Alloy 803 is used in the chemical process industry for its high temperature strength and corrosion resistance. Knowledge of the micro structural characteristics as a faction of time and temperature are essential for accurate rationalization of mechanical property performance under actual service conditions. This paper seeks to determine the microstructure of alloy 803 as a function of time and temperature for times up to 34,000 hours and temperatures ranging from 595°C to 1095C. Post-exposure room temperature tensile data are also presented as an indication of the alloy?s tolerance to downtime strains. Intermediate temperature mechanical strength can be attributed primarily to gamma prime (y?) and higher temperature strength to M23C6content.
INCOLOY@ alloy 803 was originally developed for tubing in ethylene paralysis furnaces. A derivative of alloy 800 and alloy 800H, alloy 803 has higher chromium and nickel contents to increase the oxidation and carburization resistance required in the paralysis furnaces]. The additional chromium also improves the sulfidation resistance. Altoy 803?s higher elevated temperature tensile ~and creep strengths compared to alloy 800 are largely attributable to its micro structural characteristics.
Alloy803, because of its excellent strength at intermediate temperatures, is also a candidate for long term service in certain heater element and thermocouple sheathing, heat exchanger tubing, transfer piping and steam generating components within the chemical processing industry.
The long-term stability of an alloy is an integral part of the selection process. Several studies have presented data for the 800 group of alloys2-7, A preliminary study of the thermal stability of alloy 803 was discussed in a previous paper and will be expanded upon in this study.
