If you’re a sheet metal parts supplier, we get it—designing parts that work in high temps is one of the trickiest asks we field every day. Whether it’s for industrial furnaces, aerospace engine components, or oil and gas downline equipment, a part that holds up to constant heat (or extreme swings) can make or break a customer’s whole operation. Skip the overcomplicated engineering jargon for a sec—let’s break this down like we’re chatting over a shipping container coffee break, no stuffy formulas unless they’re actually useful. Sheet Metal Parts
First off, let’s ground this: high temp applications aren’t just “hot.” There’s two big buckets we deal with as a sheet metal parts supplier—continuous high temp (like 600°F+ that sticks around 24/7) and cyclic high temp (temp spikes and drops, like a furnace that turns on and off every shift). Mess this up, and you’re looking at warped brackets, cracked welds, or parts that seize up way before their promised lifespan. We’ve seen it too many times: a customer sends us a 10-gauge mild steel part that’s supposed to handle 800°F, and it’s toast in 3 months. So let’s start with the most basic, most overlooked step: material selection.
Don’t just default to stainless steel here—yes, it’s heat-resistant, but not all stainless is created equal. For continuous high temps, 304 stainless works okay up to ~1500°F, but if you’re pushing 1800°F or higher, 310 stainless is non-negotiable. It’s got way more chromium and nickel, so it forms that tight oxide layer (the stuff that keeps oxygen from eating through the metal) way better than 304. But here’s a pro tip we learned messing up a custom oven liner job a couple years back: if your application is cyclic—say, going from room temp to 1700°F every 12 hours—don’t use solid 310. Thermal expansion (that’s when metal gets bigger when hot) will cause it to crack. Instead, go for a high-nickel alloy like Inconel 625, or even a coated mild steel if the budget’s tight. Wait, coated? Yeah—aluminized steel is a game-changer for some jobs. It’s cheaper than stainless, can handle up to 1200°F continuous, and the aluminum coating forms a protective layer that resists oxidation way better than plain steel. We’ve used it for exhaust manifolds and furnace baffles, and customers usually save 20-30% without losing performance. One rule here: never use a material’s “max temp” rating as a hard number. Subtract 100-200°F if it’s cyclic, and another 50°F if there’s any load on the part (like a bracket holding heavy machinery—heat makes metal weaker, so load + heat = bad combination).
Next up, part geometry. Even with the right material, a bad design will fail. Thermal expansion is the silent killer here—if you design a tight, rigid part that can’t move when it heats up, it’ll warp or crack. Let’s take a simple example: a rectangular duct for a foundry exhaust system. If you weld the corners solid and don’t leave any room for expansion, when it hits 1200°F, it’ll bow out in the middle because the metal can’t stretch evenly. How we fix that? Add expansion joints, or use a curved corner instead of a sharp one. Wait, sharp corners—another no-no. Sharp points and corners act like stress raisers, and at high temps, those points become weak spots. A 90-degree bend in 10-gauge 310 stainless might hold up at room temp, but at 1800°F, the stress at the corner will cause a crack in 6 months. We always round internal corners to at least twice the material thickness if we can, and for bends, use a bend radius of at least the material thickness—more if it’s high temp. For thin gauge parts (like 16-gauge foil for heat shields), we use a 3x material thickness radius to prevent cracking during forming, too. Also, avoid large flat surfaces if it’s a cyclic heat application. A big flat panel will expand and contract more, leading to warping. Instead, add slight corrugations or dimples to create rigidity without adding extra material. We did this for a customer’s heat exchanger part last year—switched from a flat 2-foot panel to a corrugated one, and their part lifespan went from 8 months to 2.5 years, no extra cost because we just tweaked the bend pattern.
Welding and joining is another area where we see tons of mistakes. A lot of customers come to us with a part that’s all MIG-welded, and it fails. Why? MIG welding uses filler metal that might not match the base material’s heat resistance, and the heat from the weld can create a brittle zone right around the weld that cracks under cyclic stress. For high temp parts, we almost always use TIG welding instead— it’s more precise, less heat input, and we can match the filler metal exactly to the base material. For example, if we’re welding 310 stainless, we use 310 filler rod, not 308. For Inconel, we use Inconel 625 filler. But wait—even TIG welds can go wrong. We’ve had a customer reject a batch because the welds were porous. When metal heats up, those small air pockets in the weld expand and act like weak points. So for high temp welds, we do a post-weld heat treatment (PWHT) to relieve stress from welding and close up those pores. What kind of PWHT? It depends on the material: for stainless, we heat it to around 1900°F and slow cool it, for Inconel, it’s around 2100°F. It adds a little time to the order, but it’s 100% worth it. We even skip welding entirely sometimes—use mechanical fasteners like rivets or bolts if the part is going to see a lot of thermal cycling. Riveted joints can move a tiny bit, which takes stress off, but make sure the fasteners are high temp grade too—standard steel bolts will seize up at 800°F, so use Alloy 8 fasteners.
Surface finish might not seem like a big deal, but it is. A lot of people think a polished surface is better, but for high temp, a matte, slightly rough surface is actually better. Wait, why? Because oxidation happens on the surface, and a rough surface gives the oxide layer more texture to grip onto—so it doesn’t flake off. Flaking oxide is a huge problem because those flakes can clog filters, get into moving parts, or expose new metal to oxygen. We also do a blast cleaning with alumina oxide on high temp parts before any finishing, not sandblasting with silica—silica can leave residue that burns off and creates impurities. For parts that need even more protection, we use ceramic coating. It’s a thin layer, adds almost no weight, and can handle up to 2500°F. We used it for a customer’s rocket engine heat shield brackets, and they’ve been going strong for 3 years now, no oxidation. Don’t overdo the coating though—some coatings can crack when the metal expands, so we test every coating on a sample first to make sure it’s compatible with the material.
Now, let’s talk about testing—because no design is perfect until you test it. As a sheet metal parts supplier, we don’t just cut metal and ship it out. For high temp parts, we do in-house tests first: put a sample in our temp-controlled oven, run it through 100 heat cycles (room temp to max temp) and check for warping, cracks, or oxidation. We also test load-bearing parts by putting a stress load on them while they’re hot, to make sure they don’t break. Last year, a customer sent us a design for a furnace door hinge—we tested the first sample, and the pin (standard steel) seized up at 900°F. Instead of just telling them “it won’t work,” we swapped the pin for a high temp alloy pin and retested, which worked. That’s the kind of value we bring, not just cutting metal. Common test mistakes we see customers make: testing only at continuous temp, not cyclic. A part that works for 1000 hours at constant 1500°F might fail in 100 hours if it cycles between 1500 and room temp every day. So make sure your test conditions match the actual application.
Wait, let’s cover some common mistakes we see all the time, just to wrap this up. First, using too thin a material. It’s tempting to go thinner to save cost, but thin metal expands and contracts way more, leading to warping. We always tell customers: for high temp parts, add 1 gauge if it’s cyclic. Second, ignoring corrosion. Wait, high temp isn’t just heat—if there’s moisture or chemicals (like in oil and gas), you’ve got high temp corrosion too. 310 stainless will work great for dry heat, but if there’s sulfur or chlorine, you need a material like Hastelloy C276, which is way more resistant to chemical corrosion at high temps. Third, not accounting for part size. A 4-foot long part will expand 2x as much as a 2-foot part, so you need way more expansion room. We had a customer design a 6-foot long exhaust duct that was too tight at the ends—when it hit 1200°F, it bowed 2 inches in the middle. We added 1 inch of expansion space at each end, and that fixed it.
At the end of the day, designing sheet metal parts for high temp isn’t just about picking the right metal. It’s about thinking through the whole life of the part: how it heats and cools, what it’s holding, what it’s exposed to, and how it’s joined. As a sheet metal parts supplier, we’ve spent years learning these lessons the hard way—messing up a batch, reworking a design, testing until it works. If you’re working on a high temp project and your design isn’t holding up, or you’re starting from scratch and need someone who actually gets high temp sheet metal, hit us up to talk through your needs. We’re not just here to cut parts—we’re here to make sure your part works, even when the heat is on.
Sheet Metal Parts References:
- ASME Boiler and Pressure Vessel Code, Section II: Material Specifications for High-Temperature Service
- Kalpakjian, S., Schmid, S.R. (2020). Manufacturing Processes for Engineering Materials, 7th Edition. Pearson Education
- International Organization for Standardization (ISO) 15793:2014, Metallic Materials for High-Temperature Application – Selection and Testing Guidelines
- Data Sheet for Inconel 625 Nickel-Chromium Alloy, Special Metals Corporation, 2022
- Sheet Metal Forming for High-Temperature Components, Fabricator’s Guide, Precision Metalforming Association, 2021
Hebei Kailu Hardware Manufacturing Co., Ltd.
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