Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field

GRD Journals- Global Research and Development Journal for Engineering | Volume 5 | Issue 11 | October 2020 ISSN- 2455-5703

Experimental and Theoretical Investigation into the Effect of Welding-Parameters and MagneticField on Structure and Properties of Weld in Arc-Welding Rudra Pratap Singh Department of Mechanical Engineering I.E.T., G.L.A. University Mathura, (U.P.)

Abstract This paper investigated the multi-response optimization of shielded metal arc welding (SMAW) process for an optimal parametric combination to yield favorable bead geometry and mechanical properties of welded joints using artificial neural networks method. Total twenty five sets of experimental input output data were obtained to train the ANN model and to verify the prediction made by the model. Cross slide of a lathe machine was used to have constant welding speed. External magnetic field was obtained with the help of a bar magnet mounted on tailstock side of the lathe machine with a wooden structure. The main aim was to derive objective functions like welding current, voltage, speed of welding and external magnetic field to be optimized within experimental domain. The objective functions have been selected in relation to parameters of SMAW welding bead geometries like bead width, reinforcement height, depth of penetration, and mechanical properties like hardness, impact strength and tensile strength. The model was trained with the help of eighteen sets of data. Optimal results have been verified through seven other data sets of experiments. This shows application feasibility of the artificial neural networks for continuous improvement in product quality in manufacturing industry.

Keywords- Back Propagation, Bead Geometry, External Magnetic Field, Input Process Parameters, Mechanical Properties, Neurons

I. INTRODUCTION The advantages of welding, as a joining process, include high joint efficiency, simple set up, flexibility and low fabrication costs [1]. Shielded metal arc welding is a versatile and flexible process requiring simple equipment, a skilled welder, welderâ€&#x;s accessories and electrodes. Welding can be done in all positions, both in shop and at site. Welded joints of sound quality and adequate mechanical properties can be obtained by using correctly designed electrodes and proper welding procedures. The process is intermittent, because welding has to be interrupted from time to time to discard the unused stub and to place a fresh electrode into the holder, and also to deslag the joint. For higher productivity, semi-automatic or fully-automatic welding processes are preferred [2]. The mechanical strength of weld is influenced not only by the composition of the metal, but also by the weld bead shape. The current, voltage, welding speed and polarity can influence the bead shape and size [3]. Due to the effect of external longitudinal magnetic field the weld bead becomes wider. Usually, the wider the nugget diameter is, the better the mechanical performance of the weld will be [4]. External magnetic field can produce electromagnetic stirring (EMS). EMS is considered as an effective way to control the weld quality of SMAW at a relatively low cost with high efficiency. The principle of EMS is the use of Lorentz force, which derives from the interactions of welding current and the externally applied magnetic field. During the welding process, the molten metal driven by the Lorentz force makes high-speed movement and eventually affects the melting and solidification process. EMS technique can successfully be applied in arc welding by affecting the shape of weld pool and refining crystal grains [5]. The weld quality is achievable by meeting quality requirements such as bead geometry which is highly influenced by various process parameters involved in the process. The weld bead geometry plays an important role in determining the mechanical properties of the weld. Hence the input welding process variables which influence the bead geometry must properly be selected to obtain an acceptable high quality joint [6].

Generally welded joints are the locations for the crack initiation due to inherent metallurgical, geometrical defects as well as heterogeneity in mechanical properties and presence of residual stresses. For maintaining structural integrity of welded structures throughout the service life of the structure, relationship between welding process, properties and performance of the structure should be well-understood and established. Several studies and researches have been conducted so far to determine the effect of welding parameters on weld properties and quality. Heat input affects the weld mechanical properties for SMAW process [7]. Investigation into the relationship between the welding process parameters and bead geometry began in the mid 1900s and regression analysis was applied to welding geometry research [8]. An ANN model can be developed successfully to All rights reserved by www.grdjournals.com

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

predict weld bead geometry and penetration by considering electrode diameter, current, voltage, travel speed; electrode feed rate, arc length and arc spread as influential factors for electric arc welding [9]. ANN modeling has been chosen by its capability to solve complex and difficult problems. It provides better result in comparison to that of multiple regression analysis [10].

II. EXPERIMENT WORK The mild steel plates of 5 mm thickness were cut into the required dimension (150 mm×50 mm) by oxy-fuel cutting and grinding. The initial joint configuration was obtained by securing the plates in position using tack welding. Single „V‟ butt joint configuration was used to fabricate the joints using shielded metal arc welding process. All the necessary cares were taken to avoid the joint distortion and the joints were made with applying clamping fixtures. The specimens for testing were sectioned to the required size from the joint comprising weld metal, heat affected zone (HAZ) and base metal regions and were polished using diferent grades of emery papers. To investigate the weldment characteristics weld beads were obtained by welding two mild steel flat plates of 150 mm x 50 mm x 5 mm dimensions in butt position using mild steel electrodes of 3.15 mm diameter. A manual welding machine was used to weld the plates. A lathe machine was used to provide uniform speed of welding and to support electrode holder and bar magnet. The work piece was kept on cross slide with an arrangement. Work-piece could move with cross slide. Bar magnet was connected with tailstock with a wooden structure. Since the weldment structure and properties depend on welding current, welding voltage, speed of welding and magnetic field, we select different set of values of these inputs [11]. Welding currents were chosen as 90, 95,100, 105 and 110 A, arc voltages were chosen as 20, 21, 22,23 and 24V, the welding speeds were chosen as 40, 60 and 80 mm/min and external magnetic field strengths were used as 0, 20,40, 60 and 80 Gauss for the experiments. Current was measured with a clamp meter, voltage was measured with a multi meter and magnetic field was measured with a Gauss meter. To study the geometry and mechanical properties of the weld bead, each welded plate was sectioned transversely at different points. As the welding at starting and at the end is considered not proper so 20 mm from start and 20 mm from the end of the welded plates, it was removed. Remaining plate was cut in several pieces; three pieces of 10 mm, and one piece of eighty mm were obtained. One piece of 10 mm was used for geometrical (depth of penetration, bead width and reinforcement height) study, second piece of 10 mm was used for hardness test and the third piece of 10 mm was used for impact strength study. The eighty mm piece was used for tensile test. To get the microstructure, the sectioned pieces were ground with emery belt grinder having 0, 2, 3 grade emery papers then polished with a double disk polishing machine. Etching was done with a mixture of 2% nitric acid and 98% ethyl alcohol solution. To measure the bead height and bead width of each sample a digital slide caliper was used. The average values of bead height, bead width and depth of penetration were measured. The unnotched smooth tensile specimens were prepared to evaluate transverse tensile properties of the joints such as yield strength and tensile strength. The gripping of tensile specimens on universal testing machine was made easy by welding the both ends of specimens with circular rods. Tensile test was conducted with a 40 ton electro-mechanical controlled universal testing machine.

Since the plate thickness was small, sub-size specimens were prepared. Charpy impact test was conducted at room temperature using pendulum type impact testing machine with a maximum capacity of 300 Joule and least count of 2 Joule. The amount of energy absorbed in fracture was recorded and the absorbed energy was defined as the impact toughness of the material [12]. The hardness test was conducted on Rockwell (B scale) hardness testing machine. Eighteen sets of values out of twenty five such sets obtained were used for training a network based on back propagation algorithm. Remaining seven sets of the values were used for prediction. These data sets were shown in table-1. A program of back propagation neural network in C++ was used for training and prediction. In this program one input layer having four neurons, two hidden layers, both having five neurons and one output layer having six neurons, were used.

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

1. Multi-mete 2. Battery Eliminator 3. Electric Board 4. Gauss Meter 5. Table 6. Measuring Prob 7. Transformer Welding Set 8. Clamp meter 9. Tail Stock 10. Sleeve 11. Link (Wood) 12. Solenoid 13. Tool post 14. Iron sheet 15. Work piece 16. Electrode 17. Electrode Holder 18.

Metal Strip Connected with head stock 19. Head stock 20. Connecting Wires Fig. 1: Experimental Setup Table 1: Data for Training and Prediction Rockwel Weld Welding Depth of l Charpy Tens.

Serial Magneti Width(m Reinforceme Curre Voltag Speed Penetrati Hardne Imp.Strengt Strengt Numbe c Field m) nt Height nt (A) e (V) (mm/mi on (mm) ss (B) h. (J) h. r (Gauss) (mm) n) (MPa)

Data for Training

0 6.95 1.13 20 6.94 1.13 40 6.96 1.14 60 6.99 1.11 80 7.03 1.09 60 6.01 1.06 60 6.08 1.07 60 6.10 1.09 60 6.15 1.11 60 6.25 1.12 40 5.94 1.17 40 5.90 1.15 40 5.86 1.11 20 5.91 1.06 20 5.92 1.09 20 5.94 1.11 20 5.95 1.13 20 5.97 1.08 0 6.92 1.14 40 6.05 1.11 60 6.04 1.04 40 6.99 1.16 40 5.98 1.14 20 5.96 1.13 20 5.97 1.10 Table 2 (a): Measured and Predicted Values Depth of Penetration (mm) Measured

Rockwell Hardness(B) Measured

Rockwell Hardness(B) Predicted

Charpy Imp. Strength (J) Measured

Charpy Imp. Strength (J) Predicted

Tensile Strength(MPa) Measured

Tensile Strength(MPa) Predicted

90

23

40

0

6.92

6.54

1.14

1.10

0.76

0.74

91

85.6

132

131.8

268

274.5

2

95

22

60

40

6.05

6.42

1.11

1.08

0.72

0.71

86

85.1

135

132.1

278

275.2

3

95

21

80

60

6.04

6.44

1.04

1.06

0.66

0.70

89

85.4

137

132.3

284

276.1

4

100

24

40

40

6.99

6.58

1.16

1.14

0.78

0.73

89

85.2

131

131.7

252

273.3

5

105

21

60

40

5.98

6.41

1.14

1.11

0.77

0.74

81

84.8

128

130.8

272

274.1

6

105

22

60

20

5.96

6.40

1.13

1.09

0.73

0.72

78

84.6

127

130.6

270

273.3

7

110

21

60

20

5.97

6.39

1.10

1.08

0.75

0.74

79

83.9

126

130.9

270

273.6

Depth of Penetration (mm)

Reinforcement Height (mm) Predicted

1

Welding Speed (mm/min)

Reinforcement Height (mm) Measured

266 266 266 268 272 284 282 280 278 276 254 258 262 282 280 278 274 272 268 278 284 252 272 270 270

Weld Wedth(mm) Predicted

131 131 131 134 135 138 136 135 133 131 132 133 134 134 132 130 129 127 132 135 137 131 128 127 126

Weld Wedth(mm) Measured

90 90 90 91 92 89 88 87 86 85 90 91 92 88 86 84 82 80 91 86 89 89 81 78 79

Magnetic Field (Gauss)

0.79 0.79 0.80 0.77 0.76 0.78 0.76 0.75 0.74 0.72 0.83 0.79 0.76 0.70 0.71 0.74 0.77 0.75 0.76 0.72 0.66 0.78 0.77 073 0.75

Voltage (V)

40 40 40 40 40 60 60 60 60 60 40 60 80 80 80 80 80 80 40 60 80 40 60 60 60

Current (A)

24 24 24 24 24 20 21 22 23 24 22 22 22 20 20 20 20 20 23 22 21 24 21 22 21

S.N.

S.N.

Data for Predictio n

90 90 90 90 90 95 95 95 95 95 100 100 100 90 95 100 105 110 90 95 95 100 105 105 110

Predicted

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 5 6 7

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

5

6

7

-3.51

-2.63

-5.53

-0.15

2.43

22

60

40

+6.12

-2.70

-1.39

-1.05

-2.15

-1.01

21

80

60

+6.62

+1.92

+6.06

-4.04

-3.43

-2.78

24

40

40

-5.87

-1.72

-6.41

-4.27

0.53

8.45

21

60

40

+7.20

-2.63

-3.90

4.44

2.19

0.77

22

60

20

+7.38

-3.54

-1.37

8.46

2.63

1.22

21

60

20

+7.04

-1.82

-1.33

6.20

3.68

1.33

Error in Tensile Strength % age

-5.49

Error in TImpact Strength % age

0

Magnetic Field (Gauss)

40

Welding Speed (mm/min)

23

Voltage (V)

Error in Hardness % age

4

Error in Depth of Penetration %age

3

Error in Reinforcement Height %age

2

9 0 9 5 9 5 1 0 0 1 0 5 1 0 5 1 1 0

Error in Bead Width % age

1

Current (A)

S. N.

S.N.

Table 2 (b): Percentage Error in Structure and Properties

III. METHODOLOGY OF ARTIFICIAL NEURAL NETWORK MODELING Generally the industrial processes are non-linear and complex in which several input variables are involved. The mathematical models are unable to describe the behavior of the processes. ANNs are easy to understand, cost effective and have the capability to learn from examples and can be applied in many industries. ANN model has been developed for general application following some steps like Database collection, pre-processing of input/output data, design and training of neural network, testing of trained network, post processing and use trained network for prediction [13]. The arrangement of neurons into layer and the connection pattern within and between the layers are called as network architecture. The ANN architecture is consisted of input layer, hidden layers and output layers. The input layer receives the welding parameters, hidden layers are considered as black boxes and output layer provides the predicted result. The performance of the neural networks depends upon, the number of hidden layers, number of neurons in the hidden layers and the number of iterations used. Hence, optimum structure is obtained by changing number of hidden layers and number of neurons in hidden layers by making many attempts. The appropriate neural networks structure was chosen by the trial and error method [9]. Feed forward artificial neural network structure was established using C++ by keeping four neurons in the input layer, two hidden layers having five neurons in each and six neurons in output layer. It was trained with help of back propagation (BP) algorithm. In training, it is essential to balance the importance of each parameter; hence the data must be normalized. Since, neural networks works better in the range of 0 to 1 [13], the input and output vector values are converted in the range of 0 to 1. Proposed feed forward neural network architecture is shown in figure-3.

Non-linearity and input-output mapping are the useful complement in neural networks. Hence, it has been adapted to model the input-output relation of non-linearity and interconnected system [14].

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 2: 4-5-5-6 ANN Diagram

IV. RESULTS AND DISCUSSION Table 2 (a) depicts, the measured weld bead width, reinforcement height, depth of penetration, hardness, tensile strength and impact strength from the experiment and predicted output values using artificial neural feed forward network. The measured and predicted output values are close to each other. The aim of this paper shows the possibility of the use of neural network to predict the weld bead geometry and mechanical properties A. Weld Width The weld width of the welded joints was almost unaffected if the magnetic field was changed from 0 to 20 gauss or from 20 to 40 gauss. If the field was increased from 40 gauss to 60 gauss, the weld width increased from 6.97 mm to 6.99 mm. and if it was increased from 60 gauss to 80 gauss, the weld width increased from 6.99 mm to 7.03 mm. If the speed of welding was increased from 40 mm/min to 60 mm/ min, the weld width decreased from 5.94 mm to 5.90 mm, and if it was increased from 60 mm/min to 80 mm/min, the weld width of the weld decreased from 5.90 mm to 5.86 mm. The effect of voltage was positive for weld width i.e. if voltage was increased from 20 V to 24 V, the weld width increased from 6.01 mm to 6.25 mm. The increment in current, increased the weld width for all the investigated values. If the current was increased from 90 A to 110 A the weld width increased from 5.91 mm to 5.97 mm. The variation of weld width with magnetic field, voltage, welding speed and current were shown in figures 3, 4, 5 and 6 respectively.

Fig. 3: Weld Width Vs Magnetic Field

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 4: Weld Width Vs Voltage

Fig. 5: Weld Width Vs Speed of Welding

Fig. 6: Weld Width Vs Current

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

B. Reinforcement Height Reinforcement heights of all the joints were evaluated and they were presented in table 1. The magnetic field had almost no effect on reinforcement height if it was changed in between 0 and 40 gauss, and after this the reinforcement height decreased if magnetic field was increased upto 80 gauss which was our investigation range. If the magnetic field was increased from 40 gauss to 60 gauss the reinforcement height decreased from 1.14 mm to 1.11 mm and if it was increased from 60 gauss to 80 gauss the reinforcement height decreased from 1.11 mm to 1.09 mm. If the speed of welding was increased from 40 mm/ min to 80 mm/min the reinforcement height continuously decreased. Increment in voltage from 20 to 24V, increased the reinforcement height from 1.06 mm to1.12 mm. if the increment in current was from 90 A to 110 A, the reinforcement height of weld generally.

The variation of reinforcement height with magnetic field, voltage, welding speed and current were shown clearly in figures 7, 8, 9, and 10 respectively.

Fig. 7: Magnetic Field vs Reinforcement Height

Fig. 8: Reinforcement Vs Voltage

Fig. 9: Reinforcement Height Vs Welding Speed

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 10: Reinforcement Height Vs Current

C. Depth of Penetration The depth of penetration of the weld cross-section was measured and the results were displayed in table 1. There was generally no effect of magnetic field on depth of penetration if the strength of the field was less than 40 gauss and if it was increased from 40 gauss to 80 gauss the depth of penetration decreased from 0.80 mm to 0.76 mm. If the speed of welding was increased from 40 mm /min to 80 mm/ min the depth of penetration decreased from 0.83 mm to 0.76 mm. If the voltage was increased from 20 V to 24 V the depth of penetration decreased from 0.78 mm to 0.72 mm. If the current was increased from 90 V to 110 V, the depth of penetration increased from 0.70 mm to 0.75 mm. The variation of depth of penetration with magnetic field, voltage, welding speed and current were shown in figures 11, 12, 13 and 14 respectively.

Fig. 11: Depth of Penetration Vs Magnetic Field

Fig. 12: Depth of Penetration Vs Voltage

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 13: Depth of Penetration Vs Welding Speed

Fig. 14: Depth of Penetration Vs Current

D. Rockwell Hardness The hardness across the weld cross-section was measured using a Rockwell hardness testing machine, and the readings were displayed in table 1. The hardness of weld metal (WM) region was found greater than the HAZ region, but lower than the base metal (BM) region, irrespective of ďŹ ller metals used. There was no effect of magnetic field on hardness if the strength of the field was less than 40 gauss and if it was increased from 40 gauss to 80 gauss the hardness increased from 90 RHB to 94 RHB. If the speed of welding was increased from 40 mm /min to 80 mm/ min the hardness increased from 88RHB to 93 RHB. If the voltage was increased from 20 V to 24 V the hardness decreased from 91 RHB to 82 RHB. If the current was increased from 90 V to 110 V, the hardness decreased from 89 RHB to 80 RHB. The variation of hardness properties with magnetic field, voltage, welding speed and current were shown in figures 15, 16, 17 and 18 respectively.

Fig. 15: Hardness Vs Magnetic Field

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 16: Hardness Vs Voltage

Fig. 17: Hardness Vs Welding Speed

Fig. 18: Hardness Vs Current

E. Impact Strength Charpy impact strength (toughness) values of all the joints were evaluated and they were presented in table 1. The magnetic field had no effect on impact strength if it was changed in between 0 and 40 gauss, the impact strength remained constant at 131 J, and after this the impact strength increased if magnetic field was increased upto 80 gauss which was our investigation range. If the magnetic field was increased from 40 gauss to 60 gauss the impact strength increased from 131 J to 136 J and if it was increased from 60 gauss to 80 gauss the impact strength increased from 136 J to 138 J. If the speed of welding was increased

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

from 40 mm/ min to 80 mm/min the impact strength continuously increased. Increment in voltage from 20 to 24V, decreased the impact strength from 138 J to 130 J., if the increment in current was from 90 A to 110 A, the impact strength of weld decreased from 134 J to 126 J. The variation of toughness (impact strength) properties with magnetic field, voltage, welding speed and current were shown clearly in figures 19, 20, 21, and 22 respectively.

Fig. 19: Impact Strength Vs Magnetic Field

Fig. 20: Impact Strength Vs Voltage

Fig. 21: Impact Strength Vs Current

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 22: Impact Strength Vs Welding Speed

F. Tensile Properties Transverse tensile property of the joints was evaluated. The specimens were tested, and the results were presented in table 1. The yield strength and tensile strength of unwelded base metal were measured as 359 and 524 M Pa, respectively. But the yield strength and tensile strength of mild steel (fabricated using E-6013, rutile electrode ďŹ ller metal) joints were reduced by about 50% in both the cases. The tensile strength of the welded joints was unaffected if the magnetic field was changed from 0 to 20 gauss or from 20 to 40 gauss. If the field was increased from 40 gauss to 60 gauss, the tensile strength increased from 266 M Pa to 268 M Pa. and if it was increased from 60 gauss to 80 gauss, the tensile strength increased from 268 M Pa to 272 M Pa. If the speed of welding was increased from 40 mm/min to 60 mm/ min, the tensile strength increased from 254 M Pa to 258 M Pa and if it was increased from 60 mm/min to 80 mm/min, the tensile strength of the weld increased from 258 M Pa to 262 M Pa. The effect of voltage was adverse for tensile strength i.e. if voltage was increased from 20 V to 24 V, the tensile strength decreased continuously from 284 M Pa to 276 M Pa. The increment in current also decreased the tensile strength for all the investigated values. If the current was increased from 90 A to 110 A the tensile strength decreased from 282 M Pa to 272 M Pa. The variation of tensile properties with magnetic field, voltage, welding speed and current were shown in figures 23, 24, 25 and 26 respectively.

Fig. 23: Tensile Strength Vs Magnetic Field

Fig. 24: Tensile Strength Vs Voltage

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

Fig. 25: Tensile Strength Vs Welding Speed

Fig. 26: Tensile Strength Vs Current

G. Prediction of Weld Bead Geometry and Mechanical Properties using Artificial Neural Networks The developed neural network architecture was trained with help of back propagation algorithm using 18 data sets. The developed network was tested out of 7 datasets. The training data sets and testing data sets are shown in table 1, the testing data were not used for training the network. The % error was calculated between the experimental and predicted values as shown in figure-2. The % error is ranging between -6.41 to 8.46. The other predictions are in between the above ranges and hence are very close to the practical values, which indicate the super predicting capacity of the artificial neural network model.

V. DISCUSSION In this investigation, an attempt was made to ďŹ nd out the best set of values of current, voltage, speed of welding and external magnetic field to produce the best quality of weld in respect of weld width, reinforcement height, depth of penetration, hardness, tensile strength and impact strength. Shielded metal arc welding is a universally used process for joining several metals.

Generally in this process speed of welding and feed rate of electrode both are controlled manually but in the present work the speed of welding was controlled with the help of cross slide of a lathe machine hence only feed rate of electrode was controlled manually which ensures better weld quality. In the present work external magnetic field was utilized to distribute the electrode metal and heat produced to larger area of weld which improves several mechanical properties of the weld. The welding process is a very complicated process in which no mathematical accurate relationship among different parameters can be developed. In present work back propagation artificial neural network was used efficiently in which random weights were assigned to co-relate different parameters which were rectified during several iterations of training. Finally the improved weights were used for prediction which provided the results very near to the experimental values.

VI. CONCLUSION The experimental analysis confirms that, artificial neural networks are power tools for analysis and modeling. Results revealed that an artificial neural network is one of the alternatives methods to predict the weldbead geometry. Hence it can be proposed All rights reserved by www.grdjournals.com

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Experimental and Theoretical Investigation into the Effect of Welding-Parameters and Magnetic-Field on Structure and Properties of Weld in Arc-Welding (GRDJE/ Volume 5 / Issue 11 / 006)

for real time work environment. Based on the experimental work and the neural network modeling the following conclusions are drawn: 1) A strong joint of mild steel is found to be produced in this work by using the SMAW technique.

2) If amperage is increased, weld width, depth of penetration and reinforcement height generally increase but hardness, tensile strength and impact strength of weld generally decrease.

3) If voltage of the arc is increased, weld width and reinforcement height generally increase but depth of penetration hardness, tensile strength and impact strength of weld, generally decrease.

4) If travel speed is increased, weld width, reinforcement height and depth of penetration of weld generally decrease but hardness, tensile strength and impact strength of weld and generally increase.

5) If magnetic field is increased, weld width, hardness, tensile strength and impact strength of weld; generally increase but reinforcement height and depth of penetration of weld, decrease.

6) Artificial neural networks based approaches can be used successfully for predicting the output parameters like weld width, reinforcement height, depth of penetration, hardness, strength and impact strength of weld as shown in table 2. However the error is rather high as in some cases in predicting depth of penetration it is more than 7 percent and in predicting hardness and tensile strength it is more than 8 percent. Increasing the number of hidden layers and iterations can minimize this error.

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