SEDL / STP / STP407-EB / STP46481S

Mechanical Properties and Fracture Surface Topography of a Thermally Embrittled Steel

Carr, F. L.
Materials engineerPersonal member ASTM, Army Materials and Mechanics Research Center, Water-town, Mass.

Nunes, J.
Materials engineerPersonal member ASTM, U.S. Army Materials Research AgencyBrunswick Corp., Needham, Mass.

Larson, F. R.
ChiefPersonal member ASTM, Army Materials and Mechanics Research Center, Watertown, Mass.

Pages: 34    Published: Jan 1968

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Abstract

Tensile flow and fracture properties of both medium and coarse grain 3140 steel in both the embrittled and unembrittled condition are presented and discussed. The fracture stress ratios of embrittled to unembrittled specimens indicate the relative decrease in toughness due to this embrittlement over the range of temperature studied. Quantitative fracture surface topography resulted in fracture transition curves for the three types of specimens utilized. Transition temperatures based on several criteria indicated differences due to grain size and temper brittleness. The well-known difference in fracture mode behavior at low-testing temperature between embrittled and unembrittled specimens was found to be due to the peculiar fracture behavior of the unembrittled material. Fracto-graphic examination revealed that the intergranular fracture of the coarse grain material had varying degrees of deformation indicating significant differences in both ductility and energy required for separation.