Evaluation of Stainless Steels for Primary Surface Recuperator Applications.

Swindeman, R. W.

Technical Information Center Oak Ridge Tennessee

关键词: Gas turbines;    Stainless steels;    Corrosion resistance;    Electron microscopy;    Evaluation;   

RP-ID  :  DE2001777679

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

In 1996, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and Solar Turbines Incorporated to develop improved stainless steels for gas turbine recuperator applications. A team was assembled that consisted of materials and fabrication specialists from ORNL, Solar Turbines, Allegheny Ludlum Research Laboratory, and the University of California-San Diego. The development strategy was to (1) identify the materials performance requirements needed for long-time operation of a recuperator with inlet gas temperatures higher than current practice, (2) select candidate commercial and near-commercial alloys with potential for meeting the performance requirements, and (3) optimize thermal-mechanical processing to meet commercial production capabilities. The performance requirements were incorporated into three categories (fabricability, corrosion resistance, and mechanical strength) and teams were assigned to address each of these issues. The composition of the steels under consideration ranged from 18 to 25% chromium and from 8 to 25% nickel. Foils of thicknesses in the range 0.08 to 0.12 mm were produced by laboratory processing and by commercial processing. Thermal-mechanical processing was varied to obtain a range of grain sizes or to vary other physical metallurgical parameters. Oxidation experiments were undertaken in laboratory air and air with controlled water vapor contents at ORNL, Allegheny-Ludlum, and the University of California San Diego. Cyclic oxidation testing was included. Testing conditions were selected to enable models to be developed that included temperature, time, water content, and foil thickness as variables. Creep testing was performed in the temperature range of 677 C to 732 C for times extending beyond 10,000 h at ORNL and Solar Turbines. Optical, scanning, and analytical electron microscopy were used to examine the evolution of microstructure during aging, corrosion, and creep exposures. Based on the experimental work, optimized compositions and thermal-mechanical processing specifications were developed.