Comparison of Advantages and Disadvantages between Alloy Steel and High Carbon Steel

1. Poor Hardenability of High Carbon Steel
When carbon steel is quenched in water, its critical quenching diameter is only about 15–20 mm. For parts with a diameter greater than 20 mm, even water quenching cannot achieve full hardening throughout the section. This results in inconsistent mechanical properties across the cross-section. Therefore, carbon steel is unsuitable for large parts with high performance requirements. In contrast, alloy steel has much better hardenability and can be used to manufacture large or complex-shaped components.

2. Low High-Temperature Strength and Poor Red Hardness of High Carbon Steel
When carbon steel is used at temperatures above 200 °C, its strength and hardness decrease rapidly. Alloy steel, on the other hand, has better tempering stability and red hardness, allowing it to maintain strength and hardness when working at higher temperatures.