Hello everyone
Setting the scene...
I am on a high-strength civil-engineering / steel-structure job. Looking for improvements - to welding technique, properties, etc.
The E71T-1 R-FCAW is guaranteed individually by the manufacturer to meet strength requirements, even though general E7 would not. Hence question about "-5" B-FCAW is about E80T-5.
The positional welds are clearly where need E71T-1 - no doubt about that. With small positional welds, strength and toughness are guaranteed.
We / I are looking at the 1G/PA seams. These are ceramic-back. There is a tendency to high heat-input values. Many ceramic-back FCAW-root are SAW fill and cap. (which also means - you can truly conclude they are not positional)
Would E80T-5 be the much better bet?
- where my questions really start *
With R-FCAW, toughness drops rapidly with higher heat-input. The old "North Sea oilrig rule" was 12mm max. bead width. That can be relaxed a bit, but not by much(???) Recommendation has been given. But asking you lot with your practical knowledge - what are the good widely-known rules for keeping high toughness (eg. low-temperature high Charpy impact value) with R-FCAW?
With B-FCAW - is there far less of a tendency for toughness to drop with increasing heat input? Basic SMAW (eg 7018) likes a slow big bead. Is this in general the same for an E0-5 B-FCAW?
What about welding technique and tolerance of the weld? I know of 6013 SMAW compared to 7018 SMAW. However, you cannot necessarily compare R-SMAW->B-SMAW with R-FCAW->B-FCAW ...
I'd be massively appreciative of s.e.j.w. "streetwise" answers and advice...
Rich S