WELDSTRONG ELECTRODES

Monday, October 26, 2015

Saturday, September 5, 2015

In this post, we will briefly see some commonly occuring Welding Defects and their Solutions.

WELDING DEFECTS	CAUSES	SOLUTIONS
Porosity	Wrong current setting Excessive speed Dirt or impurities in base metal	Set proper current Reduce speed of travel Use shallow penetration electrode.
Spatter	Amperage (heat) too high Excessive arc length .Arc Blow Wrong polarity	Reduce amperage Shorten arc Direct travel to the direction of blow. Switch to opposite
Arc Hard to Start	Current setting too low Poor or no ground Work dirty Low input line voltage Broken cable Corroded holder jaws	Increase current (Amperage) Attach ground to clean area of metal Remove rust, paint, oxides Check line voltage Usually in holder or ground- replace cable File and clean them up nicely
Slag Inclusions	Current setting too low Too short an arc Wrong bead forming procedure	Increase amperage Increase arc length Correct to proper waving bead (Welder Skills)
Poor Fusion	Current setting too low Wrong manipulation Too long an arc Incorrect work preparation	Reset current Correct speed and change weave Shorten arc length to frying sound Clean and prepare weld joint (V Joint)
Undercut	Current amperage too high Travel speed too fast Arc length excessive Incorrect electrode to work angle Wrong diameter electrode	Lower amperage Reduce welding travel speed Shorten arc length Use correct electrode angle (Welder Skills) Increase electrode diameter one size
Distortion	Improper set-up and jigging Excessive heating of weld area Wrong welding procedure	Correct set-up or jigging design Reduce heat in work Use correct welding procedure Use back step welding
Cracking	High carbon or poor quality material Wrong bead configuration Improper selection of electrode type Too fast cooling	Preheat Avoid excessive heat and puddle size Check and use correct type of electrode Preheat and post-heat, Cool slowly

Saturday, July 25, 2015

REQUIREMENTS FOR WELDING ELECTRODES RUNNING PERFORMANCE TEST

Source: Indian Railway Standard IRS M28-2011

Welding Electrodes undergo several type of Destructive and Non-Destructive testing in order to assure adherance to applicable Standard Specifications.They are Mechanical Testing, Chemical Testing, Radiography Testing, Running Performance Test, Hardness Test, Macro examination, Corrosion Resistance Test, Concentricity of flux covering, Hydrogen Diffusion Test etc.

In this Article, we will discuss on Running Performance Test of Welding Electrodes.

A 1 Running Performance: Running performance test shall be done by deploying the welder as per IS: 7310 Part 1 and IS: 7318 Part 1 and performance test shall be applicable for all class of electrodes. Following criteria shall be checked
A 1.1 General:
a) Packing condition: Shall be as per clause 5.

b) Physical condition of electrode (core wire and flux): Coating shall not be damaged / cracked. Core wire shall not be rusted.

c) Size and number of electrode in a packet shall be indicated : Diameter of core wire & length shall be within permissible limits

d) Coating factor (Ratio of dia. of core wire and dia. of electrode in flux coated area): shall be as per stipulated in respective IRS class.

e) Size of stub end and quality of end brushing: as per related IS/AWS

A 1.2 Current condition: Electrodes (except N series) for all sizes offered shall be operated in the current range (both minimum and maximum) as recommended by the manufacturer. The minimum voltage as recommended by respective IS/AWS code shall be taken. In case IS/AWS code is not applicable, minimum voltage as recommended by the manufacturer shall be considered. In lower current range, the electrode shall run smoothly without any arc breaking and in higher current range the electrode shall not become red hot upto minimum 50mm beyond stub end.
A 1.3 Performance test: Electrode (except N series) shall be operated at ± 20 Amp of the middle of the current range given. Following parameters shall be checked:
a) Ease of arc striking : The electrode should produce arc easily.

b) Arc stability : The arc must be stable & should not break during arcing.

c) Arc length : Short/Touch type/Medium/Long

d) Spatter quality & quantity: The spatter shall be less. & soft.

e) Smoke quality & quantity: The smoke shall be normal & arc should be visible.

f) Viscosity & controllability of slag: Fluid or viscous & easily controllable.

g) Colour of slag: Black/Brown/Grey/Other.

h) Slag detachability: The slag shall be easily removable.

i) Ripple of weld bead: Smooth & evenly rippled.

j) Convexity of weld bead :Flat to convex/concave.

k) Tendency to undercut: No tendency to undercut.

l) Crack, porosity etc. : Free from cracks & porosity & other defects .

There shall not be any adverse remark in any of the items indicated above.
A 1.4 Positional welding: Upto 4.00mm dia. electrode shall be operated at all the welding positions as per IS/AWS code. The appearance and quality of weld shall be satisfactory.

A 1.5 Cutting & Gouging: This shall be applicable for N series of electrodes only. A cutting electrode shall be able to cut through smoothly using the welding parameters recommended by the manufacturer. The plate can be mild steels, low alloy steels, stainless steels, austenitic manganese steels, cast iron, cast steel & non-ferrous alloys such as Nickel alloys, A1, Cu, Bronzes etc. A gouging electrode shall be able to gouge easily the plates of material as mentioned above. However, testing of N3 class of electrode shall be limited to ferrous items only.

A 1.6 Any other adversity: There shall not be any other adverse remark on the performance of the electrode.

A1.7 The precautions to be taken during welding are given in Appendix-E. These precautions must be followed during welding operation.
A 2
Accelerated Storage Stability Test: This test is applicable for all classes of electrodes.

A 2.1 Test: Ten numbers of electrode shall be kept in a humidity chamber maintained at 480C with Relative Humidity(RH) 90% min. for eight hours. After putting off the system, the electrodes shall be left in the humidity chamber for another 16 hours. After this period, the electrodes shall be taken out from the chamber and examined visually.

A 2.2 Acceptance criteria: At least eight electrodes out of ten shall not exhibit any:

a) Peeling off of flux coating.

b) Cracking of flux coating.

c) Loss of texture of flux.

d) Rusting of core wire inside flux coating.

For high deposition electrodes, deposition efficiency shall not fall below the
minimum stipulated value of 110% when tested with the electrode found acceptable as per criteria given above.

Friday, July 24, 2015

SAFETY CONSIDERATION IN WELDING

This Article deals with Safety Consideration in Welding

Source: Indian Railway Standard IRS M28-2011

Burn Protection

Molten metal, sparks, slag &hot work surfaces are produced by welding cutting & allied processes. These can causes burns.

To avoid burns worker should wear protective cloths made of fire resistance material.

Pant cuffs, open pockets or other places on clothing that can catch & retain molten metal should not be worn.

High top shoes or lather leggings & fire resistant gloves should be worn.

Halmet or hand shields that provide protection for face, neck & ear, & head covering to protect the head should be used.

The clothing should be kept free of grease & oil.

Wear insulated gloves.

Electrical Hazardus

All electrical instrument and work pieces should grounded.
To prevent shock, the work area, equipment & clothing should be kept dry all the times.
Welder should wear dry gloves & rubber sole shoes.
Cables &connection should be kept in good condition.
Correct cable size should be used to avoid over loading & subsequent failure of cable.
All electrical connections should be tight, clean & dry.

Fumes and gases

Fumes are solid particles which originates from welding filler metals and fluxes, the base metal and any coating presents in base metal.
Sufficient ventilation & exhausts should be used to keep fumes and gases away from breathing zone when welding is performed in the confined spaces.
Use auto- darkening helmets.
Follow the recommendations of manufacturers in this regard.

Radiation