happy:
A legitimate question.
It is simply to replace worn areas of blades, buckets, etc. of any machinery or equipment that undegoes wear in lieu of replacing the entire unit or structure. Often hardfacing requires an interface material for build-up or aiding in the final weld metal properties such as impact, wear, abrasion, etc.
I used to do this and we even welded additional material to new components before they ever went into service. The patterns are basically the welders signature. But, it is also a method of reducing the amount of welding required. (Kind of like waxing a floor in arcs in lieu of circluar patterns, it is simply more efficient.)
Some of us use the padding technique, others use happy faces...