This Guy in left field??or what???

By - Date 08-24-2000 05:28

Hi! I was on one of my favorite BB's and the discussion of arc and mig welding came into subject.
I have a Lincoln 225 buzz box and a Miller 185 mig and I use them both quite often.
I made mention that 7014 rod had a 30K tensil strength (I thought?) and this guy Jeff came
back with this reply:
Leave the mig welding to the artsy fartsy stuff. On your rig go stick or go home. Even
a good tig weld does not get the penatration a stick does. A tig is a good weld don't
get me wrong. I use mine for putting a root bead in pipe. But for welding a fillet weld
or butt weld the stick is the ticket. Hey maddog the 7014 you are using has a 70k
tensile strength. The first two numbers on a rod define its tensile strength, the third
number defines it current and polartiy and the fourth defines its welding positions.

------------------
Jeff
Now I've never heard of the rod identification numbers broken down that way, and I thought mig was
stronger than arc welding??? I get the feeling I'm getting a snow job from this guy and would appreciate
any information that would be helpful in my responce to him. Thanks in advance, Maddog

By RonG

Date 08-24-2000 13:29

Except for the remarks about TIG (GTAW) if you are useing "SHORT ARC" he is still in the ball park.
Maybe he has never seen "Spray ARC or Pulsed Spray".
GTAW can get what ever penatration you need.You can even "KeyHole" with it.
The Number system applys to LowHydrogen electrodes. Go to Lincoln Electric's web site for more info.
But! if you are doing a "Butt weld" with a gap between the two pipes Short Arc can do 100% penatration just like any thing else and I wonder how much more penatration does he want?

By - Date 08-24-2000 15:51

For ferritic steels (carbon and alloy steels - not stainless) the AWS designation indicates a minimum strength value except for submerged arc welding (SAW) wire. For shielded metal arc welding (SMAW) the first two digits, commonly, or three digits, for high strength materials, indicate the tensile strength. For example: an E6010 has a minimum tensile strength of 60,000 psi (60ksi), an E7014 has a minimum tensile strength of 70,000 psi, and an E12015-G has a minimum tensile strenth of 120,000 psi. The third (4th - high strength) digit indicates the positions for which the electrode is intended to be used: typically a 1 or a 2. A "1" means all position and a "2" means flat and horizontal only. The last digit, a number from "0" to "8" indicates the type of coating and therefore the type of current that can be employed and whether it is low hydrogen or not.

As far a strength is concerned for GTAW and GMAW the first two numbers indicate the minimum and for flux cored (FCAW) wire the first number indicates the minimum. Therefore for GTAW, ER70S-2, ER70S-3 or ER70S-6 all have a minimum tensile strength of 70,000 psi but differ in in the level of deoxidizers. For FCAW an E70T-1 and an E71T-1 both have 70,000 psi minimum strength but the E70 is intended for flat and horizontal welds only while the the E71 is an all position wire.

You can find the AWS welding designations explained in most basic welding text books.

The comment you've already received is correct. GMAW can be operated in any one of four modes: Short circuiting arc transfer (short arc), globular, spray, and pulsed. By varying the deposition mode you can select a very shallow, cold arc or an extremely deeply penetrating one or something in-between. This variablility is one of the reasons some people like this process. But there are some cautions - many companies, mine included, will not permit the use of short arc, even for rooting, on pipe.

Every process has it's good and bad points - a guy welding line pipe in the field may prefer using stick but in modern pipe fab shop you probably won't even find a stick welder. Weld process selection is complex and there is far more to it than selecting for depth of penetration - if that's all that mattered everything would be welded with electron beam welding.