Sulfur Percentage - Forging

[WendelTrento]

Dears,

Good morning,

Could you please help me with the question below?

I will manufacture Tees, Elbows and Crosses, austenitic stainless steel grade 316/316L - Closed die forgings.

My client's specification requests a control of the "Sulphur" element (0.005-0.012%).

Why do you have this sulfur control? Is it because the material is open die forged?

Att,

Wendel Trento
Brazil

 

[WendelTrento]

Is this sulfur requirement because the material is formed by an open matrix?
If I were to manufacture the parts with a laminated round bar, would this requirement no longer apply? because it is laminated.

 

[EdStainless]

This intermediate level of Sulphur (higher than standard but lower than free machining) is typically for weldability.
For example this is the S level required in 316L tubing for sanitary and high purity service applications.
This is because all of this tubing is orbital welded into place.
I have looked at hundreds of samples that were 0.006-0.010% S and have never seen any free S in the structure.
If you have enough forging reduction all will be fine.
What do you mean by laminated?

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P.E. Metallurgy, consulting work welcomed

 

[WendelTrento]

Hi EdStainless,

Thanks for the answer.

The Material had a reduction degree of 30.3.

I thought this sulfur gap was because of the forging process. Example: Hot ductility.

Att,

Wendel Trento

 

[EdStainless]

Has the ingot had any previous reduction from the cast size?
I am sort of surprised that someone is asking for this in forgings.
Most of this that I have seen is in thin walled systems and they use welded tube for everything, even to make the fittings.

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P.E. Metallurgy, consulting work welcomed

 

[WendelTrento]

Hi EdStainless,

I agree with you, there must be a supply specification error.

The part we will manufacture is not welded or threaded and has no wall.

Attached is a drawing of the component and my client's specification.

Att,

Wendel Trento

 

[WendelTrento]

Hi EdStainless,

Attached is specification.

 

[dik]

As Ed notes limitation for sulphur is for welding. Sulphur causes the metal to be 'hot short' which means that when heated the metal becomes brittle. This is from the formation of Iron Sulphide in the austenite grain boundaries.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdStainless]

I haven't seen those specs in years.
Yes, thin wall and it will be autogenously welded.
If manufactured correctly (with enough reduction and refinement) this S level is low enough to not cause 'hot short' issues.

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P.E. Metallurgy, consulting work welcomed

 

[MagBen]

I think I was the first to comment, but my post disappeared?! did someone remove it? I donot believe I added any type of ad. against posting guidelines!

Metallurgical reason behind is the concern of formation MnS that could cause hot cracking. deformed MnS could also form a stringer, not good for surface finish and corrosion. other concern is related to welding pool characteristics as ED pointed out.

Note, in Semiconductors Industry, the requirement for S is even tighter/lower.

 

[dik]

MnS???

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[EdStainless]

Yes, when you get too much S you will end up with Mn S stingers in the structure.
That is why free machining SS forms chips, the cut material breaks when it hits the inclusions.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[dik]

Thanks Ed... I always thought it was the FeS that caused the problems...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik