The 1943 steel cent was a variety of the U.S. one cent coin which was struck in steel due to History. Because of wartime needs of copper for use in ammunition and other military equipment during World War II, the U.S. Mint had to replace the then-standard bronze one cent coin with a zinc-coated steel composition. The cent was struck at all three mints; Philadelphia, Denver and San Francisco.
Problems began to arise from the mintage however, when fresh coins were often mistaken for silver dimes and, over time, moisture would often rust the metal of the one cent coin. Vending Machines, which took “copper” cents, had magnets to pick up steel slugs but also picked up new legitimate steel cents. After public outcry, the Mint developed a process whereby salvaged brass shell casings gathered during World War II were augmented with pure copper to produce an alloy which was used for 1944-1946 cents. This three year series is sometimes referred to as the “Shell Case Cents.” Although the 1943 cent continued to circulate through the 1960’s, the Mint collected and destroyed many of them.
The steel cent is the only coin issued by the U.S. Mint for circulation that does not contain any copper. The 1943 – 1946 Lincoln cents make a nice, affordable sub-set for collectors.
Source: Information taken from Wikipedia. (wikipedia.org)