# Effect of High Temperature Precipitation and Heating Dissolution on Microstructure and Mechanical Properties of Alloy 2618

## TL;DR

A new heat treatment method improves the strength and toughness of alloy 2618 by altering its grain boundary structure.

## Contribution

A novel heat treatment combining high-temperature precipitation and heating dissolution is introduced to enhance alloy 2618 properties.

## Key findings

- The precipitation-free zone at grain boundaries was significantly narrowed.
- Tensile strength and impact toughness increased by 5.0% and 23.7%, respectively.
- The synergistic treatment improved grain-boundary structure and mechanical properties.

## Abstract

This study employs high-temperature precipitation combined with heating dissolution to redistribute solute atoms near the grain boundaries of alloy 2618, regulating the width of the precipitation-free zone at the grain boundaries and the aging precipitates in their vicinity. Microscopy techniques, including high-resolution scanning electron microscopy and transmission electron microscopy, were used to observe the grain-boundary structure of the alloy. A universal electronic tensile testing machine and an impact tester were used to evaluate the mechanical properties of the alloy. The results show that solution treatment at 535 °C for 30 min, followed by high-temperature precipitation at 470 °C for 10 min and subsequent heating dissolution at 535 °C for 10 min, significantly narrowed the width of the precipitation-free zone at the grain boundaries of alloy 2618. The number of precipitated phases in the vicinity of the grain boundaries increased. Compared with the conventional solution aging treatment of alloy 2618, the tensile strength and impact toughness of the alloy subjected to high-temperature precipitation, heating dissolution, and aging increased by 5.0% and 23.7%, respectively. Thus, the synergistic effects of high-temperature precipitation and heating dissolution effectively improved the grain-boundary structure and enhanced the overall mechanical properties of alloy 2618.