PSI - Issue 40

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E.E. Abashkin et al. / Procedia Structural Integrity 40 (2022) 1–6 Abashkin E.E. / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 3. Permanent join t of steel St3sp plates microstructures comp (×200): (a) center of the weld; (b) weld junction and excessive heating zone; (c) zones of recovery and recrystallization.

Analysis of the images presented in Fig. 4 shows that a permanent joint obtained using an electrode with an aluminothermic powder filler is characterized by fibrous fracture (Fig. 4,a;b). A fibrous fracture may be regarded to a high energy (significant flow of crack propagation).

Fig. 4. Fractographies of weld joint specimen in rupture areas, obtained by automatic SAW method: (a) mode 1 (×1450); (b) mode 2 and 3 (×1020); (c) mode 4 (×172).

Therefore, with such a fracture, the rate of crack propagation is small. There are non-metallic inclusions observed at mode 1, due to the low thermal power value of the arc during the formation of the weld. A rapid heat dissipation appears, as the result the rate of crystallization of the metal increases. It suctions the slag to appear on the surface. The speed of crack propagation within a brittle fracture increases and becomes close to the speed of sound. The specimen presented in Fig. 4,c, can be characterized by a brittle fracture caused by excessive heating of the weld joint. The energy of such fracture is much lower than in the first case (the flow of crack propagation tends to zero). Based on the above mentioned, modes 2 and 3 appear to be more favorable for the metal surfacing formation than the thermal exposure on the steel plates seam common to modes 1 and 4. 4. Conclusions The results of experiments proved that the strength characteristics of the material deposited by the electrode wire with aluminothermic powder filler is comparable to the values of the connected St3sp steel plates material and is achieved by using the range of thermal power value of the arc q = 8.1÷9.3 kJ/s, which allows to obtain the values of the impact strength of the permanent joint weld material 66.7 kJ/m2, the nature of the specimen fracture is fibrous. The tensile strength corresponds to the range Ϭ v = 380÷465 MPa, the yield strength corresponds to the range of