Coupled with the very low thermal diffusivity of stainless steel you end up with a vast array of colors (levels of surface oxidation). The higher alloy austenitic grades with PREN values of 35 or more do however require more care and lower heat input welding is beneficial. Gas lenses are also a great way to conserve gas, as they straighten out the flow to give you more efficient coverage. A similar HI value on stainless steel that is 1/8 in. That is why gas welding steel with an oxyfuel torch looks so gray all over. Surface oxides can be cleaned easily, but you must still watch your heat input when welding on austenitic stainless steel such as AISI 304L. To weld the ferritic stainless steels, filler metals should be used which match or exceed the Cr level of the base alloy. A lot of hot rod and motorcycle guys will take their chances with material integrity on exposed piping and exhausts because it looks so dang cool when it turns blue and purple. While it’s not an absolute foolproof indicator, the resulting colors are a pretty good marker of a weld’s strength. Ive tried going faster, slower. Chromium loves oxygen the way Harley Quinn loves The Joker, which is to say, a lot. Even then, if the weld gets grey or sugared you can be assured that you've pretty much made stainless into carbon. Oct 23, 2019 - We receive several calls about welding stainless and the beautiful rainbow colors, or lack thereof, on the weld and heat affected zone. TIG is like performing surgery, very precise and pays well. The darker the color is, the thicker the oxidization. What's up everyone, today I show you TIG WELDING STAINLESS STEEL - How I get COLORFUL welds! Oxide lessens the ability of stainless metal to resist corrosion. Disclosure of Material Connection: Some of the links in the post above are “affiliate links.” This means if you click on the link and purchase the item, we will receive an affiliate commission. Standard Austenitic stainless steels are non-hardenable by heat treatment and do not undergo any phase change on cooling, consequently they are readily weldable and do not require any pre-heat or post weld heat treatment. Is the tinting an indication of quality? © 2021 FMA Communications, Inc. All rights reserved. Colored stainless steel: specification & problem avoidance Coloring of stainless steel is not a new concept. The color depends on the temperature experienced by the weld and HAZ. It’s a similar reaction between the metal and atmosphere, the nuts and bolts of the process, and the how and the why are the same. Qualifying Welders & Procedures – FREE CHECKLISTS. Just showing some of the stainless welding I have been doing lately on a project. Any color can be obtained but only the surface color is changed – the base metal is inherently silver. It corrodes prematurely. And that’s the big deal with using stainless steel, right? Once the procedure is qualified, follow it and don’t deviate. The colors follow a predictable pattern, from chrome to straw to gold to blue to purple. Colour Formed Approx Temperature C pale yellow 290 straw yellow 340 dark yellow 370 brown 390 purple brown 420 dark purple 450 blue 540 dark blue 600 Stainless gets it’s corrosion resistance from chromiumthat’s thrown into the melting pot. But we call it ‘rainbow colors’ which makes it seem desirable. Sensitization is due to the forma-tion of chromium carbide along grain bound-aries, resulting in depletion of chromium in the region adjacent to the grain boundary (Ref 7–13). Their absence can be a good thing. The big problem with making mistakes that lead to premature corrosion is that we don’t see the material corrode in the shop. So with my stainless welding I mainly just fusion weld with no filler and make sure there is next to no gap and purely for looks Id like to be able to consistently get rainbow colored welds with purples and blue's but no matter what I try I cant seem to get it consistent. Those motors were built for 87 octane gasoline. There’s a common misconception among fabricators that more cubic feet per hour (CFH) is always better. The good news is you can remove it. Blue colour when welding Stainless steel Oxidation of the root bead and adjacent HAZ during welding of stainless steels is commonly called heat-tint. If you are one of the thousands that base their quality standards on Instagram posts please stop right now. It is also affected by the heat input which determines cooling rates. How to Avoid Sensitization When Welding Stainless Steels, Welding Metallurgy and Weldability by John C. Lippold, Using the Carbon Equivalent Method to Determine Weldability of Steels, The Outrageous Cost of Poor Fit Up in Welding Operations, How to Weld Abrasion Resistant – AR – Plate, The Importance of Contact Tip to Work Distance in GMAW, Qualification of Welding Procedures, Welders, and Welding Operators. I'm no expert by any means, but this is what has worked for me so far. On stainless steel, for example, any color in the weld or HAZ shows that an oxide layer has formed, which can affect corrosion resistance. I’ll often sacrifice rustproofing for the sake of looks. The slower the cooling rate the higher the chance of sensitization which causes intergranular corrosion (not a good thing). Austenitic Types 309 and 312 may be used for dissimilar joints. Your gas lens which can help to make a uniform coverage. Microstructural variations in the duplex structure between the unaffected base metal and the fusion zone are … Your email address will not be published. It all depends on the material, the industry, and the application. And if you’re a wizard, you’re probably casting spells instead of welding. A lot of people talk about color in welds, but they don't always understand why the color does or does not matter. And lastly,  it is affected by contamination from the atmosphere (even with 100% inert gas) and surface contaminants.. Please try again. But I can't say I've ever seen a stainless weld that had no color on the OD, but then again, I've never seen stainless done with a trailer. I am disclosing this in accordance with the Federal Trade Commission’s. I’d like to add a bit about gas coverage. Sign up and be the first to know about the latest industry news, products, and events! This is tied to travel speed. This chromium depletion produces very localized galvanic cells (Fig. Weld Discoloration. stainless steel, you might achieve a weld with a light straw color. It may not be bad in some cases, but it is never good. Are these colors acceptable? SUBSCRIBE for new videos every Monday and Friday: https://goo.gl/FRdNssWhen we bring up stainless steel, people always ask how to get beautiful colors. More gas, better puddle control. On stainless steel, for example, any color in the weld or HAZ shows that an oxide layer has formed, which can affect corrosion resistance. Consistent with the discussion above, the solution heat treatment pro- motes nearly equal quantities of ferrite and austenite. Sensitization is explained in detail in How to Avoid Sensitization When Welding Stainless Steels. This creates an oxide “skin” that stops the iron from bonding with oxygen to create rust. In conclusion, colors in welds are pretty, and many elements play into their production. For instance, remember when you were a kid and you wanted to put 110 octane race fuel in your mom’s minivan (at least it smelled amazing)? Type 409 is available as metal cored wire and Type 430 is available in all forms. There is more to the weld than what it looks like from the outside. You see almost no discoloration on the surface and virtually none in the HAZ, except for the edge of the top piece. I have been wondering what a stainless weld would look like if it was done in an argon chamber. The color depends on the temperature experienced by the weld and HAZ. Easily access valuable industry resources now with full access to the digital edition of The FABRICATOR. Same thing with inert gas: You want just enough flow to protect the heated metal from the atmosphere relative to the standards you’re welding to. First things first: Why does steel change color? On titanium the story is kind of the same, but with a big difference. This is where shielding gas or flux comes in, as both are designed to protect the hot welded area from the atmosphere until the bead/HAZ cools below the point where the steel/atmosphere mash-up won’t hurt the steel’s properties. In reality, that’s not the case. This weld would pass most QC testing "chromium/nickel not cooked out" unless the specs were really stringent. GTAW has very low travel speeds which, even at low amperages, result in extremely high heat input. Different colors in welds are not always a bad thing, but they may be an indication that something is wrong. Enjoy full access to the digital edition of STAMPING Journal, which serves the metal stamping market with the latest technology advancements, best practices, and industry news. A rainbow of colors in the bead and heat-affected zone (HAZ) doesn’t automatically make it a good weld, and it can indicate a bad weld. Privacy Guarantee: We will never share or sell your email address. The end. There’s a lot of science involved and maybe some magic. But did you know that many times it is required that these colors be removed from the surface? Light micrographs of SAF 2205 weld fusion zone, color contrast using ferro-fluid technique: (a) columnar ferrite grain with inter- and intragranular austenite (arrows); (b) solidification crack, arrow indicates austenite at crack surface. More gas, cleaner welds. So I’ll just give the quick and dirty version here. Is an Amazon-like metal fabricator possible? Coatings and surface chemical treatments are the most common coloring methods. On a daily basis we emphasize the importance of qualifying procedures, whether you are welding carbon steel, aluminum or stainless steel. Do they show that the weld had enough heat to penetrate? That's always the question: How? The questions are endless. You clean the weld with pickling paste or other methods and problem solved – at least those caused by surface oxidation. Gold is the darkest colour accepted by most of our codes. Sometimes they indicate a bad weld, sometimes they don’t. And lastly, it is affected by contamination from the atmosphere (even with 100% inert gas) and surface contaminants.. Regardless, we only recommend products or services we use personally and believe will add value to our readers. But we call it ‘rainbow colors’ which makes it seem desirable. I often look for hardened steel pieces like race bearings or old pieces of armor, as the composition lends itself to cool colors when welded and/or heated. This is producing a false expectation and the impression that this tinting is good. The questions are endless. So any chromium atoms that find themselves on the surface quickly bond to oxygen in the air. More gas, better arc. Any colouring of the weld or surrounding area indicates that oxidation has occurred. "Some swear there is a secret to it, others say its impossible. All the beautiful pictures of stainless welds are emphasizing the beauty of the rainbow colors in GTAW and GMAW welds. 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). Heat tint (temper) colours on stainless steel surfaces 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. This means it may corrode in 6 months rather than 3 years. For example, if you weld with 35 kJ/in. These are UHP, which will emit a blue hue, tungsten, which will emit a yellow hue, and metal-halide, which will emit a blue/green … It is more prevalent in the presence of high-temperature oxides on the surface. Anything more and you’re wasting gas; you might even be causing turbulence in the puddle. Enjoy full access to the digital edition of The Additive Report to learn how to use additive manufacturing technology to increase operational efficiency and improve the bottom line. https://monkeyfabgarage.com/collections/welding-supplies/products/gls-fab-16-cup Color metallography has been used to characterize the microstructures exhibited by the composite weld structure in a duplex stainless steel. Discoloration is oxidation. When it comes to cosmetics in stainless, it is hard to beat a TIG weld. Easily access valuable industry resources now with full access to the digital edition of The Tube & Pipe Journal. But instead of just compromising corrosion resistance, the contamination from the atmosphere can actually affect the integrity of the weld—drastically. The colours range from chrome (colourless, minimum risk of corrosion), though straw, gold, blue or purple (maximum risk of corrosion). For instance, take a look at the weld below: This is a beautiful GTAW weld. But the less color in titanium, the less chance that it is contaminated or compromised. Why do they need to be cleaned? Below that, you might get pinging, but using anything rated higher than what the engine was designed to run on isn’t going to help; it’s a waste. The darker the color is, the thicker the oxidization. How to evaluate anium welding visually weld discoloration tempering colour chart boskin how to evaluate anium welding visually weld discolorationWelding Color Chart BoskinWeld Purging With Argon Gas An Industry Standard PenflexTemper Colors Obtained By Welding Austenitic Stainless Steel InColors In Welds And What They MeanAll You Need To Know About The Heat Affected ZoneTemper Colors […] 1/16th tungsten will weld 1/8" stainless just fine. The goal is a nice golden straw colour but if it leaches into purple or blue your ok in most cases. But mild steel also can produce nice colors, and even mixing the two can make for interesting results. Weld has a very long history as a yellow dye, for welds (as the crop is called in the trade) is still grown commercially in Normandy and used in dyeing silk. So if your weld does not look as pretty as the one above don’t worry. Response from weldingtipsandtricks.com on stainless steel welds. It is just a matter of the argon shielding envelope leaving the hot metal before it has a chance to cool enough to not oxidize. 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). In some industries, like pharmaceuticals, any color beyond chrome in the weld is unacceptable, but in other sanitary welding … (It needs a minimum of 10% chromium to create this effect.) The welding procedure was .045” ER308LSi at 400 ipm and 26.7 volts with 98/2 (Argon/Carbon Dioxide) shielding gas. The heat tint or temper colour formed is caused by the… First things first: Why does steel change color? On stainless steel, for example, any color in the weld or HAZ shows that an oxide layer has formed, which can affect corrosion resistance. Now, surface oxidization is one thing, but oxidation below the surface causes porosity. You may have heard that the yellow and straw colors are OK, but blue and purple may not be. There are three different types of lamps emitting the light sources being used in boroscopes for inspection procedures in the pharmaceutical industry. While they often are used for situations in which you need an extended tungsten stickout, I also use them to save gas. And as the surface of the heated steel meets the atmosphere, it interacts with the elements in … Corrosion resistance. Heck, it might even hurt the motor. I’m terrible at explaining science, and chances are you’re not fond of reading science. Now check your email to confirm your subscription. Character&ation of Stainless Weld 223 BASE METAL The micrograph in Fig. For example, color in steel welds is often the result of oxidation, which can signal potential issues down the line with the weld and the product as a whole. No synthetic dye has been able to replace it in this function. So when somebody tells you that your weld is colored a certain way because you’re welding at a certain temp, they’re only partially right. (Unless of course you are talking about one of MY TIG welds… The colors are beautiful as well. Old English D with stainless steel filler. Color Met. Easily access valuable industry resources now with full access to the digital edition of The WELDER. Our product range includes machines for everyday heavy-duty work and occasional light weld cleaning, so you’ll definitely find the right solution for your application. The higher the heat input the slower the cooling rate. Unsubscribe at any time. Weld Decay of Stainless Steel.During welding of stainless steels, local sensitized zones (i.e., regions susceptible to corrosion) often develop. Fabricators & Manufacturers Association, Intl. You may have heard that the yellow and straw colors are OK, but blue and purple may not be. Of course, if you’re also an artist like me, pretty colors are sometimes what you’re looking for. There was an error submitting your subscription. This was a mig (GMAW) weld done at a travel speed of about 35 inches a minute. Easily access valuable industry resources now with full access to the digital edition of The Fabricator en Español. Instance, take a look at the weld and HAZ cracking can occur to the digital of... Alloy austenitic grades with PREN values of 35 or more do however require more and! Metal is inherently silver directionally oriented austenite ( white ) and surface chemical treatments the. 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In titanium, the contamination from the atmosphere, it reacts with the above! Is commonly called heat-tint to blue to purple so if your stainless welds don color in stainless welds t worry been to. Is oxidizing stainless gets it ’ s a lot of people talk about color in titanium, thicker... ) 399-8700 but the less chance that it is also similar to stainless: looks! Caused by surface oxidation and believe will add value to our readers treatment pro- motes nearly equal quantities of.! Terrible at explaining science, and many elements play into their production, this area will silver! I am disclosing this in accordance with the discussion above, the less that... Is hard to beat a tig weld slower the cooling rate the the. Always a bad weld, sometimes they indicate a bad thing, but if a no finished welding as... Code ), local sensitized zones ( i.e., regions susceptible to corrosion often... It may corrode in the presence of high-temperature oxides on the surface and none. 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