INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier,
Emad Abdulradh Al-Faraj
ABSTRACT- The aim of this paper is to study the effect of welding polarity of the shielded metal arc welding
process on bead geometry, microstructure and hardness of welding 1020 carbon steel plate. The results show that the highest hardness measurement was recorded when welding was performed using the DC- polarity. In all samples, the hardness values decreased along the distance were taken away from the weld metal toward the parent metal through the Heat Effected Zone (HAZ). The lowest hardness measurements were recorded when the welding was performed using the AC polarity. When the microstructure was analyzed, it was found that the DCpolarity samples consisted of martensitic with some bainitic structure in the weld metal and bainitic structure in the HAZ. The undesired microstructure in the weld metal using this polarity resulted from the heat difference between the cathode and the anode. The DC+ polarity samples were observed to have bainitic structure in the weld metal and a mixture of bainite and ferrite was observed in the HAZ. The AC polarity samples were noticed to have more complex microstructures compared with the other two polarities, and a bainitic microstructure was observed in the weld metal and the HAZ. Some regions in these samples were noticed to be contained some widmanstatten ferrite and martensite.
INTRODUCTION
Welding is commonly used in industries fabrication and to repair damaged structures such as pipelines, heat exchangers and pressure vessels. Unfortunately, the thermal effect of the welding process sometimes produces hard and brittle microstructure which affects adversely the mechanical properties in the Heat
Affected Zone (HAZ), see Aloraier (2005). In
Shielded Metal Arc Welding (SMAW) process, the heat for welding is generated by an arc established between a flux-covered consumable electrode and the workpiece. The core wire conducts the electric current to the arc and provides filler metal for the joint. The heat of the arc melts the core wire and the flux covering at the electrode tip into metal droplets.
Molten metal in the weld pool solidifies into the weld metal while the lighter molten flux floats on the top surface and solidifies as a slag layer. The weld area is protected by a gaseous shield obtained from the combustion of the flux. Additional shielding is
Journal of Engineering and Technology
provided by the slag, see Robert and Messler (2004).
The quality of SMAW can be affected by several welding parameters such as arc-length, type of electrode, metal deposition, arc-travel rate and welding polarity [ Robert J., Messler W (2004), Seow
Chandel and Cheong (1997)]. In particular, these factors have control on the bead geometry, depth of penetration and heat affected zone (HAZ). Apps
,Gourd and Nelson (1963) reported that several arc welding parameters such as current, voltage, welding speed and polarity can influence the bead shape and size. In addition, it has been demonstrated that the depth of penetration is influenced by polarity, current, voltage and arc-travel rate , see [ Gill and Simons
(1950), Jefferson (1951), and Jackson (1960).
Moreover, some researchers like Nagesh and
Datta(2002), and Yang, Chandel., and Bibby (1992) considered welding polarity as a primary factor which influences SMAW process. The importance of the polarity arises mainly out of the difference in the amount of heat input into the workpiece. Changing
100
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS the polarity affects the amount of heat in the weld zone, and thus alters the bead geometry, depth of penetration, and HAZ.
From the literature, there seems to be no agreement on the magnitude of effect between the anode & cathode. Therefore, the present work is a study of the effect of welding polarity of the shielded metal arc welding process on bead geometry, microstructure, residual stresses, and hardness of 1020 carbon steel.
HEAT INPUT
Heat input is a relative measure of the energy transferred per unit length of weld. It is an important characteristic because, like preheat and inter-pass temperature, it influences the cooling rate, which may affect the mechanical properties and metallurgical structure of the weld and the HAZ.
Murti V., and et al (1993) show the heat input rate can be varied by changing the voltage, current setting and welding speed as can be seen in Eq. (1). Higher voltages alter the bead geometry and fusion area, which affects the resultant microstructure, and can also destabilize the arc and produce spatter. Heat input is typically calculated as the ratio of the power
(i.e., voltage x current) to the velocity of the heat source (i.e., the arc) as follows:
Q
60 V I
1000 S
(1)
Where, Q is the heat input in (kJ/in or kJ/mm), V is the arc voltage (volts), I is the current (amps), S is the travel speed (in/min or mm/min) and η is the process efficiency. Gery , Long , and Maropoulos (2005) show the increase of heat input in the welding process result in a coarsening of the microstructure of the weld metal
(WM) and mainly of the HAZ and promotes the formation and coarsening of upper bainite in this zone and even the appearance of some ferrite side plates, a loss of hardness, and increases the yield and tensile strength under-matching of the WM, and also produces HAZ under-matching.
Journal of Engineering and Technology
POLARITY
There are three different polarities which might be used when using SMAW depending on the power supply being used. The direction that the electrons flow is referred to as the polarity. Electrons generally flow from a negatively charged (polarized) body to a positively charged body. If a direct current power supply is used and the workpiece is connected to the positive terminal is called direct current electrode negative (DC-). On the other hand, if the parent material is connected to the negative terminal of a direct power supply is called direct current electrode positive (DC+). If an alternating current power supply is used the polarity is referred as to AC [2].
Moreover, about 70% of the heat in DC- polarity is directed to the workpiece and 30% of the heat is directed to the electrode and vice versa when DC+ polarity is used. In AC polarity about 50% of the heat is directed to the workpiece and the other 50% of the heat is directed to electrode. The difference in heat distribution results in varying the weld geometry. In the DC- polarity produces narrow and deep weld pool due to high energy in the parent metal. The arc forces the droplets away from the workpiece due to the low rate of electron emission from the negative electrode.
For the DC+ polarity, the weld pool is shallow. This method can be used to clean the surface of the workpiece by knocking off oxide films by the positive ions of the shielding gas. The AC polarity provides reasonably good penetration of the weld pool and oxide cleaning, see Kou (2003).
EXPERIMENTAL METHODOLOGY
The main requirement of the experimental work was to study the effect of welding polarity of the shielded metal arc welding process on mechanical properties and bead geometry of 1020 carbon steel.
Welding machine description
A constant current DIALARC 250 AC/DC welding power source (Miller) was used in this experimental work, see figure (1). The polarities used in this
101
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS experimental work were direct current positive polarity (DC+), direct current negative polarity (DC-) and alternating current polarity (AC).
Fig. 2: The electrode used in the experimental work confirming to AWS E6013
Material selections and electrodes
Welding electrode confirming to AWS E6013 with diameter and length of 5.0 mm x 400 mm respectively was used to lay down the weld beads.
Figure (2) shows the electrode used in this experimental work. The parent material used in this experimental work was AISI 1020 carbon steel having dimensions of 200x100x10 mm3 as shown in
Elements
C
Si
Mn
P
S
Composition
(%)
≤0.12
≤0.35
≤0.30.6
≤0.04
≤0.035
figure(3). The chemical composition of the parent material and the deposited metal are shown in table
(1) and table (2) respectively. The chemical composition analysis for the parent material was obtained using the spectrometer. This test was repeated three times and the results were averaged to be as accurate as possible. Table (3) shows the results of these three tests.
Table 1: Chemical analysis of the parent material used in the experimental work
Table 2: Chemical analysis of the weld metal used in the experimental work
Table 3: Chemical analysis of the parent material used in the experimental work
Test-2
Test-3
Average
Fe
98.75
98.71
98.64
98.700
0.187
0.201
0.199
0.196
Si
0.19
0.2
0.21
0.200
Mn
0.56
0.57
0.6
0.577
P
0.01
0.015
0.014
0.013
S
0.01
0
0.01
0.007
Cr
0.04
0.038
0.05
0.043
Ni
0.048
0.044
0.055
0.049
Mo
0
0
0
0.000
Cu
0.07
0.07
0.07
0.070
Ni
Journal of Engineering and Technology
Test-1
C
Fig. 1: The welding machine used in the experimental work Elements
0.013
0.01
0.014
0.012
102
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Elem ents C
Si
Mn
P
S
Cr
Ni
Cu
Ni
Comp ositio n (%)
0.19
6
0.2
0.5
77
0.0
13
0.0
07
0.0
43
0.0
49
0.0
7
0.0
12
Welding procedure
To study the effect of different polarities, the bead on plate technique was adopted. In this experimental work the bead was deposited on the center of the plate so that it would have a start and stop distances of 25 mm from both sides of the plate. The weld bead length was 150 mm as shown in figure (3). Figure (4), figure (5), and figure (6) show the deposited beads when using the three proposed polarities, DC+, DCand AC polarities respectively. The current used was
175 amps as specified by the electrode manufacturer.
The welding speed was between the range of 69 to 73 seconds for each single bead (150 mm) as shown in table (4).
Fig. 5: Bead on plate sample when the polarity used is
DC-
Fig. 3: Schematic illustration of the bead on plate location and dimensions
Fig. 6: Bead on plate sample when the polarity used is
AC
Fig. 4: Bead on plate sample when the polarity used is
DC+
Journal of Engineering and Technology
103
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Table 4: Welding parameters used in the experimental work Time
(Seconds)
Amperage
(Amp.)
J
Type of current &
Polarity
DC-
(at the bottom surface of the workpiece). The hardness measurements were taken on 2 mm intervals. Figure (8) shows locations of hardness measurements. 71
175
Fig. 8: Hardness measurements locations
K
DC+
69
175
L
AC
73
175
DCN
DC-
71
175
DCP
DC+
70
175
AC
AC
73
175
Specimen
No.
Mechanical testing
After the weld has been completed, the plate was left to cool down to the ambient temperature. The plate was then sectioned from the middle using a band saw as can be seen in figure (7).
The weld bead geometry was examined to evaluate the effect of welding polarity on the weld bead height and width. The effects of welding polarity on the size of the heat affected zones were also examined in this experimental work.
Fig. 7: Location of plate sectioning
Fig. 9: shows different variables of the weld bead geometry. After that, various types of mechanical tests were selected to evaluate and compare the effect of welding polarity on the mechanical properties of the selected steels. Hardness testing for example was selected to compare different zones of the weldments.
The mechanical tests were conducted at different locations of the weldment. This include weld metal, heat affected zone and parent material. Rockwell hardness B scale tests were carried out using 1/16" ball indenter with 100 kgf load. The hardness measurements were taken along the sample thickness at the center of bead, starting from the weld metal (at the top surface of the bead) towards the parent metal
Journal of Engineering and Technology
Microscopy
Optical microscopy was used mainly to evaluate the microstructure in different areas such as the weld metal, the heat affected zones and the parent material produced using different polarities. Basically after sectioning the required test specimen from the weldments as shown in figure (7), this sectioned part
(coupon) was then cut from both ends using abrasive wheel cutter as can be seen in figure (10-A).
Fig. 10: (A) Abrasive wheel cutter and (B) Mounting machine 104
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Fig. 12: (A) Lapping Disc (15m) and (B) Lapping
Disc (1m)
(A)
(A)
(B)
(B)
Fig. 11: (A) Manual grinding process and (B)
Automatic grinding process
Fig. 13: (A) Etching with 2% natal and (B) Optical
.microscope
(A)
(B)
Journal of Engineering and Technology
105
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Finally, the specimens were immersed in the etchant
(2% nital) as can be seen in figure (13-A) until a good definition of the structure was obtained.
An optical microscope was used to measure the bead geometry as can be seen in figure (13-B). A metallurgical microscope with a digital camera was also used to evaluate the microstructure of the weld for each polarity type as can be seen in figure (14).
RESULTS AND DISCUSSION
Fig. 14: Metallurgical microscope with digital camera
The cut surface was then milled and ground until a satisfactory surface finish was obtained. Samples were then mounted face down for easy handling during the automatic grinding and polishing. Figure
(10-B) shows the mounting machine used to produce mounted samples. The machined surface was then abraded on successively finer grades of waterproof silicon carbide paper. A sequence of grit sizes of
P100, P240, P600 and P1200 were used. These grinding and polishing processes were carried out manually and automatically as can be seen in figure
(11- A and B).
A high quality surface finish was then achieved using lapping discs with diamond grades of 15 and 1m respectively as can be seen in figure (12-A and B).
Journal of Engineering and Technology
Effect of Welding Polarity on Bead Geometry
The element of bead geometry studied were bead width, height and HAZ size as can be seen in figure
(9) Each bead geometry element for each polarity was measured. Table (5) shows the measurement of these elements. It was observed that welding using DCpolarity provided the maximum bead width and HAZ size. The bead width and HAZ size were 15.1 and 6.6 mm respectively for the DC- polarity. The minimum bead width and HAZ size were for DC+ polarity
(12.5 and 4.5 mm respectively). In addition, the maximum bead height of 4.3 mm was found in the sample which was welded using the DC+ polarity, while the minimum bead height of 3.7 mm was recorded when welding was performed using the DCpolarity. The results in general suggest that the DCpolarity provided extra heat input for the workpiece, compared to DC+ and AC polarities, and thus resulted in bead flattening and larger HAZ. Bead reinforcement (height) was observed to have maximum peak in the samples which were welded using the DC+ polarity.
Table 5: Measurements of bead geometry elements using different polarities
Polarity
DCDC+
AC
Bead
Width
(15.1 mm) 12.5
12.7
Bead
Height
(mm)
3.7
4.3
3.9
HAZ Size
(mm)
6.6
4.5
6.0
106
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Effect of welding polarity on mechanical properties the hardness measurements of the DC- polarity, the hardness measurements of the DC+ polarity, and the hardness measurements of the AC polarity is shown in figure (15). The measurements were made at the center line of the bead. Each hardness measurement was repeated three times and the average measurement was recorded and plotted against its location. The highest hardness was identified for sample with DC- polarity, with maximum of 88 HRB at the weld down to 80 HRB for the parent metal. The lowest hardness measurements were recorded when the welding was performed using the AC polarity.
Welding polarity of DC (-) and (+) demonstrated an enhancement of the hardness in the weld area. This is mostly due to the development of acicular ferrite and/or bainite in their microstructures. On the other hand, welding with AC polarity caused only little improvement in the hardness. The results of hardness are found to be consistence with common hardness for 1020 steel.
Fig. (15): Hardness comparison of the three polarities used in the experimental work
Effect of welding polarity on microstructure the microstructure of the as received 1020 carbon steel in cold rolled condition is shown in figure (16).
The parent metal consists of fine structure of ferrite and pearlite. The weld microstructure of the DCpolarity workpiece is presented in figure (17), and examined further at locations a, b, and c. Location (a) presents the microstructure at the center of the weld metal which consists mainly of columnar grains of grain boundary ferrite (allotriomorphs),
Widmanstätten ferrite and some martensite as can be seen in Figure (17) (a). Small amount of acicular ferrite and bainite can also be observed. Location (b) describes the microstructure at the weld/HAZ interface which has large equiaxed grains consisting of grain boundary ferrite and Widmanstätten ferrite as shown in figure (17) (b). Figure (17) (c) shows microstructure at location c, i.e. the interface between
HAZ and parent metal, indicating similar ferrite phases to that in location b but with finer grain size.
Moreover, figure (18) shows microstructure of the sample welded using DC+ polarity. The weld area, shown in figure (18) (a), is primary made of columnar grains of grain boundary ferrite and Widmanstätten ferrite, with minor amount of acicular ferrite. The weld/HAZ and HAZ/parent metal interfaces are very similar to that obtained for the DC- polarity sample.
Figure (18) (b) and (c) show the microstructure at locations b and c. For the AC polarity sample, shown in figure (19), the microstructure is very similar to that of the DC+ polarity.
Fig. 16: Microstructure of the parent metal 1020 carbon steel plates before welding consisting of ferrite and pearlite
Journal of Engineering and Technology
107
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS was also observed in the current study, as demonstrated by the low formation of Widmanstätten ferrite at the top layer of the bead as can be seen in figure (20).
Fig. 17: Microstructure of the DC- polarity welded workpiece at: a) weld, b) weld/HAZ interface, and c) interface between HAZ and parent metal. (W: Grain boundary ferrite, X: Widmanstätten ferrite, Y:
Acicular ferrite, Z: Bainite)
In general, all samples shows small amount of acicular ferrite and/or bainite that decrease towards the HAZ; at some points, pearlite was also detected at the interface between HAZ and parent metal. For steels of low carbon content (0.2% to 0.4%C), a significant amount of Widmanstätten ferrite can be formed when an appreciable under-cooling below the eutectoid temperature is made during solidification of the weld. It was also indicated that the structural constituents that form in the HAZ depends on the composition of the parent metal as given by the carbon equivalent (CE), as shown in Eq. (2), see
Kalpakjian S. and Schmid (2010):
CE = C + Mn/6
(2)
The structure of HAZ zone is mostly pearlitic for small CE, with proeutectoid ferrite (i.e. grain boundary ferrite and Widmanstätten ferrite) in decreasing amount as CE increases. For the current parent metal, CE is 0.292, which favors the formation of proetectoid ferrite and small amount of pearlite. It was indicated that for low CE, the formation of martenistic structure rarely occurs. Moreover, it is reported that the development of Widmanstätten ferrite is affected by decarburization [13]. This was demonstrated by the scarcely formation of
Widmanstätten ferrite at the outermost layer of the sample which had the lowest amount of carbon content due to decarburization. Such phenomenon
Journal of Engineering and Technology
108
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Fig. 18: Microstructure of the DC+ polarity welded workpiece at: a) weld, b) weld/HAZ interface, and c) interface between HAZ and parent metal
Journal of Engineering and Technology
Fig. 19: Microstructure of the AC polarity welded workpiece at: (a) weld, (b) weld/HAZ interface, and
(c) interface between HAZ and parent metal
109
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Fig. 20: Decarburization of the weld at the bead top surface undesired microstructure in the weld metal using this polarity resulted from the heat difference between the cathode and the anode. The DC+ polarity samples were observed to have bainitic structure in the weld metal and a mixture of bainite and ferrite was observed in the HAZ. The AC polarity samples were noticed to have more complex microstructures compared with the other two polarities. A bainitic microstructure was observed in the weld metal and the HAZ. Some regions in these samples were noticed to be contained some widmanstatten ferrite and martensite. When studying the hardness profiles in this experimental work, it was noticed that the highest hardness measurement was recorded when welding was performed using the DC- polarity. In all samples, the hardness values were dropped down as the measurements were taken away from the weld metal moving through the HAZ to the parent metal. The lowest hardness measurements were recorded when the welding was performed using the AC polarity
REFERENCES
CONCLUSIONS
In this experimental work, three different polarities
(AC, DC- and DC+) were used to examine their effects on bead geometry, microstructure, residual stresses and hardness of low alloy steel. The bead geometry elements were measured in this experimental work and it was found that the maximum bead width and HAZ size were recorded when welding was performed using DC- polarity. The minimum bead width and HAZ size were recorded when welding was performed using DC+ polarity.
Also, the maximum bead height was observed in the samples which were welded using DC+. However, the minimum bead height was observed in the samples which were welded using DC- polarity.
The microstructure analysis in this experimental work showed that the DC- polarity samples consisted of martensitic with some bainitic structure in the weld metal and bainitic structure in the HAZ. The
Journal of Engineering and Technology
Aloraier A. (2005) Optimization of Flux Cord Arc
Welding with Bead Tempering for Repair of Critical
Structures without Post Weld Heat Treatment, in
Mechanical Engineering. Monash University:
Melbourne, Australia.
Apps R., Gourd L., and Nelson K. (1963) Effect of welding variables upon bead shape and size in submerged arc welding. Welding Metal Fabrication.
31(11): p. 453.
Gery D. , Long H., and Maropoulos P. (2005) Effects of welding speed, energy input and heat source distribution on temperature variations in butt joint welding. Journal of Materials Processing Technology.
167: p. 393-401.
Gill E. and Simons E. (950) Modern Welding
Techniques: Sir Issac Pitman and Sons Ltd. 120.
110
Riyadh Mohammed Ali Hamza, Abdulkareem Aloraier, Emad Abdulradh Al-Faraj
INVESTIGATION EFFECT OF WELDING POLARITY IN JOINT BEAD GEOMETRY AND
MECHANICAL PROPERTIES OF SHIELDED METAL ARC WELDING PROCESS
Jefferson T. (1951) The Welding Encyclopedia. 13 ed. , New York: McGraw-Hill. 491.
Jackson C., The science of arc welding-Part III.
Welding Journal, 1960. 39(6): p. 25-230.
Nagesh D. and Datta G. (2002) Prediction of Weld
Bead Geometry and Penetration in Shielded MetalArc Welding using Artificial Neural Networks.
Journal of Materials Processing Technology. 123(2):
p. 303-312.
Kalpakjian S. and Schmid S. (2010) Manufacturing engineering and technology. Seventh ed.: Prentice
Hall.
Robert J., Messler W. (2004) Welding as a Joining
Process, in Joining of Materials and Structures.
Butterworth-Heinemann: Burlington. p. 285-348.
Kou S. (2003) John Willey and Sons, Inc., USA,
Welding metallurgy. 2nd ed.
Seow H., Chandel R., Cheong F. (1997) Effect of increasing deposition rate on the bead geometry of submerged arc welds. Materials Processing
Technology 72, p. 124-128.
Murti V., et al. (1993), Effect of heat input on the metallurgical properties of HSLA steel in multi-pass
MIG welding. Materials Processing Technology. 37:
p. 723-729.
Journal of Engineering and Technology
Yang L., Chandel R., and Bibby M. (1992), The
Effects of Process Variables on the Bead width of
Submerged-Arc Weld Deposits. Journal of Materials
Processing Technology, 29(1-3): p. 133-144.
111
References: Apps R., Gourd L., and Nelson K. (1963) Effect of welding variables upon bead shape and size in Gery D. , Long H., and Maropoulos P. (2005) Effects of welding speed, energy input and heat source Jefferson T. (1951) The Welding Encyclopedia. 13 ed Welding Journal, 1960. 39(6): p. 25-230. Nagesh D. and Datta G. (2002) Prediction of Weld Bead Geometry and Penetration in Shielded MetalArc Welding using Artificial Neural Networks. Kalpakjian S. and Schmid S. (2010) Manufacturing engineering and technology Robert J., Messler W. (2004) Welding as a Joining Process, in Joining of Materials and Structures. Kou S. (2003) John Willey and Sons, Inc., USA, Welding metallurgy Seow H., Chandel R., Cheong F. (1997) Effect of increasing deposition rate on the bead geometry of Murti V., et al. (1993), Effect of heat input on the metallurgical properties of HSLA steel in multi-pass
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One type of popular welding that you can learn to do is arc welding. Arc welding is highly used because it is cheaper to do than the other types of welding. The arc welder has a device that has an electric current that goes through it. A arc welder can give a weld that looks like an arch. Another highly used type of welding is MIG welding. MIG stands for metal inert gas. MIG welding is a type of welding where the welder uses a gas to shield the weld metal. MIG welding can be used for many different jobs. There is also different types of MIG welding. One more commonly used type of welding is TIG welding. TIG stands for tungsten inert gas. TIG welding is similar to MIG welding. The major difference between the two types of welding is that TIG welding uses a tungsten current form while MIG uses a metal electrode. There is also many different types of TIG welding that you can learn how to do. There are many other types of welding including heliarc, hydrogen arc, plasma arc, water jet cutting, percussion welding, thermite welding, forge welding and magnetics pulse welding. Each type of welding has its own use and its own types of materials that you would have to buy for the…
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Welding is the only process which is carried out to merge two metals and it is an absolute need that a person who welds should wear a helmet to protect himself from the fire sparks. The headgear protects the welder's eyes, face and neck from flash burn, ultraviolet light, sparks, heat and infrared light. It will prevent from retina burns which lead to loss of vision. In order to avoid this unprotected exposure to the ultraviolet and infrared rays it is necessary to make use of the right helmet which safeguards the body.…
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Cited: "AWS Certified Welder Program." American Welding Society (AWS). American Welding Society and Weld-Ed Center. 19 Jan. 2010. 26 Jan. 2011. .…
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The dictionary defines electric arc welding as “A technique in which metals are welded using heat generated by an electric arc.”…
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periods, for example from 50 to 100 years. When this method is used, the steel…
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Welding can be performed in a diverse range of locations such as underwater. However, not all forms of welding are the same. Some use gas while others use electric and some use the newest form of laser welding. Depending on the form and thickness of the material you were using would make a difference on the type of welding process you would have to use. Some of the most used welding techniques used are Arc, Electroslag, Flux-Cored, Gas Metal-Arc, Gas Tungsten-Arc, and Metal Inert Gas. Arc welding is popular for industrial, automotive, and farm repair because its equipment is relatively inexpensive and can be made portable. “More welders have learned this process than any other” (Galvery/Marlow 107). “Today there are more than one hundred welding processes recognized by the AWS” (Galvery/Marlow…
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To increase the use of common resources, long run jobs with high concentration of welding. Possible future repetition are more desirable, because this can minimize engineering and other initial costs and create standard products that uses the welding competitive advantage from Fabtek…
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The test has following objectives, to check the hardenability of different metals, the effect of carbon on the material’s hardenability and the comparison of the link between the microstructure and the cooling rate [1].…
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