High-carbon steels are decidedly more difficult to weld than low- or medium-carbon steels. However, a variety of measures are available to ensure a strong weld.
Steel is an alloy, or metallic mixture, containing primarily iron. A variety of other metals, such as carbon, are used to promote certain properties in the alloy. Carbon has a strengthening effect when added to iron.
There are different types of steel available, including several varieties of carbon steel. Low-carbon steel contains a maximum concentration of 0.3 percent carbon, while high-carbon steel contains a maximum concentration of 1 percent carbon.
Carbon in Steel
Carbon strengthens steel, but also reduces its ductility, or pliability. The low ductility of high-carbon steel makes it more difficult to weld.
Effects of Welding on High-Carbon Steel
When welding high-carbon steel, a high concentration of martensite may form in the weld. Martensite makes the metal extremely brittle, causing a weak weld that may break as soon as it cools.
Welding High-Carbon Steel
According to ESAB Welding and Cutting, Inc., a low hydrogen electrode must be used when welding high-carbon steels. Additionally, annealing, or heating, the metal prior to welding slows the cooling process and prevents the concentration of martensite. Post heating will also reduce stress and strengthen the weld.