[MW:2966] Re: Rolling machine Rolls repair

I would recommend following the requirements of AWS D14.7, Recommended Practice for Surfacing and Reconditioning of Industrial Mill Rolls.  David Landon   Sent from my Windows Mobile® phone.  -----Original Message----- From: ali asghari <asgharialigl@gmail.com> Sent: Tuesday, August 18, 2009 9:16 AM To: materials-welding@googlegroups.com <materials-welding@googlegroups.com> Subject: [MW:2964] Re: Rolling machine Rolls repair  

Dear Prem Nautiyal

i don't have relatedexprience .but i suggest you must have a ductile material in core(inner surface ) and a  hard material in surface.therefore to achieve it ,first you make  holes in both starting and ending of crack, then remove and groove that area.

use from low hydrogen electrodes (basic type) such as 9018 or 10018.during welding the temperature of preheat not be lower than  150 or 200.before compeletion of weld(5-7 mm lower of base metal surface) use from hard surfacing electrodes.

do you have equipment for heat treating of rolling.

regards.

On Mon, Aug 17, 2009 at 8:00 AM, PREM SHANKARDUTT NAUTIYAL <prem_nautiyal@rediffmail.com> wrote:

Dear Friends

We have a Four Roll Plate Rolling Machine in our Fabrication shop. We had purchased this machine from Italy a couple of years ago.
Now we have observed some cracks on two rollers of length @100mm. The depth is @28mm,confirmed by UT.
We have also done spectro-chemical analysis of the roller by a portable spectro. The results are:
C=0.45, Si=0.29, Mn=0.81, Cr=0.1, Mo=0.03, Ni=0.14, Fe=97.14, S=0.002, P=0.003
Hardness= 53-55HRC (checked by portable hardness tester on surface).
Since the supplier / manufacturer of this Rolling Machine is not responding to us we have decided to repair these 2 rollers on our own inhouse.
Does any one have such experience in the past.
What would be the correct electrode, preheat,interpass, postheat,PWHT, welding precautions ?
We have dismantled these two rollers and are ready for repair.
Expert suggestions are welcome..

Regards

Prem Nautiyal



PREM S NAUTIYAL
CELL : 9820313278

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