At college, I want to experience commercially useful welds.
Want to try 7018's for the first time.
Never met them before - only get 6013's in colleges in UK. Always have some 6011's "for the pipewelders" which I can grab. Have used "Google groups" to look at post postings on the subject of 7018. Was thinking of buying my own xx18's so I can be in practice for when I go to a job. So want to check that I am doing the right thing before parting with my money.
Experimenting at college on 1/4inch / 6mm plate and largest rods available are 3.2mm (1/8"):
Find fastest way with stick to good h-v T-joint fillet weld is 3.2mm (1/8") 6011 fillet corner first pass and two 3.2mm (1/8") 6013 stringer capping passes. All DCEP at 125A, as current max. for 6011 and don't want to be resetting welding machine per run (3.2mm 6013 ->140A max.).
Regarding hydrogen and strength, am interested in trying 7018.
Read in SEJW postings that in US, use 6010 root / fillet-corner / first-run and 7018 cap.
Does using 7018 as "hot pass" capping runs dilute-down and disperse the hydrogen and make the procedure OK even on slightly quench-hardenable steels (eg. up to 0.25%C) - so you can get reliable pen. and fast procedure without concerns over cracking?
How fast should a 7018 weld be?
I read from past SEJW postings that you use a very short arc with xx18. The suggestion is that you are so close as to lightly drag to flux edge on the job. So if you have the rod slope angle at60deg. (30deg. off vertical), you can have the leading-edge flux scraping on the previous run? Running at a rate which means the formed, welling-up weld-pool's leading-edge slope brings it really close to the burning end of the rod?
Where do you start your run, given that the start is prone to porosity? Do you start on top of the previous run so far, say about6mm (1/4") back and run up and over the previous finish, than grind off the "standing-up" restart for a high-quality weld?
What other things I should be watching / doing?
Rod recommendation and size:
I read that Lincoln Excalibur 7018 recommended. Any knowledge Bohler / Boehler "Fox EV 55"?
Have DC welders at home and at college.
What sizes, thinking of productivity? Is 3.2mm large enough for good productivity on 6mm (1/4") plate? Should I try to blag 4mm (5/32") rods? Is 4mm 6010/6011 root, 4mm 7018 cap good?
Thanks in advance.