Determining if it's stainless steel and what type

[ARC-170]

I have a few hunks of stainless steel that I'd like to get rid of. I thought of placing them on the metals exchange forum here, but I want to be able to describe them accurately. I'm pretty sure they are stainless, just not sure what type. They are very hard to machine; I tried to make something and it took forever! How would I go about doing this? Or, should I just post them and state that they are some sort of stainless? Thanks!

 

[Jim F]

Scrapyards here use magnets.
Need XRF to determine grade, somewhat.

 

[ARC-170]

I guess my question is really: does it matter what particular type of stainless it is or is posting that it's stainless good enough?

 

[jwmelvin]

I’d say that at least identifying as magnetic or not would be a start. Most likely not magnetic, then probably assumed to be 304.

To answer your question, that’s plenty to justify posting. Some applications will care about the type so not knowing will limit your market some.

 

[benmychree]

Excuese me, but 304 is definitely magnetic; the 400 series are mostly non magnetic or only slightly so. If I understand your posting correctly.

 

[OTmachine]

Look at this chart :https://www.mchoneind.com/stainless-steel-grades-chart/
Different types for different purposes

 

[RJSakowski]

My understanding is that austenitic stainless steels, which is primarily the 300 series, are either non magnetic or weakly magnetic. while ferritic and martensitic stainless, which is primarily the 400 series is magnetic. To test for weak magnetism, I suspend a magnet from a thread. If the stainless is weakly magnetic, you will observe the magnet deflecting slightly when the magnet is brought near the sample.

 

[rwm]

400 series is noticeably more magnetic than 304. Unless tested very carefully 304 and 316 appear almost non magnetic. Try it.

"Austenitic stainless steels contain 15%-30% chromium and 2%-20% nickel for better surface quality, corrosion and wear resistance, and workability. They are nonmagnetic when annealed but — depending on the nickel content and other composition factors — can become slightly magnetic when cold worked."

 

[Ulma Doctor]

304 and 316 fit into the difficult to machine group
203, 303 and 416 are nearly free machining
410, 420, & 430 are relatively difficult to machine, but slightly softer than 304, & 316
440 bring carbide or go home

 

[mmcmdl]

440C is some nice stuff for heat treating . Way back in the day we built up a Vette motor for one of our machinists . Ran like a bat outta heck until he rolled the car .