Specifications for Flux Cored Electrodes: Weld Metal Toughness and Safety Considerations, Exercises of Materials science

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FIG. 12 DIMENSIONS OF STANDARD 8, 12 AND 14 in. (200, 300 AND 350 mm) SPOOLS

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PART C — SPECIFICATIONS FOR WELDING RODS, ELECTRODES, AND FILLER METALS SFA-5.

FIG. 13 DIMENSIONS OF 22, 24 AND 30 in. (560, 610, 760 mm) SPOOLS

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PART C — SPECIFICATIONS FOR WELDING RODS, ELECTRODES, AND FILLER METALS SFA-5.

FIG. A1 CLASSIFICATION SYSTEM FOR CARBON STEEL FLUX CORED ELECTRODES

Not Specified is used in those areas of the specification that refer to the results of some particular test. It indicates that the requirements for that test are not specified for that particular classification. Not Required is used in those areas of the specification that refer to the tests that must be conducted in order to classify an electrode (or a welding material). It indicates that that test is not required because the requirements (results) for the test have not been specified for that particular classification. Restating the case, when a requirement is not specified, it is not necessary to conduct the corresponding test in order to classify a electrode to that classification. When purchasers want the information provided by that test in order to consider a particular product of that classification for a certain application, they will have to arrange for that informa- tion with the supplier of the product. They will have

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to establish with that supplier just what the testing procedure and the acceptance requirements are to be for that test. They may want to incorporate that informa- tion (via ANSI/AWS A5.01, Filler Metal Procurement Guidelines ) in the purchase order. A2.4.3 When an electrode cannot be classified according to some classification other than a “G” classi- fication, the manufacturer may request that a classifica- tion be established for that electrode. This may be done by following the procedure given below. When the manufacturer elects to use the “G” classification, the Filler Metal Committee recommends that they still request a classification be established for that electrode as long as the electrode is of commercial significance. A2.4.4 Written requests for establishing a new electrode classification shall provide sufficient detail to

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permit the Committee or the Subcommittee to decide whether a new classification or the modification of an existing classification is more appropriate, and whether either is necessary to satisfy the need. The request shall state the variables and their limits for such a classification or modification. The request should contain some indication of the time by which completion of the new classification or modification is needed.

A2.4.5 Requests shall be received at AWS Head- quarters by the Secretary of the Committee, who will: (1) Assign an identifying number to each request. This number shall include the date the request was received. (2) Confirm receipt of the request and give the identification number to the person who made the request. (3) Send a copy of the request to the Chairman of the Filler Metal Committee and to the Chairman of the particular subcommittee involved. (4) File the original request. (5) Add outstanding requests to the agenda of meet- ings of the Committee and the subcommittee.

A3. Acceptance

Acceptance of all welding materials classified under this specification is in accordance with ANSI/AWS A5.01, Filler Metal Procurement Guidelines, as the specification states. Any testing a purchaser requires of the supplier, for material shipped in accordance with this specification, shall be clearly stated in the purchase order, according to the provisions of ANSI/AWS A5.01. In the absence of any such statement in the purchase order, the supplier may ship the material with whatever testing is normally conducted on material of that classi- fication, as specified in Schedule F, Table 1, of the ANSI/AWS A5.01. Testing in accordance with any other schedule in that table must be specifically required by the purchase order. In such cases, acceptance of the material shipped will be in accordance with those requirements.

A4. Certification

The act of placing the AWS specification and classi- fication designations on the packaging enclosing the product, or the classification on the product itself, constitutes the supplier’s (manufacturer’s) certification that the product meets all of the requirements of the specification. The only testing requirement implicit in this certifica- tion is that the manufacturer has actually conducted

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the tests required by the specification on material that is representative of that being shipped, and that the material met the requirements of the specification. Rep- resentative material, in this case, is any production run of that classification using the same formulation. “Certification” is not to be construed to mean that tests of any kind were necessarily conducted on samples of the specific material shipped. Tests on such material may or may not have been conducted. The basis for the certification required by the specification is the classification test of “representative material” cited above, and the “Manufacturer’s Quality Assurance Sys- tem” in ANSI/AWS A5.01.

A5. Ventilation During Welding A5.1 Five major factors govern the quantity of fumes in the atmosphere to which welders and welding operators are exposed during welding: (1) Dimensions of the space in which welding is done (with special regard to the height of the ceiling) (2) Number of welders and welding operators work- ing in that space (3) Rate of evolution of fumes, gases, or dust, ac- cording to the materials and processes used (4) The proximity of the welders or welding operators to the fumes as the fumes issue from the welding zone, and to the gases and dusts in the space in which they are working (5) The ventilation provided to the space in which the welding is done

A5.2 American National Standard Z49.1, Safety in Welding, Cutting, and Allied Processes (published by the American Welding Society), discusses the ventilation that is required during welding and should be referred to for details. Attention is drawn particularly to the section of that document entitled Protection of Personnel and the General Area and Ventilation.

A6. Welding Considerations A6.1 When examining the properties required of weld metal as a result of the tests made according to this specification, it should be recognized that in production, where the conditions and procedures may differ from those in this specification (electrode size, amperage, voltage, type and amount of shielding gas, position of welding, electrode extension, plate thickness, joint geometry, preheat and interpass temperatures, travel speed, surface condition, base-metal composition and dilution, for example), the properties of the weld

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A7.2 EXXT-2 and EXXT-2M Classifications. Elec- trodes of these classifications are essentially EXXT- and EXXT-1M with higher manganese or silicon, or both, and are designed primarily for single-pass welding in the flat position and for welding fillet welds in the horizontal position. The higher levels of deoxidizers in these classifications allow single-pass welding of heavily oxidized or rimmed steel. Weld metal composition requirements are not speci- fied for single-pass electrodes, since checking the com- position of the undiluted weld metal will not provide an indication of the composition of a single-pass weld. These electrodes give good mechanical properties in single-pass welds. The manganese content and the tensile strength of the weld metal of multiple-pass welds made with EXXT- 2 and EXXT-2M electrodes will be high. These elec- trodes can be used for welding base metals which have heavier mill scale, rust, or other foreign matter that cannot be tolerated by some electrodes of the EXXT- 1 or EXXT-1M classifications. The arc transfer, welding characteristics and deposition rates of these electrodes are similar to those of the EXXT-1 or EXXT-1M classifications (see A7.1).

A7.3 EXXT-3 Classification. Electrodes of this clas- sification are self-shielded, used on DCEP, and have a spray-type transfer. The slag system is designed to make very high welding speeds possible. The electrodes are used for single-pass welds in the flat, horizontal, and vertical (up to 20 degree incline) positions (downward progression) on sheet metal. Since these electrodes are sensitive to the effects of base-metal quenching, they are not generally recommended for the following: (1) T- or lap joints in materials thicker than 3 ⁄ 16 in. (4.8 mm) (2) Butt, edge, or corner joints in materials thicker than 1 ⁄ 4 in. (6.4 mm) The electrode manufacturer should be consulted for specific recommendations.

A7.4 EXXT-4 Classification. Electrodes of this clas- sification are self-shielded, operate on DCEP, and have a globular-type transfer. The slag system is designed to make very high deposition rates possible and to produce a weld that is very low in sulphur, which makes the weld very resistant to hot cracking. These electrodes are designed for low penetration beyond the root of the weld, enabling them to be used on joints which have been poorly fit, and for single- and multiple- pass welding.

A7.5 EXXT-5 and EXXT-5M Classifications. Elec- trodes of the EXXT-5 classification are designed to be

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used with CO 2 shielding gas; however, as with the EXXT-1 classification, argon-CO 2 mixtures may be used to reduce spatter. Electrodes of the EXXT-5M classification are designed for use with 75–80% argon/ balance CO 2 shielding gas. Electrodes of the EX0T- and EX0T-5M classifications are used primarily for single- and multiple-pass welds in the flat position and for welding fillet welds in the horizontal position. These electrodes are characterized by a globular transfer, slightly convex bead contour, and a thin slag that may not completely cover the weld bead. These electrodes have a lime-fluoride base slag. Weld deposits produced by these electrodes typically have impact properties and hot and cold crack resistance that are superior to those obtained with rutile base slags. The EX1T-5 and EX1T-5M electrodes using DCEN, can be used for welding in all positions. However, the operator appeal of these electrodes is not as good as those with rutile base slags. A7.6 EXXT-6 Classification. Electrodes of this clas- sification are self-shielded, operate on DCEP, and have a spray-type transfer. The slag system is designed to give good low-temperature impact properties, good penetration into the root of the weld, and excellent slag removal, even in a deep groove. These electrodes are used for single- and multiple-pass welding in flat and horizontal positions. A7.7 EXXT-7 Classification. Electrodes of this clas- sification are self-shielded, operate on DCEN, and have a small droplet transfer to a spray-type transfer. The slag system is designed to allow the larger sizes to be used for high deposition rates in the horizontal and flat positions, and to allow the smaller sizes to be used for all welding positions. The electrodes are used for single- and multiple-pass welding and produce very low sulphur weld metal which is very resistant to cracking. A7.8 EXXT-8 Classification. Electrodes of this clas- sification are self-shielding, operate on DCEN, and have a small droplet or spray-type transfer. The electrodes are suitable for all welding positions and the weld metal has very good low temperature notch toughness and crack resistance. The electrodes are used for single- and multiple-pass welds. A7.9 EXXT-9 and EXXT-9M Classifications. Elec- trodes of the EXXT-9 group are classified with CO 2 shielding gas. However, gas mixtures of argon-CO 2 are sometimes used to improve usability, especially for out-of-position applications. Increasing the amount of argon in the argon-CO 2 mixture will affect the metal analysis and mechanical properties of weld metal depos-

PART C — SPECIFICATIONS FOR WELDING RODS, ELECTRODES, AND FILLER METALS SFA-5.

ited by these electrodes, just as it will for weld metal deposited by EXXT-1 and EXXT-1M electrodes (see A7.1). Electrodes of the EXXT-9M group are classified with a 75–80% argon/balance CO 2 shielding gas. Their use with argon/CO 2 shielding gas mixtures having reduced amounts of argon, or with CO 2 shielding gas, may result in some deterioration of arc characteristics and out-of-position welding characteristics. In addition, a reduction of the manganese and silicon contents in the weld will result, which will have some effect on properties of weld metal from these electrodes, just as it will on properties of weld metal deposited by EXXT- 1 and EXXT-1M electrodes (see A7.1). Both the EXXT-9 and EXXT-9M electrodes are designed for single- and multiple-pass welding. The larger diameters (usually 5 ⁄ 64 in. [2.0 mm] and larger) are used for welding in the flat position and for welding fillet welds in the horizontal position. The smaller diameters (usually 1 ⁄ 16 in. [1.6 mm] and smaller) are often used for welding in all positions. The arc transfer, welding characteristics, and deposi- tion rates of the EXXT-9 and EXXT-9M electrodes are similar to those of the EXXT-1 or EXXT-1M classifications (see A7.1). EXXT-9 and EXXT-9M elec- trodes are essentially EXXT-1 and EXXT-1M electrodes that deposit weld metal with improved impact properties. Some electrodes in this classification require that joints be relatively clean and free of oil, excessive oxide, and scale in order that welds of radiographic quality can be obtained.

A7.10 EXXT-10 Classification. Electrodes of this classification are self-shielded, operate on DCEN, and have a small droplet transfer. The electrodes are used for single-pass welds at high travel speeds on material of any thickness in the flat, horizontal, and vertical (up to 20 degree incline) positions.

A7.11 EXXT-11 Classification. Electrodes of this classification are self-shielded, operate on DCEN, and have a smooth spray-type transfer. They are general purpose electrodes for single- and multiple-pass welding in all positions. Their use is generally not recommended on thicknesses greater than 3 ⁄ 4 in. (19 mm) unless preheat and interpass temperature control are maintained. The electrode manufacturer should be consulted for specific recommendations.

A7.12 EXXT-12 and EXXT-12M Classifications. Electrodes of these classifications are essentially EXXT- 1 and EXXT-1M electrodes which have been modified to improve impact toughness and to meet the lower manganese requirements of the A-1 Analysis Group in

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the ASME Boiler and Pressure Vessel Code, Section IX. They, therefore, have an accompanying decrease in tensile strength and hardness. Since welding procedures influence all weld metal properties, users are urged to check hardness on any application where a required hardness level is a requirement. The arc transfer, welding characteristics, and deposi- tion rates of the EXXT-12 and EXXT-12M electrodes are similar to those of the EXXT-1 and EXXT-1M classifications (see A7.1).

A7.13 EXXT-13 Classification. Electrodes of this classification are self-shielded and operate on DCEN, and are usually welded with a short-arc transfer. The slag system is designed so that these electrodes can be used in all positions for the root pass on circumferen- tial pipe welds. The electrodes can be used on all pipe wall thicknesses, but are only recommended for the first pass. They generally are not recommended for multiple-pass welding.

A7.14 EXXT-14 Classification. Electrodes of this classification are self-shielded, operate on DCEN, and have a smooth spray-type transfer. The slag system is designed with characteristics so that these electrodes can be used to weld in all positions and also to make welds at high speed. They are used to make welds on sheet metal up to 3 ⁄ 16 in. (4.8 mm) thick, and often are specifically designed for galvanized, aluminized, or other coated steels. Since these welding electrodes are sensitive to the effects of base-metal quenching, they are not generally recommended for the following: (1) T- or lap joints in materials thicker than 3 ⁄ 16 in. (4.8 mm) (2) Butt, edge, or corner joints in materials thicker than 1 ⁄ 4 in. (6.4 mm) The electrode manufacturer should be consulted for specific recommendations.

A7.15 EXXT-G Classification. This classification is for multiple-pass electrodes that are not covered by any presently defined classification. Except for chemical requirements to assure a carbon steel deposit and the tensile strength, which is specified, the requirements for this classification are not specified. They are those that are agreed to by the purchaser and the supplier.

A7.16 EXXT-GS Classification. This classification is for single-pass electrodes that are not covered by any presently defined classification. Except for the tensile strength, which is specified, the requirements for this classification are not specified; they are agreed upon by the purchaser and supplier.

PART C — SPECIFICATIONS FOR WELDING RODS, ELECTRODES, AND FILLER METALS SFA-5.

facturer should be consulted regarding probable damage to low-hydrogen characteristics and possible recondi- tioning of the electrodes.

A8.2.9 Not all flux cored electrode classifications may be available in the H16, H8, or H4 diffusible hydrogen levels. The manufacturer of a given electrode should be consulted for availability of products meeting these limits.

A8.2 Aging of Tensile Specimens. Weld metals may contain significant quantities of hydrogen for some time after they have been made. Most of this hydrogen gradually escapes over time. This may take several weeks at room temperature or several hours at elevated temperatures. As a result of this eventual change in hydrogen level, ductility of the weld metal increases towards its inherent value, while yield, tensile, and impact strengths remain relatively unchanged. This spec- ification permits the aging of the tensile test specimens at elevated temperatures up to 220°F for up to 48 hours before subjecting them to tension testing. The purpose of this treatment is to facilitate removal of hydrogen from the test specimen in order to minimize discrepancies in testing. Aging treatments are sometimes used for low-hydro- gen electrode deposits, especially when testing high- strength deposits. Note that aging may involve holding test specimens at room temperature for several days or holding at a higher temperature for a shorter period of time. Consequently, users are cautioned to employ adequate preheat and interpass temperatures to avoid the deleterious effects of hydrogen in production welds.

A9. Safety Considerations

A9.1 Burn Protection. Molten metal, sparks, slag, and hot work surfaces are produced by welding, cutting, and allied processes. These can cause burns if precau- tionary measures are not used. Workers should wear protective clothing made of fire-resistant material. Pant cuffs, open pockets, or other places on clothing that can catch and retain molten metal or sparks should not be worn. High-top shoes or leather leggings and fire-resistant gloves should be worn. Pant legs should be worn over the outside of high-top shoes. Helmets or hand shields that provide protection for the face, neck, and ears, and a protective head covering should be used. In addition, appropriate eye protection should be used. When welding overhead or in confined spaces, ear plugs to prevent weld spatter from entering the ear canal should be worn in combination with goggles, or the equivalent, to give added eye protection. Clothing

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should be kept free of grease and oil. Combustible materials should not be carried in pockets. If any combustible substance has been spilled on clothing, a change to clean, fire-resistant clothing should be made before working with open arcs or flames. Aprons, cape sleeves, leggings, and shoulder covers with bibs designed for welding service should be used. Where welding or cutting of unusually thick base metal is involved, sheet metal shields should be used for extra protection. Mechanization of highly hazardous processes or jobs should be considered. Other personnel in the work area should be protected by the use of noncombustible screens or by the use of appropriate protection as described in the previous paragraph. Before leaving a work area, hot work pieces should be marked to alert other persons of this hazard. No attempt should be made to repair or disconnect electrical equipment when it is under load; disconnection under load produces arcing of the contacts and may cause burns or shock, or both. (Note: Burns can be caused by touching hot equipment such as electrode holders, tips, and nozzles. Therefore, insulated gloves should be worn when these items are handled, unless an adequate cooling period has been allowed before touching.) The following references are for more detailed infor- mation on personal protection: (1) American National Standards Institute. Practice for Occupational and Educational Eye and Face Protec- tion, ANSI/ASC Z87.1. New York: American National Standards Institute. (2) American National Standards Institute. Safety- Toe Footwear, ANSI/ASC Z41.1. New York: American National Standards Institute. (3) American Welding Society. Safety in Welding, Cutting, and Allied Processes, ANSI/ASC Z49.1. Mi- ami, FL: American Welding Society. (4) OSHA, Code of Federal Regulations, Title 29— Labor, Chapter XVII, Part 1910. Washington, D.C.: U. S. Government Printing Office.^5

A9.2 Electrical Hazards. Electric shock can kill. However, it can be avoided. Live electrical parts should not be touched. The manufacturer’s instructions and recommended safe practices should be read and under- stood. Faulty installation, improper grounding, and in- correct operation and maintenance of electrical equip- ment are all sources of danger. All electrical equipment and workpieces should be grounded. The workpiece lead is not a ground lead;

(^5) OSHA standards may be obtained from the U. S. Government Printing Office, Washington, D.C. 20402.

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it is used only to complete the welding circuit. A separate connection is required to ground the workpiece. The correct cable size should be used since sustained overloading will cause cable failure and can result in possible electrical shock or fire hazard. All electrical connections should be tight, clean, and dry. Poor connec- tions can overheat and even melt. Further, they can produce dangerous arcs and sparks. Water, grease, or dirt should not be allowed to accumulate on plugs, sockets, or electrical units. Moisture can conduct elec- tricity. To prevent shock, the work area, equipment, and clothing should be kept dry at all times. Welders should wear dry gloves and rubber-soled shoes, or stand on a dry board or insulated platform. Cables and connections should be kept in good condition. Improper or worn electrical connections may create conditions that could cause electrical shock or short circuits. Worn, damaged, or bare cables should not be used. Open circuit voltage should be avoided. When several welders are working with arcs of different polarities, or when a number of alternating current machines are being used, the open circuit voltages can be additive. The added voltages increase the severity of the shock hazard. In case of electric shock, the power should be turned off. If the rescuer must resort to pulling the victim from the live contact, nonconducting materials should be used. If the victim is not breathing, cardiopulmonary resuscitation (CPR) should be administered as soon as contact with the electrical source is broken. A physician should be called and CPR continued until breathing has been restored, or until a physician has arrived. Electrical burns are treated as thermal burns; that is, clean, cold (iced) compresses should be applied. Con- tamination should be avoided; the area should be cov- ered with a clean, dry dressing; and the patient should be transported to medical assistance. Recognizing safety standards such as ANSI/ASC Z49.1 and NFPA No. 70, The National Electrical Code should be followed.^6

A9.3 Fumes and Gases. Many welding, cutting, and allied processes produce fumes and gases which may be harmful to health. Fumes are solid particles which originate from welding electrodes and fluxes, the base metal, and any coatings present on the base metal. Gases are produced during the welding process or may be produced by the effects of process radiation on the surrounding environment. Management, welders, and other personnel should be aware of the effects of these fumes and gases. The amount and composition of these

(^6) NFPA documents are available from the National Fire Protection Association, Batterymarch Park, Quincy, MA 02269

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fumes and gases depend upon the composition of the electrode and base metal, welding process, current level, arc length, and other factors. The possible effects of overexposure range from irritation of eyes, skin, and respiratory system to more severe complications. Effects may occur immediately or at some later time. Fumes can cause symptoms such as nausea, headaches, dizziness, and metal fume fever. The possibility of more serious health effects exists when especially toxic materials are involved. In confined spaces, the shielding gases and fumes might displace breathing air and cause asphyxiation. One’s head should always be kept out of the fumes. Sufficient ventilation, exhaust at the arc, or both, should be used to keep fumes and gases from your breathing zone and the general area. In some cases, natural air movement will provide enough ventilation. Where ventilation may be question- able, air sampling should be used to determine if corrective measures should be applied. More detailed information on fumes and gases pro- duced by the various welding processes may be found in the following: (1) The permissible exposure limits required by OSHA can be found in Code of Federal Regulations, Title 29—Labor, Chapter XVII, Part 1910. (2) The recommended threshold limit values for these fumes and gases may be found in Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment published by the American Conference of Governmental Industrial Hygienists (ACGIH).^7 (3) The results of an AWS-funded study are available in a report entitled, Fumes and Gases in the Welding Environment.

A9.4 Radiation. Welding, cutting, and allied opera- tions may produce radiant energy (radiation) harmful to health. One should become acquainted with the effects of this radiant energy. Radiant energy may be ionizing (such as x-rays), or nonionizing (such as ultraviolet, visible light, or infra- red). Radiation can produce a variety of effects such as skin burns and eye damage, depending on the radiant energy’s wavelength and intensity, if excessive exposure occurs.

A9.4.1 Ionizing Radiation. Ionizing radiation is produced by the electron beam welding process. It is

(^7) ACGIH documents are available from the American Conference of Governmental Industrial Hygienists, 6550 Glenway Avenue, Building D-5, Cincinnati, OH 45211.