Dip a soft cloth in vinegar and rub over the surface of the stainless steel. I am a metal stamper producing a star washer out of 410 annealed stainless. Steel Wire Products, The part was always bright after heat treating. SUS310S Stainless Steel Sheet | High temperature discoloration | Reason. Nor should brushes that have been used to clean plain steel. As noted in an AK Steel data sheet on 304 stainless steel, the alloy reaches its melting point at the 2,550 °F – 2,650 °F (1399 °C – 1454 °C) range. How do you clean oxidized stainless steel? The heat treater asked if discoloration was a problem. Length of time that the alloy is subjected to a given temperature. I have further information about the blueing of stainless steel during annealing in hydrogen atmosphere. From sterilization of parts to the heat treatment of specific alloys, there are a ton of applications that might require a custom parts cleaning basket to be put through temperatures in excess of 1,000 °F. Sharp, sudden impacts could also cause similar issues. Marlin Steel is a leading manufacturer of custom‐engineered products from steel wire Stainless Steel Discoloration: 4 Questions Engineers Need Answered, resistance to oxidation and discoloration. Marlin Steel is a leading manufacturer of custom‐engineered products from steel wire The photos far left show the weld discoloration using the naked eye while the photos Response from weldingtipsandtricks.com on stainless steel welds. Let’s go back to the times approaching the 20th century. The photo at left illustrates the color on the weld and in the HAZ of a weld made with 10 ppm O 2. While Penn Stainless says that 330 resists scaling and oxidation at temperatures up to 2,000 °F, we generally recommend limiting exposure to 1,900 °F, or 940 °C. 440C stainless steel (the “C” denotes a higher carbon content) is well-suited for tool and die applications in the food processing industry due to its higher hardness. Though these marks appear as damage to the surface, they are simply a discoloration that can easily be removed. Another leading cause of discoloration in stainless steel is the use of extremely caustic chemicals that override the steel’s protective oxide layer. In trying to minimize distortion, different heat treat options were being tried. It is easy to care for and clean, but occasionally an unsightly discoloration develops. I have a question about 302 and 304 stainless steel turning blue during heat treating. Passivation typically is accomplished either through an appropriate bright annealing of the stainless steel or by subjecting the surface to an appropriate chemical treatment. These are just a few of the things that a mechanical engineer will need to know prior to creating a custom stainless steel basket or tray so as to ensure top performance and minimize the risk of discoloration. Some alloys can better resist oxidation from high temperatures, which is a major factor in choosing a particular alloy to use. of a piece of 1-1/2" 316L stainless steel tube split in half. However, before you settle on a specific alloy for the custom parts washing baskets in your production application, be sure to check with an experienced mechanical engineer, as they can take into account other factors that might affect your custom basket’s design needs, such as chemicals used in your process or weight load of the basket. While stainless steel is famous for its resistance to oxidation and discoloration in most “normal” use cases, it’s important to note that no alloy is 100% impervious under all situations. I asked my customer, he said no. Is Grade 317 Stainless Steel Worth the Cost Over 316 & 304? 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. of parts/materials, and had a capacity of 100 lbs. The colors are affected to some extent by the composition of the steel and the method may not be dependable. The cleaning fluid still remains on the surface of the stainless steel screw, so after a period of use, the cleaning fluid will react with it. For example, say that you had a container made of plain steel that you were passing through a process where the temperature would reach 1,000 °F. and sheet metal. What is the Temperature Range for 304 Stainless Steel vs. 316 vs. 330? An oxide layer that you can see by color change is not a protective oxide layer that is obtained by chemical passivation. The surface discoloration on stainless steel after grinding or welding is surface oxidation. On the other hand, 304 stainless is one of the oldest variants of stainless steel and is typically used in household applications and is one of the most common metal alloys available today. This expansion coefficient not only varies between steel grades, it also increases slightly with temperature. The method of moving a basket affects what impact risks there are, as well as what special attachments the basket might need (handles, hoist rings, flat/rounded corners, etc.). In many cases, exposure to extreme temperatures will compromise the steel’s protective oxide layer, stripping it away and allowing rust to start accumulating. You will have noticed that it gets a brown stain within minutes. This is because the basket would now have a maximum weight limit of 20 lbs. Chromium carbides form in stainless steels along either side of a weld. Also, extremely high temperatures might limit the viability of different coatings that might be used with the steel. Hand Sanitizer Stands in Stock - Ships Today! Simply setting a hot pan on the surface can result in a mark left behind. Looking at your picture, something either came into contact with the bottom of the iPhone grill area or it’s heat that’s being produced from your charger, which is discoloring the metal like that. The stainless steel then is rapidly cooled (through the temperature range of 1,600 and 800 degrees F, or 870 and 425 degrees C) to inhibit carbide precipitation, and then at lower temperatures exposed to air, where the protective oxide film forms spontaneously. On the other hand, 304 stainless is one of the oldest variants of stainless steel and is typically used in household applications and is one of the most common metal alloys available today. Melting Points of Heat-Treating Baths Another popular alloy of stainless steel, grade 316 SS is often used for applications that involve powerful corrosives, as its corrosion resistance generally exceeds that of grade 304 SS. Iron or plain steel brushes should never be used to scour the surface of a stainless steel object. To protect your stainless steel wire forms and sheet metal products against discoloration, there are numerous questions that engineers designing stainless steel products will need answered, including: Different stainless steel alloys will have different reactions to elevated temperatures. While not normally a contributing factor to the discoloration of stainless steel, the load on a piece of stainless steel wire or sheet metal can be a contributing factor to damage when other stress factors are present. When cooking with stainless steel, we recommend that you use lower heat to cook your food. However, the downside to using chromium is that when it is heated to extremely high temperatures, it will leave a different colored surface behind. The Difference is in the Numbers The parts came back dull grey almost black appearance. Contact: 01937 584440 That is why gas welding steel with an oxyfuel torch looks so gray all over. With a well-optimized starting design and proper care, you can prevent the discoloration of your stainless steel baskets and trays for years or even decades—longer than the useful life of most polymer compounds. Other alloys, such as grade 316 SS, are much less susceptible to discoloration and corrosion from salt. 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. During welding, some discoloration, which is a thin oxide layer, will be evident in the heated area near the weld. The heat tint or temper colour formed is caused by the… Q. I'm new to the whole method of heat treating but I've got a question that I hope some of you have the answers to. Removal of weld discoloration. Surgical instruments, food processing parts and mold components are typically made from 420 stainless steel. Grade 304 has a coefficient of 17.2 x 10-6 /°C over the temperature range 0 to 100°C but increases above this temperature. Bright Annealing.Bright annealing entails heating the stainless steel to a suitably high temperature (usually more than 1,900 degrees F, or 1,040 degrees C) in a reducing atmosphere such as dry hydrogen gas. The heat treater asked if discoloration was a problem. That’s *exactly* what stainless looks like when it’s under a higher temperature, it starts to form a rainbow-like color. In laser cleaning of stainless steel surfaces, the discoloration takes place on the surfaces irradiated by excimer lasers in the air as laser fluence and pulse number exceed a discoloration threshold. Naturally, the closer the steel is to its melting point, the more tensile strength it loses. Also, take a look at the chart to see how the temperature can discolor your grill. Color temperature imaging. Figure 3. For any formulation of stainless steel alloy, there is always some combination of temperature, chemicals, mechanical force, and other stress factors that could compromise the appearance of the steel. 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. ing of stainless steel parts is performed in continuous mesh belt conveyor furnaces at tem-peratures up to approximately 1150 °C (2100 °F). 2648 Merchant DriveBaltimore, MD 21230-3307. Because of this, many of Marlin’s clients ask the following question: “what’s the temperature range for (insert given steel alloy here)?”. From the above analysis of the discoloration principle, it can be seen that the root cause of the discoloration is the oxidation of the surface of the stainless steel sheet, which leads to the interference color caused by the change of the thickness of the passivation film (oxide film). With this in mind, what are the temperature ranges of different stainless steel alloys such as grade 304, 316, and 330? Oxidation of stainless steel indicates that the metal temperature at the oxidized surface was in excess of 1000 °F. Contact: 01937 584440 hbspt.cta._relativeUrls=true;hbspt.cta.load(223565, 'b7462dd0-e24f-4f7a-a87d-5e26bfa0ff87', {}); A summary sheet comparing key characteristics of commonly used stainless steel alloys. 2. This discoloration is sometimes known as “bluing.” Date: August 24, 2019 Author: Thanh ( QC ) Nguyen Le 0 Comments Discoloration on a stainless steel weld caused by overheating, which not only affects a material’s color but degrades its c orrosion resistance and mechanical properties as well. Excessive weight well beyond the maximum load of the steel alloy can cause it to deform. In other words, you can expose grade 304 alloy steel to temperatures of up to 1,598 °F for short periods of time without ill effect, and for extended periods of time in temperatures of up to 1,697 °F. If your application’s operating temperature exceeds 1,900 °F, you might want to consider a different alloy, such as Inconel, which is specifically formulated for high-temperature applications. In addition, the quality of the air and what contaminants are in it can also affect the thickness of the layer. At that temperature, the steel would lose its tensile strength, becoming only a fifth as strong as it is at room temperature. The designation 18/10 refers to the ratio of metals in stainless steel. One of the key properties of any stainless steel alloy is its resistance to oxidation. So, if the basket were to be loaded with 50 lbs. Is 316 Stainless Steel Worth the Extra Cost over 304? Its industrial material handling containers serve many industries including aerospace, defense, medical and automotive. While this technique may seem basic to some of you — cooking on high heat can burn food and give you less flexibility as you cook — stainless steel will discolor from constant high heat. This could, in turn, impact other performance characteristics of the steel, such as its resistance to discoloration. Heat stains can occur on stainless steel appliances for a variety of reasons. As metals heat up, they can undergo expansion that causes them to lose their shape—ruining delicately-assembled custom wire and sheet metal forms. Stainless Steel Baskets. In trying to minimize distortion, different heat treat options were being tried. and sheet metal. Figure 3 | 303 stainless steel parts discolored (gray/greenish tint) by a heat exchanger leak opening up with exposure to hot gases during quenching then closing up again at room temperature. Heating the stainless steel to temperatures in excess 800 °F can cause metallurgical changes and reduce corrosion resistance in a manner that is not corrected by surface cleaning or chemical passivation. But really, stainless steel that is exposed to high heat can cause some discoloration depending on the temperature reached. The Difference is in the Numbers In The color of stainless steel surfaces changes to that of γ-Fe 2 O 3. In This oxidation causes the discoloration often seen on steel after heat treatments. The heat streaks should … normally, the basket would fail. Well, the answer varies based on a few different factors, including: Just to name a few potential factors that might affect the performance of a steel alloy being exposed to high temperature applications. Cleaning stainless steel pans with baking soda brings them back to the shine they had when you first purchased them. Organic contamina… This is why engineers need to know not only the maximum load weight of a basket, but how it will be moved from one manufacturing process to the next. Mechanical removal or this heat tint should be limited to clean glass bead blasting, flapper wheels, aluminum oxide discs, and wire brushing with austenitic stainless steel wire brushes. The temperature tolerance of grade 316 stainless steel is close to that of grade 304, being just a little bit lower. A discussion started in 2007 but continuing through 2019. for high-temperature service. So, there are the operation temperature limits of three of the most popular stainless steel alloys. The part was always bright after heat treating. Stainless Steel Baskets. Also discussed, but as a secondary consideration, are the corrosion-resistance qualities of stainless steels at elevated temperatures. The photos far left show the weld discoloration using the naked eye while the photos Surface discoloration and red rust after heat treatment of the phosphate film on the surface of the stainless steel screw. Figure 3. Chromium gives stainless steel its rust and stain-resistant properties, while nickel gives it its color. Heat Treating Stainless Steel Discoloration. If steel is heated in an oxidizing atmosphere - like air - a film of oxide forms on the surface and the color changes as the temperature increases. Discoloration is oxidation. The chromium is included in the creation of stainless steel to avoid rusting or corrosion over time. High temperatures can compromise the the oxidation resistance of steel alloys, leading them to become rusted and weakening their structural integrity. Unlike the previous two stainless steel alloys, grade 330 stainless is frequently specifically marketed as a high-temperature resistant alloy. The characteristics that make some of the stainless steels particularly useful in high-temperature environments are described, and typical engineering data are presented. at 1,000 °F. Stainless steel is made of different components, and one of those components is chromium. As noted on the Penn Stainless website, grade 330 alloy “has great oxidation resistance and resists scale formation up to about 2000°F due to its chromium and nickel content.”. For example, salt and other chlorides may compromise the outer layer of a piece of grade 304 stainless steel with ease. Colors that are likely to form on stainless steel 304 if heated in air. Typically speaking, the alloy has between 18 and 22% chromium content, and 34 to 37% nickel content. Contact a Marlin Steel Mechanical Engineer Expert for your next 316 Stainless Steel project. While stainless steel is famous for its resistance to oxidation and discoloration in most “normal” use cases, it’s important to note that no alloy is 100% impervious under all situations. Steel Tempering Colour Chart – West Yorkshire Steel Co Ltd, ISO quality steel suppliers, UK delivery only £25 The largest knowledge of steel grades online. Mix the baking soda with a small amount of water to make a paste and clean with a damp cloth. Steel Tempering Colour Chart – West Yorkshire Steel Co Ltd, ISO quality steel suppliers, UK delivery only £25 The largest knowledge of steel grades online. The reaction causes discoloration of the surface of the stainless steel screw. Stainless steel brings the look of sleek sophistication to your kitchen. Basic cleaning to remove particulates from the surface of stainless steel can help prevent discoloration—unless the wrong tools and techniques are applied. Have you ever sliced an apple with a carbon steel knife? Carbide precipitation may occur in certain austenitic stainless steels in a temperature range of 800-1650°F (427-899°C). Its industrial material handling containers serve many industries including aerospace, defense, medical and automotive. Overheating in Stainless steel welding! Check with the manufacturer to make sure your pan is oven-safe, but most high-quality stainless steel is rated for temperatures up to 500°. Custom Wire Baskets, Color temperature imaging. The effect of thermal expansion is most noticeable where components are restrained, as the expansion results in buckling and bending. For any formulation of stainless steel alloy, there is always some combination of temperature, chemicals, mechanical force, and other stress factors that could compromise the appearance of the steel. In both procedures the surface is cleaned of contaminants and the metal surface is subsequently oxidized. First, the fact that the discoloration (staining) is brown in coloration suggests that the oxide is forming on the part surface during cooling when the temperature is in the range of (approximate) 245 ºC – 270ºC (475 ºF – 520ºF). The parts came back dull grey almost black appearance. A sample of stainless that was heated to 600 degrees for a long time may display the same color as one heated to 800 degrees for a shorter time. Figure 2 | 13-8Mo precipitation hardening stainless steel medical part discolored by air in the backfill gas. Plain iron, once embedded in the surface of the steel, creates gaps in the oxide layer that allow rust particles to accumulate. This may alter other characteristics of some stainless steel alloys as the crystalline structures of the steel atoms change. More specifically, 18/10 means that the stainless steel flatware has roughly 18 percent chromium and 10 percent nickel. Learn more about how to choose the perfect basket design for the job at the link below: hbspt.cta._relativeUrls=true;hbspt.cta.load(223565, 'f95d92a2-f57c-4816-abed-e8c490318c13', {}); A summary sheet comparing key characteristics of commonly used stainless steel alloys. Hand Sanitizer Stands in Stock - Ships Today! 2648 Merchant DriveBaltimore, MD 21230-3307. we generally recommend limiting exposure to 1,900. While most stainless steels are resistant to oxidation at low temperatures, the various metal in the steel formulation (iron, chromium, molybdenum, etc.) We have examined our setup which is as follows: We use a stainless steel rectangular tube filled with hydrogen running at 1900 Deg F. If we have a new tube we can run either bottled gas or new house hydrogen and the material is spotless. The effect of thermal expansion is most noticeable where components are restrained, as the expansion results in buckling and bending. Contact a Marlin Steel Mechanical Engineer Expert for your next 304 Stainless Steel project. The photo at left illustrates the color on the weld and in the HAZ of a weld made with 10 ppm O 2. I asked my customer, he said no. Simply setting a hot pan on the surface can result in a mark left behind. Vinegar helps rid the pan of blue streaks created when the pan is washed in a … Of course, to maximize the useful life of any custom metal form, it’s important to take proper care of it—using it in the conditions for which it was designed, routinely cleaning it using appropriate processes, and not putting too much weight on it beyond the recommended amount prescribed by the engineer who designed it. Another issue would be the thermal expansion the metal could experience. 2007. We used to use an old Stuart cell hydrogen generator to produce our atmosphere for the furnace but when we annealed stainless it would turn dark blue. Contact a Marlin Steel Mechanical Engineer Expert for your next project. Stainless steel is a sturdy and reliable material commonly used in kitchen sinks, appliances and cookware. As stated in an AK Steel data sheet for grade 316 stainless steel, the melting range of 316 SS is 2,500 °F – 2,550 °F (1,371 °C – 1,399 °C), roughly 50 to 100 degrees Fahrenheit lower than the melting point of grade 304 stainless. This makes grade 316 alloy slightly less desirable for high temperature applications than grade 304 alloy. This surface oxide must be removed for the surface to be passivated and reach optimum corrosion resistance. Pusher, walking beam, and vacuum furnaces are used for higher temperatures up to approximately 1345 °C (2450 °F). This expansion coefficient not only varies between steel grades, it also increases slightly with temperature. Many of Marlin Steel’s customers use production processes that involve high temperatures. However, this can compromise the corrosion resistance of the metal, making it more susceptible to corrosion damage from exposure to moisture. In other words, you can expose grade 304 alloy steel to temperatures of up to 1,598 ° F for short periods of time without ill effect, and for extended periods of time in temperatures of up to 1,697 ° F. However, this can compromise the corrosion resistance of the metal, making it more susceptible to corrosion damage from exposure to moisture. As stated by AZO Materials, grade 304 stainless steel possesses “good oxidation resistance in intermittent service to 870 °C and in continuous service to 925 °C.” However, they warn that “continuous use of 304 in the 425-860 °C range is not recommended if subsequent aqueous corrosion resistance is important.”. of a piece of 1-1/2" 316L stainless steel tube split in half. Although Dutch ovens get the most exposure as being stovetop- and oven-friendly pans, you can also use your stainless steel pans in the oven. My plant machines small cones for a valve assembly out of 17-4 PH Condition A Stainless Steel. Each Figure 2. 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). Each Figure 2. Stainless steel discoloration during heat treating 2002. This causes a loss of toughness and – except for the low- carbon L grades and the stabilized types – may make the steel subject … It combines good elevated temperature corrosion resistance and medium strength, good formability and inexpensive overall cost. Though these marks appear as damage to the surface, they are simply a discoloration that can easily be removed. Don’t Neglect the Oven. 416 stainless steel is a free-machining martensitic stainless steel with 12-13% chromium that can be hardened by heat treatment to higher strength and hardness levels. Heat stains can occur on stainless steel appliances for a variety of reasons. Grade 304 has a coefficient of 17.2 x 10-6 /°C over the temperature range 0 to 100°C but increases above this temperature. Get the wayback machine, Sherman. It combines good elevated temperature corrosion resistance and medium strength, good formability and inexpensive overall cost. 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