Magnetic stainless steel?

[mole]

I know that some stainless steels are attracted to magnets, but has anyone seen it act like it's a weak magnet? I was using my pocket knife, an older Gerber 450 E-Z-OUT made of "400 series stainless steel"---whatever that means, to point to something on my monitor and noticed that the color changed and bent slightly around the knife blade. I figured it had a magnetic field and didn't use it any more on the screen.

I replaced my crappy old monitor with a another one (older Gateway EV700 $5 at a thrift store ). I decided to test steels against the crappy old monitor. I used various guns and knives, carbon and stainless. The only other peice of metal that affected the montor was one of my brother's cheesy Chinese throw away knife that was stainless. Of all the metals tested only the two stainless steel blades did this.

Is there any advantage or benefits to testing the magnetic field of stainless steel, such as being able to tell the difference between classes of steels? Could being magnetic be a sign of a lesser quality stainless steel?

 

[Any Cal.]

Stainless steels have varying amounts of carbon. Those with little carbon are "more stainless". Those with high carbon will corrode easier. Each has it's purposes. A higher carbon content allows the stainless to harden more. If a material is going to be submerged for an extended period or needs high corrosion protection, you want almost no carbon. Oh yeah, the higher carbon ones are the ones that are attracted by a magnet.

 

[hso]

No

 

[cyanide]

Your knife is radioactive , made with contaminated steels meant to be disposed of -- instead sold to the Chinese.

I'm not really sure but it has happened before for real.

 

[moxie]

Sometimes steel gets magnetized,

from exposure to some magnetic field or other. It could have been placed on a stereo speaker or next to an electric motor, for example, or from cold working. I'm not a metallurgist but i'm pretty confident this has nothing to do with the quality of the steel. See this for more info:

http://www.azom.com/details.asp?ArticleID=1140

 

[hksw]

Having worked in the flexible magnet industry for a while in the past, it depends on the grade of SS you are looking at. Some SS can surely be attracted to magnetic fields and magnets. The Azom sight gives a pretty good short article on the subject.

 

[steveno]

300 series sst is considered non-magnetic. 400 series and others will be magnetic. the amount of carbon has nothing to do with it being magnetic

 

[Zero_DgZ]

The process of machining the shape and edge of a cheap knife can make the blade magnetic. 4xx steels are magnetic - 400, 420, 440, &c. Most hardware grade stainless steels (like 18-8) are nonmagnetic or trivially magnetic.

I think the steel becomes magnetized by exposure to the grinding wheel or possibly EM from the motors used to drive the machinery. I've seen it with a lot of cheap knives when sharpening them, and all the filings want to stick to the blade...

 

[steveno]

I got this from a friend that is a Mach. engineer


It is austenitic.

Austenitic means: a face-centered-cubic phase of iron. What this means is that the iron is in full solution at ambient temperatures. All iron alloys become austenitic at about 1400 degrees F.

In 301 SS it is the 18% chrome and 8% nickel that makes it austenitic, therefore, non magnetic

 

[Jim Watson]

My FLG was modifying some stainless steel magazines for me the other day and we saw the shavings magnetically clinging to the metal. We went through the same speculation as Zero_DgZ as to whether it was the impact of the mill cutter or drive field from the motor coming down the shaft.

 

[Zero_DgZ]

I do know that it's not inherent magnetism. I have a Pakistani 'ninja' sword that I use for crashing around in the brush that was quite strongly magnetic (picking up pins and nails off of the floor...) and would make my friend's TV go all paisley, but after knocking a few trees with it and shaking up those ferrous atoms it became considerably less magnetic.

Attacking it with a Kershaw style zip sharpener made it a little more magnetic. Funky voodoo.