Heat Treat Temp

Plas62

Well-Known Member
I'm looking at a used heat treat oven with a max temp of 2057 degs. I'm new to heat treating and knife making. I'm starting out with 01 and 1084 steels but plan in the future to use stainless steels such as ATS 34 or other high grade stainless such as Sandvik 14C28N stainless steel.

Will a max temp range of 2057 degs handle most of the steels commonly used in knife making?
 
Rarely will a steel require about 2000F......there are a few, but generally they are not "knife" steels. Have you tested the oven personally? Make sure you do, or you may get stuck with a dud. Just because an oven carries a given temp "rating"....doesn't mean it can/will achieve that temp. Any heat treat oven that is in good condition, should be able to reach 1950-2000F in less than 2 1/2 hours. (provided it's rated for that)
 
Ed- The guy who has the oven is getting it out of storage Saturday and I'm going to look at it this Sunday. I already told him I'd have to see it come all the way up to max temp before buying.

According to the person who has it. The oven was never used and that he had bought it at a plant closing auction at a place he had worked.

It is a Fisher Scientific. Model 550-126 muffel furnance. It is 240vac / 4600 Watts. The chamber is 12 x 14 x 13 inches.

Below are more specs from the pdf manual the guy emailed me.

Operating Range 50°C to 1125°C (90°F to 2025°F)

Average Temperature Uniformity
Model 126 ±10°C (±18°F)

Average Temperature Stability ±1°C (±2°F)

Set Point Repeatability ±1°C (±2°F)

Set Point Accuracy
Model 126: ±15°C (±27°F)

Rise Time
Model 126: 25 minutes

Recovery Time 10 minutes

Cool Down Time (Door opened)
(1125°C to 200°C) 25 minutes

For $500 I thought it looked like a good deal, as long as it tested OK. What do you think.

Jim
 
Fisher Scientific is very well known in lab equip, so I expect the oven will be very well made. With 4600 watts I can see how it would heat up nicely, max temp I suspect will be very close to spec'd max temperature.

I do find interesting the specs on the temperature accuracy - note the ±27ºF. This is a combination of Type K thermocouple (standard accuracy is ±0.75% at 2,000ºF - or ±15ºF) as well as temperature controller limitations. Even type 1 type K TC is only ±8ºF at 2,000 ºF - and this is when new without the effects of aging. The Set Point Repeatability is very good at ±2ºF and is all we're really concerned about providing the oven is calibrated.

Another interesting spec for Average Temperature Uniformity of ±18°F - "IF" I understand that correctly, they are talking about how even the temperature inside oven is from min to max. That would indicate to me a blade could well be 36ºF difference from one end of blade to other end.

While the accuracy can be calibrated by the magnetic point of 1414ºF due to the close repeatability specs, the un-even heating could not be calibrated out. If a high quality lab type oven manuf'd by Fisher has a 36ºF spread in only a cubic ft model oven, what do you think the spread would be in the typical HT'ing oven of 24" long?

All this is from a newbie in HT'ing ovens, but many years in chemical plant process control.

Ken H>
 
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