CU-1C-1985-19 Cud

Description

The composition of die steel directly influences how and where fractures develop, and CU-1C-1985-19 on the 1985 Philadelphia Lincoln Memorial cent was struck by a die made from tool steel engineered for high-cycle fatigue resistance. U.S. Mint dies in the 1980s were typically manufactured from air-hardening tool steels in the AISI D-series or similar high-chromium compositions, heat-treated to achieve a balance between hardness and toughness. Higher hardness increases resistance to wear — the gradual loss of fine design detail — but reduces toughness, the steel's ability to absorb energy without cracking. This tradeoff means that die steel optimized for long production runs and sharp detail retention is inherently more susceptible to brittle fracture modes, including the rim breaks that produce cuds. The fracture typically propagates along grain boundaries in the steel's microstructure, following paths of least resistance through the crystalline matrix. Inclusions — microscopic impurities trapped during steel manufacturing — can serve as initiation points for these fractures. Each cud therefore reflects not only the mechanical loads imposed during coining but also the specific metallurgical characteristics of the individual die. Struck at Philadelphia on copper-plated zinc planchets at 2.5 grams and 19mm from the 1985 mintage of approximately 5.65 billion cents.

Attribution History

• Discovered by Geoffrey Noe
• CU-1C-1985-19
• Expert attribution by Cuds on Coins

External References