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Title: Mechanisms influencing the cryogenic fracture-toughness behavior of aluminum-lithium alloys

Abstract

Cryogenic strength-toughness relationships for advanced aluminum-lithium alloys 2090, 8090, 8091 and 2091 are examined as a function of microstructure, plate orientation and wrought-product form (plate vs. sheet), with specific emphasis on the underlying micro-mechanisms associated with crack advance. It is found that, with decrease in temperature from 298 K to 77 and 4 K, strength, tensile elongation and strain-hardening exponent are increased for all alloy chemistries, microstructures and product forms; however, the longitudinal (L-T, T-L) fracture toughness may increase or decrease depending upon the prevailing microscopic mechanism (microvoid coalescence vs transgranular shear) and macroscopic mode (plane strain vs plane stress) of fracture. In general, alloy microstructures that exhibit changes in either the fracture mechanism or mode at low temperatures show a decrease in L-T toughness. Conversely, when the fracture mechanism is unchanged between ambient and 4K, observed variations in toughness with temperature are a strong function of the degree of local stress-triaxiality that develops at the crack tip. 55 refs., 18 figs., 2 tabs.

Authors:
;  [1]
  1. Lawrence Berkeley Lab., CA (United States) Univ. of California, Berkeley (United States)
Publication Date:
OSTI Identifier:
7267093
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Acta Metallurgica et Materialia; (United States)
Additional Journal Information:
Journal Volume: 38:11; Journal ID: ISSN 0956-7151
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; FRACTURE PROPERTIES; LITHIUM ALLOYS; MICROSTRUCTURE; PLATES; SHEETS; TEMPERATURE EFFECTS; ALLOYS; CRYSTAL STRUCTURE; MECHANICAL PROPERTIES; 360103* - Metals & Alloys- Mechanical Properties; 360102 - Metals & Alloys- Structure & Phase Studies

Citation Formats

Venkateswara Rao, K T, and Ritchie, R O. Mechanisms influencing the cryogenic fracture-toughness behavior of aluminum-lithium alloys. United States: N. p., 1990. Web.
Venkateswara Rao, K T, & Ritchie, R O. Mechanisms influencing the cryogenic fracture-toughness behavior of aluminum-lithium alloys. United States.
Venkateswara Rao, K T, and Ritchie, R O. 1990. "Mechanisms influencing the cryogenic fracture-toughness behavior of aluminum-lithium alloys". United States.
@article{osti_7267093,
title = {Mechanisms influencing the cryogenic fracture-toughness behavior of aluminum-lithium alloys},
author = {Venkateswara Rao, K T and Ritchie, R O},
abstractNote = {Cryogenic strength-toughness relationships for advanced aluminum-lithium alloys 2090, 8090, 8091 and 2091 are examined as a function of microstructure, plate orientation and wrought-product form (plate vs. sheet), with specific emphasis on the underlying micro-mechanisms associated with crack advance. It is found that, with decrease in temperature from 298 K to 77 and 4 K, strength, tensile elongation and strain-hardening exponent are increased for all alloy chemistries, microstructures and product forms; however, the longitudinal (L-T, T-L) fracture toughness may increase or decrease depending upon the prevailing microscopic mechanism (microvoid coalescence vs transgranular shear) and macroscopic mode (plane strain vs plane stress) of fracture. In general, alloy microstructures that exhibit changes in either the fracture mechanism or mode at low temperatures show a decrease in L-T toughness. Conversely, when the fracture mechanism is unchanged between ambient and 4K, observed variations in toughness with temperature are a strong function of the degree of local stress-triaxiality that develops at the crack tip. 55 refs., 18 figs., 2 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/7267093}, journal = {Acta Metallurgica et Materialia; (United States)},
issn = {0956-7151},
number = ,
volume = 38:11,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1990},
month = {Mon Jan 01 00:00:00 EST 1990}
}