Time Temperature Analysisof

Welding Processes

Prepared by:Kaustav Datta (12BME010)Kawan R. Jain (12BME019)8th Semester B.Tech., Dept. of Mechanical Engineering,School of Technology, Pandit Deendayal Petroleum University,Gandhinagar

Guided by:Dr. Vishvesh J. BadhekaAssociate ProfessorDepartment of Mechanical Engineering,School of Technology, Pandit Deendayal Petroleum University,Gandhinagar

2

Contents discussed during Mid-Semester Review• Project title and Introduction• Literature Survey – Why Time Temperature Analysis• Literature Survey – GMAW (Process & its Advantages)• Literature Survey – FCAW (Process & its Advantages)• Literature Survey – MCAW (Process & its Advantages)• Method of Experiment• Materials and Tools• Experimental Method

Figure 1. Process Schematic Diagram for MIG/FCAW/MCAW

Source: AU : IPRM 2007 : Section 4 : Welding Processes

4

Materials and ToolsGases used:Argon (80%)CO2 (20%)

Kempact Pulse 3000MVUKemppi K5 MIG/MAG welder

Software: Pro Weld Data v 3.17

Metal Consumables:GMAW WireFCAW WireMCAW Wire

Figure 2. Electrode Gun used for MIG/FCAW/MCAW

Source: AU : IPRM 2007 : Section 4 : Welding Processes

Previous Work

• We have learned about all the 3 Welding Processes, i.e., GMAW, FCAW, MCAW thoroughly & understood the welding operation as well as their advantages individually.

• Later we also discussed several differences between the 3 Processes, and observed Economic Advantage of Cored Tubular Wire over Solid Wire Use.

• The Method of Experiment has been Covered earlier itself.

• After Getting the Samples from the Welding, We performed several Tests to find out Few properties of the Weld Metal.

Post ExperimentAll Samples are properly cleaned by using brushes.Further, Two samples are cut from Between of size 10mm*100mm*10mm, for further inspection & testing purposes.Above step is repeated for All 3 Processes.

Figure 4. Flux Cored Wire (Fcaw), SampleFigure 3. Test Sample cutting under Band Saw Machine.

Process Parameters & Their Effects

In arc welding processes, a number of welding parameters exist that can affect the size, shape, quality and consistency of the weld. Producing a weld bead of the right size, shape and depth involves many variables. Few of them are:

1. Amperage2. Arc Voltage3. Travel Speed4. Arc Length5. Work Angle

Our main objective was to find out the Heat Input or Power requirements for three different welding processes, i.e, GMAW, FCAW and MCAW, so we have kept all these parameters constant for our experiment work.

Table1 Process Parameters used in the Experiment

  GMAW FCAW MCAW

Amperage 198 A 191 A 186 A

Arc Voltage 27.7 V 27.9 V 28 V

Travel Speed 220 mm/min 220 mm/min 220 mm/min

Arc Length 2 mm 2 mm 2 mm

Work Angle 90° 90° 90°

Total Energy Used 443 KJ 406.7 KJ 420.3 KJ

1. Amperage – Higher the Current, Deeper the Penetration2. Arc Voltage – Higher Voltage leads to more wider & flat Bead3. Travel Speed – Faster the travel speeds, results in narrower beads with less

penetration.4. Arc Length – Size of the Electrode and Amperage Increases, Arc Length

Increases

RESULTS AND DISCUSSION

Contents to be discussed here….

1. Time Temperature Variation for GMAW, FCAW, MCAW Processes.

2. Heat Input Calculations and Plots.

3. Macrostructure Testing & Imaging.

4. Weld Dimensional Analysis.

5. Microstructure Images and Analysis.

6. Microhardness Test Results.

7. Conclusion.

8. References.

Table 2 Time-Temperature data of the Experiments

Time (s) Temperature (°C)

  GMAW FCAW MCAW

0 14 23 20

2 14 23 21

4 14 23 21

28 17 33 33

30 18 41 36

36 22 57 69

38 33 80 97

40 48 133 144

42 92 211 213

44 116 272 263

46 178 306 284

48 234 319 299

50 259 330 308

52 285 337 315

54 298 340 318

56 309 341 320

58 315 341 321

62 318 340 321

66 318 334 318

Time Temperature Variation For Gmaw

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 700

50

100

150

200

250

300

350 318 °C

Temperature vs. Time plot for GMAW

Temperature

Time (s)

Tem

pera

ture

(°C

)

Table 3 Time-Temperature data from Software for GMAWWeld name Date Start time Arc time Av.Current(A) Av.Voltage(V) Av.Wfs(m/min) Energy used(kJ)

W0001 1/26/2016 1:10:13 PM 01:21 198 27.7 7.9 443.3

Figure 5. Temperature vs. Time plot for GMAW

Time Temperature Variation For Fcaw

Table 4 Time-Temperature data from Software for FCAWWeld name Date Start time Arc time Av. Current(A) Av. Voltage(V) Av.Wfs(m/min) Energy used(kJ)

W0002 2/5/2016 3:44:57 PM 01:17 191 27.9 7.9 406.7

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 700

50

100

150

200

250

300

350

400

Time – Temperature Analysis of FCAW

Temperature

Time (s)

Tem

pera

ture

(°C

) 342 °C

Figure 6. Temperature vs. Time plot for FCAW

Time Temperature Variation For Mcaw

Table 5 Time-Temperature data from Software for MCAWWeld name Date Start time Arc time Av.Current(A) Av.Voltage(V) Av.Wfs(m/min) Energy used(kJ)

W0003 1/26/2016 2:59:56 PM 01:16 196 28 7.9 420.3

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 700

50

100

150

200

250

300

350 322 °C

Time – Temperature Analysis of MCAWTemperature

Time (s)

Tem

pera

ture

(°C)

Figure 7. Temperature vs. Time plot for MCAW

Heat Input Calculations And Plots

The Heat Input for an ideal arc welding process is given by:

where, HI = Heat Input V = Voltage I = current S = Welding Speed

• For a lower heat input value, it is observed that the FCAW process witnesses the highest temperature observed during the welding.

• This means that the temperature is raised easily to a higher value for the FCAW process, as compared to the MCAW and GMAW. Also, higher heat input should yield better strength/toughness of weld.

• GMAW Process requires Maximum Heat Input among all the three, but still Maximum Temperature reached is very low compared to others.

Table 6PROCESS ENERGY USED (KJ) HEAT INPUT CALCULATED

(KJ)PEAK TEMPERATURE (°C)

GMAW 443.3 438.50 318

MCAW 420.3 416.90 322

FCAW 406.7 410.23 342

Macrostructure Testing & Imaging• To achieve good Microstructure of the sample, we had to achieve Mirror Like

finishing. • For this purpose, samples were cleaned and then grinded on the Belt Grinder for

the first time to remove any present burrs. • Later different grades of paper were used on the Paper Grinder Machine to

enhance the quality of the finish. • After doing this, samples were put in a beaker such that they were completely

submerged in the Etchant. • The purpose of etching is to optically enhance the microstructural features such as

grain size and phase features. Etching selectively alters these microstructural features based on composition, stress or crystal structure.

• The most common technique for etching is selective Chemical Etching and numerous formulations have been used over the years.

Fig. 9 Beaker after 12 mins heating Fig. 10 Macrostructure measurement

Fig 8 Samples being heated at 70°C for 12-15 mins in a beaker

• We used a 35% concentrated Hydrochloric Acid (HCl) solution for the etching process, where the beaker was heated for 12-15 mins at 75°C.

• After this, the samples were washed and cooled down and then observed under a microscope with magnification 10X to obtain the following Macrostrucural Images and measure the weld dimensions

S1 M1 F1

• The macrostructure images show that FCAW has the least visible depth of weld penetration and the also the least weld reinforcement.

• We have found visible elongated porosity in the solid wire weld. • The Weld Heat Affected band is clearly visible in case of solid and metal cored welding and is

obstructed by the elongated porosity in the case of the flux cored welding

Table 7 Macro Images of the Samples

Weld Dimensional Analysis

• The weld bead dimensions are measured using a microscope under a 10X magnification lens at the Metallurgy Laboratory in PDPU premises.

• The following are the weld bead dimension measurements according to the image attached for reference.

Table 8 Measurement of Weld Bead Width

Sample Name Sample No. D1

(mm)

D2

(mm)

Bead Width

(D2 – D1)

(mm)

Average Bead

Width

(mm)

SolidS1 2.05 3.15 1.10

1.345S2 1.45 3.04 1.59

MetalM1 2.05 3.27 1.22

1.235M2 2.08 3.33 1.25

FluxF1 0.55 1.91 1.36

1.380F2 0.56 1.96 1.40

Table 9 Measurement of Weld Reinforcement and Depth of Penetration

Sample

Name

Sample No. H1

(mm)

H2

(mm)

H3

(mm)

Reinforcement

(H2 – H3)

(mm)

Average Reinforcement

(mm)

Depth of Penetration

(H1 – H2)

(mm)

Average

DOP

(mm)

SolidS1 3.72 3.36 2.92 0.44

0.480.36

0.365S2 3.37 3.00 2.48 0.52 0.37

MetalM1 3.80 3.37 3.01 0.36

0.370.43

0.365M2 3.73 3.43 3.05 0.38 0.30

FluxF1 3.14 3.08 2.77 0.31

0.300.06

0.070F2 3.13 3.05 2.76 0.29 0.08

H2 – H1

H3 – H2

D2 – D1

Figure 11. Weld Bead Shape generated during Weldinghttp://www.azom.com/article.aspx

• As expected, the lower current in the FCAW process is responsible for a lower DOP amongst the three processes.

• Also, the voltage input is very slightly higher (0.1 V) in case of FCAW and due to the slight variation, the weld bead width is observed to be maximum where the Voltage is also maximum.

Microstructure Images And Analysis

• For the study of the Micro Structure, we have used an Olympus GX 51 Metallurgical Microscope. For this, we availed the services of Hertz testing Centre in Vatva, Ahmedabad.

• Optical microscopy revealed that the use of different electrode wires has a significant effect on the microstructures in the different welded samples.

• In this study, the effects of performing welds using solid, flux and metal cored wires were examined.

• The comparison of microstructure of the different regions is shown in the table 4.5 for samples S1, F1 and M1 respectively.

• The images were captured at different magnifications of 100X, 200X, 500X and 1000X from which the images taken at 200X and 500X are compared.

Table 10 Observation of Microstructures of different regions in the three welds

Region S1 F1 M1

Weld

Zone

(200x)

Weld

Zone

(500x)

Table 10 (contd.) Observation of Microstructures of different regions in the three

welds

Region S1 F1 M1

HAZ

(200x)

Base Meta l

(200x)

• A high heat input gives slower cooling and the grain size in the HAZ can become very coarse if the temperature is high enough to promote grain growth prior to transformation.

• GMAW Process required Maximum Heat Input among the three.• From the microstructural images, we can observe that the grain boundaries are

clearly visible and finer in case of FCAW and MCAW processes as compared to GMAW process.

• This is justified as the heat input is also lower in case of the cored-wire welding processes. Also, the finer microstructure leads to a higher hardness value.

• This is verified by the Micro Hardness measurement done thereafter.

Microhardness Test Results

• Finally, the Micro Hardness test of the samples was done, for which we have used a Vicker cum Brinell Hardness Tester BIE / BV-250 SPL.

• For this, we availed the services of Hertz testing Centre in Vatva, Ahmedabad. Measurement of Micro-Hardness of the different regions is shown in the table 4.6 for samples S1, F1 and M1 respectively.

• The measurements were done using a 1 Kgf force on a diamond shaped indenter. The table is followed by a comparative graph of the same.

Table 11. Micro Hardness (Brinell) Data for the weld samples

Sample Name Base Metal(HBN)

Average(HBN)

HAZ(HBN)

Average(HBN)

Weld Metal(HBN)

Average(HBN)

S1

114.97

115.76

137.81

139.34

152.22

155.16122.57 140.00 153.26

109.73 140.22 160.00

M1

113.18

107.66

137.81

137.89

153.26

159.09101.75 142.69 165.00

108.06 133.18 159.00

F1

114.97

111.59

147.33

138.66

169.00

163.33104.83 135.47 165.00

114.97 133.18 156.00

Series180

90

100

110

120

130

140

150

160

170

180

Micro-Hardness variation across the Samples

Solid Metal Flux

Weld metal region

Mic

ro h

ardn

ess (

Bri

nell)

Fig. 12. Micro-Hardness variation across the Samples

• From the Micro-Hardness test results and data, we can observe that the Flux-cored Welding Process produces the highest value of hardness in the weld metal region as compared to the rest of the two processes.

• The values are almost the same in the HAZ region for all the three processes. The values justify the theoretical knowledge of the subject that the hardness of the flux cored or metal cored electrodes is higher than that of the solid metal wire.

• In theory, metal cored wires show a higher hardness as compared to the flux cored wires, but the comparison may vary depending on the material and composition of the metal or flux cored wire used.

CONCLUSIONS

The FCAW process has the lowest weld reinforcement (0.30 mm) as well as depth of penetration (0.070

mm).

Despite the low weld reinforcement and depth of penetration, FCAW still shows the highest Micro-

Hardness in the weld region (163.33), followed by MCAW (159.09) and GMAW (155.16).

The peak temperature of the bead is maximum for FCAW Process (342 °C), then MCAW (322 °C) & then

GMAW (318 °C)

Thus, FCAW process is the one that reaches the maximum peak temperature using the least Power/Heat

input and also the least weld reinforcement and depth of penetration. Apart from all this, it produces the

strongest weld amongst the three processes.

CONCLUSIONS (contd.)

Power Consumption / Heat Input – Maximum in case of Metal Cored Wires (420.3 KJ) than the

Solid Wire (443.3 KJ)& the least in Flux Cored Wires (406.7 KJ).

The Micro-structure images show clearly that the weld zone in FCAW and MCAW contains granules of

metallic materials deposited onto them from the electrode wires.

After performing FCAW, we have observed various ‘Chicken Marks’ on the Sample, which are due to

Hydrogen Content in the electrode. These are undesirable, as they can cause problem later. This Problem

has not been occurred in other two processes.

References

• Howard B. Cary, 4th Edition1997, Modern Welding Technology, Prentice Hall.• D.B.Holliday, Gas Metal Arc Welding, Westinghouse Electric Corporation. • David Widgery, Tubular Wire Welding, Jaico Publishing House.• ASM Handbook Volume 6: Welding, Brazing and Soldering (1993), ASM

International.• Modern Arc Welding Technologies, Ador Welding Limited, Second edition, 2005.• V. Vasantha Kumar and N. Murugan; Effect of FCAW Process Parameters on Weld

Bead Geometry in Stainless Steel Cladding; Journal of Minerals & Materials Characterization & Engineering, Vol. 10, No.9, pp.827-842, 2011

• [Online]http://www.weldguru.com/support-files/flux-cored-arc-welding.pdf• [Online] http://www.thefabricator.com/article/consumables/an-introduction-to-

metal-cored-wire• [Online] http://www.esabna.com/us/en/education/blog/advantages-and-

disadvantages-of-metal-cored-wires.cfm• [Online]http://www.lincolnelectric.com/assets/global/Products/

Consumable_MIGGMAWWires-SuperArc-SuperArcL-56/c4200.pdf

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