Medium Temperature Annealing Furnace

Danyang Dingfeng Industrial Furnace Co., Ltd. is one of the most reliable manufacturers and suppliers of medium temperature annealing furnace in China. If you're going to wholesale durable medium temperature annealing furnace made in China, welcome to get pricelist from our factory. All customized products are with high quality and low price.

Medium temperature annealing furnace runs roughly from 650°C to 950°C. This is where recrystallization happens for a lot of common metals – carbon steel, alloy steel, copper, aluminum. If you've cold worked something – rolled it, drawn it – it gets hard and brittle. This furnace softens it back up. Restores ductility and toughness so you can keep working it.

I've sold these to spring makers, wire drawers, and tube mills. They all have the same problem: work hardening stops production. This medium temperature annealing furnace fixes that.

Working Principle

 

Heat up the material to your target temp, hold it there, then cool it down. Basic cycle. Electric or gas fired – both work. The real art is controlling the heating rate, the soak time, and the cooling rate.

For recrystallization, you need to get above the recrystallization temperature of that specific alloy. For low carbon steel, that's around 540°C to 650°C. But we run hotter – 680°C to 760°C – to get complete recrystallization in a reasonable time. Copper recrystallizes around 350°C to 400°C, but medium annealing for copper is often done at 450°C to 650°C. Depends on the alloy and what grain size you're after.

Soak time rule of thumb I've used for 30 years: one hour per inch of section thickness. A 2 inch thick part? Hold for two hours. That gives the new grains time to nucleate and grow.

Cooling rate after soak: for most recrystallization annealing, air cool is fine. But some alloy steels will harden if you cool them too fast. Those need slow cooling. I learned that the hard way early in my career.

• Restores ductility. That's the main job. Cold rolled or cold drawn metal comes out soft again. You can stamp it, bend it, draw it further without cracking. One customer was scrapping 20% of his deep drawn parts before he bought our furnace. Dropped to under 2%.
• Recrystallization range. This furnace hits the sweet spot for carbon steels, alloy steels, copper, and aluminum. For higher alloys like some stainless, you need higher temps – that's a different furnace.
• Uniform grain structure. The internal grain structure gets refined and evened out. Consistent mechanical properties across the whole part.
• Atmosphere options. Run it in air for non-critical parts. Or add a protective atmosphere – nitrogen or hydrogen – for bright annealing. No scale. One aerospace customer insisted on 100% hydrogen atmosphere. Works great but you have to be careful. Hydrogen leaks can be dangerous.
• Efficient for this range. Insulation is either refractory brick or ceramic fiber. Fiber is better for cycling. Brick is fine for 24/7 operation. I usually ask customers how often they shut down before recommending.

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