# A Rapid Spheroidizing Annealing Process for High-Carbon Steel

## TL;DR

This paper introduces a faster heat treatment for high-carbon steel that reduces processing time while maintaining desired material properties.

## Contribution

A novel rapid spheroidizing annealing method using low-temperature pretreatment and subcritical heating is developed.

## Key findings

- A pretreatment at 400 °C enables carbide nucleation for faster spheroidization.
- The process achieves a hardness of 206.7 HV comparable to traditional methods.
- Significant reductions in time and energy consumption are realized.

## Abstract

Spheroidizing annealing is a critical heat treatment process for high-carbon steels to balance hardness and machinability. This study develops a rapid spheroidizing annealing process by employing low-temperature pretreatment followed by subcritical heating. The key is to utilize carbide precipitates from non-equilibrium phases (e.g., martensite/lower bainite) as nucleation sites, thereby accelerating spheroidization. At an optimized pretreatment temperature of 400 °C, the process achieves a homogeneous spheroidized microstructure with a hardness of 206.7 HV, comparable to that obtained via conventional prolonged annealing. This method significantly reduces processing time and energy consumption.