Magnetic "stainless steel"

[Physopto]

13 hours ago, Davey-T said:

Hi Derek, are you returned or still on holiday ?

I only enquired about this because quite by chance I discovered that the stainless steel threaded rod that I bought was rather strongly magnetic and an off cut that was out in the rain was showing signs of rust, I was a bit concerned as I intended burying them in the concrete patio.

None of the sundry stainless steel washers and nuts I purchased showed any sign of being magnetic and some more threaded rod from a different supplier is also non magnetic.

Obviously sticking an ordinary magnet on it is hardly a rigorous test but it satisfies me, standard galvanised rod would probably see me out anyway 

Dave

Hi Dave,

 Still away back late tomorrow night.

Poor quality S/S does rust a bit. Once in concrete with a water proofer additive  it will be fine though! If you want little or no rust you have to go for 304 grade, but costly. Not worth the worry or cost.

Most cheap S/S knives and forks are like that anyway, rust buckets. It depends upon amount of chromium and other additives in the mix. The chromium surrounds crystalline  iron content and stops air and moisture penetration causing the rusting or oxidisation.

Good quality S/S is regarded as non magnetic for most uses. But for work in physics at the atomic scale it does exhibit magnetism and exhibits a magnetic qualities if placed in an applied magnetic field.  Aluminium  and molybdenum are used  precisely because of these problems.

Derek

[mapstar]

On Sunday, August 07, 2016 at 11:44, Physopto said:

Sorry Damian, but all types of Stainless Steel exhibit some magnetic qualities. Some are just mostly not of any real detriment for most purposes. I have seen some very high quality S/S ruined because a technician tried to show me it was not magnetic by touching it with a strong magnet. You can only test it with a magnetometer, nothing else!

 

I think you took what I said in the wrong sense Derek. Austenitic stainless can be magnetised but it is non magnetic in the sense that magnets do not stick to the stuff.

We use slings/grabs on our finishing bank cranes as the electro magnets will not pick it up. 

[Physopto]

22 hours ago, mapstar said:

I think you took what I said in the wrong sense Derek. Austenitic stainless can be magnetised but it is non magnetic in the sense that magnets do not stick to the stuff.

We use slings/grabs on our finishing bank cranes as the electro magnets will not pick it up. 

I know what you were getting at Damian.

what I was trying to get across was that many people take all  s/s as being non magnetic, when all s/s is to some extent as it contains iron. For me it is a devil in physics. Sometimes we can use it but in the sort of experiments I did it is rarely used, if ever, as it skews all results and null and voids them.