Accession Number : AD0820476

Title :   CORROSION CRACKING OF METALLIC MATERIALS.

Descriptive Note : Summary technical rept. no. 1, 1 Jul 66-30 Jun 67,

Corporate Author : OHIO STATE UNIV COLUMBUS DEPT OF METALLURGICAL ENGINEERING

Personal Author(s) : Fontana, Mars G.

Report Date : JUN 1967

Pagination or Media Count : 74

Abstract : The aim of this work is to obtain the fundamental information necessary for the design of alloys and the control of environments which will be less susceptible to stress corrosion cracking. Titanium Alloys: Slow crack growth in a Ti-8Al-1Mo-1V alloy when potentials are applied occurs over a range of 960 to + 2040 Mo (SHE) in salt water implying that the hydrogen evolution is not a necessary factor in crack propagation. Crack propagation of this alloy is also being studied in methanol-water-salt solutions. High Strength Steels: Dissolution studies of thin foils of 4340 steel examined in the electron microscope show that preferential dissolution occurs adjacent to carbide at low pH; and at high pH the carbides themselves dissolve. In crack growth studies in 4340 steel, K sub I to initiate first fracture is much higher when the specimens are exposed to the aqueous salt solution suggesting that a crack blunting process is operating. Field Ion and LEED Studies: A LEED system has been designed and is being built. Field ion techniques will be used to study adsorption-desorption of hydrogen in iron. Oxide Growth: The behavior of Cr(+3) in a NiO lattice has been studied and quantitative results obtained on solubility, effect of PO2, and internal oxidation.

Descriptors :   *CRACK PROPAGATION), (*STRESS CORROSION, NIOBIUM ALLOYS, CRYSTAL GROWTH, TITANIUM ALLOYS, SOLUTIONS(MIXTURES), WATER, CARBINOLS, DENSITY, FOILS(MATERIALS), ELECTRON MICROSCOPES, PH FACTOR, STEEL, CARBIDES, CRYSTAL DEFECTS, FRACTURE(MECHANICS), ORGANIC SOLVENTS, IONS, ADSORPTION, HYDROGEN, IRON, CHROMIUM ALLOYS, NICKEL ALLOYS, OXIDES, OXIDATION, ELECTROCHEMISTRY, RECRYSTALLIZATION.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE