THE EFFECT OF SEVERAL GEOMETRICAL VARIABLES ON THE NOTCH TENSILE STRENGTH OF 4340 STEEL SHEET HEAT TREATED TO THREE STRENGTH LEVELS
A systematic study was conducted to evaluate the effects of initial stress distribution and strength level on the notch tensile behavior of a typical high-strength-steel sheet alloy (SAE 4340) in the presence of stress concentrations. The initial stress distribution, characterized by the stress concentration factor (K) and the stress gradient at the root of a notch, was determined analytically from the notch geometry according to elastic theory. As part of the study, K was kept constant and the stress gradient allowed to vary for different notch depths and section widths. The 4340 steel sheet alloy was tested in three differert heat treat conditions ranging from ductile (F/sub tu/ = 150 ksi) to moderately notch brittle (F/sub tu/=260 ksi). For the material conditions investigated, it was found that the effect of stress gradient on notch strength was fundamentally identical with that of section widtb. Increasing the section width (or decreasing the stress gradient) resulted in a decrease in notch strength when all other factors were held constant. However, the effect was small when compared to the section size effect observed previously for notched cylindrical hars. In addition, results of tests on an extremely brittle titanium sheet alloy indicated that the stress gradient is the predominant factor that influences notch strength. For a truly brittle material, which exhibits no plastic deformation prior to fracture, it appears that the stress concentration factor, the depth of a notch and the specimen width are significant only insofar as they contribute to the magnitude of the stress gradient and the maximum stress at the notch root. (auth)
- Research Organization:
- Syracuse Univ., N.Y. Research Inst.
- DOE Contract Number:
- AF33(616)-6523
- NSA Number:
- NSA-15-011605
- OSTI ID:
- 4084351
- Report Number(s):
- WADD-TR-60-310
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- United States
- Language:
- English
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