Segregation Behavior of Phosphorus and Its Effect on Microstructure and Mechanical Properties in Alloy System Ni-Cr-Fe-Mo-Nb-Ti-Al

Xie, Xiangyu; Liu, X.; Dong, Jianxin; Iu, Y.; Xu, Zhichao; Yaoxiao, Zhu; Luo, Wei; Zhang, Z.; Thompson, R. G.

doi:10.7449/1997/superalloys_1997_531_542

Cited by 12 publications

(7 citation statements)

References 7 publications

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“…Recently Wei-Di Cao and R. Kennedy has developed a modified 718 Alloy to be used at 700 designated as Allvac ® 718 Plus T M [9] . Xishan Xie and Jianxin Dong [10][11][12][13][14] at the University of Science & Technology Beijing systematically studied the modification of Alloy 718 as a long-term project in variation of main precipitation strengthening elements such as Nb, Al and Ti, solid solution strengthening elements Mo, W and occasionally Co and also in control of minor elements such as P, S and Mg [15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

The Effect of Nb, Ti, Al on Precipitation and Strengthening Behavior of 718 Type Superalloys

Xie¹,

Dong²,

Wang³

et al. 2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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Inconel 718 characterizes with unique mechanical properties and has wild application in different high temperature industries. However, the ceiling temperature for Alloy 718 is 650 because of the instability of main strengthening phase γ″-Ni 3 (Nb,Ti,Al). At high temperatures the metastable γ″ changes for stable phase δ-Ni 3 Nb with large size and plate-like morphology. In result of that Alloy 718 looses structure stability and strengthening effect.Recently, many researchers have studied the stability of Alloy 718 and try to develop modified 718 Alloys to be used beyond 650 . The basic idea of this paper is to raise the stability of γ″ and γ′ strengthening phases in the following ways: raising the solution temperature of γ″ and γ′, retarding the γ″ phase change for δ-Ni 3 Nb and changing the precipitation behavior of γ″/γ′ phase.The experimental heats were prepared for this study in variation of Nb, Ti, Al and the atomic ratio among them on the base chemical composition of Alloy 718. The precipitated phase γ″ and γ′ behavior was studied in detail by means of SEM and TEM and the weight fraction of γ″+γ′ phases was exactly determined by electrolytic isolation and followed by micro-chemical analyses. The mechanical properties including hardness, tensile properties and stress rupture for several heats were also tested.The structure of a new developed 718 type Alloy Allvac ® 718 Plus TM has been also adopted for comparison. A detail discussion has been conducted for 718 type superalloys in structure stability and strengthening effect both.

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Section: Introductionmentioning

confidence: 99%

The Effect of Nb, Ti, Al on Precipitation and Strengthening Behavior of 718 Type Superalloys

Xie¹,

Dong²,

Wang³

et al. 2005

Superalloys 718, 625, 706 and Various Derivatives (2005)

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“…But Cao indicated further that when P reached 200-300 ppm, 650℃ tensile ductility began to decline. And it might be in connection with that P improved the degree of microsegregation, promoting Laves phase formation [3,6].…”

Section: Discussionmentioning

confidence: 93%

“…But investigators usually focus on GH4169 alloy as STD when they study the effect of P, and little attention has been paid to DA GH4169 alloy. There is still some controversy to the mechanism of P [3][4][5][6][7]. This paper studies the rule of P on tensile and stress rupture properties of GH4169 alloy with different heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Effects of Phosphorus on tensile and stress rupture properties of GH4169 alloy

Tang¹,

Du²,

Deng³

et al. 2012

Proceedings of the 2nd International Conference on Electronic and Mechanical Engineering and Information Technology (2012)

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The influence of P on tensile properties at room temperature and 650℃ as well as the effects of P on rupture properties at 650℃/690 MPa of GH4169 alloy with standard heat treatment (STD) and direct aging heat treatment (DA) were investigated in this paper. Mechanism of the influence of P was also undertaken with microstructure and fractograph analysis. The results show that P content has little effect on tensile properties of alloys. While the stress rupture life improves significantly with an increase of P content due to grain boundary segregation of P increasing grain boundary bonding force. And P has less influence on stress rupture life of GH4169 alloy as STD than that as DA, which may be relevant to the enrichment of P on δ phase interface. Increasing P content from 0.006% to 0.019%, the stress rupture failure mode shows mainly transgranular fracture, decreased fraction of fine microvoids and deep dimple structure arises gradually.

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“…The ideal can even be less than 5ppm. Minor Elements Control Besides controlling harmful elements, a series of studies on optimizing minor elements such as P, B, Zr, and Mg have also been carried out in China to improve the performances of superalloys [4][5][6][7][8][9][10]. One of the significant efforts involved is optimization of phosphorus in GH4169, whose content had always been controlled under 50ppm, and once been pursued to the "ultra-low" level as it was initially considered harmful to the alloy.…”

Section: Introductionmentioning

confidence: 99%