I'm working with 316L/A4 steel and I was wondering which precautions I should take when heating it. I want to heat bend a 316L steel rod, so it will need to be heated up to arround 1000°C.

316 is a stainless steel alloy, which has the following composition (If I've understood correctly 316L should be the same but with lower carbon content):

             Min. %     Max %
Carbon         0         0.08
Silicon        0         1.00
Manganese      0         2.00
Nickel       10.00      14.00
Chromium     16.00      18.00
Molybdenum    2.00       3.00
Nitrogen       0         0.10
Phosphorous    0        0.045
Sulphur        0         0.03

[Source interlloy.com.au]

I'm worried I will inhale something toxic since the alloy contains nickel and molybdenum. I think chromium shouldn't be much of a problem since any CrO3 compounds will decompose when heated.


1 Answer 1


Main precaution ; Do not touch it while it is hot. No vapors will come off the steel . What does A4 mean ? Your heating would be about right for forging. But for bending , try room temperature. It will bend very well unless you paid a premium for strain hardened bar. If you bend it extensively at room temperature it will harden. If you need to bend it more ,then heat it. 316 has no particular temperature requirements. A low red heat of about 1200 F should soften it ,cool in water.Then bend it at room temperature. You may repeat as often as needed. Bending at room temperature will be substantially more convenient than hot bending. Heating will discolor it from straw, to blue, to black depending on temperature and time. Color may be removed by sanding-polishing , if necessary. You are correct on one thing , today 316 is the same as 316 L ,the only difference is that you have to pay more if you order L grade.

  • I believe A4 is the 'European' name for what Americans call 316L
    – walrus
    Oct 16, 2018 at 10:49

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