the grooves of the enhanced surface so the effect on flow is minimal the external bead 31 is easily removed without damage to the enhancement pattern fig1 shows a fin insert 60 in accordance with a second embodiment of the invention the fin insert 60 has a first angle 44 having a positive value similar to that of the preceding embodiment the second angle 48 39 is any angle less than 180 u00b0 preferably the second angle is from about 170 u00b0 to about 180 u00b0 and most preferably from about 175 u00b0 to about 179 u00b0 an inflection zone 52 39 in the region where the enhanced portion 50 terminates converts the fin insert from the positive first angle 44 to the second angle 48 39 with a small zero degree region preferably this zero degree region has a length of from about 10 to about 30 the thickness of the non enhanced portion of the base metal as shown in cross sectional representation in fig1 the first angle produces a solid weld bead 62 in the base portion 46 of the metallic strip 34 the second angle forces the material out of the enhanced region such that the weld tapers off in the inflection zone 52 34 and there is no weld in the second angle zone 48 34 of the enhanced portion 50 the use of the fin insert produces a.