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When stainless is heated beginning at about 500 degrees F the oxidation reaction is enhanced and the layer becomes thicker. The surface discoloration on stainless steel after grinding or welding is surface oxidation.
This is why it is crucial to clean a discolored stainless steel pan to retain its shine and appearance.
Discoloration of stainless steel due to heat. The downsides with stainless steel can include stains or discolorations such as. Black residue White residue on pots and pans of stainless steel Tumeric stains Caramel-brown stains burnt sticky oil residue Heat. The colour formed when stainless steel is heated either in a furnace application or in the heat affected zone of welds is dependent on several factors that are related to the oxidation resistance of the steel.
The heat tint or temper colour formed is caused by the progressive thickening of the surface oxide layer and so as temperature is increased the colours change. While most stainless steels are resistant to oxidation at low temperatures the various metal in the steel formulation iron chromium molybdenum etc can form oxides at higher temperatures. This oxidation causes the discoloration often seen on steel after heat treatments.
But really stainless steel that is exposed to high heat can cause some discoloration depending on the temperature reached. It is true that it does have to be some extreme heat but you should still know a little about what heat damage does to your stainless steel. Also take a look at the chart to see how the temperature can discolor your grill.
Cleanse the discolored stainless steel with a terry cloth soaked in white vinegar. This is especially effective at removing heat stains. Step 3 Pour a bleach-free powdered cleanser and polisher onto a cloth and scrub over stubborn discolored spots until they are removed.
According to the heat treater this discoloration is inherent to the process. I find it hard to believe when we see batches of good non-discolored parts and then batches of discolored parts. Also and please tell me if this is standard in the industry is that our heat treater is supposed to take the stainless steel from condition A to condition H.
When stainless is heated beginning at about 500 degrees F the oxidation reaction is enhanced and the layer becomes thicker. As the thickness of the layer increases the wavelength of light transmitted changes and hence the color we see. Therefore the development of different colors is related to the temperature the stainless has been exposed to.
Heat stains can occur on stainless steel appliances for a variety of reasons. Simply setting a hot pan on the surface can result in a mark left behind. Though these marks appear as damage to the surface they are simply a discoloration that can easily be removed.
Steps to Remove the Heat Stain. The surface discoloration on stainless steel after grinding or welding is surface oxidation. At elevated temperature the metal comprising the stainless steel will combine with oxygen to form an oxide layer on the metal surface.
The color of the stain is a function of the layer thickness. The heat treater is not correct. Any time stainless steel is oxidized more chromium is pulled into the oxide than its percentage in the underlying surface.
This depletes the underlying metal surface of chromium which hurts its corrosion resistance. Stainless Steel A304discoloration problem. By 4600 Date 10-15-2010 1316.
Hi A power wire brush should remove the discolouration but you would probably need to brush the entire area to achieve a uniform finish. I would prefer to use a pickling paste which should re-passivate the areas and will also remove all discolouration. How to Clean Stainless Steel That Is Discolored From Heat Step 1.
Wash the stainless steel using a soft cloth dipped in hot water into which a few drops of dishwashing soap have. Dry the stainless steel object with a towel. Dip a soft cloth in vinegar and rub over the surface of.
However like much other cookware the discoloration of stainless steel due to heat is curable so do not worry about it. Cleaning stubborn scratches on your cooktops can be quite difficult especially if the scratches look discolored. The stainless steel cookware is long lasting and durable but they are easy to stretch.
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. Colors that are likely to form on stainless steel 304 if heated in air. Stainless steel has a lower rate of heat transfer than carbon steel so the weld joint tends to stay at an elevated temperature longer than in a similar carbon steel application.
However in larger pieces of base material or ones with the greater chance of heat sink overall mass that can absorb heat from the weld zone there should be a corresponding lower amount of discoloration. Feb 03 2011 if per chance you take a piece of stainless 304L and heat it with a torch. Discoloration will begin around 600F.
This is more a straw color. After that it begins to change to hues of blue and indigoindicating higher temperatures. This is mostly due to oxidation of the metal in particular the chrome thats in stainless.
If memory serves its like 11 chromium. Heat input and discoloration in stainless steel welding. Facebook Twitter LinkedIn Pinterest WhatsApp Share via Email.
Nino Mascalo and Rob Koltz discuss heat input and weld discoloration in stainless steel welds. What are some ways to identify acceptable levels of heat. At times discoloration of stainless steel pans occurs due to high heat or settling oil on the surface.
It is essential to clean a stainless steel pan when it discolors. Since it is resistant to heat it wears out easily. This is why it is crucial to clean a discolored stainless steel pan to retain its shine and appearance.
When we heat the stainless steel this chromium reacts with the air gets oxidized. These oxidation spots are known as rainbow spots. Therefore we can conclude here- the rainbow stains are discoloration of stainless steel due to heat air-Causes Of White Spots Appearing On The Stainless Steel Pans.