Magnetic Stainless Steel ??? 5

[rgrunner]

I am a Fabrication Manager for a company that designs and manufactures packaging equipment. We sell a great deal of equipment that is water wash down and stainless steel framing. We recently received a shipment of S'STL tubing (304) that was highly magnetic. The country of origin of the S'STL is Taiwan. We sent the S'STL back because of concerns of it rusting, the material is for a food industry water wash down application. There is generally some magnetism in the S'STL we have used in the past but never this magnetic. I have been with the company 26 years and with all my experience I have never seen S'STL this magnetic. I am now waiting on our vendors to send mat'l of a better quality. I have heard in the last year that some offshore S'STL manufacturers have been cheapening the mat'l and I worry about the rusting of our machines in the field. This is a $350,000 machinery order and we want to get it right. We told our vendor we will not accept any S'STL from the Far East, this seems to be where the poorer quality is coming from. Are our concerns warranted, I would appreciate any feedback. Thanks

 

[desertfox]

Hi fgrunner

Ask for material certificates showing properties, chemical composition, yield stress etc for the grade of stainless that your company purchases, it not perfect but its a start
and reduces some risk of getting any old cheap material.

regards

desertfox

 

[vesselfab]

What type of stainless steel are you talking about?

400 series stainless is pretty magnetic and will rust

 

[rgrunner]

vesselfab and desertfox,
Thanks for responding, the matl coming from our vendor is supposed to be 304, that is what we request. This matl had no markings other than country of origin. Usually the matl we see coming in from Europe, Canada, US has a 304 marking or other markings on it. This had nothing which also makes it suspect to me.
rgrunner

 

[Dinosaur]

If you can't buy from a reliable source, I guess you have to be prepared to obtain a metalergical analysis with the condition that the material will be returned if the metalurgy doesn't pass. Either way, I'd also ask for the certs.

 

[rgrunner]

Dessert Fox, Vessel Fab and Dinosaur;
Thanks for all of your feedback. We are going to ask for the certs. for the material we sent back and the certs. for the replacement material that is coming to compare the two. I also want to send a signal to the supplier that we are checking what they are sending us. I am still curious though if anyone has been seeing material that is supposed to be 304 S’STL grade matl. coming in, especially coming from the Far East that is sub par. Our vendor lists this material as 304 on the packing slip we receive but what are they really getting. For many applications this material is probably fine but for our Food Industry it will not work. This sounds similar to the lead issue Mattel is having with the Chinese. Any thoughts?
Thanks again, rgrunner

 

[vesselfab]

IF IN DOUBT

why not get it PMI'd

 

[stanweld]

rgrunner,
In our global economy, we need to be concerned with materials purchases (how we specify and how we appraise suppliers)to assure receiving correct materials.

Did you order your materials by ASTM (or other)specification and grade or by grade, product form and dimension alone? You may have received cold drawn 304 tube, which would be magnetic if not subsequently solution treated; or you may not have. Magntetic properties could also be obtained if the manufacturer lowered the nickel content too much (high nickel prices = potential to cheat). The steel could also simply have been mixed, certainly not uncommon.

Chemical analysis will readily confirm whether the material is 304. Microstructural analysis can reveal cold work or sensitization. We have the methods to assure receipt of correct materials; if only we would use them.

 

[bcd]

Stainless steel can be slightly magnetic, especially if it is work hardened. Tubing would be work hardened during manufacture. So some degree of magnetisim is normal.

We recently had a far east supplier "forgetting" to put the full amount of chrome and nickel into our stainless. Reason is the cost of these materials rose so quickly so they thought they could save some money by not adding them. We caught them because material quality is critical to us so we check with an analyzer.

Do not trust material certs. Consider their source. If the material is critical to you, purchase an analyzer and do period checks yourself. An alternative is to send samples to an outside lab. that specializes in material analysis.

bcd

 

[Welder4956]

If you are purchasing any metal products from China, you need to have an independent chemical analysis, mechanical testing and microstructural evaluation. Even when they supply documentation it is usually not correct. They will tell you whatever you want to hear, even if it is wrong.