Dear Jaydeep,
Please refer to the following info as a guideline.
On pure copper or most of its alloys, any application of heat will soften work piece, hence HAZ is likely to be weak.
Two additional characteristics of copper and most of its alloys are:
- High thermal conductivity, meaning that preheat is required for many joints, even at quite modest thicknesses,
- High coefficient of thermal expansion warrants proper care against distortion, a major issue indeed, initiating from the root pass, with root gaps rapidly distorting during welding.
The filler metal most often selected to weld pure and oxygen-free copper are as follows:
a. AWS A5.7 ERCu, ERCu typically contains 0.4% of Si and Mn with 0.8% of Sn to aid fluidity.
b. Also, check BS EN ISO 24373:2009 Welding consumables. Solid wires and rods for fusion welding of copper and copper alloys.
Shielding gases for welding pure / oxygen-free copper are argon, helium and nitrogen or mixturees of two or more of these. Pure argon may be used for TIG welding up to a thickness of some 2mm and for MIG welding up to approximately 5 mm - above these thicknesses an argon-helium mixture will give better results with greater heat input and less risk of lack of fusion defects.
The following table should be of some help.
| Process | Thickness (mm) | Shielding Gas | Preheat °C | Welding Current (amps) |
|---|---|---|---|---|
| TIG | ||||
| 1.0 | argon | >10 | 20 - 60 | |
| 1.0 - 2.0 | argon | >10 | 50 - 160 | |
| 2.0 - 5.0 | argon/75helium | 50 | 120 - 300 | |
| 6.0 - 10.0 | argon/75helium | 100 - 200 | 250 - 375 | |
| 12.5 | argon/75helium | 350 | 350 - 420 | |
| 15.0 | argon/75helium | 400 - 450 | 400 - 470 |
In your case grove geometry will be something like this:
12 mm to 25 mm single V, included angle of 60 to 70°, 1.5 to 3 mm root face, 1.5 mm maximum root gap. At high currents, proper safety measures must be carefully worked out.
From: Joshi Jaydeep <jaydeep.p.joshi@gmail.com>
To: materials-welding@googlegroups.com
Sent: Thursday, 8 December 2016 1:18 PM
Subject: [MW:25804] Welding of Oxygen free (Pure) copper
Dear Experts,
Do anybody have an experience of welding Pure copper (99.997%) i.e Oxygen free grade by TIG welding (with filler wire). For info.: My job thickness range if 12-15mm plate to plate full penetration butt welding.
http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk=anet_ug_hm
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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