Overlaid Hard-Facing Alloy Hardness Differs Widely:

"... how come the value happen to be rather higher in the straight area and lower along the circle...."

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It could be that the variation in geometry is effecting the rebound leading to variation in measurement.

what aspect might the rebound change. weld pool depth, speed( manipulattion speed of electrode was kept constant). Is it an assumption or conclusion based on previously similar experience? if it is a logic assumption do you have experimental evidence?

If this is not a large piece, things other than hardness may be influencing the rebound. On pieces that are thin in one dimension, especially something that rings if held right and struct with something hard, the shape instead of just hardness may be having a large effect on rebound.

I have no evidence for you...just relating something fundamental that can influence the way things rebound.

I would think that temperature variation due to more weld surface area being exposed along the edge of the circle plays a critical role in the test results.

I would also think that controlled post weld annealing of the work piece would be in order to equalize hardness values evenly throughout the metal.

by the way this check valve is DN800(32 inch), body base metal is 700mm high , overlay in 1F position

temperature variation would not affect the ECoCr-A hardness. plz refer to the last 3 paragraphs below. if it does why is the hardness uniformly low from the intersetion with straight overlay band to middle in the ring.

As suggested in the first thread the dilution shall be the same, therefore i thought firstly the CoCr, C, CrC shall be diluted to the same extent. however, after one sleepness night , it occurs to me that the angle is different, when surfacing the ring the welder arrange the angle so that the arc is slightly back inclined and yet towards the valve wall for easy travel and arc melts adjacent and front basemetal leading to more dilution, whereas surfacing the straight area the welder slightly inclined the electrode backwards and yet in parallel with the straight bead melting the front area nearly exclusive of the adjacent basement leading to dilution to a lesser extent.( if you have any different idea, put it here)

I to a small extent agree on ur second guess. as per ASME SFA 5.13 SPECIFICATION FOR SOLID SURFACING WELDING ROD AND ELECTRODE.

para A5.13 it states the cobalt filler metal are not subject to hardening transformation like steel and have negligible response to heat treatment.and

para A5.2 it says MANY SURFACING ALLOYS ARE SOFTENED PERMANANTLY BY HEATING TO ELEVATED TEMERATURE. CoCr filler metal is an exception. while they do exhibite lower hardness while hot, they return to approximately their original hardness upon cooling and can be consiered immune to tempering. it has been proven this way in our manufacturing involving PWHT.