Determination of the hardness of the weld metal and the metal of the heat affected zone (HAZ) during low-frequency oscillations of the weld pool

Abstract

Work rele vance. The using of mechanical harmonic oscillations of welding pool or tool are inexpensive and quite simple procedure formation desirable degree of dispersion structure it means weld metal strength. Possibility of oscillations differently applied relative of the surfacing (welding) process axis lets welding seam or surfacing bead formation with certain anizotropy of mechanical properties in given direction.Many works have dedicated of researches of microstructure formation by conditions of periodic action on weld melt. However, the most part of it are devoted mostly researching to influence oscillations with frequency much superior value of 5 Hz and amplitude value range from some microns to 2–3 mm.Purpose of work is getting quantity dependencies which defining hardness value of weld metal and metal of HAZ as a function of technological and oscillations modes parameters.Research methods. For researchers the samples have had prepared and polished to #8 Mirror Finish by ISO (ГОСТ 25593 – 83). The surfacing process in CO2 protection environment had has carried out by alloy wire named G3Si1 by EN 13479 ISO 143341 (ТУ У 322-4-392-96) which diameter1.2 mm. Base metal was common quality carbon steel type Е 235-С by ISO 630:1995, ISO 1052:1982 (ДСТУ 2651:2005). Measurement of hardness (by Vickers) had carried out on hardness tester named LECO M-400 under indenter load1 kgby ISO 6507-1:2007 (ДСТУ ISO 6507-1:2007). Research resultants had treatment by regression analysis methods with application of analytics software package STATISTICA 12 and engineering math software PTC Mathcad Prime 3.1.Results. Regressive models of hardness value as function magnitudes arc current, the surfacing process velocity, amplitude and frequency oscillations have received. Contour plots of depend of hardness value from amplitude and frequency magnitudes were created. Variant of predict of the receiving maximum value hardness weld metal and metal of HAZ at arc current125 Aand the surfacing process speed 14 m/h are presented.Scientific novelty. The experiments were carried out with different amplitude and frequency values which were given through programming step motor.Empirical depends of influence of technological and oscillation modes parameters of certain range on weld metal hardness and metal HAZ hardness values are created.Practical value. An increase possibility of hardness values of weld metal and metal of HAZ due to use weld pool oscillations with frequency value range 2.5–4.5 Hz and amplitude value range 3–7 mm was proven. The magnitudes of amplitude and frequency permitting receives maximum hardness values at optimal values of arc current and the surfacing velocity were obtained.