Accession Number : ADA180354

Title :   Fatigue Crack-Growth Resistance of Aluminum Alloys Under Spectrum Loading. Volume 1. Commercial 2XXX and 7XXX Alloys.

Descriptive Note : Final technical rept. 30 Sep 82-31 Mar 85,

Corporate Author : NORTHROP CORP HAWTHORNE CA AIRCRAFT GROUP

Personal Author(s) : Scarich,G V ; Bretz,P E

PDF Url : ADA180354

Report Date : Dec 1985

Pagination or Media Count : 87

Abstract : The purpose of this program is to obtain metallurgical guidelines and test methodologies for selection and development of spectrum fatigue-resistant, high-strength aluminum alloys for application to aircraft structures. This volume (I) of this report describes the results of baseline characterization of two high-strength aluminum alloys, and compares these results to those obtained in the two previous phases of the program. Twelve commercial 2XXX and 7XXX aluminum alloys were chosen and characterized for chemical composition, microstructure, tensile properties, and fracture toughness. Fatigue crack propagation (FCP) tests were conducted on specimens of each alloy for both constant-amplitude loading (including the near-threshold region) and two F-18 load spectrums. One of the spectrums was dominated by tension loads and the other contained tension and compression loads of nearly equal magnitude. The spectrum FCP testing was performed at the maximum peak stress of 145 MPa (21 ksi) with limited testing at 103 and 169 MPa (15 and 24.5 ksi) to obtain additional data at the low and high end of the crack-growth range. Pertinent fracture surface features were documented on the spectrum fatigue specimens.

Descriptors :   *ALUMINUM ALLOYS, *CRACK PROPAGATION, *FATIGUE(MECHANICS), AIR FORCE RESEARCH, BINARY ALLOYS, MICROSTRUCTURE, LIFE EXPECTANCY(SERVICE LIFE), COMPRESSIVE PROPERTIES, STRESS CONCENTRATION, AIRCRAFT, AIRFRAMES, CHEMICAL COMPOSITION, FATIGUE, FRACTURE(MECHANICS), HIGH STRENGTH ALLOYS, INSTRUCTIONS, METALLURGY, MICROSTRUCTURE, PEAK VALUES, RESISTANCE, SPECTRA, STRESSES, SURFACES, TENSILE PROPERTIES, TENSION, TEST METHODS, THRESHOLD EFFECTS, TOUGHNESS

Subject Categories : Properties of Metals and Alloys
      Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE