Accession Number : AD0638169

Title :   SOURCES AND CAUSES OF POROSITY IN TITANIUM ARC WELDS.

Descriptive Note : Technical rept.

Corporate Author : ARMY MATERIALS RESEARCH AGENCY WATERTOWN MASS MATERIALS TECHNOLOGY DIV

Personal Author(s) : D'Andrea,Mark M. , Jr

Report Date : MAR 1966

Pagination or Media Count : 26

Abstract : An exploratory study was conducted in which theoretical concepts were investigated and established to account for the phenomena of porosity formation in titanium arc welds. Significant and nonsignificant sources of gas evolution and the probable causative gases were determined. The work was limited to a study of the effects of seemingly pertinent material and welding parameters pertaining to single-pass, open-air, inert-gas-shielded consumable electrode (MIG) welding procedures in 1/8-inch-thick Ti-6Al-4V sheet material. The results of the study were deemed applicable in general for arc welds made in titanium plate and other titanium base materials. The important conclusion was that individually molecular hydrogen and oxygen were considered to be definite, independent, causative gases. The following gases were considered not causative: H2O, N2, NsubxOsuby compounds, CO, CO2, A, He, S and P plus their oxides, and CsubxHsuby and CsubxHsubyOsubz compounds. Sources of hydrogen porosity were considered hydrogen-bearing foreign matter on and entrapped in the surface of base material, and hydrogen contained in the base material essentially in the form of titanium hydride. The source of oxygen porosity was considered to be oxygen-bearing scale on the surface of base material The qualitative and somewhat quantitative aspects of sources and causes as well as the mechanisms of gas evolution and entrapment are presented herein. (Author)

Descriptors :   (*TITANIUM ALLOYS, *ARC WELDS), POROSITY, ALUMINUM ALLOYS, VANADIUM ALLOYS, INERT GAS WELDING, GASES, DEGRADATION

Subject Categories : Couplers, Fasteners, and Joints

Distribution Statement : APPROVED FOR PUBLIC RELEASE