304L vs 316 SS in high heat environment 1

[jjdavis]

I've seen some discussion on 304L vs 316 SS in a high heat environment, but would like some clarification. Or maybe material recomendation.

We use tooling that we use as a form to anneal steel into a particular shape. Temperatures reach around 1550 degrees F. Because we are annealing, better temperature conduction is a plus. Because it's only being used as a form, strength is not critical. It does get a little banged around from inserting the tooling and removing the tooling. Right now we use 316 SS and my understanding was that the naterial was originally chosen because it has better heat resistance. However, it seems that the data that I have looked at and in thread discussions, 304L is not any worse than 316 for heat. Can I get a confirmation on that from someone? I am thinking about trying the 304L for cost reduction reasons. Or if there is another material that anyone wants to suggest?

Thanks,

 

[mcguire]

The moly in 316 helps hot hardness but not oxdation resistance. You can save money by using 304. Don't use 304L;
it has lower hot hardness. The carbon is your friend. Use 304H if you can get it. 309 and 310 are the classic alloys for heat treating hardware, but both are more expensive, high-nickel grades.

 

[EdStainless]

309 and 310 may be higher in Ni, but the don't have any Mo.
The surcharge this month for 304 is 0.65, for 316 it is 1.35, and for 309 it is 0.85 ($/#).
The 309 base price will be higher, but that will be partially offset by the surcharge, and by the longer life.

Depending on the properties that you are looking for you might consider either 430 (ferritic) or a cast high temp grade.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[arunmrao]

Like in medicine a general prescription of antibiotics is a cure all for most common ailments. Similarly L grade is suggested as the cure all. It is time one ponders seriously before making a decision. jjdavis good that you raised this issue though it has been discussed quite often. When in doubt always ask is the age old adage.

 

[hacksaw]

304L is unsuited to the temperature range you've given at least in the processes i've seen

 

[rolledalloy]

309 stainless is plenty oxidation resistant enough for 1550F service. In general it can be used up to a maximum temperature around 1900F based on its oxidation resistance. 316 and 304 type grades at their limit at the operating temperature of 1550F.

Related to molybdenum at high temperature my experience is that moly is detrimental to oxidation resistance. Molybdenum trioxide is non protective and if the atmosphere is stagnant can actually result in catastrophic oxidation.

 

[unclesyd]

Nickel has pronounced effect on the scaling resistance and resultant spalling of SS in cyclic service. Of the more common alloys 310 show the greatest resistance to weight loss cycling at 1800°F.

If you can get 310 SS or 310H SS, if they still produce it, I think the additional cost will justify itself due to the minimized spalling.