high hardness values 4

[teokal]

Dear all,
when we perform SAW welding at 1G rotating position (pipe or rolled plate) with diameter <20" of P No1 material, I receive high hardness values ( > 220 HB). The thing is that we have tried different combinations of wire/flux trademarks, Amperage, Voltage, welding speed etc. The result is always the same: high hardness values. Is there a tip, or I should just forget welding of less than 20" pieces automatically? Another thing is that the same machine gives me good results of hardness tests when welding longitudinal joints...
Thanks for you reply.

teokal

 

[DG72]

What kind of hardness tester?

 

[metengr]

More important, high hardness values of what - BM, HAZ, WM?

 

[gr2vessels]

teokal,
According to what you say, miracles must be common at your place. At my place, no miracles, but we can achieve variable hardness of the weld metal, HAZ and parent metal, simply by using/modifying the welding conditions as listed by you. Perhaps a curse from your opposition...maybe woodoo...

 

[teokal]

Dear DG72,
the hardness tester does not matter, we have used diferent types and brands (all portable). (e.g. EQUOTIP PROCEQ)
Dear metengr,
measurements have been taken on BM and WM (on the reinforcing of the weld - slightly grinded).
Dear gr2vessels,
first, there is no opposition! Curse? maybe... now I am trying a temper bead procedure... statistically, welds larger than 20" diameter (irrespectively of thickness) come out with good hardness results; the smaller the diameter, the higher the hardness...
anyway, thank you all for you fast replies.

 

[vesselfab]

smaller pipe = less cool down between passes

are you watching interpass temps?

you can reduce wire diameter/speed/heat input and the values will probably be better.

also...i hate equotips....try a tried and true tellebrinneller and see if it matches portable machine results