30 November 2022

Selection of welding electrodes

Selection of welding electrodes

1.) Section Basis:-

To ensure compatible property with  base  material

Strength / toughness related compatibility

Environment / specific environment  related  compatibility – e.g.. Corrosion / high or low  temperature related application

Welding procedure / position related  compatibility – e.g.. V-up / v-down / oh welding

Crack resistant weld  during welding  in  specific cases – SS / cast iron / dissimilar  welding

2.) Section of Welding Electrode for Different Metallurgy:-

A.) Selection of Welding Electrode for C-Mn Steels:-

Group contains:- Mild steels (IS 2062), Boiler quality steel (IS: 2002), Micro-alloyed steels (IS: 8500), Weathering steels (IS : 11587)

E6013 medium coated electrodes: – For mild steel non-critical applications in static loading up to 40 mm combined thickness,

E6013 heavy coated electrodes:-  For mild / boiler quality steel semi-critical applications in dynamic loading up to 40 mm combined thickness

E 7018 electrodes + pre-heat as required:- For higher thicknesses for mild / boiler quality steel for all applications above 40 mm combined thickness –

B.) Selection of Welding Electrode for Micro-alloyed steels

  1. These are medium & high tensile steels developed for improved strength and toughness without impairing weldability. (Covered by IS:8500 – 1991)
  2. They contain small amounts of carbide forming elements e.g.. Nb, V, Ti etc. (Total 0.20% max).  They are characterized by very fine grain size (ASTM 12 – 14)
  3. Properties : 
  • UTS     450 – 600 MPa
  • YS  400 – 500 MPa
  • Elongation 20 – 22 %

4. Weld all sections with E7018 / E8018 G electrodes depending on minimum yield requirements

C.) Selection of Welding electrode for weathering steels

  1. These are medium tensile steels with Cu, Cr & small amount of P added to improve atmospheric corrosion resistance.  However, P  gives hot shortness and lower impacts and latest grades have reduced P levels.

Example – Corten A, B & C and Sailcor HR & CR steels used for rolling stock in railways and other transportation sectors. Corten B & C with lower P levels have better weldability

  1. For the lower strength Corten A & B type use E7018 – W1 electrodes
  2. For higher strength Corten C use E8018 – W2 electrodes.
  3. Note the electrode weld metal does not contain P

D.) Selection of electrodes for Creep Resisting steels

  1. These steels have additions of Cr, Mo & V for improving  their  creep / stress rupture properties at high temperature.
  2. They are used in turbines, boiler tubes and associated piping that carry  superheated steam at elevated temperatures.
  3. These are called chrome-moly steels  and the higher grades are alloyed with Vanadium for higher strength
  4. These are welded by electrodes of equivalent compositions.

3.) Electrode used for Steel Applications:-

 

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