Stainless steel screw and bolt material acceptance testing
Stainless steel screw and bolt material acceptance testing
(OP)
Does anyone know or can guide me to a source that has a good procedure/practice for acceptance testing of stainless steel scews and bolts?
I am trying to develop an incoming inspection to ensure we recieve good guality corrosive resistant stainless steel hardware. Need to find a quick spot check method to use to inspect lots recieved. Is using a magnet to check for ferrous contamination in stainless steel a good test method?
Please advise
I am trying to develop an incoming inspection to ensure we recieve good guality corrosive resistant stainless steel hardware. Need to find a quick spot check method to use to inspect lots recieved. Is using a magnet to check for ferrous contamination in stainless steel a good test method?
Please advise





RE: Stainless steel screw and bolt material acceptance testing
A magnet is not 100% effective as many screws are cold worked and will be moderately magnetic. If you test a SS fastener and its shows some magnetic properties you have to heat a sample to cherry red and air cool. If it's SS it will show no magnetic properties.
RE: Stainless steel screw and bolt material acceptance testing
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Stainless steel screw and bolt material acceptance testing
I will have to try the heat test you mentioned to prove that out..
Thanks.
RE: Stainless steel screw and bolt material acceptance testing
In addition to the magnetic test if you have the facilities and are familiar with handling acids you can use a 50/50 v/v solution of Nitric Acid.
Are you familiar with using acids?
RE: Stainless steel screw and bolt material acceptance testing
I really dont want to open up another hazmat waste profile just for testing hardware, cost and man hours alone will be inefficient for me right now..
I have instructed purchasing dept to have certificates of compliance from the vendor of the hardware batch lots sent, hoping to put the ownership on the vendor, but I still need some quick test method for in house.
RE: Stainless steel screw and bolt material acceptance testing
RE: Stainless steel screw and bolt material acceptance testing
I am not too concerned on how pretty it may look but rather its resistance to corrosion to help reduce and possibily elimnate the amount of warranty repairs performed through out the year.
For now I have my inspectors using magnets to inspect incoming material and have seen these past few days a large amount of 18-8 fastners are attracted to magnets.
Is this normal with 18-8?
RE: Stainless steel screw and bolt material acceptance testing
What is the country of origin for the current fasteners? I ask this because all sorts of alloys are being used according to my buddy in the fastener business.
Ideally if corrosion or failure is a big concern you would specify a specific alloy like 304 SS or better yet 316 SS. Another approach would be to require domestic if in the US. Slightly higher but someone has to put their name on the box.
I have to admit that most anything labeled 18/8 should last longer than a year.
RE: Stainless steel screw and bolt material acceptance testing
I had my techs do a heat test on various fastners we have in stock. Most has some significant amount of attraction to magnets.
After the heat test this attraction to magnetism was still present but not as strong as before. thus was able to develop an inspection criteria.
I have implemented an AQL sampling on all fastners to be checked with magnets first and pass those with less magnetic attraction and perform heat test on those that have stronger attraction to magnet.
This I am sure will help monitor incoming material and keep the vendors honest...
Thanks again
RE: Stainless steel screw and bolt material acceptance testing
RE: Stainless steel screw and bolt material acceptance testing
So are my stainless AN bolts bogus?
RE: Stainless steel screw and bolt material acceptance testing
No your bolts are probably not bogus as there are numerous Stainless Steels that are fully magnetic in all forms all the time especially the higher strength ones.
The heat test is specific for checking "Austenitic Stainless Steel" which are normally none magnetic except if they have been cold worked. 18-8 is a catch all term used to describe a family of Austenitic Stainless Steel fasteners.