Can 304 stainless steel be used for a car spaceframe?

[DasKleineWunder]

Any drawbacks or challenges from using 304 stainless steel tubes for a car spaceframe?

Some say stainless steel is brittle and will fatigue soon, while others say its not a big deal as Chrome-Moly is also somewhat brittle yet is has been used many times, even in aircraft.

Are SS 304 welds weak?
Some say so while others say welds are corrosion prone (maybe chrome plating them).

 

[TVP]

In general, arc welds in austenitic stainless steels will be weak. Resistance spot welding can create quite good joints. Type 304 can be cold rolled to relatively high strengths, but its usefulness in an automotive structure will depend upon the joining technology and the corrosion resistance required. Any environments that use salt for road de-icing will cause excessive corrosion of Type 304 (general, pitting, crevice). The following are some useful links on the subject:

http://www.worldstainless.org/Files...sssteelinstructuralautomotiveapplications.pdf

http://www.aperam.com/uploads/stain...utomotive structural components offer (1).pdf

http://www.euro-inox.org/pdf/auto/StructuralAutomotiveApp_EN.pdf

 

[yoshimitsuspeed]

There are some notable drawbacks.
Welding is definitely one of them. One big issue is that a SS weld needs to be back purged in order to get full penetration without sugaring which causes serious weakening of the welds. A flux like solar flux can be used in some situations but it is still sensitive and adds more work to the process.
The other issue I see is strength to weight and cost to gains over other metals. Aluminum and titanium can have significantly better strength to weight ratios than steel in the right setting making it worth the extra cost and challenges in some situations. Stainless steel is going to cost a lot more than many alloys while having less desirable properties than a lot of steel alloys. The only benefit is it's corrosion resistance and that is only of high importance if you don't plan on protecting or coating the metal. In production coatings are so fast and easy it is going to be the logical solution. Welding something fast and easy out of the preferred alloy then dipping it in a zinc or other plating or any other coating would add very little cost per unit.