we have an order for forging some maraging steel and the customer has asked for 3 stages heat treatment. one at nearly 940 one at nearly 790 and one aging op.
am I right to think the first one is some kind of annealing or stress reliving op? as normally they have two stages heat treatment.

Thank you in advance.

We would need more info.
Degree C or F?
Material?

the temperature units are in C, the grade is 250.

Thanks

Sounds as if they are wating a homogenizing treatment before the solution treatment.  Kind of redundant for a forging, I would think, since forging temperatures are in the same range as the homogenizing temperatures, but the customer is the customer.

rp

Thanks RP, we have chosen 1080 as forging temp based on previou trial but as you said they are nearly in the same range. what you think about forging temp?

The temperature range of 750 °C to 1095 °C is recommended for maraging steels.

What were the times listed for the 940 °C and 790 °C stages?  What is your expected time for forging?

I agree with redpicker that the first stage is for homogenization.  If the forging time is short, then maybe a longer time homogenization is warranted.  There are multiple reasons why the customer may want this (corrosion, toughness, etc.).

Why not ask the customer directly instead of attempting to justify or solicit a response from others? I always appreciate a vendor or supplier providing clarification or exceptions to our engineering specification.

Quote:

Thanks RP, we have chosen 1080 as forging temp based on previou trial but as you said they are nearly in the same range. what you think about forging temp?

There are many factors that affect the optimal forging temperature, so I'd have to say if your trials indicate that 1080 works best for you, I am not sure what you are asking.  My experience with forgers is they will always use as high a temperature as they can (plus a little bit, if they can get away with it), so that temperature does not surprise me.

My point was that the heat treating temperatures you posted appeared to include a homogenizing treatment, which may not be needed considering the heating cycle you use for forging.  In many circumstances, a homogenizing treatment is beneficial for this alloy, which is likely why your customer has specified it.  If you have a history of processing this material that indicates this treatment is not necessary, you can often negotiate with the customer, using this experience in support of your position.  As metengr points out, many manufacturers/users will appreciate this feedback, particularly if it improves their specifcations.  However, if you try to support your position by information found on an internet message board, you may not be taken too seriously.

rp

Thanks guys.

Time asked for homogenising and aging are not long around 2 hrs.

unfortunately all the customers are not same and asking question here was purely for my own information. we do not have much historical data to prove homogenising is not necessary but definitely we will consider it as improvement opportunity for the future.

thank you all for your responses.