**6. Verification of the results of numerical simulation of phase transitions with the results of metallographic research**

In order to verify the results of the numerical calculations, metallographic tests of the buttwelded joint were carried out. For this purpose, two flats with identical geometry as calculated, that is, two flats with a thickness of 0.012 m and width of 0.1 m, were welded. The material of the flats was steel S235. Before making the joint, sheet chamfering was conducted. Then, welding was carried out with the submerged arc welding method, under welding flux Taste-3 and with SPG*Φ*15 wire. Welding parameters were voltage U = 30 V, current I = 600 A and welding speed 20 m/h. The diagram of the elements prepared for joining is presented in **Figure 5** (identical to the welded joint adopted for numerical analysis). Cross-section of the weld joint (the image of the sample taken for metallographic examinations) is presented in **Figure 22**. Metallographic analysis was performed for specific zones of a welded joint, that is, for the area of weld, heat-affected zone and parent material. **Figure 23** shows an image of the middle part of the welded joint (at the junction of welded flats) with a clearly visible dendritic structure which is characteristic of solidification. **Figure 24** shows an image of the structure in the right symmetrical part of the welded joint in the area from the weld to the ferrite-pearlite structure of the parent material. On the border of the weld, dendrites are visible, which change in the heat-affected zone into a structure with the Widmannstatten structure elements.

**Figure 22.** Cross-section of a welded joint: sample taken for metallographic analysis, magnification 2×.

**Figure 25.** Weld, Nital Etch, magnification 250×, ferritic-pearlitic dendritic structure.

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**Figure 26.** Heat affected zone, Nital Etch, magnification 250×, ferritic-pearlitic structure.

Next, the images of structures of individual areas are presented. In the area of the weld (**Figure 25**), we observe the ferritic-pearlitic structure with a small amount of supercooled pearlite and island bainite in the dendritic system characteristic of solidified structures. In the

**Figure 23.** Weld, magnification 140×.

**Figure 24.** Transition zone, magnification 140×.

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**Figure 25.** Weld, Nital Etch, magnification 250×, ferritic-pearlitic dendritic structure.

**Figure 23.** Weld, magnification 140×.

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**Figure 24.** Transition zone, magnification 140×.

**Figure 26.** Heat affected zone, Nital Etch, magnification 250×, ferritic-pearlitic structure.

Next, the images of structures of individual areas are presented. In the area of the weld (**Figure 25**), we observe the ferritic-pearlitic structure with a small amount of supercooled pearlite and island bainite in the dendritic system characteristic of solidified structures. In the heat-affected zone (**Figure 26**), ferrite, pearlite and pearlite balls supercooled with a number of non-metallic inclusions are visible. Primary structure of the parent material (**Figure 27**) consists of ferrite and pearlite in the band system (hardly visible).

**Author details**

Address all correspondence to: winczek@gmail.com

Welding J. 1941;20:220s–234s

Welding J. 1983;62:346s–355s

Metall Trans. 1984;15B:299–305

plates. Proc Inst Mech Eng. 1990;204B3:175–183

Springer-Verlag; Berlin Heidelberg. 1992; 348 p.

arc welding. Sci Technol Weld Join. 2008;13:539–549

Int J Num Meth Biomech Eng. 2011;27:595–607

2013;59:333–338

distribution in fillet arc welds. Welding J. 1997;76:223s–232s

Czestochowa University of Technology, Czestochowa, Poland

[1] Rosenthal D. Mathematical theory of heat distribution during welding and cutting.

The Analysis of Temporary Temperature Field and Phase Transformations in One-Side Butt-Welded Steel Flats

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[2] Rykalin N N. Fundamentals of heat flow in welding. AN SSSR: Moskva;1947. 272 p.

[3] Eagar T W, Tsai N S. Temperature fields produced by traveling distributed heat sources.

[4] Goldak J, Chakravarti A, Bibby M. A new finite element model for welding heat sources.

[5] Bo K S, Cho H S. Transient temperature distribution in arc welding of finite thickness

[6] Radaj D. Heat effects of welding. Temperature field, residual stress, distortion,

[7] Jeong S K, Cho H S. An analytical solution to predict the transient temperature

[8] Nguyen N T, Mai Y W, Simpson S, Ohta A. Analytical approximate solution for double

[9] Kwon Y, Weckman D C. Analytical thermal model of conduction mode double sided

[10] Fachinotti V D, Anca A A, Cardona A. Analytical solutions of the thermal field induced by moving double-ellipsoidal and double elliptical heat sources in a semi-infinite body.

[11] Antonakakis T, Maglioni C, Vlachoudis V. Closed form solutions of the heat diffusion

[12] Ghosh A, Barman N, Chattopadhyay H, Hloch S. A study of thermal behaviour during submerged arc welding. Strojniški vestnik – Journal of Mechanical Engineering.

equation with Gaussian source. Int J Heat Mass Transf. 2013;62:314–322

ellipsoidal heat source in finite thick plate. Welding J. 2004;84:82s–93s

Jerzy Winczek

**References**

**Figure 27.** Parent material, Nital Etch, magnification 250×, ferritic-pearlitic banded structure.

The results of metallographic tests show high conformity with the results of numerical simulation and testify to the correctness of the developed numerical model.
