Medium-carbon steels sit at the heart of many impact-heavy industrial operations, from grinding mills to crushing systems. They are relied on because they are strong, affordable, and relatively easy to manufacture. But as this new study shows, making these steels harder can lead to premature cracking and failure under repeated impacts.

Researchers explored how silicon affects wear performance when paired with common industrial heat treatments. They focused on how different microstructures respond to real service conditions where impact and abrasion act together. 

In the study, researchers focused on how different microstructures respond to real service conditions. They compared three medium-carbon steels with increasing silicon content and processed them by quenching and tempering, quenching and partitioning, or austempering. The results showed that steels designed to absorb energy performed better than steels designed to resist indentation.

Based on the findings, silicon stabilized retained austenite, a phase that can transform under stress and helps dissipate impact energy. An increase in silicon content suppressed cementite formation and allowed carbon partitioning in retained austenite. This made the retained austenite more abundant and stable. 

Researchers also found that its shape mattered. Between larger, blocky areas and thinner, film-like regions, the latter are more prone to trigger cracking.

In addition, they discovered that the specific choice for heat treatment matters. Of the three, quenched and tempered steels recorded the highest hardness values. However, they developed cracks and spalling early on during wear testing. 

On the other hand, quenching and partitioning yielded mixed results. This suggests that processing conditions influence the outcome. But compared to the first two, austempered steels, which are treated at lower temperatures, proved to exhibit the ideal balance of wear resistance and toughness.

This improved performance was linked to several related factors: stable retained austenite that transformed gradually during service, a deep strain-hardened layer beneath the surface, and much lower tensile residual stresses. With all these features together, they delayed crack formation and slowed damage accumulation under repeated impacts.

Read the full article here to learn more about silicon's effect on medium-carbon steel's wear resistance.

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