Welding rods

Filler metal for OFW of low-carbon steel is available in the form of cold-drawn steel rods 915 mm (36 in.) long and 1.6 to 4.0 mm in diameter. Welding rods for OFW of other metals are supplied in various lengths, depending on whether they are wrought or cast.

Specifications:

  • Steel welding rods have been standardized in the American Welding Society (AWS) specification A5.2, “Iron and Steel Gas Welding Rods.”
  • This specification shows three classifications of welding rods based on the minimum tensile strength of all-weld-metal and transverse weld test specimens:

(A) ALL-WELD-METAL TEST SPECIMENS, 6.40 ± 0.13 MM (0.252 ± 0.005 IN.) IN DIAMETER

(B) ELONGATION IN APPROXIMATELY 25 MM (1 IN.)

The mechanical properties specified for the RG65, RG60, and RG45 rods are obtained by welding in a neutral to slightly excess acetylene atmosphere.

The specification covers the chemical composition of the welding rods only to the extent of limiting sulfur and phosphorus to 0.040% maximum, and aluminum, if present, to 0.02% maximum. Therefore, welding rods of different manufacturers may vary appreciably in chemical composition.

Rods for OFW of steel have no flux covering. In the absence of flux coverings, weld-metal properties depend on chemical composition of the welding rod, control of the welding atmosphere, and techniques used to provide for mixing of base metal and filler metal.

Weld-Metal Strengthening:

  • The ability to control the properties of the weld by mixing base metal and filler metal in the weld pool means that the choice of welding rod can influence weld strength to a considerable extent.
  • Fully reinforced welds in thin-walled tubes of 4130 welded with RG45 rod consistently showed tensile strengths of 620 to 690 MPa (90 to 100 ksi).
  • When the welds were made with RG60 rods, the strengths increased to 690 to 860 MPa (100 to 125 ksi), and with RG65 rods, strengths as high as 1000 MPa (145 ksi) were attained when the joint was heat treated after welding.

Class RG65 welding rods have a low-alloy steel composition and are used for OFW of carbon and low-alloy steels that have strengths of 450 to 515 MPa (65 to 75 ksi).

  • They are used on sheet, plate, tube, and pipe.
  • These rods give the highest strengths in welding 4130, 4340, and 8630 alloy steels when base metal and filler metal are mixed properly.
  • The end use has a marked effect on selection of filler metal. If the base metal was selected to meet a specific corrosion- or heat resistant application, the filler metal should be of similar composition.
  • However, if a room-temperature mechanical property is the primary requirement, the strength and ductility of the filler metal should be the basis of selection.

Class RG60 welding rods are probably used most widely. They are generally made of low-alloy steel and are preferred for OFW of carbon and low-alloy steels in the tensile-strength range of 345 to 450 MPa (50 to 65 ksi). Class RG60 rods are most commonly used for welding carbon steel pipes for power plants.

Class RG45 welding rods have a simple low-carbon steel composition. These rods can be used for OFW of carbon and low-alloy steels.

Look for more information about stick welding machine at Hong Ky welding machine