Due to the high alloy content and hardness of the hardface rod, you usually can put down no more than 2 to 3 layers of weld. This is because the weld metal is designed with an excessive amount of certain alloying elements with the designers knowing that it is to be applied over a much softer metal which will act as a cusion, and will mix in with the hardface overlay. when the hardface is applied it melts and mixes in with a certain ammount of the softer buildup or base metal. this dilutes the deposited hardfacing material to a useable level. If you apply more than 3 passes you loose this dilution, and cushoning provided by the buildup or base metal. Because of this the hardface will tend to become excessively hard and brittle, and will eventually tend to chip off or check badly (spider crack). |