Structural Changes in High-Strength Steel Associated with Stress Corrosion and Its Relationship to Delayed Failure

摘要

Microscopic and crystal-structure examinations have been made on AISI 4340 steel heat treated to four strength levels, to provide a basis for investigating changes in these materials during stress-corrosion cracking and hydrogen embrittlement. Preliminary studies on stress-corrosion fracture surface reveal two, and possibly three, morphological characteristics that coincide with specific areas in the fracture. Metal-hydrogen reactions that have been studied suggest different behavior for martensite and ferrite. The net result of the metal-hydrogen reaction was found to be an induced compressive stress in the surface. (Author)