Comparison opinions on Mild Steel vs Stainless Steel Headers...
05-26-16, 08:31 AM
#16
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^^^^Exactly what I plan on doing, better safe than sorry
06-12-16, 08:20 PM
#17
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Doing some more research on Mild Steel vs Stainless 304 and came across this thread from a Mercedes forum (MBworld) http://mbworld.org/forums/w211-amg/4...ess-steel.html
Very good info between the differences of mild steel and stainless 304........it's only 1 page and 18 posts but has some valuable information for both sides of the argument.
Very good info between the differences of mild steel and stainless 304........it's only 1 page and 18 posts but has some valuable information for both sides of the argument.
06-13-16, 02:05 AM
#18
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Another quote here:
Bumping this old topic with detailed info.
I'm nearly graduated M.Sc. and I've been studying welding and welding metallurgy, so I have bit knowledge to back my sayings.
As far as strength goes, mild steel (S355) and 304 are similar. Yield strengths are 355/205MPa and ultimate tensile strengths are 470-630/515MPa. As you can see S355 is a tad stronger and especially yield strength is important when building manifolds. You really dont want your manifold to yield.
Thermal expansion coefficent for S355 is 11,1 (10^-6/K) and for 304 its 17,2. So 304 will expand roughly 1,5 times more as said before, which will result more stress in curves. Thermal conductivity on other hand goes for 304. Conductivity for S355 is 42,7 (W/m*K) and for 304 its 16,2. So 304 will need more time to warm up, but it will stay hot longer than S355.
Big thing with 304 is corrosion resistance. As everyone knows, mild steel will rust. Stainless steels wont rust as easily, but austenic stainless steels will loose their corrosion resistance when they get hot enough. For 304 limit for continous temperature is 870°C and above that temperature it will rust quickly. That is the reason for inconel manifolds. Inconel can handle way higher temperatures without loosing its corrosion resistance.
To summarize a bit:
S355 pros:
-Tad stronger
-Can handle heat better
-Easy to weld (Both GMAW and TIG)
-Easier to machine
-Price
S355 cons:
-Rust (Needs thermal coating)
-Higher thermal conductivity (In changing exhaust temperatures. Although some ceramic coatings have very low conductivity, so they will solve this problem)
304 pros:
-Corrosion resistance to 870 °C
-2,5 times lower thermal conductivity
304 cons:
-Price
-Harder to machine
-Needs back purge
-Tad weaker
-More expensive
Thread here: http://honda-tech.com/welding-fabric...3013967/page2/
Post #36
Just more things to chew on when deciding between Mild steel vs Stainless steel...... especially with the possibility of a S/C down the road and the headers are going to be running hotter than they do now @ N/A
Bumping this old topic with detailed info.
I'm nearly graduated M.Sc. and I've been studying welding and welding metallurgy, so I have bit knowledge to back my sayings.
As far as strength goes, mild steel (S355) and 304 are similar. Yield strengths are 355/205MPa and ultimate tensile strengths are 470-630/515MPa. As you can see S355 is a tad stronger and especially yield strength is important when building manifolds. You really dont want your manifold to yield.
Thermal expansion coefficent for S355 is 11,1 (10^-6/K) and for 304 its 17,2. So 304 will expand roughly 1,5 times more as said before, which will result more stress in curves. Thermal conductivity on other hand goes for 304. Conductivity for S355 is 42,7 (W/m*K) and for 304 its 16,2. So 304 will need more time to warm up, but it will stay hot longer than S355.
Big thing with 304 is corrosion resistance. As everyone knows, mild steel will rust. Stainless steels wont rust as easily, but austenic stainless steels will loose their corrosion resistance when they get hot enough. For 304 limit for continous temperature is 870°C and above that temperature it will rust quickly. That is the reason for inconel manifolds. Inconel can handle way higher temperatures without loosing its corrosion resistance.
To summarize a bit:
S355 pros:
-Tad stronger
-Can handle heat better
-Easy to weld (Both GMAW and TIG)
-Easier to machine
-Price
S355 cons:
-Rust (Needs thermal coating)
-Higher thermal conductivity (In changing exhaust temperatures. Although some ceramic coatings have very low conductivity, so they will solve this problem)
304 pros:
-Corrosion resistance to 870 °C
-2,5 times lower thermal conductivity
304 cons:
-Price
-Harder to machine
-Needs back purge
-Tad weaker
-More expensive
Thread here: http://honda-tech.com/welding-fabric...3013967/page2/
Post #36
Just more things to chew on when deciding between Mild steel vs Stainless steel...... especially with the possibility of a S/C down the road and the headers are going to be running hotter than they do now @ N/A
06-13-16, 08:39 AM
#20
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Thread Starter
No not here they just put mag-chloride on the roads, don't know if that's corrosive to Mild steel or not?
06-13-16, 09:46 AM
#21
After reading that post by MileHIFcar, i called Paul over at PPE and changed my mild steel headers to full stainless steel headers. dont want to take any chances especially out here in NY during winter they love to drop salt like crazy during snow storms or even storm warnings. i rather run safe then sorry. these aint no cheap headres.
06-13-16, 01:43 PM
#22
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Thread Starter
Glad I could help someone out here
Agreed though these are not cheap headers by any means and I want to make sure I make the right decision
Agreed though these are not cheap headers by any means and I want to make sure I make the right decision
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