How to MIG Weld Stainless Steel
Metal inert gas, or MIG, welding is a class of welding processes that use a consumable wire electrode and a shielding gas. The pulsed arc process is a popular MIG welding technique that uses a high current pulse to transfer a drop of molten metal across an arc. Stainless steel is a common term that generally applies to any steel alloy that contains more than 12 percent chromium. Most types of stainless steel are relatively easy to MIG weld with a pulsed arc.
Instructions
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Choose the electrode. The diameter of the electrodes used in stainless steel pulsed arc welding typically ranges from 0.03 to 0.045 inches. The composition of the electrode will be generally similar to that of the base metal, although the electrode should melt at a lower temperature.
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Mix the shielding gas. Pulsed arc welding uses a shielding gas that's 99 percent argon and 1 percent oxygen. The chemical reactivity of this small amount of oxygen provides the additional weld penetration that stainless steel requires.
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Select the pulse frequency. MIG welding generally uses a standard power supply that delivers a constant current. The pulsed arc process will need a special power supply capable of alternating between a high and low current. This technique typically uses a current frequency that pulses between 30 and 400 times per second.
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Estimate the maximum current to use in pulsed arc welding. A chart is usually attached to each MIG welding machine that provides the specific current to use for each combination of electrode thickness and base metal thickness. The pulse arc mode generally uses less current than other MIG welding techniques.
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Use a slower welding speed. Pulsed arc welding is somewhat slower than other MIG welding techniques and is normally limited to 200 inches per minute. This technique is best suited for a thin base metal, and the weld should generally be made with a single pass.
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