ASSIGNMENT-1 ENMT610029 WELDING
ANDARADHI NARARYA/1206291992
1. Explain the definition in welding according to AWS or British Standard Institution (BSI)!
o
The AWS (American Welding Society) definition for a welding process is "a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure or by the application of pressure alone and with or without the use of filler material". In another definition by AWS, welding welding is “the process of joining two pieces of metal by creating a strong metallurgical bond between them by heating or pressure or both. The filler metal with the same melting point can be used o r not”. (American Welding Society 1989 Welding Handbook Volume I 8th ed.)
o
The BSI (British Standard Institution) definition of welding is “joining between two or more material in a plastic or liquid state using thermal (heat) or pressure or both. Filler metal with a melting temperature equal to the melting temperature of parent metal can be used or not”. (British Standard Institution Standard Institution 1983; BS 499; Part 1)
2. Give the main difference among Welding, Brazing, and Soldering in general! o
Welding involves the process of fusion which takes place along with the melting
of base metal and a filler metal. o
Brazing has been defined as a group of joining processes specially arranged in a
manner to produce coalescence of materials. The process involves heating of these materials at a brazing temperature by using a filler metal which has a liquidus above 840°F (450°C), and below the solidus of the base metals. Also, the filler metal is distributed in the joint by capillary action. o
Soldering has the same definition as brazing except for the fact that the filler metal
pastes used has a liquidus below 840°F (450°C) and below the solidus of the base metals.
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ASSIGNMENT-1 ENMT610029 WELDING
ANDARADHI NARARYA/1206291992
3. Explain the difference between welding and casting process in general! Welding
Casting
Bond with mold
There must be a bond
There should be no bond
Heat input
Continuously
Un-continuously
Structure
Columnar
Dendritic
Solidification time
Fast
Slow
Surface shape
Constant
Have an ability to change
4. Looking at the engineering side and economic side, how do you think for a selection process of joining on steel plates using process among: Welding, Nut and Bolt (Screwing), Adhesive Bonding and Brazing or Soldering? Which join process gives the stress which is axial direction (not shear stress)? Explain what you choose! Welding
Screwing
Adhesive Bond.
Brazing - Soldering
Joint strength
Strongest
Weakest
Quiet strong
Strong
Stress
Almost
Biggest
Big
Quiet big
Concentration
nothing
Joint dimension
Parallel
Overlap
Overlap
Overlap
Price
Most
Most cheap
Quiet cheap
Quiet cheap
expensive
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ASSIGNMENT-1 ENMT610029 WELDING
ANDARADHI NARARYA/1206291992
5. As a metallurgist, how do you explain the use of metallurgical science to control the quality of welds to be free from defects? It is due to the fact that the welding heat resulting the changes in material structure.
There are several explanations by using metallurgical science to control the quality of welds to be free from defects: o
Controlling the chemical composition in order to avoid cracking clotting, such as reducing the sulfur and phosphorus content, do grain refinement, reducing the strain of the heat source, and improve weld geometry.
o
Perform a surface preparation in order to avoid from con tamination, e.g. in the form of hydrogen ions H2O which can cause HE (hydrogen embrittlement) or HIC (hydrogen induced cracking).
o
Controlling the cooling rate in order to avoid the formation of martensite at HAZ and residual stress.
o
Perform a heat treatment process in the form of pre-heating after the welding process in order to make the hydrogen diffuses out, thus to prevent the presence of HE (hydrogen embrittlement) or HIC (hydrogen induced cracking).
6. Briefly describe the level qualification of welding personnel in the world based on the International Institute of Welding (IIW) scheme and American Welding Society (AWS) scheme. Explain the duty of responsibility each welding personnel in related to Welding Job in general! o
Qualification of welding personnel based on IIW:
International Welding Specialist (IWS)
Personnel with basic technical knowledge where the level of technical knowledge needs to be sufficient for the planning, executing, supervising and testing of the tasks and responsibilities within a limited technical field involving only simple welded constructions.
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ASSIGNMENT-1 ENMT610029 WELDING
ANDARADHI NARARYA/1206291992
International Welding Technologist (IWT)
Personnel with specific technical knowledge where the level of technical knowledge needs to be sufficient for the planning, executing, supervising and testing of the tasks and responsibilities in welding fabrication within a selective or limited technical field.
International Welding Engineer (IWE)
Personnel with comprehensive technical knowledge where full technical knowledge is required for the planning, executing, supervising and testing of all tasks and responsibilities in welding fabrication.
o
Qualification of welding personnel based on AWS:
Inspectors
Personnel who responsible for overseeing and make a drawing that make sure each welded area has been inspected with the acceptance criteria code in specifically.
Educators
Personnel who directed professionally in the field o f welding education that has the ability, talent, and knowledge directly and can perform welding training or instruction in the classroom.
Radiographic Interpreters
Personnel with the ability to assess the indications welding resulting in radiographic films and other similar matters.
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ASSIGNMENT-1 ENMT610029 WELDING
ANDARADHI NARARYA/1206291992
Supervisors
Personnel with the ability to increase productivity and maintain the welding quality.
Sales Reps
Sales professionals in the welding industry that offers solutions and recommendations of the welding problems, such as improving quality and productivity.
Engineers
Personnel with the ability to direct the operation of welding and other joining methods according to the documents, codes, and other standards to produce a satisfactory product.
Robotics
Personnel with the ability to work with a variety of codes, standards, and specifications welding.
Fabricators
Personnel who have the resources, procedures, and personnel to create a quality management system for welding fabrication activities.
Welders
Personnel with the ability to weld quality. Qualification of welding personnel consist of qualifying stages and specific qualifications.
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ASSIGNMENT-1 ENMT610029 WELDING
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ANDARADHI NARARYA/1206291992
Stages Qualification
SMAW (Shielded Metal Arc Welding)
o
GMAW (Gas Metal Arc Welding)
GTAW (Gas Tungsten Arc Welding)
SAW (Submerged Arc Welding)
Brazing & Braze Welding
OAW (Oxyacetylene Welding)
Specific Qualification
Welding Supervisor
In charge of improving the productivity of welding and maintain the quality welding and perform internal and external quality control.
Welding Inspector
In charge to overseeing projects that concentrate on the quality of welding and welding structure and ensure all have inspected with code specific acceptance criteria.
Welder (SMAW/Non SMAW)
In charge of do welding operation which is suitable with standard criteria. References: o
http://www.engineershandbook.com/Tables/welding%20processes.htm
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http://ewi.org/technologies/soldering-and-brazing-main/
o
http://www.aws.org/certification/
o
http://www.wim.org.my/training/iiw_diploma.php
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