SA182 F11 heat treatment 1

[metalguesser]

Hi All!

We have some parts that are finish machined and made of SA182 F11 material. These were originally qualified for SA182 F11 - Cl 1, in the Normalized and tempered condition. Now the customer wants it to be qualified as SA182 F11 - Cl 2. We need to quench and temper the parts that are already machined and so we are considering heat treating the parts in atmosphere furnace to minimize scaling. The problem that we face is whether we shall achieve SA182 F11 Cl2 properties if we quenced the parts in oil. We have been quenching these parts in water all the time. Is it ok to oil quench the parts?? Appreciate any or all the help.

Thanks and regards

HAPPY THANKS GIVING TO Y'ALL

 

[metengr]

metalguesser;
Yes, you can quench these parts in oil for re-heat treatment because you will be re-austenitizing, quenching (in oil) and tempering per SA 182. If you review SA 182 material specification, the recommended heat treatment is as follows for all three Classes 1,2,3

anneal (furnace cool) or
normalize and temper (air cool to achieve the necessary mechanical properties).

A liquid quench can be by agreement between the Purchaser and the Supplier in this specification. Since oil is a liquid quench medium, like water, the difference is the aggressiveness of the water quench over oil.

In reviewing the Class 2 properties below, I believe you should be able to reach the minimum mechanical property requirements for F11 Class 2 using the oil quench on re-heat treatment.

Class 1 UTS 60 Ksi YS 30 Ksi
Class 2 UTS 70 Ksi YS 40 Ksi


Are you sure these were water quenched or was it water spray cooling? I would run a few parts through this re-heat treatment and measure hardness per the SA 182 specification What is the maximum thickness of these parts?

 

[metalguesser]

Thanks for the useful post, Metengr.

For SA182 class 2 we normally quench and temper and never had any problems achieving desired properties. In this particular case it was customer requirement to normalize and temper for Class 1 properties. We had no problem with that too. So the parts were made heat treated, machined and ready to be shipped when we get this request for Class 2 properties. Hence all this heartache.

The parts have hardness of 191 BHN in the Normalized and Tempered condition. They were normalized at 1650 deg F and tempered at 1280 deg F. The section thickness on these parts are approx 0.66" to 0.75" and weigh about 26 to 28 lbs.

Thanks again

 

[metengr]

metalguesser;

The parts have hardness of 191 BHN in the Normalized and Tempered condition. They were normalized at 1650 deg F and tempered at 1280 deg F.

For my own clarification, is this hardness of 191 BHN above for the re-heat treated Class 1 or the original Class 1 you provided to your customer and now they want Class 2? You already have met the hardness requirements for Class 2 if this part has not been subjected to re-heat treatment, see below

Class 1 BHN 121-174
Class 2 BHN 143-207

 

[metalguesser]

Metengr,

Yes, you are correct the hardness we achieved is 161 BHN in the normalized and tempered condition okayed for SA182-F11 Class 1. My bad-it was a typo.

We are heat treating it again to achieve SA182 F11 Class 2 properties. This time it will be oil quenched and tempered in atmosphere furnace. We are keeping our fingers crossed.

Thanks again,

Regards