ARC WELDING ELECTRODE

ARC WELDING ELECTRODE

03/12/14 03/12/14 ARC WELDING ELECTRODES ARC WELDING ELECTRODES 1 1 ARC WELDING ARC WELDING ELECTRODE ELECTRODE NAFFAA. AL-ANEZI NAFFAA. AL-ANEZI MECHANICAL INSPECTOR MECHANICAL INSPECTOR OCTOBER 30,2005 OCTOBER 30,2005 03/12/14 ARC WELDING ELECTR ODES 2 CONTENTS OF PRESENTATION CONTENTS OF PRESENTATION  HISTORY OF ARC WELDING COATED HISTORY OF ARC WELDING COATED ELECTRODE ELECTRODE  WHAT IS AN ELECTRODE ? WHAT IS AN ELECTRODE ?  SIZE OF ELECRODE SIZE OF ELECRODE  TYPES OF ELECTRODES TYPES OF ELECTRODES  COATING OF ELECTRODES COATING OF ELECTRODES  TYPES OF ELECTRODE COATING TYPES OF ELECTRODE COATING  STORAGE AND DRYING OF STORAGE AND DRYING OF ELECTRODES ELECTRODES  TESTING OF ELECTRODES TESTING OF ELECTRODES 03/12/14 ARC WELDING ELECTR ODES 3 HISTORY OF ARC WELDING COATED HISTORY OF ARC WELDING COATED ELECTRODE ELECTRODE During first stage of work with metal arc During first stage of work with metal arc welding a bare electrode was in use which welding a bare electrode was in use which was producing brittleness in the welded was producing brittleness in the welded area and the weld was considerably weak. area and the weld was considerably weak. overheating effect on weld metal was overheating effect on weld metal was noticed as there was no arc stability. noticed as there was no arc stability. To overcome these difficulties researchers To overcome these difficulties researchers developed a number of electrodes in 1907 developed a number of electrodes in 1907 that were covered with organic or mineral that were covered with organic or mineral materials which is known as coating or materials which is known as coating or flux. flux. 03/12/14 ARC WELDING ELECTR ODES 4 WHAT IS AN ELECTRODE ? WHAT IS AN ELECTRODE ? The electrode may be defined as “it is The electrode may be defined as “it is metal of which the sole purpose to carry the metal of which the sole purpose to carry the current and sustain the electric arc between current and sustain the electric arc between its tip and base metal as well as in some its tip and base metal as well as in some cases it melts and supplies filler metal cases it melts and supplies filler metal addition in the proposed joint.” addition in the proposed joint.” Electrode can be divided into two groups Electrode can be divided into two groups depending upon their functions which are depending upon their functions which are given below. given below. ELECTRODE COSUMABLE NON CONSUMABLE 03/12/14 ARC WELDING ELECTR ODES 5 CONSUMABLE AND NON- CONSUMABLE AND NON- CONSUMABLE CONSUMABLE  The consumable electrodes refers to The consumable electrodes refers to conduct current from electrode holder to conduct current from electrode holder to metal and supply filler metal to the joint, metal and supply filler metal to the joint, like in SMAW. like in SMAW.  non-consumable electrodes are only used to non-consumable electrodes are only used to work as conductor carrying the current from work as conductor carrying the current from electrode holder to base metal, like in electrode holder to base metal, like in GMAW GMAW 03/12/14 ARC WELDING ELECTR ODES 6 SIZE OF ELECTRODE SIZE OF ELECTRODE THE SIZE OF ELECTRODE REFERS TO THE DIAMETER OF ITS THE SIZE OF ELECTRODE REFERS TO THE DIAMETER OF ITS CORE WIRE. THE SIZE IS AVAILABLE IN METRIC AS WELL CORE WIRE. THE SIZE IS AVAILABLE IN METRIC AS WELL AS IN ENGLISH SYSTEM. LIKE 1/8”, 3/32” AND 2 MM , 4 AS IN ENGLISH SYSTEM. LIKE 1/8”, 3/32” AND 2 MM , 4 MM ETC. MM ETC. STRIKING END CORE BARE END FOR GRIPPING FLUX OR COVERING Dd D = COVERING DIA , d= CORE DIA 03/12/14 ARC WELDING ELECTR ODES 7 Arc welding electrodes are classified in Arc welding electrodes are classified in groups by American Welding Society (AWS groups by American Welding Society (AWS a5.1-91) based upon their type of coating, a5.1-91) based upon their type of coating, mechanical properties and performance mechanical properties and performance characteristics characteristics as well as weld metal as well as weld metal chemistry. for our discussion we can chemistry. for our discussion we can categorize the electrode as under . categorize the electrode as under . TYPES OF ELECTRODE TYPES OF ELECTRODE 03/12/14 ARC WELDING ELECTR ODES 8 ELECTRODES TYPES ELECTRODES TYPES ELECTRODE ELECTRODE BASED UPON MATERIALS BASED UPON COATING 03/12/14 ARC WELDING ELECTR ODES 9 BASED UPON MATERIALS BASED UPON MATERIALS  MILD STEEL ELECTRODES (AWS A5.1) MILD STEEL ELECTRODES (AWS A5.1)  LOW ALLOY STEEL ELECTRODES (AWS A5.5) LOW ALLOY STEEL ELECTRODES (AWS A5.5)  STAINLESS STEEL ELECTRODES (AWS A5.4) STAINLESS STEEL ELECTRODES (AWS A5.4)  ELECTRODES FOR CAST IRON (AWS A5.15) ELECTRODES FOR CAST IRON (AWS A5.15)  COPPER AND COPPER ALLOY ELECTRODE COPPER AND COPPER ALLOY ELECTRODE (AWSA5.6 (AWSA5.6 ) )  NICKEL AND NICKEL ALLOY ELECTRODE NICKEL AND NICKEL ALLOY ELECTRODE ( ( AWS A5.11) AWS A5.11)  ALUMINIUM AND ALUMINIUM ALLOY ALUMINIUM AND ALUMINIUM ALLOY ELECTRODE ELECTRODE ( ( AWS A5.3) AWS A5.3) ONLY FIRST THREE OF THE ABOVE WILL BE ONLY FIRST THREE OF THE ABOVE WILL BE DISCUSSED. DISCUSSED. 03/12/14 ARC WELDING ELECTR ODES 10 MILD STEEL ELECTRODES MILD STEEL ELECTRODES AMERICAN WELDING SOCIETY SPECIFICATION AMERICAN WELDING SOCIETY SPECIFICATION AWS 5.1 DESCRIBES THE REQUIREMENTS FOR AWS 5.1 DESCRIBES THE REQUIREMENTS FOR MILD STEEL ELECTRODES. AN IDENTIFICATION MILD STEEL ELECTRODES. AN IDENTIFICATION SYSTEM HAS ADOPTED IN ORDER TO KNOW THE SYSTEM HAS ADOPTED IN ORDER TO KNOW THE PROPERTIES AND CHEMISTRY OF THE ELECTRODE. PROPERTIES AND CHEMISTRY OF THE ELECTRODE. THE IDENTIFICATION HAS EXPLAINED AS UNDER. THE IDENTIFICATION HAS EXPLAINED AS UNDER. EXXXX EXXXX “ “ E” DESIGNATES FOR ELECTRODE E” DESIGNATES FOR ELECTRODE [...]... temperature of the electrodes will not be uniform 03/12/14 ARC WELDING ELECTR 29 TEMPERATURE REGULATOR BAKING OVEN 03/12/14 ARC WELDING ELECTR 30 POTABLE OVEN 03/12/14 ARC WELDING ELECTR 31 When the electrodes are initially placed in the oven, the temperature should not be greater than half the re-drying temperature The electrodes should be held at that temperature for ½ hour before heating the electrode to... RENDER IT LOW HYDROGEN ELECTRODES THE ELECTRODES HAVING THIS TYPE OF COATING IS PREFERRED TO USE FOR MINIMISE THE RISK OF HYDROGEN-INDUCED CRACKING OR COLD CRACKING IN THE BASE METAL EXX15,16,18 OR THE EXAMPLES OF THIS TYPE OF COATING 03/12/14 ARC WELDING ELECTR 23 STORAGE AND DRYING OF Arc weldingELECTRODE properly electrodes must be stored in order to deposit quality welds when electrodes absorb moistures... 03/12/14 ARC WELDING ELECTR 27  Electrodes should be supplied to welders in quantities that can be consumed within time limits that are dependent on the electrode type and strength level For example, standard E7018 electrodes can be safely be exposed to the atmosphere for 4 hours whereas standard E11018 electrodes are restricted to only ½ hour 03/12/14 ARC WELDING ELECTR 28 Re-drying Of Low Hydrogen Electrodes... 0.3%Mn, 0.1% V 03/12/14 ARC WELDING ELECTR 15 STAINLESS STEEL ELECTRODES STAINLESS STEEL ELECTRODES ARE USED FOR THE WELDING OF CORROSION – RESISTING AND HEAT- RESISTING STEELS THEY ARE EXPLIANED IN AWS A5.4 “SPECIFICATION FOR CORROSION – RESISTING Cr AND Cr-Ni STEEL COVERED ELECTRODES” SOME SS ELECTRODES HAVE GIVEN WITH THEIR MECHANICAL PROPERTIES IN THE FOLLOWING TABLE 03/12/14 ARC WELDING ELECTR 16 Mechanical... once Electrodes that have become wet or moist shall not be used and shall be discarded 03/12/14 ARC WELDING ELECTR 34 Standard Tests For Electrodes Type Of ISO BS639 Test 2560 AWS A5.1 X DIN 1913 X TRANSVERSE BEND X X X TRANSVERSE TENSILE X X X DEPOSITION EFFECIENCY X DIFFUSIBLE HYDROGEN X TENSILE & IMPACT X X CHEMICAL COMPOSITIO N 03/12/14 X ARC WELDING ELECTR 35 THE END THANKS 03/12/14 ARC WELDING ELECTRODES...  03/12/14 ARC WELDING ELECTR 13 EXXXX The last two numbers together indicate the type of welding current the electrode can be used with For example EXX10 DC+ EXX11 AC OR DC+ EXX20 AC , DC +,EXX12 AC OR DC- EXX24 AC , DC +,EXX13 AC , DC+,- EXX27 AC, DC +,EXX14 AC , DC+,- EXX28 AC, DC + EXX15 DC+ EXX16 AC , DC+ EXX18 AC , DC+  03/12/14 ARC WELDING ELECTR 14 LOW ALLOY STEEL ELECTRODE THESE ELECTRODES... None None ARC WELDING ELECTR 17 BASED UPON COATING   CELLULOS TYPE RUTILE TYPE  ACID TYPE OXIDIZING TYPE  BASIC TYPE  03/12/14 ARC WELDING ELECTR 18 CELLULOS TYPE THE CELLULOSE IS A ORGANIC MATERIAL WHICH CONTAIN 30 % IN THE ELECTRODE COATING BY WEIGHT IT DECOMPOSES IN THE ARC AND PRODUCE A GAS SHIELD WHICH PROTECTS ARC FROM AUTMOSPHERIC OXYGEN AND NITROGEN EXX10 IS THE EXAMPLE OF THIS TYPE ELECTRODE. .. 03/12/14 ARC WELDING ELECTR 20 ACID TYPE THIS TYPE OF COATING CONTAIN IRONOXIDE AS A MAJOR CONSTITUENT DURING WELDING IT PRODUCE A IRON-MANGANESE OXIDE –SELICA FLUID SLAG WHOSE METALLARGICAL EFFECT IS ACIDIC THIS SLAG SOLIDIFIES LIKE HONEYCOMBSTRUCTURE AND EASLY DETACHED ELECTRODE HAVING THIS COATING IS GOOD FOR FILLET WELD ONLY EXX22 IS THE EXAMPLE OF THIS TYPE OF ELECTRODE 03/12/14 ARC WELDING ELECTR... “60” 03/12/14 ARC WELDING ELECTR 11 EXX X X THIRD NUMBER IS DENOTING THE POSITION IN WHICH THE ELECTRODE CAN BE USED EXAMPLE:  “1” FOR ALL POSTION (F, V,OH,H)  “2” FOR FLAT AND H-FILLET POSITION  “3” HAS NO DESIGNATION  “4” FOR F, OH, H AND V-DOWN BUT MOSTLY SUITABLE FOR V-DOWN ONLY  03/12/14 ARC WELDING ELECTR 12   EXXXX LAST NUMBER REFERS TO CHEMICAL COMPOSITION PRESENT IN THE ELECTRODE COATING... Hydrogen Electrodes When the electrodes have been exposed to the atmosphere for period of a four hours , the electrode can be re-dried The following re-drying procedure should be used:  To re-dry, electrodes should be removed from the can, and placed in suitable oven The electrodes should be spread out in the oven so that all electrodes will reach the drying temperature The can of electrodes should not be