High temperature creep properties of a linear friction welded newly developed wrought Ni-based superalloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:710

Article

Masoumi, F.¹  Thelaud, L.^2,3  Shahriari, D.¹  Jahazi, M.¹  Cormier, J.²  Devaux, A.³  Flipo, B. C. D.⁴ 

[1] ETS, Dept Mech Engn, Montreal, PQ H3C 1K3, Canada

[2] CNRS, Inst Pprime, UPR 3346, Phys & Mech Mat Dept,ISAE,ENSMA, BP 40109, F-86961 Chasseneuil, France

[3] Aubert & Duval, Site Ancizes,BP1, F-63770 Les Ancizes, France

[4] TWI Ltd, Granta Pk, Cambridge CB21 6AL, England

关键词: Linear friction welding;    Ni-based superalloy;    AD730 (TM);    Mechanical properties at elevated temperatures;    Creep mechanisms;   

DOI  :  10.1016/j.msea.2017.10.091

来源: Elsevier

【 摘 要 】

AD730 (TM) Ni-based superalloy specimens in solution-treated conditions were linear friction welded. Then, post weld heat treatment (PWHT), consisting of gamma' sub-solvus solution treatments followed by aging, was conducted on the linear friction welded samples. High temperature creep tests were performed on the as-welded and PWHTed joints at two different temperatures: 700 degrees C under 600 and 750 MPa stress levels, and 850 degrees C under 100 and 200 MPa stresses. The creep resistance of the PWHTed joints was higher than that of the as-welded samples. The PWHTed, joints exhibited better ductility than that of the base material at 850 degrees C, while they showed slightly lower creep life at 700 degrees C in comparison to the base metal. Microstructure examination showed that cracks initiated at the interface of oxidized particles at 700 C. The decrease in creep resistance of the AD730 (TM) Ni-based superalloy at 850 degrees C was related to a combination of the formation of precipitate-free zones (PFZ) in the vicinity of the grain boundaries (GBs) and microcracking assisted by oxidation. The Larson-Miller Parameter (LMP) was used to correlate the creep strength, temperature and time to failure for the as-welded and PWHTed samples. LMP values varied between 21.5 x 10(3) and 24.5 x 10(3). It was found that in the investigated temperature range, the PWHTed AD730 (TM) has similar creep characteristics as Udimet (TM) 720 Li and Inconel 738LC at low values of LMP and better creep properties than those of the Inconel 617 alloy at higher LMP values.

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