Microstructural Study of Failure Mechanisms during Mechanical Testing in Coal Gasification Environments

摘要

This annual progress report sets forth the program objectives and approach for a microstructural study of the behavior of iron-chromium-nickel alloys under the combined effects of stress and corrosive species encountered in coal gasification. The work involves systematic study of the effects of variations in alloy and environment compositions. Included are oxidizing and sulfidizing gas compositions. Model alloys have been procured and heat treated. In addition, microstructural changes which occur in 310 stainless steel, Incoloy 800H, RA 333 and IN 657 during stress rupture testing in a simulated coal gasification environment at 1500F have been examined. Optical metallography and energy dispersive X-ray analysis were used to characterize the microstructure. This characterization is continuing and a mechanism has been proposed.