Carbon Equivalent Calculation
The carbon equivalent calculation gives a value that estimates the steel's behavior during welding. A high carbon equivalent leads to more martensite and increases the risk of cracking.
Physical-Chemical Mechanism of Action
The carbon equivalent calculation sums up the percentage of carbon (C) and certain alloying elements such as nickel (Ni), chromium (Cr), molybdenum (Mo), and vanadium (V). This sum provides an indicator of the steel's danger during welding.
Metallurgical Relevance & Welding Risks
A high carbon equivalent means the steel transforms strongly into martensite during rapid cooling. This leads to increased hardness and susceptibility to cracking. With an excessively high carbon equivalent (e.g., above 0.7%), the weld can become very hard and lose its ductility.
Workshop Practice & Instructions
Before welding begins, calculate the steel's carbon equivalent. For a steel with 0.5% carbon and 1% nickel, the carbon equivalent is 1.5%. For a value above 0.7%, a slow cooling rate (e.g., oven cooling) should be applied to avoid cracks. The exact cooling rate depends on the steel type and desired microstructure.