How to Harden Welding Steel
Hardening steel after it has been welded is a task that only takes a few moments to successfully accomplish. Because the heat from welding changes the temper of the steel surrounding the weld, you can often end up with a part that has all of the strength of the part located in the weld itself. This can make the surrounding metal prone to breakage. Tempering and then annealing the steel and the weld significantly improves the strength of the part being welded, making it much less susceptible to cracks and fatigue damage. Does this Spark an idea?
Things You'll Need
- Metal bucket
- Propane torch
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Instructions
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Plunge the steel part that was welded into a bucket filled with water. This process is called quenching. This produces a very hard surface on the metal, but makes the part brittle. In order to offset this brittle tendency, the part must be annealed.
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Heat the part with a propane torch after it has been quenched. Don't worry about drying the part off. The weld and the surrounding steel should be heated so that it reaches an orange color, but not white or yellow.
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Place the part in a draft-free area where it can cool to room temperature without being disturbed. Drafts cause the steel to cool too quickly and the weld is not as strong as it would be otherwise. When the steel has cooled completely, both the weld and the steel that was welded together have the same level of hardness. After a final heat treatment, the steel part is strong throughout the part, rather than just at the weld or just at the steel.
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Heat the part once again to the same temperature with the propane torch. After it has been heated, quench the part in the bucket of water to harden the weld and the surrounding metal and improve its hardness.
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References
- "How to Weld"; Todd Bridigum; 2008
- Photo Credit Ablestock.com/AbleStock.com/Getty Images
