M. L. Grossbeck

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1.04.1 Introduction

The most commonly considered mechanical proper­ties of metals and alloys include strength, ductility, fatigue, fatigue crack growth, thermal and irradiation creep, and fracture toughness. All these properties are important in the design of a structure that is to experi­ence an irradiation environment. While determining the mechanical properties of irradiated materials, ten­sile properties, typically yield strength, ultimate tensile strength, uniform elongation, total elongation, and reduction of area are the most commonly considered because they are usually the simplest and the least costly to measure. In addition, the tensile properties can be used as an indicator of the other mechanical

properties. Space in a reactor or in an accelerator target is often so limited that the larger specimens required for fatigue and fracture toughness testing are not prac­tical; consequently, the number of specimens that can be irradiated is so small that a meaningful test matrix is not possible. Shear punch testing of 3-mm diame­ter disks, typically used as transmission microscopy specimens, was developed to address the problem of irradiation space. Although much information can be obtained from shear punch testing, the tensile test remains the most reliable indicator of strength and ductility. For these reasons, the tensile test is usually the first mechanical test used in determining the irradiated properties of new materials. This chapter addresses the tensile strength and ductility of alloys.