Reputable heat treatment companies will give you the best solution.
But Just if you failed to find a reliable reference, try Simulation heat treatment with different cooling rates on two or three coupons of your 310 material.
Then test them (mechanical tests or metallographic evaluation or whatever test is required for your PQR). Vertical axis for the results and horizontal axis for cooling rates.
By interpolation (or extrapolation) you can draw a curve which relates cooling rate to results of each type of test.
Let's say you have done an impact test.
Draw the curve by interpolation or extrapolation
Min acceptable result is 27 J
Draw a horizontal line passing from 27 on vertical axis
wherever the horizontal line meets the curve, draw a vertical line and you will find the minimum cooling rate.
apply a safety factor on it and you will have your minimum cooling rate.
for example if it was 100C/min you should go for minimum 110C/min
Of course this is costly and time consuming but gives you a solid base for your decision and if things went wrong, you can defend your decision. Before you do this, officially discuss this with your client and agree on the method.
Regards
On Wed, Jul 24, 2013 at 7:39 PM, Marc Vleminckx <vleminckx.m@gmail.com> wrote:
We are building a 310S vessel, 22mm thick, that needs solution annealing. Within our organisation there are some questions about the cooling rate this vessel needs.--ASME II SA-480 only say's the material needs to be quenched in water or rapidly cooled by other means.Somebody mentioned the temperature should drop from 1040°C to 427°C within 15 minutes to guarantee material requirements. Because of the design of the vessel and possible difficulty to maintain an equal cooling rate along the surface the choice was made to cool with forced air. To some of us a 600°C temp. drop with forced air in 15min is nearly impossible with forced air. So the main questions are "What is the definition of rapidly?", "Are there other means to reach this cooling rate?" and "Is there somebody who can provide this service within Holland or maybe Germany?". Heating rate is between 150 and 200°C/h starting from 482°C, and holding time 1h at 1040°C.
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