[MW:8059] MW: 8056- consumable containing more than 1% nickel in sour environment

Limesh,

 

For sour service application involving MR-0175, the maximum Nickel content in the weld and BM is restricted  to 1%. It had been there for many years. Though there had been many theories behind the restrictions, it's difficult to find proven work , behind  this restriction. Addition of Nickel in C-Mn steel  is thought to cause the following:-

1. formation of acicular ferrite, which is desired for good toughens and strength.The optimum limit of  Nickel  to get these properties at the best level is generally 1% max.
2. Polygonal or soft ferrite, this is the basic nature of ferrite.Polygonal ferrite turns to acicular with more addition of nickel.
3. Martensite and austenite constituent.- With increase of Nickel beyond 1%, more and more  martensite +austenite phases would form in the weld. Note Nickel is a strong austenite forming element. Following heat treatment this(martensite+austenite) will transform to Carbides+ferrites and cause an increase of hardness, and makes weld more prone to SSC, which is not desirable for sour service.

Based on the various experiences the last one(item 3) is considered to be highly undesirable, hence the 1% restriction still stands.

 

The attached paper provides good fundamentals( that's my feel) on the same issue.

 

I hope you would enjoy this.

 

Thanks.

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of limesh M
Sent: Wednesday, November 03, 2010 10:29 AM
To: Materials & Welding
Subject: [MW:8056] Re: consumable containing more than 1% nickel in sour environment

Dear All,

 

I have searched a lot and reviewed many articles.Unfortunately I couldn't find any proven direct correlation between SSC and Nickel from those articles !!! Almost all reference materials simply says nickel percentage is restricted to 1% by NACE MR0175 and discussing more about hardness!!!Anybody having any research paper on nickel effect and SSC?

 

Regards,

 

Limesh

 

On Mon, Nov 1, 2010 at 8:22 AM, limesh M <limesh78@gmail.com> wrote:

Dear All,

 

Most of the client specification banned usage of consumable containing more than 1% nickel in sour environment.What would happen if we use consumable having more than 1% nickel?

If any damage will be the result,how it happening?

 

 

Regards,

 

Limesh

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