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Geometria przetopień powierzchni odlewów żeliwnych uzyskanych metodą GTAW

Orłowicz W., Trytek A.

Problemy Eksploatacji

2000

nr 2

263-275

W pracy przedstawiono wyniki badań wpływu prędkości przemieszczania elektrycznego oraz zmian natężenia prądu spawania na ilość ciepła pochłoniętego przez odlew płytki z niestopowego żeliwa sferoidalnego. Pomiary wykonano na stanowisku kalorymetrycznym. Określono sprawność cieplną procesu oraz geometrię przetopień. Wyniki przedstawiono wykreślnie.

Tests were performed castings with unalloyed ductile graphite iron obtained in cupola. The castings were made in form of plates with dimensions 300 x 200 x 20 mm. From those castings small plates with dimensions 210 x 50 x 10 mm were cut up. These cast iron plates were fused by GTAW process using currents I = 50÷300 A, on arc motion speed vs = 200÷800 mm/min, and tungsten electrode 2,4 mm dia in helium atmosphere on a stand equipped with calorimeters. The width, depth and length of fusion area were measured on the samples and the surface area of its cross section was calculated. The tests to determined arc heat as well as the calorimetrically measured heat over the surface fused castings were carried uot. This in turn enabled the determination of the thermal efficiency of the process. Also, the relations between arc motion speed and welding current and the depth, width and length pool, cross section area of fusion or volume of melt pool have determined. In the fusion of unalloyed ductile iron the total heat input varied within 5.2 to 281,3 kJ. On the basis of obtained test results, it was found as follows: The highest thermal efficiency of the process, n = 78%, was obtained while using current of I = 300 A and arc motion speed of vs = 200 mm/min, The lowest thermal efficiency of the process, n = 44%, was obtained using current of I = 50 A And arc motion speed of vs = 800 mm/min, Arising the weld current and arc motion speed reduction is accompanied with arising value all evaluated fusion parameter. The obtained results can be explained by the fact that the heat flux flow and convection in molten pool are important from the point of view of pool penetration.