making the strongest and lightest stainless steel frame

[HackAsaw]

I have been looking at some of the super duplex alloys and although I haven't ruled out doing Titanium, stainless would be easier to weld without difficult complications as the assembly becomes too large to avoid chamber welding.

Is 316B the logical and wisest choice for a tubular motorcycle frame whose tubing must tolerate cold bending and tig welding?

I do see some of the super duplex metals that have both high tensile and yield strengths but I'm not sure about their ultimate suitability..... especially regarding brittleness, cold bending, and welding.

All things being equal...... I'm not looking for it to be as light as a 4130 frame but would like a stainless frame lighter than 1020 or 1026......

Of course I'd like it to work good and last a long time under use. Thanks

 

[Metalguy]

Dunno what 316B is, but annealed 316/316L has rather low fatigue cracking resistance. Why not use 4130 and plate/coat it?

 

[HackAsaw]

Well, because I really want a frame for this project that can be left bare and not rust...... I would surely do the 4130 if the object was adequate strength with very light weight

I am reasonably sure that 316B is what the builders of stainless frames use but you very well may be right about the 316L

I was very impressed with the strength numbers of some of the exotic duplex metals but contacting the manufacturers so far hasn't answered all my questions since these metals are typically used for other applications.

 

[NickE]

I'm not sure if its available, Or even an appropriate grade, but what about a PH like 17-4 or 17-7. If you got the tube in an annealed condition. Forming it cold should be ok since that would only strengthen the area (x-form to Cond. C). Welded it up and then heat treat to the H1150 you should get a good combination of corrosion resistance and strength/fatigue performance.

Then again this is only really just a guess and I'm not even sure that the PH SS are available or suitable for this type of design.


Nick
I love materials science!

 

[TVP]

There are a number of stainless steel alloys that can be rolled to high strength levels, and have adequate formability and weldability for use on structural applications like a motorcycle frame. Austenitic stainless steels like Type 201/301 strain harden significantly during rolling, and are used in very high strength applications like flat springs. Nitronic 30 is a similar grade that is cheaper. You can obtain more information by using the following link:

http://www.aksteel.com/pdf/markets_products/stainless/austenitic/Nitronic_30_Data_Bulletin.pdf

For more info on an interesting automotive structure designed for this stainless steel alloy, use the following link:

http://www.memagazine.org/backissues/february97/features/steelcar/steelcar.html