# Effects of Solid Solution Heat Treatment on the Corrosion Behavior of 800H Used in Fourth-Generation Nuclear Power Generators

## TL;DR

This study examines how different heat treatments affect the corrosion resistance of Incoloy 800H, a key material in next-generation nuclear power systems.

## Contribution

The study identifies optimal solid solution heat treatment temperatures for maximizing the corrosion resistance of Incoloy 800H.

## Key findings

- Insufficient heat treatment at 1120 °C leads to uneven grain growth and poor corrosion resistance.
- Heat treatment at 1150 °C results in uniform grain structure and best corrosion resistance.
- Excessive heat treatment at 1180 °C causes severe intergranular corrosion.

## Abstract

Incoloy 800H is important structural alloy for heat exchange tubes of Generation IV nuclear power systems. Revealing the key heat treatment effects on the microstructure and corrosion behavior of 800H is a key issue for its performance optimization and safe application in IV nuclear power industries. This work investigated the solid solution heat treatment–microstructure–corrosion resistance relationship using various electrochemical corrosion techniques and morphology characterizations. The results showed that 1120 °C was an insufficient solid solution heat treatment temperature for 800H, at which 800H demonstrated uneven enlargement of grains and undissolved Cr-carbides, which resulted in fast corrosion. 800H demonstrated even growth of grains with best grain uniformity and dissolution of Cr-carbides at 1150 °C, thus showing the best corrosion resistance. However, the further increase in solid solution temperature to 1180 °C resulted in excessive grain growth and severe intergranular corrosion (IGC) attack. This work deepened the understanding of the corrosion mechanism of 800H and provided data for its performance optimization.