Introduction
The goal of this project is to improve the weldability of heat-resistant austenitic stainless steels, specifically 20Cr-32Ni-1Nb, by modifying the chemical composition of the alloy to reduce or eliminate the formation of detrimental phases after high temperature exposure (“aging”).
Plan for Experimental Investigation
Exploration/Identification of Beneficial Modifications to 20Cr-32Ni-Nb Composition
Several investigators have worked on this area in the past, including Hoffman, and Dewar and Gehrlich. Additionally, there are a number of other similar efforts which have been undertaken to modify the chemistry of other heat-resistant alloys (e.g. CF8C-Plus developed by ORNL) to optimize creep properties and the information from these projects regarding alloying elements effects on phase/precipitate evolution will be used as a starting point for determining what changes could be made to CT15C. The first step of the project will involve a detailed search of the current literature to identify prior work on the modification of CT15C chemistries.
To address the prior work on Hoffman \cite{hoffman_cast_2003} and Dewar and Gehrlich \cite{dewar_correlation_2013} in more detail, these investigators have
Production of Experimental Heats of 20Cr-32Ni-1Nb Alloys
MetalTek Corporation will provide the experimental heats of 20Cr-32Ni-1Nb material. These will encompass the following:
- Unmodified alloy to be representative of the "typical" composition
Simulation of High Temperature Exposure
The experimental heats of CT15C will be heat-treated to simulate the effects of long-term exposure to typical operating temperatures in hydrogen reforming furnaces. The heat treatment will be performed at 800C for time increments of