Effect of Ca on weldability of pipeline steels 3

[sayee1]

1. How and why is Ca added(if at all added purposely) to line pipe steels?
2. DnV 2000 restricts the Ca content to 0.6%. Does increasing the Ca content affect weldability? If so how does it affect weldability?
3. Does increasing Ca in line pipe steels affect welding(especially automatic GMAW/P-GMAW welding) by any of the following:
Does Ca have anything to do with the fluidity of the weld pool?
Or does it have to do with the hardness of HAZ?
Or does it affect the desired HI to do the welding? (By probably preventing fusion with base metal…LOF is one of the most prominent defects when using automatic GMAW/P-GMAW welding of pipe lines)


Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The whole of science is nothing more than a refinement of everyday thinking!!!

 

[CoryPad]

The answer to question 1 is that Ca is added to line pipe steels (or any other steel) for inclusion shape control. For example, MnS inclusions usually are ductile and hot working temperatures, so they get elongated in the rolling/drawing direction. If Ca is added, the inclusions are spheroidal and don't get elongated. The end result is less stress concentration at the inclusion interface, which provides improved fracture and fatigue properties. I don't have enough expertise to answer the welding questions.


Cory

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

 

[sayee1]

Thanx Cory,a star for ur reply..... One more question though
Does Ca have anything to do with grain refinement by increasing nucleation sites during solidification???

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The whole of science is nothing more than a refinement of everyday thinking!!!

 

[stanweld]

In addition to corypad, Calcium is used in the desulfurization part of the steel melting process. Its "bad" effect in GMAW welding is to promote excessive spatter buildup in the torch nozzle. Antispatter sprays and frequent torch cleaning are required to avoid downtime. It is not added as a grain refiner - aluminum, vanadium and niobium are the common grain refiners.

 

[sayee1]

Stan, A star for your reply!!! Thanx

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The whole of science is nothing more than a refinement of everyday thinking!!!