CHARACTERISTICS & APPLICATIONS
ímet-75 is a low-hydrogen sodium type electrode commonly used for making small welds on thick base metal, since the welds are less susceptible to cracking. These were developed for welding low-alloy high-strength steels, some of which were high in carbon content. Electrodes with other than low-hydrogen coverings may produce “hydrogen-induced cracking” in those steels. These under-bead cracks occur in the base metal, usually just below the weld bead. Weld metal cracks may also occur. ímet-75 should be used when welding high-sulfur or enameling steels. Other electrodes are likely to cause porosity and/or cracks in high-sulfur steels. Welds made with ímet-75 electrodes on high-sulfur steels may produce a very tight slag and a very rough or irregular bead appearance in comparison to welds with the same electrodes in steels of normal sulfur content. The arc of these electrodes is moderately penetrating. The slag is heavy, friable, and easy to remove. The weld face is convex, although a fillet weld face may be flat. These electrodes up to and including the 4.0 mm size are used in all welding positions. Larger electrodes are used for groove welds in flat welding position and fillet welds in horizontal and flat welding positions. ímet-75 can be used with dcep. The shortest possible arc length should be maintained for the best results with these electrodes. This reduces the risk of porosity. The necessity for preheating is reduced; therefore, better welding conditions are provided.
Storage and Drying Conditions: To maintain low-hydrogen electrodes with minimal moisture in their coverings, these electrodes should be stored and handled with considerable care. Electrodes which have been exposed to humidity may absorb considerable moisture and their low-hydrogen character may be lost. Then conditioning can restore their low-hydrogen character.
Hydrogen can have adverse effects on welds in some steels under certain conditions. One source of this hydrogen is moisture in the electrode coverings. For this reason, the proper storage, treatment, and handling of electrodes are necessary.
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Holding Ovens: 30°C-140°C above ambient temperature. Drying Conditions: 260°C-425°C for 1-2 hours prior to use.
CHEMICAL COMPOSITION OF WELD METAL
| C | Mn | Si | P | S | Ni | Cr | Mo | V | Mn+Ni+Cr+Ni+V |
| 0.15 | 1.25 | 0.90 | 0.035 | 0.035 | 0.30 | 0.20 | 0.30 | 0.08 | 1.50 |
Single values are maxima, except where specified otherwise.
ALL-WELD-METAL MECHANICAL PROPERTIES
| Tensile Strength, MPa | Yield Strength, At 0.2% Offset, MPa | Elongation, % | Charpy V-Notch Impact at
-30°C | -35°C, Joules |
| 490 | 400 | 22 | 27 | 27 |
Single values are minimal.
Limit of Moisture Content, % by weight max: 0.60 (As Received or Reconditioned). Diffusible Hydrogen Content Average, Maximum, mL (H2)/100 g Deposited Metal: 4.00
ELECTRODE SIZE & WELDING CURRENT
| Diameter, mm | Length, mm | DCEP, Amperes |
| 2.50 | 350 | 65-110 |
| 3.15, 3.20 | 450 | 100-150 |
| 4.00 | 450 | 140-200 |
| 5.00 | 450 | 180-255 |
WARNING: Safety and health information is available from many sources, including, but not limited to Safety and Health Fact Sheets listed in A11.3, ANSI Z49.1 Safety in Welding, Cutting, and Allied Processes published by the American Welding Society, 8669 Doral Blvd., Suite 130, Doral, FL 33166., and applicable federal and state regulations. The Safety and Health Fact Sheets are revised, and additional sheets added periodically.