Aqueous environmental crack propagation in high-strength beta titanium alloys

Journal Article · Mon May 01 04:00:00 EDT 1995 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02670620· OSTI ID:72791

Young, L M ^[1]; Young, Jr, G A ^[2]; Scully, J R; Gangloff, R P ^[3]

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1. General Electric Corporate Research and Development Center, Schenectady, NY (United States)
2. Knolls Atomic Power Lab., Schenectady, NY (United States)
3. Univ. of Virginia, Charlottesville, VA (United States)

The aqueous environment-assisted cracking (EAC) behavior of two peak-aged beta-titanium was characterized with a fracture mechanics method. Beta-21S is susceptible to EAC under rising load in neutral 3.5 pct NaCi at 25 C and {minus}600 mV{sub SCE}, as indicated by a reduced threshold for subcritical crack growth (K{sub TH}), an average crack growth rate of up to 10 {mu}m s, and intergranular fracture compared to microvoid rupture in air. In contrast, the initiation fracture toughness (K{sub ICi}) of Ti-15-3 in moist air is lower than that of Beta-21S at similar high {sigma}{sub YS} (1,300 MPa) but is not degraded by chloride, and cracking is by transgranular microvoid formation. The intergranular EAC susceptibility of Beta-21S correlates with both {alpha}-colonies precipitated at {beta} grain boundaries and intense slip localization; however, the causal factor is not defined. Data suggest that both features, and EAC, are promoted by prolonged solution treatment at high temperature. In a hydrogen environment embrittlement (HEE) scenario, crack-tip H could be transported by planar slip bands to strongly binding trap sites and stress/strain concentrations at {alpha} colony or {beta} grain boundaries. The EAC in Beta-21S is eliminated by cathodic polarization (to {minus}1,000 mV{sub SCE}), as well as by static loading for times that otherwise produce rising-load EAC.

• Sponsoring Organization: USDOE
• OSTI ID: 72791
• Journal Information: Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 5 Vol. 26; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORROSION RESISTANCE
CRACK PROPAGATION
FRACTURE PROPERTIES
HYDROGEN EMBRITTLEMENT
SODIUM CHLORIDES
TEMPERATURE RANGE 0273-0400 K
TITANIUM BASE ALLOYS
TITANIUM-BETA