Is all stainless created equal?

[Rhone]

I recently made a mistake by using stainless sheet metal screws to hold my liner together. I pulled it all out and replaced them with stainless rivets. I was really surprised at how much the screws lost the battle to the liner. Really glad I removed the whole thing to replace them.

Were these screws made of inferior stainless? My liner has gone through a whole year of heating/cooling already, not being familiar with metal if stainless tempers, perhaps the year of heating/cooling has my liner stronger and why the screws were simply outmatched.

Thanks!

 

[Roospike]

Sooooooooooooo ............ What happened to the stainless steel screws ?

was really surprised at how much the screws lost the battle to the liner.

 

[Rhone]

Many were stripped, could be pulled out with fingers. Some had only 1/8" tread left, some had already started working themselves out from the vibrations of pushing the liner down and pulling it back out. Had one screw out of the dozen I put in that worked like it should've. Glad I took someone's advice and decided to put the effort in to pull the whole thing back out and replace them with rivets. The screws I purchased at Aubuchon Hardware, I replaced them with stainless rivits purchased from Home Depot.

 

[GVA]

No all stainless isn't created equal..... There are many different grades most machine screws, bolts and tek screws are made of 18-8 grade stainless it is a little stronger than 300 series stainless steels but will eventually break down and fail. (Could take a while though) 400 series is what most knives are made of, this has iron added to it for strength and since it has iron in it it will rust. Quality fasteners will be certified.... Hardware stores don't carry top quality fasteners. MIL Spec are the best but pricy. Anyway before I get to far off track, stainless when machined too fast will work harden, the heat cause this to happen I would assume that the heat running through the liner would do this also...
The rivets seem like a good choice since they can't back out when the liner expands and contracts.

Now comes my final attempt to bore all of the people that read this....... :down:

I have used more than my share of TEK screws and when drilling into sheet metal regardless of steel or stainless metals sometimes no mater how low you set the clutch on the drill it will either strip the hole or the threads. This may be what happenned.

Allright everyone wake up i'm done ...

 

[BrotherBart]

Yeah. And I wish everybody luck with those "self-tapping" stainless screws that come with some liner kits. Get out the drill and tap a hole. Forget about getting one of those things to self tap in a nice slick piece of 304 stainless on a liner collar. In fact I figure I am corroding faster than screws up there will so I just put sheet metal screws in the thing.