CHARACTERISTICS & APPLICATIONS
ícast-NM is covered electrode for all welding positions and is designed specifically for the welding of cast iron. It has a low-melting- point covering and differs from the ordinary mild steel electrodes included in ANSI /AWS A5.1, Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. Weld metal from this electrode is not readily machinable.
Since it is virtually impossible to prevent the formation of a hard zone or layer in the weld metal because of dilution from the base metal, this type of electrode is largely confined to the repair of small pits and cracks, with some application in the repair of castings that require no post weld machining. Since the shrinkage of steel is greater than that of cast iron, high stresses develop as the weld cools. Residual stresses may be severe enough to cause cracking.
Preheating is employed only when necessary to prevent excessive stresses in other parts of the casting. ESt electrodes generally are used at low amperage to minimize the dilution effect in the fusion zone and consequent weld and base metal cracking. The beads should be short and widely separated, to distribute the heat, and each bead should be peened lightly. The slag volume is low but very alkaline. Residual slag should be removed completely if the weld area is to be painted.
CHEMICAL COMPOSITION OF SOLID ELECTRODES AND RODS
| C | Mn | Si | P | S | Fe | Ni* | Mo | Cu | Al | Oth |
| 0.15 | 0.80 | 0.15 | 0.04 | 0.04 | Rem | NS | NS | NS | NS | NS |
Single values shown are maximum, unless otherwise noted. * Chemical requirements for the ESt classification are based on the composition of the core wire without any flux coatings.
ALL-WELD-METAL MECHANICAL PROPERTIES
| Tensile Strength, MPa | Yield Strength, At 0.2% Offset, MPa | Elongation % | Hardness, BHN |
| NS | NS | NS | 250–400 |
SIZES & CURRENT CONDITIONS (AC or DCEP)
| DIAMETER, mm | LENGTH, mm | Amperes |
| 2.50 | 350 | 60-95 |
| 3.15, 3.20 | 350 | 80-110 |
| 4.00 | 350 | 110-150 |
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.