Best steel for bolt threads

[Loganberry]

How much difference is there in terms of longevity of the threads, between bolts made of 304 stainless steel and bolts made of surgical steel. I am a vaper (electronic cigarette user) and the atomisers screw into the battery tubes and the threads on both the atomiser and battery tube are the weakest link ie the devices usually last as long as the threads are good.
Thanks

 

[mrfailure]

Surgical stainless steels will be harder and have longer life in this regard. They do need to be compatible with what they screw into (I do not know materials in e-cigarettes) to make sure they do not corrode from a galvanic couple.

 

[racookpe1978]

Is it 9the threaded screws or member) going into another stainless piece (probably - since its a "put in your mouth and inhale" kind of thing or is it threaded into plastic.

Also, don't forget the planned obsolescence part of design: the maker may not want a long-lived gadget.

 

[tbuelna]

Loganberry,

could you be a bit more specific in your definition of "surgical steel". The term "surgical steel" is a somewhat generic description, and can include several different stainless steel alloys.

304 stainless is normally a crappy material for threaded fasteners. It does not machine well, and it tends to gall in contact with other austenitic stainless alloys such as 316 "surgical steel". If material strength or ultimate corrosion resistance are not an issue, you might consider making the screws from a free-machining stainless like 303. 303 stainless will be far less likely to gall in contact with other stainless parts.

 

[Loganberry]

Where they actually state the grade of surgical steel they say 316 although often just "surgical steel" but it is a monkey see - monkey do business, so they probably all use 316.

Thanks for the replies.

 

[mrfailure]

ASTM does specify surgical grades of Type 316 - as I recall, you have to look for the type of tool to see how it is specified and what sort of strength/hardness it has.