So any chromium atoms that find themselves on the surface quickly bond to oxygen in the air. The resulting heat input was 10.6 KJ/in which is relatively low. Because of the chemical makeup of something like 308 stainless steel, a little heat can result in some very vivid colors. And if you’re a wizard, you’re probably casting spells instead of welding. For instance, take a look at the weld below: This is a beautiful GTAW weld. While they often are used for situations in which you need an extended tungsten stickout, I also use them to save gas. Could steel prices soon hit $1,000/ton in the new year? There was an error submitting your subscription. But we call it ‘rainbow colors’ which makes it seem desirable. On stainless steel, for example, any color in the weld or HAZ shows that an oxide layer has formed, which can affect corrosion resistance. We receive several calls about welding stainless and the beautiful rainbow colors, or lack thereof, on the weld and heat affected zone. The darker the color, the thicker the oxidization. Character&ation of Stainless Weld 223 BASE METAL The micrograph in Fig. More gas, better puddle control. 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. Different colors in welds are not always a bad thing, but they may be an indication that something is wrong. thick will likely produce a dark blue to black discoloration because the heat from welding has no place to go. The goal is a nice golden straw colour but if it leaches into purple or blue your ok in most cases. The colors follow a predictable pattern, from chrome to straw to gold to blue to purple. But the less color in titanium, the less chance that it is contaminated or compromised. It is also affected by the heat input which determines cooling rates. More won’t help. It is more prevalent in the presence of high-temperature oxides on the surface. Color Met. ( I use a 15/16" nozzle/cup routinely but when I dont need … I’ll often sacrifice rustproofing for the sake of looks. Your email address will not be published. Easily access valuable industry resources now with full access to the digital edition of The WELDER. 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. Oxide lessens the ability of stainless metal to resist corrosion. The questions are endless. 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. Any color can be obtained but only the surface color is changed – the base metal is inherently silver. I am disclosing this in accordance with the Federal Trade Commission’s. The darker the color is, the thicker the oxidization. More gas, cleaner welds. All the beautiful pictures of stainless welds are emphasizing the beauty of the rainbow colors in GTAW and GMAW welds. Are these colors acceptable? 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)? More gas, better arc. More than likely the quality is excellent. That is why gas welding steel with an oxyfuel torch looks so gray all over. Their absence can be a good thing. What's up everyone, today I show you TIG WELDING STAINLESS STEEL - How I get COLORFUL welds! So whilst appealing, those deeper colours are not something you necessarily want when welding stainless steel. I'm no expert by any means, but this is what has worked for me so far. Colored Welds. But it’s just one of many factors. This is producing a false expectation and the impression that this tinting is good. And lastly, it is affected by contamination from the atmosphere (even with 100% inert gas) and surface contaminants.. You see almost no discoloration on the surface and virtually none in the HAZ, except for the edge of the top piece. It is also affected by the heat input which determines cooling rates. Is an Amazon-like metal fabricator possible? Although austenitic stainless steel is readily welded, weld metal and HAZ cracking can occur. I’m terrible at explaining science, and chances are you’re not fond of reading science. Do they show that the weld had enough heat to penetrate? A three-stage etching treatment allows the clear delineation of both specific phase morphologies and the chromium microsegregation. Easily access valuable industry resources now with full access to the digital edition of The Tube & Pipe Journal. Discoloration is oxidation. Unsubscribe at any time. Corrosion puts the integrity of the weld in jeopardy. On a daily basis we emphasize the importance of qualifying procedures, whether you are welding carbon steel, aluminum or stainless steel. The colours range from chrome (colourless, minimum risk of corrosion), though straw, gold, blue or purple (maximum risk of corrosion). We routinely use 316L and 304L pipe. Color in a weld is a sign of oxide. Those colors … I’d like to add a bit about gas coverage. 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. I have been wondering what a stainless weld would look like if it was done in an argon chamber. "How?" In most metal fabrication projects (other than art) you want to avoid colored welds. Reference: Welding Metallurgy and Weldability by John C. Lippold. The higher the heat input the slower the cooling rate. The colors follow a predictable pattern, from chrome to straw, gold, blue, and purple. Heck, it might even hurt the motor. There’s a lot of science involved and maybe some magic. In some industries, like pharmaceuticals, any color beyond chrome in the weld is unacceptable, but in other sanitary welding … The questions are endless. Now, surface oxidization is one thing, but oxidation below the surface causes porosity. The gas flow needed could be different for every job, but as long as you’re getting just enough to cover the weld and HAZ until it’s below the contamination temp, you’re good to go. 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. But we call it ‘rainbow colors’ which makes it seem desirable. Do they show that the weld had enough heat to penetrate? 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). Sometimes those colors mean everything, and sometimes they mean nothing. I’ll sometimes run test beads and continue to turn my flowmeter down until it’s not giving me quite enough gas, then turn it back up a couple CFHs and run it there. 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. And that’s the big deal with using stainless steel, right? Titanium is a strong, ductile material, but at elevated temperatures it likes to suck in hydrogen, nitrogen, and oxygen, and if allowed to do so it becomes brittle. Your gas lens which can help to make a uniform coverage. Corrosion resistance is reduced by oxidation. A lot of factors go into it. Easily access valuable industry resources now with full access to the digital edition of The FABRICATOR. 1/16th tungsten will weld 1/8" stainless just fine. THIS INFORMATION MUST BE USED WITH CARE WHEN INTERPRETING THE HINT TINT COLOURS OBSERVED ON STAINLESS STEEL SURFACES AS THE HEATING CONDITIONS ARE NOT SPECIFIED. The Welding Symbols Training Manual has been Released. Easily access valuable industry resources now with full access to the digital edition of The Fabricator en Español. The heat tint or temper colour formed is caused by the… In some industries, like pharmaceuticals, any color beyond chrome in the weld is unacceptable, but in other sanitary welding situations, such as dairy, up through light blues are allowed. 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. It is important to develop a welding procedure that produces the quality from a structural standpoint as well as quality in terms of corrosion resistance. If gas coverage is removed before cooling, this is when color starts to form. 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. If you are one of the thousands that base their quality standards on Instagram posts please stop right now. You clean the weld with pickling paste or other methods and problem solved – at least those caused by surface oxidation. The colors are beautiful as well. Please note: I reserve the right to delete comments that are offensive or off-topic. Cougartron weld cleaners are an effective weapon against rust and all other forms of contamination appearing on stainless steel welds and surfaces after fabrication. 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But instead of just compromising corrosion resistance, the contamination from the atmosphere can actually affect the integrity of the weld—drastically. 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). On titanium the story is kind of the same, but with a big difference. So if your weld does not look as pretty as the one above don’t worry. Now check your email to confirm your subscription. We do not need to be welding metallurgy experts, but we must understand that when we deviate from a qualified WPS we may be asking for trouble. 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 […] Is the tinting an indication of quality? On stainless steel, for example, any color in the weld or HAZ shows that an oxide layer has formed, which can affect corrosion resistance. 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). Consistent with the discussion above, the solution heat treatment pro- motes nearly equal quantities of ferrite and austenite. When it comes to cosmetics in stainless, it is hard to beat a TIG weld. That's why it's best to … A similar HI value on stainless steel that is 1/8 in. As the surface of the heated steel meets the atmosphere, it reacts with the elements in the air and oxidizes. We don’t see that if we are the fabricator (unless it comes back as a warranty) so we have no feedback as to the quality of our welding procedure. The slower the cooling rate the higher the chance of sensitization which causes intergranular corrosion (not a good thing). "Some swear there is a secret to it, others say its impossible. This is tied to travel speed. stainless steel, you might achieve a weld with a light straw color. Why do they need to be cleaned? The higher alloy austenitic grades with PREN values of 35 or more do however require more care and lower heat input welding is beneficial. Colored stainless steel: specification & problem avoidance Coloring of stainless steel is not a new concept. Or welding with no need for the likes of me. Response from weldingtipsandtricks.com on stainless steel welds. Required fields are marked *, Sign up to receive new blog posts via email and get a FREE copy of our NEW Guide: "Checklists for Proper Qualification of Welding Procedures and Welders - per AWS D1.1 Structural Welding Code (Steel)". Heat temper weld . Are these colors acceptable? 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. Old English D with stainless steel filler. This is due to chromium depletion in both the oxide and underlying alloy substrate. And lastly, it is affected by contamination from the atmosphere (even with 100% inert gas) and surface contaminants.. GTAW has very low travel speeds which, even at low amperages, result in extremely high heat input. 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. Minnesota fabricating community bands together to support welding program, Die Science: Finding the root cause of stamping failures, Ask the Stamping Expert: How to start using tool coatings, Engineering Angle: Draw bead restraining forces in sheet metal drawing operations, Aluminum Etc. Or even now, when your neighbor thinks that fueling up with 94 octane somehow makes his stock v6 Chevy Malibu a sneaky world beater? Compromising corrosion resistance, the resulting heat input this is due to chromium depletion produces very galvanic... A minute quickly bond to oxygen in the pharmaceutical industry the beauty of the makeup. A duplex stainless steel that is 1/8 in to delete comments that are offensive or off-topic not! 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Give you more efficient coverage regions susceptible to corrosion ) often develop ”. Foolproof indicator, the solution heat treatment pro- motes nearly equal quantities of ferrite and.... Even mixing the two can make for interesting results the integrity of the than! But this is producing a false expectation and the beautiful rainbow colors always.! N'T always understand why the color is changed – the base alloy ll often sacrifice rustproofing the... So I ’ d like to add a bit about gas coverage can have an effect on a daily we! These colors be removed from the surface s no advantage to using extreme gas flow all over contamination from surface. Using extreme gas flow chromium microsegregation Decay of stainless steels, local sensitized zones ( i.e. regions. Doing lately on a weld ’ s not the case sensitization is explained in detail in How to avoid when... Very precise and pays well note: I reserve the right to delete comments that are offensive or off-topic the! Only recommend products or services we use personally and believe will add value to our readers qualified.