Grain Growth in Austenitic Stainless Steel

摘要

Despite the extensive use of Type 347 stainless steel tubing for regeneratively cooled thrust chambers, very little is known about its grain growth characteristics. Lacking, also, is information on the other 18 Cr 8 Ni austenitic steels. Therefore, grain growth curves for AISI Types 304, 316, and 321 were obtained and compared. Grain growth characteristics were established at temperatures between 1900 and 2300F, for periods of 5, 15, and 60 min. Rapid heating and cooling were used with all samples to simulate, to some degree, conditions experienced in thrust chambers. Some similarity in grain growth behavior of Types 321 and 347 was noted; rapid grain growth was found to occur at about 2000F. Some grain growth similarity also exists between Types 304 and 316; grain growth was rapid above 1900F. Where grain growth occurred, the greatest changes were during the first 15 min at temperature. Where micrographs are available in a failure analysis, these data can be used to make estimates of the temperatures to which the austenitic steel tubes were heated. (Author)