AC vs DC in stick welding

By - Date 10-28-2003 14:31

DC,is better because you can choose more out of position electrodes! DC has a smoother arc,and arc starts are easier for most rods such as 7018

By RonG

Date 10-28-2003 21:10

DC provides better (deeper) penetration in most cases. That is to say the penetration caracteristics can be controled with voltage adjustments.

As far as it being stronger; I would think if a full penetration weld was done correctly the process is a moot point. But I have heard opinions from well established Metallugist to the contrary.

By jwright650 (*****)

Date 10-28-2003 22:06

I believe a 70ksi rod is worth 70ksi of deposited weld material. And 60ksi is worth 60ksi.....AC/DC??what ever the mfg. recommends for the particular rod you are running. I agree with RonG that a DC rod in RP has better digging characteristics and SP gives a higher electrode melting rate.
But to say one is stronger than the other(AC vs DC) is not an accurate statement.
my two cents,
John Wright

By rodofgod (**)

Date 10-30-2003 00:52

I was always lead to believe that DC SP(+)? polaity gave the best 'penetration'
We don't use 'straight' and 'reverse' over here in the UK, only + and -, so it can get a bit confusing!!
However, as long as a test piece is acceptable to whatever 'code', I don't see a problem!
I have found that it is easier to weld structual steel ie 'I' beams with AC because of the arc-blow problems with DC! I think this gives a better weld overall than one done with DC (less spatter etc) But that is my thoughts only!

By jwright650 (*****)

Date 10-30-2003 11:35

rodofgod,
AC rods are what we use here in our shop too.
John Wright

By R. Johnson (**)

Date 10-30-2003 12:36

All things being equal, DC+ (reverse polarity) gives you the most penetration. AC is next and DC- (straight polarity) the least amount of penetration. In my opinion, DC+ is a much smoother running arc.