FW: 10221] Effect of phosphorus as an alloying element on microstructure and mechanical properties of pearlitic gray cast iron

[pgoswami]

Hi Herman,

The attached literatures would be of interest to you. The issue looks to be formation  the formation  low melting  but hard eutectic called stedite. Phosphorus is good for fluidity  and hard phosphides/stedites increases the wear resistance of  grey iron castings. However it's always  advisable to restrict phosphorus within the specified limits, otherwise excess phosphides would make CI very brittle.

This effect would be less pronounced in S.G iron, where the impurities are inoculated and rounded up through injection of magnesium.

Thanks.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario,Canada.
Email-p...@sympatico.ca,
pgos...@quickclic.net

-----Original Message-----
From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of hpi001
Sent: Tuesday, March 08, 2011 8:55 AM
To: Materials & Welding
Subject: [MW:10221] Effect of phosphorus as an alloying element on microstructure and mechanical properties of pearlitic gray cast iron

Does anyone within this group has experience and/or some documentation which shows the effects of adding phosphor to pearlitic Gray Cast Iron, and what the reason is for such addition?

Thank you in advance.

Best Regards,

Herman Pieper

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[Pieper QSI]

Dear Pradip,

 

Thank you very much for this information it is indeed very interesting information. The reason why I’m looking for such info is that a client of me is facing problems with casted bushes from which they machine Piston Rings. Hardness of the material is sometimes to low and there are inclusions present in the casting which first show up during machining. This kind of problems are mentioned in these documents and could be helpful finding the underlying problem.

 

Met vriendelijke groeten / Best Regards

 

Herman Pieper

 

Pieper Quality Support & Inspection

Phone: +31 (0)521 380083

Fax:     +31 (0)84 7539225

Cell:     +31 (0)6 51691215

www.pieper-qsi.nl

[shaji nair]

Dear Goswami,

                         Can you please explain to us the purpose of checking ferrite element in 347H SS matl.

 

What is the requirement of ferrite in 347 material  ?

What are effects of ferrite if found high or low in 347 SS matl ? 

How it can be lowered or maintained correctly in the welding process or material. ?

 

Thanks & Regards,

 

Shaji Nair

 

 

[pgoswami]

 Hello Shaji

Ferrite is needed in austenitic weld metal to reduce  sensitivity to hot cracking.The minimum ferrite limit necessary to assure freedom from cracking depends, among other factors, on the weld metal composition.

As per IIW, IX-1695-92-Guidance on specifications of ferrite in stainless steel weld metal- For high-temperature applications(up to 700 deg C)  for SS 316H, 308H, 347, typically  3-8 FN range suits most applications.

As per API RP582:- The minimum FN for type 347 shall be 5 FN. The minimum FN may be reduced to 3FN provided the fabricator submits data verifying that hot cracking will not occur using the lower FN consumable to be used in production and this is approved by the purchaser.

Welding technique , especially arc length can alter ferrite readings in the weld.Longer arc can cause ingress of Nitrogen in the weld and loss of Chromium  through oxidation. Nitrogen being a strong austenitie stabilizer would reduce ferrite. However controlling (increase or decrease) ferrite by this technique is not advisable. One can not control the arc length precisely.

The best way to get the correct ferrite values would be  through adjusting the correct  weld metal composition. Please see the attached document which illustrates the Schaeffler and Delong  diagram. The very basic difference between the two is that Delong considers the effect of Nitrogen in the weld metal.

Traditionally for S.S 347 weld metal ASME SFA 5.4 does not allow any Nitrogen.The correct composition, together with welding technique will be helpful to get ferrite between 3-8 FN as stated above.

Hope this clarifies  your query.

Thanks.

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgos...@quickclic.net

 

---

From: shaji nair [mailto:shaji...@gmail.com]
Sent: Thursday, March 10, 2011 9:26 AM
To: pgos...@sympatico.ca; pgos...@quickclic.net
Cc: Jignesh Panchal
Subject: Effect of ferrite element on 347H material

[ashish chauhan]

in stainless steel there is a chances of solidification cracking
during solidification of weldment. ferrite can avoid this
solidification cracking if it is in limit. limit of ferrite depends on
stainless steel application. generally it is good to have 2 to 4 FN in
stainless steel. above this range it may reduce ur toughness value

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> w.r.t. applicable code/standard/contract documents.
>

--
Thanks and Regards

Ashish Chauhan
ME-Welding Technology
MSU-Baroda