Heat treatment
Tempering
Tempering reheats the quenched part below the critical temperature to relieve stresses and trade part of the hardness for toughness.
What we do
- Single or double tempering, as specified
- Furnaces with temperature and time control and recording
- Forgings, bars, blocks and machined parts
- Report with the cycle applied and, on request, mechanical tests after treatment
Materials
Capacity, maximum dimensions and lead time on request: send the drawing. See alloys in stock.
How tempering works
The quenched part is reheated below the critical temperature, held for a time proportional to the thickness and cooled. The heat relieves the quenching stresses and transforms part of the martensite into a tougher structure. The higher the tempering temperature, the lower the hardness and the higher the toughness: the temperature is chosen by the hardness or strength class required.
Ranges to avoid and double tempering
Some steels lose toughness when tempered in specific ranges (temper embrittlement), and the cycle is chosen to avoid them. Martensitic stainless such as F6NM and steels for H₂S service usually require double tempering, which ensures complete transformation and the maximum hardness required by NACE MR0175 / ISO 15156.
Checking the result
Hardness is measured on every part or by sampling, as specified. When the order requires, we take coupons for tensile and Charpy tests from the same treatment lot, and the results go on the certificate.
What to send with a quote request
To get a quote, send the alloy and standard of the material, the drawing or the dimensions of the part, the quantity, the required cycle (or the hardness and properties to be reached) and whether verification tests are needed. Parts that will still be machined are treated with allowance, so that the oxidized layer is removed in finish machining.
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Frequently asked questions
What is the difference between tempering and annealing?
Tempering comes after quenching and adjusts hardness and toughness. Annealing is an independent treatment that softens the material for machining or forming, with slow cooling in the furnace.
Does Dustre perform this service on customer-supplied material?
Yes, as long as the alloy and the specification are defined. We can also supply the material from our stock, with EN 10204 3.1 certificate.
