scholarly journals Effects of the γ″-Ni3Nb Phase on Fatigue Behavior of Nickel-Based 718 Superalloys with Different Heat Treatments

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3979 ◽  
Author(s):  
Li-Shi-Bao Ling ◽  
Zheng Yin ◽  
Zhi Hu ◽  
Jun Wang ◽  
Bao-De Sun
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Fatigue Behavior ◽  
Hot Isostatic Pressing ◽  
Solution Treatment ◽  
Standard Heat Treatment ◽  
Isostatic Pressing ◽  
Standard Heat ◽  
Direct Aging ◽  
The Matrix

The effects of the γ″-Ni3Nb phase on fatigue behavior of nickel-based 718 superalloys with standard heat treatment, hot isostatic pressing + solution treatment + aging, and hot isostatic pressing + direct aging were investigated by scanning electron microscope, transmission electron microscopy, and fatigue experiments. The standard heat treatment, hot isostatic pressing + solution treatment + aging, and hot isostatic pressing + direct aging resulted in the formation of more and smaller γ″ phases in the matrix in the nickel-based 718 superalloys. However, the grain boundaries of the hot isostatic pressing + direct aging sample showed many relatively coarse disk-like γ″ phases with major axes of ~80 nm and minor axes of ~40 nm. The hot isostatic pressing + direct aging sample with a stress amplitude of 380 MPa showed the longest high cycle fatigue life of 5.16 × 105 cycles. Laves phases and carbide inclusions were observed in the crack initiation zone, and the cracks propagated along the acicular δ phases in the nickel-based 718 superalloys. The precipitation of fine γ″ phases in the matrix and relatively coarse γ″ phases in the grain boundaries of the hot isostatic pressing + direct aging sample can hinder the movement of dislocation.

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.

scholarly journals Hot Isostatic Pressing of Aluminum–Silicon Alloys Fabricated by Laser Powder-Bed Fusion

Technologies ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 48
Author(s):  
Stephan Hafenstein ◽  
Leonhard Hitzler ◽  
Enes Sert ◽  
Andreas Öchsner ◽  
Markus Merkel ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Supersaturated Solid Solution ◽  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Solution Annealing ◽  
Laser Powder Bed Fusion ◽  
Sand Cast ◽  
Powder Bed ◽  
Isostatic Pressing ◽  
Direct Aging

Hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties of Al–Si–Mg alloys fabricated by laser powder-bed fusion (L-PBF). The implementation of post processing densification processes can open up new fields of application by meeting high quality requirements defined by aircraft and automotive industries. A gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve a supersaturated solid solution. Direct aging uses this pressure related effect during heat treatment in modern hot isostatic presses, which offer advanced cooling capabilities, thereby avoiding the necessity of a separate solution annealing step for Al–Si–Mg cast alloys. Hot isostatic pressing, followed by rapid quenching, was applied to both sand cast as well as laser powder-bed fused Al–Si–Mg aluminum alloys. It was shown that the critical cooling rate required to achieve a supersaturated solid solution is significantly higher for additively manufactured, age-hardenable aluminum alloys than it is for comparable sand cast material. The application of hot isostatic pressing can be combined with heat treatment, consisting of solution annealing, quenching and direct aging, in order to achieve both a dense material with a small number of preferred locations for the initiation of fatigue cracks and a high material strength.

Technical Evaluation of Gas Turbine Blades Run 53,000 Hours After Repair

1986 ◽  
Author(s):  
Stephen C. Pearman ◽  
J. H. P. Thiellier
Keyword(s):  
Heat Treatment ◽  
Turbine Blades ◽  
Hot Isostatic Pressing ◽  
Test Results ◽  
Standard Heat Treatment ◽  
Complete Evaluation ◽  
Gas Turbine Blades ◽  
Standard Heat ◽  
Platinum Aluminide ◽  
Technical Evaluation

This paper describes the complete evaluation of GE MS 5001 first stage turbine buckets run for 53,000 hours following repair and coating. The IN738 buckets were repaired and coated with a platinum aluminide coating1 in late 1977 and then run in base load operation by Akzo Zout Chemie. When the buckets were removed from service, several buckets were selected for evaluation, while the balance were again repaired and returned to service. Metallurgical and chemical analysis of the base metal and coating and mechanical property tests were conducted on an engine run part. These test results are reported as well as results on other engine run parts that have been subjected to a standard heat treatment or Hot Isostatic Pressing plus standard heat treatment prior to testing.

Combination of hot isostatic pressing and subsequent heat treatment for additively manufactured Zr-1Mo components

2021 ◽  
Vol 285 ◽  
pp. 129123
Author(s):  
Xiaohao Sun ◽  
Debao Liu ◽  
Minfang Chen ◽  
Weiwei Zhou ◽  
Naoyuki Nomura ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hot Isostatic Pressing ◽  
Subsequent Heat Treatment ◽  
Isostatic Pressing

scholarly journals Effect of T6 Heat Treatment on Microstructure and Hardness of Nanosized Al2O3 Reinforced 7075 Aluminum Matrix Composites

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 44 ◽  
Author(s):  
Peng-Xiang Zhang ◽  
Hong Yan ◽  
Wei Liu ◽  
Xiu-Liang Zou ◽  
Bin-Bing Tang
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Solution Treatment ◽  
Aluminum Matrix ◽  
Aging Treatment ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
X Ray ◽  
T6 Heat Treatment ◽  
The Matrix

In this study, 7075 aluminum matrix composites reinforced with 1.5 wt.% nanosized Al2O3 were fabricated by ultrasonic vibration. The effect of T6 heat treatment on both microstructure and hardness of nanosized Al2O3 reinforced 7075 (Al2O3np/7075) composites were studied via scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, transmission electron microscopy, and hardness tests. The Mg(Zn,Cu,Al)2 phases gradually dissolved into the matrix under solution treatment at 480 °C for 5 h. However, the morphology and size of Al7Cu2Fe phases remained unchanged due to their high melting points. Furthermore, the slenderness strips MgZn2 phases precipitated under aging treatment at 120 °C for 24 h. Compared to as-cast composites, the hardness of the sample under T6 heat treatment was increased ~52%. The strengthening mechanisms underlying the achieved hardness of composites are revealed.

Fine structure of steel 5Kh3V3MFS after LTMT and standard heat treatment

1979 ◽  
Vol 21 (4) ◽  
pp. 273-277
Author(s):  
E. S. Sevast'yanov ◽  
A. I. Strikelev ◽  
I. V. Rakhov
Keyword(s):  
Heat Treatment ◽  
Fine Structure ◽  
Standard Heat Treatment ◽  
Standard Heat

Effect of the Two-Step Solution Heat Treatment on the Microstructure of Semisolid Cast 7075 Aluminum Alloy

2012 ◽  
Vol 488-489 ◽  
pp. 243-247 ◽  
Author(s):  
Saowalak Kongiang ◽  
Thawatchai Plookphol ◽  
Jessada Wannasin ◽  
Sirikul Wisutmethangoon
Keyword(s):  
Heat Treatment ◽  
Treatment Condition ◽  
Solution Heat Treatment ◽  
Solution Treatment ◽  
Heat Treatment Condition ◽  
Single Step ◽  
Eutectic Phase ◽  
Solution Treated ◽  
The Matrix ◽  
Black Particle

Effect of the two-step solution heat treatment on the microstructure of semisolid cast 7075 aluminium alloy has been studied. The microstructure of the as-cast specimens mainly consisted of matrix-α (Al) and grain boundary (GB)-eutectic phase (α-Al + Mg(Zn,Cu,Al)2). After solution treating, coarse black particles were found to form in the single-step solution treated specimens at the condition of 450 °C for 8 h and 480 °C for 1 h, respectively. Two-step solution heat treatment resulted in the reduction of coarse black particle formation while maintaining the same amount of eutectic MgZn2phase dissolution as the high temperature single-step solution treatment. Therefore, the two-step solution heat treatment enables alloying elements dissolved into the matrix without overheating and hence decreases coarse black particles. The optimum two-step solution heat treatment condition derived from this study was 400 °C for 8 h + 450 °C for 4 h.

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