Andrew T. Becker; Alan M. Russell; L. Scott Chumbley
Abstract
Anhydrous ammonia is a toxic material that is transported from distribution centers to farm fields in steel pressure vessels called nurse tanks. Numerous accidents have occurred in which nurse tanks failed and ammonia was released, often with explosive force. The majority of such accidents are caused ...
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Anhydrous ammonia is a toxic material that is transported from distribution centers to farm fields in steel pressure vessels called nurse tanks. Numerous accidents have occurred in which nurse tanks failed and ammonia was released, often with explosive force. The majority of such accidents are caused by stress corrosion cracking of the tank steel. Stress corrosion cracking is caused by the combination of stress in the tank's steel and the corrosive effect of ammonia. Neutron diffraction analysis was used to map the residual stress state in and near circumferential welds from two used anhydrous ammonia nurse tanks, one manufactured in 1966 and the other manufactured in 1986. Notched SA455 steel test specimens were held under tensile load (stress concentration factors of 40 to 80 MPa·√m) while immersed in NH3 for seven months to generate crack propagation rate data. The results from these measurements were then used to predict stress corrosion crack growth rates for various pre-existing crack sizes at various temperatures. These data may be useful for estimating safe service lifetimes of nurse tanks that contain cracks.
Andrew E. Frerichs; Alan M. Russell
Abstract
The yield strength, ultimate tensile strength, elastic modulus, and strain rate sensitivity of pure Sr metal in the as-extruded condition were determined by tensile testing and compared with the properties of other alkaline metals. Two strain rates were used for testing. At a strain rate of 6.5×10 ...
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The yield strength, ultimate tensile strength, elastic modulus, and strain rate sensitivity of pure Sr metal in the as-extruded condition were determined by tensile testing and compared with the properties of other alkaline metals. Two strain rates were used for testing. At a strain rate of 6.5×10 -4 s -1 , Sr has a 0.2% offset yield strength of 71.6 MPa, an ultimate tensile strength of 88.1 MPa, and 10.4% elongation at fracture. At a strain rate of 6.3×10 -3 s -1 , Sr has a 0.2% offset yield strength of 81.9 MPa, and ultimate tensile strength of 101.5 MPa, and 5.0% elongation at fracture. The strain rate sensitivity was determined to be 0.059.
