Dear Sevak:
Mr. Swamy mentioned the methods of fabrication to avoid cracks of overlays on sensitive base metal which is not the case here.
Chromium Carbide Deposit will crack whatsoever the method is. That's inherent to this material but the point is you shall manage these cracks. If you decide to avoid these cracks, maybe you can manage it for a while but suddenly you will see a big wide crack tearing your workpiece apart. So you have to accept its presence and control it in your favor.
You should be critical on the crack size (width and length), quantity per square feet and their direction. It means that ideally it is better to have many short perpendicular cracks rather than a few long parallel cracks.
Chromium Carbide Deposit will crack whatsoever the method is. That's inherent to this material but the point is you shall manage these cracks. If you decide to avoid these cracks, maybe you can manage it for a while but suddenly you will see a big wide crack tearing your workpiece apart. So you have to accept its presence and control it in your favor.
You should be critical on the crack size (width and length), quantity per square feet and their direction. It means that ideally it is better to have many short perpendicular cracks rather than a few long parallel cracks.
How can you do that...?
For this purpose, you want cracks to be formed as soon as possible. Don't hold them back...!!!
Do not use much preheat unless your base metal calls for it (I don't think your base metal needs preheat), interpass temperature shall not exceed a certain limit (like Austenitic stainless steels). Some people actually use water to quench these overlays right after the arc is off and inspect the cracks after depositing each lb of filler metal and before they continue overlaying and it works...!!!
It's better to have a crossed pattern for weld directions. Normally cracks appear in transverse direction (with reference to weld direction) so if you want to avoid parallel cracks, you should weld in different directions. Chess pad pattern works well.
I think you got the idea...
Regards
On Fri, Jun 21, 2013 at 8:49 AM, sevak hiren <hirensevak80@gmail.com> wrote:
Dear Experts,One of the manufacturer is using XL-CCH electrodes for Hard Facing Weld Overlay on c arbon steel material. (Chromium Carbide Alloy Deposit Hard Facing Electrode).The weld overlay outer surface is showing parallel hair line cracks.The manufacturer is arguing that these cracks are bound to develope due to inherrent properties of electrode & it is good to observe cracks on weld for ensuring the application of these type of electrode. The electrode catalogue also states that cracks can be developed on weld surface.My question is which code/standard allow cracks on such hard facing overlay ?--
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