Chromium Equivalent Formula I Haven't Seen Before 2

[myshadeofglory]

I work as a process engineer at a machine shop, but occasionally our quality inspector will bring me a question.

Right now we have a job in the shop that requires us to provide a chromium equivalent to our customer per their spec. The formula they give us to use isn't one that I've seen anywhere before.

The CE works out to be just above what the "supplier should aim for..." I'd like to try to get the material approved, so want to calculate the nickel equivalent and show the material is still Martensitic, but I need the corresponding formula and chart.

Anyone know whose formula this is and the corresponding information?

CE= CR + 6*Si + 4*Mo - 40*C - s*Mn - 4*Ni - 30*N

 

[myshadeofglory]

Any help on this one?

 

[stanweld]

I've never seen anything like it. It appears to be a modified Chrome equivalemnt minus a modified Ni equivalent.

 

[myshadeofglory]

That was my thought as well. I'm no CE expert, but I just don't get this one as it produces a number much lower than every other version I've seen.

 

[stanweld]

I would ask the customer as to its origin/meaning or if it is a typographical error. A reality check may be in order if the minimum chrome equivalent specified cannot bve met with the formula for the alloy grade specified.

 

[myshadeofglory]

Actually, the standard formulas are way off from their requirement, but using theirs it's only off by .97. Their quality department is less than helpful and would prefer to just tell us to order new material rather than reason. I was hoping I could do some research and present a solid case that they'd have trouble reasoning away.

 

[metengr]

This chromium equivalent equation is called the Newhouse equation and pertains to 9-12%Cr stainless steels.

http://www.google.com/url?sa=t&rct=...VoODN-ocpiyfZubMA&sig2=FxtQOzhm5IlouBJKQKe4Yg

 

[myshadeofglory]

Wow. Thank you. This is exactly what I needed.

 

[steelmtllrgst]

correct, this formula I have seen before on 9-12 Cr steels except with the Mn factor being 2 not s. That part may be a typo.