Stick electrode

Stick electrodes

The stick electrode is a minerally coated metal rod that is used for welding .

Stick electrodes for manual arc welding

construction

The stick electrode consists of a metallic core rod and a cover. The stick electrode is used for electric welding and forms the filler material that is necessary for welding . Most of the time, this filler metal is surrounded by a coating that contains additives. The first stick electrodes were not covered and therefore difficult to weld. The electrodes were later covered with materials that made welding easier, protected the weld metal and had a metallurgical effect on the process. The first patent for a covered stick electrode comes from the Swede Oscar Kjellberg in 1908. The welding electrode is connected to a welding power source with the associated welding electrode holder. If you touch the workpiece to be welded with the electrode, an electrical short circuit occurs . After the ignition process, the electrode is lifted from the workpiece and an arc is created which melts the material of the workpiece to be welded. At the same time, the electrode melts and connects to the workpiece to be welded. The jacket of the electrode forms gases which stabilize the arc and at the same time prevent oxidation of the weld seam . It also contains substances that lead to the formation of slag . It serves as a flux to reduce the surface tension of the melted material, ensures even cooling and binds impurities.

The covers of the electrodes essentially have the following tasks:

• Ionization and stabilization of the arc through admixtures (e.g. through rutile )
• Compensation for the burnout of the alloy components by adding appropriate additives
• Increase in output (e.g. with build-up welding)
• uniform cooling of the weld seam
• Shielding of the melted material by protective gases against nitrogen and oxygen (embrittlement, pore formation)

Abbreviations of the wrapping materials

• A = sour
• R = rutile
• RR = rutile, thickly coated
• RA = rutile acid
• C = cellulose
• R (C) = rutile cellulose
• RR (C) = rutile cellulose, thickly coated
• B = basic
• R (B) = rutile with basic components
• RR (B) = rutile basic, thickly coated

Core rod

The material of the core rod depends on the material to be welded and its chemical composition.

Selection of stick electrodes

The selection of stick electrodes is based on material and welding aspects. First, a comparison of the mechanical quality values ​​of the filler metal with the quality values ​​of the base material is made, whereby the minimum requirements of the base material must also be achieved in the pure weld metal.

The following criteria can be specified for the selection of stick electrodes:

• The base material to be welded
  • for unalloyed steels and fine-grain structural steel
  • for high-strength steels
  • for heat-resistant steels
  • for stainless and heat-resistant steels
  • for cast iron materials
  • for non-ferrous metals ; further subdivided according to:
    • the chemical composition
    • the metallurgical and physical properties

• The stress on the component ordered according to
  • constructive design of the component
  • predominantly static or predominantly non-static stress
  • Stress condition (size of the load)

• The welding task sorted by
  • Welding conditions
  • Welding position
  • existing welding power source
  • suitable wrapping type

• The economic efficiency ordered by
  • Deposition rate
  • Application
  • Line energy

The coated stick electrodes are usually selected according to the manufacturers' catalogs for welding consumables.

Example: core rods for unalloyed electrodes

• Carbon content: 0.06% to 0.12%
• Manganese : 0.3% to 1.8%
• Silicon : 0.06%
• Phosphorus and sulfur <0.03%

In addition, it is a conductor, iron support and cladding support.

Example of a stick electrode designation according to DIN EN ISO 2560-A (unalloyed steels and fine-grain steels)

Example: E 38 2 B 1 2 H5

• E Abbreviation according to DIN 1910 for the welding process; manual arc welding here
• 38 Minimum yield strength in N / mm²; here 380 N / mm²

Tensile strength in N / mm²; here 470-600 N / mm²

Elongation at break in%; here 20%

• 2 Minimum impact energy (47 joules) at −20 degrees Celsius
• B cladding type; here basic coated
• 1 application; here <105%

Type of current; here: direct and alternating current

• 2 welding position; all here except case position
• H5 hydrogen content here <5 ml / 100g weld metal

DIN EN ISO 2560-A: 2010-03 only uses MPa instead of N / mm²; the diffusible hydrogen content is expressed in ml / 100 g weld metal.

literature

Christian Guilino: Expertise for locksmiths, steel workers , fusion welders . Craft and technology, Hamburg 1984, ISBN 3-582-00077-X .