# Influence of Rare Earths on Microstructure and Wear Resistance of High-Chromium Cast Iron

## TL;DR

Adding lanthanum and optimizing heat treatment improves the toughness and wear resistance of high-chromium cast iron.

## Contribution

Demonstrates that lanthanum refines carbides and optimal quenching enhances mechanical properties of high-chromium cast iron.

## Key findings

- Lanthanum addition refines carbides and reduces segregation without altering phase composition.
- Quenching at 1000 °C with lanthanum yields the best hardness, impact energy, and wear resistance.
- Excessive quenching temperatures (1050 °C) degrade the material's performance.

## Abstract

High-chromium cast iron is widely used in cement, mining and metallurgy, but its as-cast state has defects such as coarse carbides, uneven distribution and severe elemental segregation, resulting in insufficient toughness and poor wear stability. Taking Cr20 type high-chromium cast iron as the research object, two sample groups (without/with La) were designed. XRD, OM, SEM, EDS, mechanical property tests and impact wear experiments were used to study the effects of La addition and different quenching temperatures (900 °C, 950 °C, 1000 °C, 1050 °C) on its properties. The results show that La does not change the phase composition but refines carbides, alleviates segregation and promotes secondary carbide precipitation. Suitable heat treatment enhances properties, while excessive temperature (1050 °C) causes performance degradation. Sample 2 (with La, quenched at 1000 °C) has the optimal comprehensive properties, with superior hardness, impact energy and wear resistance. This study provides an experimental basis and technical reference for optimizing high-chromium cast iron properties.