Hi all
Interested in an article in last month's Welding Journal. There's a current issue of cracking of weld metal when cellulosic electrodes (typically 8010's) are too dry. The article:
author={Ramirez,J. E. and Johnson,M.}, year={2010}, title={Effect of welding parameters and electrode condition on alloying enrichment of weld metal deposited with coated cellulosic electrodes}, journal={Welding Journal}, volume={89}, number={11}, pages={232s-242s},
Are the authors reading here, by the way? Would be delighted to hear from you.
The authors talk of cellulosics being stored in a rod-oven with the basics (7016/7018) - which would be crazy, wouldn't it? Some cellulosics get too dry to use in an open dry-atmosphere college workshop at 20degC!
For anyone who hasn't access to Welding Journal - in the new outbreak of weld bead cracking they find very "rich" compositions, with high Manganese (eg. 1.9%) and Silicon, in all samples where there are weld cracks. And in their test welds where they dried (86degC for 1 week) the cellulosics, they found similar - these compositions increasing from a short distance into the weld run and rod burn.
I looked through the paper and formed these questions:
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No comment arc characteristics. Was the "roaring" cellulosic arc no longer present in the "dried" electrodes? Was the end of the electrode charred when the arc was broken? (reckon charring is a sign all has gone wrong(?))
No measure of nitrogen in the crucial "dried electrode" samples !!! We want to know - is there simple large-scale failure of entire gas-generation and shielding mechanism? Nitrogen level would tell us that and the information we most want isn't there!
(they measure nitrogen in other series of tests and find it increases as you go to 5mm arc length - which tells us shielding is compromised even with cellulosics at this long 5mm arc length. OK, no great surprise though. Pity they don't tell us the nitrogen level where we really need it)
Didn't measure what composition you get if you "cast" weld metal into a chilled copper mould. Make a "rod" of weld metal. What is the composition of that "rod"? Is it similar to what you get in the "dried" electrodes? If so, would hint at lack of dilution as explanation - also see penetration test next. Regardless - whatever is measured is likely to give hints.
Didn't measure penetration with as-received and "dried" electrodes eg. in a std. groove-in-plate or similar.
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What doesn anyone reckon? Are these good questions and if so what are the answers I am looking for?
Happy Christmas all
Richard S