Alexander Vasilyevich Stepanov (26.08.1908 — 16.05.1972) was a Soviet physicist and a corresponding member of the USSR Academy of Sciences (1968). He was born in St Petersburg. He graduated from the Leningrad Polytechnic Institute (1930). From 1924 he worked at the Leningrad Physico-Technical Institute (in 1929—30 he was a laboratory assistant and assistant at the Kharkov Physico-Technical Institute), and from 1937 also at the Leningrad Pedagogical Institute (professor from 1939).
His research was in solid-state physics. In 1933 — 34 he put forward the idea that centres of fracture arise in crystals because plastic deformation proceeds non-uniformly, and in 1937 he confirmed that it was correct. He established the two-stage nature of the formation of shears in crystals — the formation of a nucleus of shear and its growth. He studied the growth of shear nuclei and their transformation into macroshears, discovering in the process the existence of so-called left and right shears, or dislocations of different signs, and the interference of shears, and traced the influence of dissolution on the conditions of shear formation. He developed a number of methods of studying stressed states in crystalline, semicrystalline and anisotropic media, and a theory of the photoelastic effect in cubic crystals under plane loading. He laid (1948 — 50) the foundations of a physical theory of the fracture of periodically inhomogeneous and anisotropic media, and developed (1955—65) methods of measuring the elastic constants of crystals. He studied (from 1955) the mechanical properties of many metals at temperatures of 4.2—1.6 K, discovering a number of new phenomena. He contributed to the study of the properties of whiskers. He developed a new method of producing profiled articles and single crystals directly from the melt (the Stepanov method).