Weld cleaning | Ask Cougartron | Wednesday, 18 April 2018 Show
Ask Cougartron Part 4: How to remove heat-tints from stainless steel?Over the past month, we received a lot of questions related to discoloration and heat tints appearing on stainless steel welds after fabrication (welding). Thus, we devoted an entirely new episode in our Ask Cougartron Q/A series to this problem faced by many industry professionals. YOUR QUESTION: How to remove heat tints that appear after welding? Harry – one of our weld cleaning experts – first explains how and why heat tints are created and then elaborates on how to successfully solve the problem. See below for a more detailed explanation of the issue. What are heat tints and how are they created?Heat tints appearing after stainless steel welding are a common occurrence in the industry. Industrial terminology recognizes a variety of related terms signifying the same phenomenon – discoloration, oxide scale, and rainbow effect are just some of the popular examples. All of them indicate a change in color on the top layer of stainless steel – around the weld bead and within the HAZ (heat-affected zone).  The color combination depends largely on the amount of heat used during welding – darker colors (brown, blue, and purple) are usually formed at higher temperatures (> 370 °C or 698 °F). Welding speed and shielding are also important factors to consider when discussing precaution measures. But what causes the symptomatic change in colors? As explained in one of the previous articles, stainless steel is ‘stainless’ due to its chromium-rich composition and a passive outer layer that helps it to successfully fight corrosion.
Is discoloration only a cosmetic issue?The attractive appearance of stainless steel is undoubtedly impaired once discoloration appears on its surface. However, the real problem concerns the underlying chromium-depleted layer of the alloy which becomes susceptible to corrosion and rusting. Thus, we are dealing with a twofold problem. The restoration of the passive state of stainless steel is impossible without removing the tempered oxide scale first. But how is this done properly? Removing heat tints in the right waySeveral methods are commonly used to remove discoloration on stainless steel after welding.
Click to read more about these methods However, the choice of method depends largely on the scope of the problem. Usually, discoloration involving lighter (yellow) shades is much easier to remove since it forms under the influence of lower temperatures during welding.
The use of pickling paste is widespread. However, chemical pickling should definitely be avoided due to the harmful effects of nitric and hydrofluoric acids. We explained all the important health & safety reasons here. What about dark(er) heat tints? Electrochemical cleaning and passivation provide excellent results with darker discoloration as well. However, the potency of the machine used is also a highly relevant factor to consider. We offer a variety of weld cleaning machines developed to successfully remove different types of weld tints and discoloration. When it comes to low-powered systems, the process of removing the oxide scale can become more complicated. In certain cases, the use of various methods is necessary but electrolytic cleaning in most situations is the best solution. How can Cougartron help you with cleaning stainless steel?If you are experiencing a specific challenge related to discoloration and stainless steel weld cleaning, send us a message to arrange a free consultation or Cougartron machine demonstration with one of our qualified product experts. Loading...Please wait while the form loads. How do you get rid of heat discoloration on stainless steel?Vinegar is an effective ingredient for ridding your pan of any unsightly discoloration typically caused by overheating. Simply wash your pan with vinegar and rinse with water to remove discoloration.
Can you polish heat marks out of stainless steel?Clean the stainless-steel oven regularly with undiluted white vinegar and a soft cloth to remove heat spots as they begin to develop. Polish your stainless-steel oven by moistening a clean, soft cloth with olive oil and rubbing it in the direction of the grain on the stainless steel.
How do you remove heat treat discoloration?Electropolishing removes a uniform layer of metal from the surface of parts to effectively remove stains and discoloration resulting from lubricants, heat-treating or other finishing processes. Electropolishing not only removes the discoloration, but provides other important benefits as well.
How do you remove heat stains from a stainless steel cooktop?To remove burn marks or heat stains from stainless steel, apply Penny Brite® cleaning paste to a sponge and lightly rub with the grain until the burn marks are gone. Wipe any remaining residue with a clean, damp cloth or sponge. Apply a polish to maintain luster and protect the surface from future food stains.
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Remove heat discoloration from stainless steel
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