Thread: Isuzu into D1/RRC

Originally Posted by lokka

John that manifold looks good and wouldent be hard to make either ..
As for staino grades i thought 316L or 309L would be the go as thats what i use to use mainly for the exhaust components on underground stuff ...

I thought it should b easy to make.

309 has a higher service temp (980 C) than 304, 316 and 321 (870 C).

The low carbon grades are not as strong as the same grade with high carbon 304L vs 304, etc.

Carbide precipitation at the grain boundaries at elevated temps is a problem, so 312 stabalised with titanium or low carbon grades are used.

Another problem is formation of Sigma Phase at high temps, which makes the material brittle. 304 grade is immune but grades with high chrome (309) or with molybdenum (316) have problems.

Edit: Sigma phase formation occurs at temps between 590 and 870 C, a range where exhaust manifolds for turbo diesels operate.

IMHO 321 is a better choice, but 304L would be ok.

Edit: I mentioned duplex stainless in an earlier post. Duplex stainless is good where stress corrosion cracking is a problem with chloride containing environments, but the temps were are talking of are too high for these grades.

Originally Posted by Bush65

I thought it should b easy to make.

309 has a higher service temp (980 C) than 304, 316 and 321 (870 C).

The low carbon grades are not as strong as the same grade with high carbon 304L vs 304, etc.

Carbide precipitation at the grain boundaries at elevated temps is a problem, so 312 stabalised with titanium or low carbon grades are used.

Another problem is formation of Sigma Phase at high temps, which makes the material brittle. 304 grade is immune but grades with high chrome (309) or with molybdenum (316) have problems.

Edit: Sigma phase formation occurs at temps between 590 and 870 C, a range where exhaust manifolds for turbo diesels operate.

IMHO 321 is a better choice, but 304L would be ok.

Edit: I mentioned duplex stainless in an earlier post. Duplex stainless is good where stress corrosion cracking is a problem with chloride containing environments, but the temps were are talking of are too high for these grades.

Yep duplex or saf as its known to those in the game is the go but has a preaty good price tag

Tho 309 isnt much cheaper at the moment staino in all grades is up in price as there s a problem in the market and has been for a while ...

Originally Posted by lokka

Yep duplex or saf as its known to those in the game is the go but has a preaty good price tag

Tho 309 isnt much cheaper at the moment staino in all grades is up in price as there s a problem in the market and has been for a while ...

Sandvik designate their duplex staino grades as SAF xxxx. They produce equivalent grades to ASTM specifications for duplex staino such as S31803 and S32304 etc. used in the pressure vessel and piping codes.

My comment in the previous post was to correct a recommendation in a previous post. IMHO, SAF would not be suitable for the temperatures of a turbo diesel exhaust manifold.