tensile and fatigue properties was investigated. The strip cast Al 300 alloy exhibited a unique globular shaped rapid-cooled solidification structure, and the microstructural characteristic remained after heat-treatment. Asstrip cast (F) and heat-treated (O) alloys were commonly composed of Al matrix and strengthening phases such as Al<sub>6</sub>(Mn,Fe), α-Al(Mn,Fe)Si. In the phase analysis and Factsage simulation result, Al<sub>6</sub>(Mn,Fe) fraction increased while α-Al(Mn,Fe)Si fraction decreased after heat-treatment. Strengthening phases were more uniformly and finely distributed in the case of O alloy, than F alloy. In the Vickers hardness results, F alloy (measured 59.7 Hv) showed higher hardness than O alloy (measured 53.4 Hv). The yield strengths (YS) and ultimate tensile strengths (UTS) measured 124.8 MPa and 166.4 MPa (F alloy), and 111.2 MPa and 167.2 MPa (O alloy), respectively. F alloy exhibited superior YS compared to O alloy, while UTSs were similar in both alloys. For elongation, the F alloy (19.6%) had a lower value than the O alloy (23.0%). High cycle fatigue tests were performed at room temperature under a stress ratio (R) of 0.1 and frequency (F) of 10 Hz. The F alloy exhibited higher fatigue than the O alloy under all cyclic stress conditions. However, the deviation in the fatigue property of the F alloy was relatively broader than the O alloy. Tensile and fatigue fracture surfaces were examined, and the tensile and fatigue deformation mechanisms of the strip cast Al 3003 alloy were also discussed.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

Effect of post heat treatment on fatigue properties of EBM 3D-printed Ti-6Al-4V alloy

2018 ◽  
Vol 25 (4) ◽  
pp. 340-345 ◽  
Author(s):  
Young-Sin Choi ◽  
◽  
Ji-Hoon Jang ◽  
Gun-Hee Kim ◽  
Chang-Woo Lee ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
3D Printed

Long-Term Gamma Prime Phase Stability after Various Heat Treatment Conditions with Temperature Dropping during Solution Treatment in Cast Nickel Base Superalloy, Grade Inconel-738

2017 ◽  
Vol 891 ◽  
pp. 420-425
Author(s):  
Sureerat Polsilapa ◽  
Aimamorn Promboopha ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
Turbine Blades ◽  
Solution Treatment ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Nickel Based Superalloy ◽  
Treatment Conditions ◽  
Nickel Base ◽  
Base Superalloy

Cast nickel based superalloy, Grade Inconel 738, is a material for turbine blades. Its rejuvenation heat treatment usually consist of solution treatment condition with temperature range of 1125-1205 oC for 2-6 hours. Then it is following with double aging process including primary aging at 1055oC for 1 hour and secondary aging at 845oC for 24 hours. However, the various selected temperature dropping program were performed during solution treatment to simulate the possible error of heating furnace. The maximum number of temperature dropping during solution treatment is varied from 1-3 times From all obtained results, the various temperature dropping during solution treatment conditions showed extremely the significant effect on the final rejuvenated microstructures and long-term gamma prime stability after heating at temperature of 900oC for 200 hours.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2004 ◽  
Vol 126 (3) ◽  
pp. 590-603 ◽  
Author(s):  
N. K. Arakere
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high-performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4, and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the space shuttle main engine fuel turbopump are discussed. During testing many turbine blades experienced stage II noncrystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β=45+/−15 deg tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined low cycle fatigue properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75°F–1800°F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for low cycle fatigue data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the low cycle fatigue data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature low cycle fatigue data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with low cycle fatigue test data. These curve fits can be used for assessing blade fatigue life.

Fatigue Properties and Life Prediction of 8630 Cast Steel in the Presence of Weld Repair and Porosities

2013 ◽  
Author(s):  
Alireza Shirazi ◽  
Ihab Ragai
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Endurance Limit ◽  
Cast Steel ◽  
Fatigue Properties ◽  
Weld Repair ◽  
Treatment Conditions ◽  
Weld Material ◽  
Set Up

The objective of the this work is to study the effect of weld repair and macro-porosities on fatigue properties and fatigue life of AISI 8630 cast steel subjected to bending cyclic loads. Test specimens were cut from a cast steel component that contains macro-porosities. To regain the structural integrity, the component is typically excavated and weld repaired. In this study, weld repairs are simulated by machining a cylindrical groove across the width of the specimen then the groove is welded using different weld rods and various pre and post weld heat treatment conditions. All specimens were examined by radiography (X-Ray) in accordance with ASTM E446 before depositing the weld in order to verify the quality of the samples. After welding, the quality of the welded grooves was examined using ultrasonic testing (UT) and magnetic particle inspection (MPI) in accordance with ASTM A609 and ASTM E709 standards, respectively. Qualified samples were then machines to the final dimensions. The fatigue test was performed under pure bending conditions using four-point bend set up. This set up allows localizing stresses at the sites where weld repairs were applied. Experimental results show that specimens with stronger weld material tested under no heat treatment conditions have comparable fatigue performance to those heat treated specimens with lower strength weld material. Furthermore, it was found that the fatigue test results are highly affected by the presence of micro-porosities within the cast steel material. Therefore, an analytical approach to predict the fatigue life is also presented in this work. A good agreement is achieved between the predicted fatigue lives and the experimental results. Generally, the results show that for porosities with width to depth ratios between 0.25 to 1 and width size smaller than or equal to 1 mm the life is reduced by up to 1.5 orders of magnitude while the endurance limit was reduced by a factor of 1.57. Similarly for porosities with ratios between 1.5 and 2.5 and width greater than 1.5 mm the life was reduced by 2.5 orders of magnitude and the endurance limit was reduced by a factor of 2.2.

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