Effect of manganese in 303SS 1

[jasgeer]

Most of the material standards state that the amount of manganese in 303SS should be less than 2%. We have a supplier who wants to supply '303' with >2% manganese. What is the effect if the manganese runs 0.5-1.0% high?

Thanks,
Jim

 

[mcguire]

The effect of more managanese should be imperceptible to both machinability and corrosion resistance. The solubility product for MnS
log[Mn]= -9020/T+2.93
ensures that nearly all the MnS precipitates as the beneficial inclusions in the liquid. Adding more Mn won't change that. As you know the corrosion resistance is nothing to write home about. Adding Mn is slightly detrimental. Does your supplier insist on adding Mo to compensate for the bad influence of sulfur? Probably not, but you should pressure him to do so. It really helps.

 

[mcguire]

That sure came out funny. I did not intend for those statements to be crossed out. Some kind of typo. Sorry

 

[CoryPad]

mcguire,

In your equation you typed [ignore][/ignore], which is the part of the TGML code of this site that creates strikethrough text. In the future, you can prevent this by using ignore /ignore tags surrounding the [ignore][/ignore].





Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mcguire]

Thanks, Coreypad!

 

[Austenitepro]

More Mn in any SS has many detrimental effects to surface quality, fluidity, and folding. An increase in Mn with a comparable increase in Si will solve some of these problems. However, what is your application? If you are using 303SS as is with the higher Mn you will find micro-folds which contain, upon metallurgical confirmation, wustite, Iron Spinel, and Fayalite, among other oxides nearby. (depending on the manufacturing process) The fayalite is very detrimental to corrosiveness, as published from Columbus Laboratories in 1972.
Recent studies by the the american foundry society point to some of the same conclusions, however, I am not sure what you are using this material for. Ingots will contain these defects, rolled will not. Hope this helps.