Mechanisms of ambient temperature fatigue crack growth in Ti-46.5Al-3Nb-2Cr-0.2W

被引：0

作者：

Worth B.D. ^{[1
]}

Larsen J.M. ^{[2
]}

Balsone S.J. ^{[2
,3
]}

Jones J.W. ^{[4
]}

机构：

[1] Structural Integrity Division, University of Dayton, Research Institute, Dayton

[2] United States Air Force, Wright Laboratory, WL/MLLN

[3] Physical Metallurgy Laboratory, General Electric Company, Schenectady

[4] Department of Materials Science and Engineering, University of Michigan, Ann Arbor

来源：

Metallurgical and Materials Transactions A | 1997年 / 28卷 / 13期

关键词：

Fatigue Crack; Crack Growth Rate; Fatigue Crack Growth; Fatigue Crack Propagation; Fatigue Crack Growth Rate;

D O I：

10.1007/s11661-997-1010-9

中图分类号：

学科分类号：

摘要：

Fatigue crack growth studies have been conducted on a two-phase alloy with a nominal composition of Ti-46.5Al-3Nb-2Cr-0.2W (at. pct), heat treated to produce duplex and lamellar microstructures. Fatigue crack growth tests were conducted at 23 °C using computer-controlled servohydraulic loading at a cyclic frequency of 20 Hz. Several test methods were used to obtain fatigue crack growth rate data, including decreasing-load-range-threshold, constant-load-range, and constant-K max increasingload-ratio crack growth control. The lamellar microstructure showed substantial improvement in crack growth resistance and an increase in the threshold stress intensity factor range, ΔK th, when compared with the behavior of the duplex microstructure. The stress ratio had a significant influence on crack growth behavior in both microstructures, which appeared to be a result of roughness-induced crack closure mechanisms. Fractographic characterization of fatigue crack propagation modes indicated a highly tortuous crack path in the fully lamellar microstructure, compared to the duplex microstructure. In addition, limited shear ligament bridging and secondary cracking parallel to the lamellar interfaces were observed in the fully lamellar microstructure during fatigue crack propagation. These observations were incorporated into a model that analyzes the contribution of intrinsic vs extrinsic mechanisms, such as shear ligament bridging and roughness-induced crack closure, to the increased fatigue crack growth resistance observed for the fully lamellar microstructure.

引用

页码：825 / 835

页数：10

共 37 条

[11]

Bowen P., Chave R.A., James A.W., Mater. Sci. Eng., pp. 443-456, (1995)

[12]

Sobayejao W.O., Deffeyes J.E., Aswath P.B., Mater. Sci. Eng., A138, pp. 95-101, (1991)

[13]

Soboyejo W.O., Mercer C., Scripta Metall. Mater., 30, pp. 1515-1520, (1994)

[14]

Davidson D.L., Campbell J.B., Page R.A., Metall. Trans. A, 22 A, pp. 377-391, (1991)

[15]

Davidson D.L., Materials Research Society Symposia Proceedings, 273, pp. 67-80, (1992)

[16]

Davidson D.L., Campbell J.V., Metall. Trans. A, 24 A, pp. 1555-1574, (1993)

[17]

Proc. 1st Int. Symp. on Structural Intermetallics, pp. 223-230, (1993)

[18]

Chan K.S., Metall. Trans. A, 24 A, pp. 569-583, (1993)

[19]

Chan K.S., Y.-Kim W., Metall. Mater. Trans. A, 25 A, pp. 1217-1228, (1994)

[20]

Chan K.S., Y.-Kim W., Acta Metall. Mater., 43, pp. 439-451, (1995)

← 1 2 3 4 →