LD (7Cr7Mo2V2Si) is a high-strength, high-toughness steel refined through vacuum carbon deoxidation. It was originally developed by adjusting the alloying elements of the patented cold-work die steel, SVSCO-DIE.

Key Characteristics and Metallurgy
High Austenite Alloying: The steel features a high degree of austenitic alloying, leading to a significant secondary hardening effect.

Optimized Carbon Content: Its carbon content is lower than the "Balanced Carbon" rule recommended by G. Steven. This specific chemistry allows the steel to maintain high hardness without sacrificing impact toughness.

Alloying Elements (Cr, Mo, V): The addition of Chromium, Molybdenum, and Vanadium facilitates secondary hardening, ensuring superior strength and excellent wear resistance.

Performance and Applications
Performance Comparison: LD steel outperforms W6 and offers several times the wear resistance of 9CrSi and Cr12MoV.