To optimize the plating process is necessary to know the behavior of surfaces plated during the exploitation and in particular susceptibility to cracking, the formation of cracks from the inside to outside or reverse, embrittlement in the heat affected zone. Research has been realized considering several samples plated by welding without ultrasonic activation and with ultrasonic activation, and these samples were made of AISI 4130 steel, and as filler material was used Inconel 625 Fe developed as electrode wire ø 1,2 / mm. The plating process was realized by a WIG welding process in Ar100 /% environment with non-consumable tungsten electrode, in two versions, respectively with and without the use of ultrasonic energy. Four pieces played by welding there were analyzed the metallographies structure in the base material, the deposited material and the material from the heat affected zone

D. Dobrotă

Gh. Amza

R. G. Albulescu

V. Petrescu

Z. Apostolescu

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Influence of use of ultrasound on metallographic structure of plated pieces by welding in ultrasonic field

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523METALURGIJA 54 (2015) 3, 523-526GH. AMZA, D. DOBROTĂ, V. PETRESCU,  Z. APOSTOLESCU, R.G. ALBULESCUINFLUENCE OF USE OF ULTRASOUND ON METALLOGRAPHIC STRUCTURE OF PLATED PIECES BY WELDING IN ULTRASONIC FIELD Received – Primljeno: 2014-08-08Accepted – Prihvaćeno: 2015-01-10Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 54(3) 523-526 (2015)UDC – UDK 621-41:621.791.052:534-8:620.17=111Gh. Amza, Z. Apostolescu, Faculty of Engineering and Management of Technological, Polytehnic University of Bucharest, RomaniaD. Dobrotă,  Engineering Faculty, “Constantin Brâncuşi” University of Târgu-Jiu, RomaniaV. Petrescu, Engineering Faculty, Lucian Blaga University of Sibiu, RomaniaR.G. Albulescu, The Oil Company, Ploiesti, RomaniaTo optimize the plating process is necessary to know the behavior of surfaces plated during the exploitation and in particular susceptibility to cracking, the formation of cracks from the inside to outside or reverse, embrittlement in the heat affected zone. Research has been realized considering several samples plated by welding without ultra-sonic activation and with ultrasonic activation, and these samples were made of AISI 4130 steel, and as filler mate-rial was used Inconel 625 Fe developed as electrode wire ø 1,2 / mm. The plating process was realized by a WIG welding process in Ar100 /% environment with non-consumable tungsten electrode, in two versions, respectively with and without the use of ultrasonic energy. Four pieces played by welding there were analyzed the metallogra-phies structure in the base material, the deposited material and the material from the heat affected zone.Key words: plating by welding, ultrasonic energy, metallographic structure, porosityINTRODUCTIONUsing a complex system of plating by welding with ultrasonic activation, the pieces can be plated with a uniform layer in comparison with a conventional sys-tem of plating by welding [1]. There are several tech-niques for plating pieces, but plating by welding in ul-trasonic field is expected to replace other techniques with very good results. This should be taken into con-sideration the relationship between energy density and the ultrasonic energy input mode [2]. Plating is realized in optimal conditions if the material deposited by weld-ing with the base material forms a couple with a far bet-ter behavior in exploitation than if the piece would be made of only the base material or only the filler mate-rial which is usually very expensive, and the pieces must entirely correspond to the functional role they be-long. To explain and optimize the plating by welding process is necessary to know the behavior of plated sur-face during exploitation, behavior given by tensile strength, yield strength, resistance to dynamic loads, susceptible to cracking, the formation of cracks from the inside to outside or inverse, embrittlement in the heat affected zone [3]. When plating by welding of the pieces it should be considered the fact that heat cycle, which is obey to the base material and the filler material (heating - melting - cooling - solidification) cause changes in chemical composition due to the phenomenon of dilution and changes in functional and technological properties, due to changes of structure in three distinct areas around the boundary (base material, heat affected zone and filler material) [4].Plating pieces by welding in ultrasonic field in-volves the following process steps: initial control of plated piece, produced by forging, casting or welding; surface preparation on which is not deposited filler ma-terial; surface preparation on which is plated by weld-ing; marking and / or protecting the surface on which is not deposited filler material; preheating surfaces; plat-ing itself; checking the characteristics of the layer / lay-ers deposited; processing to final dimensions required by the functional role; thermal treatment post welding and final control. A quality  palting by welding is char-acterized by: high resistance to corrosion and / or wear, low roughness, high adhesion between the deposited and base material, low porosity [5].MATERIALSPlating the surfaces with a layer of filler material to provide high resistance to corrosion and / or wear, should be realized  so that the thickness of a plating lay-er does not exceed the thickness of 3 – 4,2 / mm. In or-der to determine the optimum technological plating there were plated pieces using different parameters for the plating process presented in Table 1 or Table 2. Plat-ed was performed using a couple of the base material, namely AISI 4130 steel and filler material Inconel 625 Fe developed as electrode wire ø 1,2 / mm.524GH. AMZA et al.: INFLUENCE OF USE OF ULTRASOUND ON METALLOGRAPHIC STRUCTURE OF PLATED PIECES... METALURGIJA 54 (2015) 3, 523-526RESULTS AND DISCUSSIONSTo highlight these properties of plated pieces it was released a metallographies analysis of  samples pro-cessed in all eight samples plated without ultrasonic ac-tivation in ultrasonic field. Figure 1 shows the basic structure of the base material at plating by welding with ultrasonic activation (Figure 1, a) and playing in an ul-trasonic field (Figure 1, b) for sample 1u (amplitude 38,9 μm,  frequency 33 867 / Hz) sample 2u (Figure 1, Table 1 The values  of parameters of welding regime in Ar 100 / % environment by deposition a single layer without ultrasonic activationNo. Sample Parameters of welding regimeUa  / V Is / A Vs / cm/min El / KJ/cm Wire type Gas values / l/min1 Sample 1 11,9 320 52,3 7,30 Cold wireØ 1,2 mm1513,1 280 52 7,40 14,512,5 270 46,5 6,45 14,92 Sample 2 14,3 229 48,2 6,79 Cold wireØ 1,2 mm15,515,6 246 50,6 7,58 14,816,4 285 53,5 8,73 15,03 Sample 3 15,4 252 45,2 8,58 Cold wireØ 1.2 mm15,016,8 272 47,8 9,55 14,917,2 310 49,6 10,75 14,84 Sample 4 20,1 180 38,5 9,39 Cold wireØ 1,2 mm14,621,6 210 42,3 10,72 14,522,3 240 45,7 11,71 15,0Table 2  The values of parameters of welding regime adn ultrasonic activation at plating by WIG welding in Ar 100 / % environment by deposition of a single layer with ultrasonic activationNo. Sample Parameters of welding regime Parameters of ultrasonic fi eldUa / V Is / A Vs / cm/min El  / J/cm Ia / W/cm2 F / kHz Al / mm Wave type ar / μm1 Sample 1u 11,9 320 52,3 7,30 7,8 15 38,9 longitudinal and radial17,613,1 280 52 7,40 9,6 14,5 57,5 23,212,5 270 46,5 6,45 12,3 14,9 58,8 24,52 Sample 2u14,3 229 48,2 6,79 6,5 15,5 53,2 longitudinal and radial25,615,6 246 50,6 7,58 8,9 14,8 62,7 25,216,4 285 53,5 8,73 11,7 15,0 52,5 54,83 Sample 3u15,4 252 45,2 8,58 10,9 15,0 35,7 longitudinal and radial21,116,8 272 47,8 9,55 13,7 14,9 39,9 22,217,2 310 49,6 10,75 15,8 14,8 38,2 23,54 Sample 4u20,1 180 38,5 9,39 9,6 14,6 46,8 longitudinal and radial28,921,6 210 42,3 10,72 14,8 14,5 69,7 30,222,3 240 45,7 11,71 16,3 15,0 70,5 32,7c) conditions: amplitude 62,7 / μm and frequency 38 204 / Hz and 4u sample (Figure 1, d) conditions: ampli-tude 70,5 / μm and frequency 35 797 / Hz. It is found that as the amplitude increases, the crumbling of struc-ture is becoming more pronounced, the grains become smaller. Figure 2 shows the structure of the filler mate-rial at plating by welding without ultrasonic activation (Figure 2, a) and playing in an ultrasonic field 1u sam-ple (Figure 2, b) conditions: amplitude 38,9 / μm and frequency 33 867 / Hz, 2u sample (Figure 2 c), under  a b c dFigure 1  Structure of base material (AISI 4130): a – in case of plating by welding without ultrasonic activation; b – in case of plating by welding in ultrasonic field, in conditions: f = 33 867 / Hz, A=38,9 / μm, Is=320 / A, vs=52,3 / cm/min; c - in case of plating in ultrasonic field, in conditions: f = 38 204 / Hz, A=62,7 / μm, Is=240 / A, vs=50,6 / cm/min; d – in case of plating in ultrasonic field, in conditions: f = 35 797 / Hz, A=70,5 μm, Is=240 / A, vs=45,7 / cm/min; zoom 200x525GH. AMZA et al.: INFLUENCE OF USE OF ULTRASOUND ON METALLOGRAPHIC STRUCTURE OF PLATED PIECES...METALURGIJA 54 (2015) 3, 523-526the conditions: 62,7 amplitude / μm and frequency 38 204 / Hz and 4u sample (Figure 2 d) in the following conditions: amplitude 70,5  / μm and frequency  35 797 / Hz. Similarly, it is found that the amplitude increases and it works in resonance system, the fragmentation of the structure is becoming more and more pronounced and it is obtained a fine grain structure with equidistant grains with great technological and functional proper-ties. Most spectacular results are obtained in the heat affected zone (Figure 3) where we can see the action of ultrasonic waves during the solidification process, hav-ing an essential contribution in obtaining a structure with equiaxed grains for more than 80 / % and the re-maining 20 /  % are small grains but disorderly placed depending on how the solidification front goes ahead.In case of plating by welding without ultrasonic ac-tivation, carbides occur between grain boundary and, especially in the martensite matrix, in the case of  ultra-sonic activation where the possibility of occurrence of rough carbides in the heat affected zone is getting smaller and there are situations when they were finely dispersed in the two materials of the couple along the demarcation line (Figure 3 d). It is found that the best results are obtained when operating under a resonance regime, maximum amplitude and vibration mode is closest to the resonance frequency, for it has been calcu-lated the ultrasonic system. Fine grain structure ob- a b c dFigure 2  Structure of filler material (Inconel 625 Fe): a – in case of plating by welding without ultrasonic activation; b – - in case of plating in ultrasonic field, in conditions: f = 33 867 / Hz, A=38,9 / μm, Is=320 / A, vs=52,3 / cm/min; c - in case of plating in ultrasonic field, in conditions: f = 38204 / Hz, A=62,7 / μm, Is=240 / A, vs=50,6 / cm/min; d – - in case of plating in ultrasonic field, in conditions: f = 35 797 / Hz, A=70,5 / μm, Is=240 / A, vs=45,7 / cm/min; zoom 200x; attach 5ml H2SO4 + 3mlHNO3 + 92ml HClFigure 3   Structure of materials in heat affected area: a – at plating by welding without ultrasonic activation; b – at plating by welding in ultrasonic field, in conditions: f = 33 867 / Hz; A=38,9 / μm; Is=320 / A; vs=52,3 / cm/min; c - at plating by welding in ultrasonic field, in conditions: f = 38 204 / Hz; A=62,7 / μm; Is=240 / A; vs=50,6 / cm/min; d – at plating by welding in ultrasonic field, in conditions: f = 35 797 / Hz; A=70,5 / μm; Is=240 / A; vs=45,7 / cm/min; zoom 200x; attach 5ml H2SO4 + 3mlHNO3 + 92ml HCl a b c dFigure 4   The formation of carbides: a - at plating by welding without ultrasonic action; b - at plating by welding in the ultrasonic field in conditions: f = 33 867 / Hz, A = 38,9 / μm; Is = 320 / A vs = 52,3 / cm / min; c - in the case of plating in the ultrasonic field in conditions: f = 38 204 / Hz, A = 62,7 /  μm; Is = 240 / A; vs = 50,6 / cm / min; d - in case of plating in ultrasonic field, in conditions: f = 35 797 / Hz, A = 70,5 /  μm; Is = 240 / A; vs = 45,7 / cm / min; zoom 200x; attach Nital 2 / %526GH. AMZA et al.: INFLUENCE OF USE OF ULTRASOUND ON METALLOGRAPHIC STRUCTURE OF PLATED PIECES... METALURGIJA 54 (2015) 3, 523-526tained in the heat-affected zone under the action of ul-trasound explain the properties of the area which means less hardness, good tenacity, no embrittlement and ab-sence of cracking tendency.Method of forming of carbides in the martensite ma-trix of the grain boundary shown in Figure 4, where it can be seen very well their arrangement at the limit of grains under the action of ultrasonic waves. Compres-sion action - extent at propagation of ultrasonic waves in the solidification leads to fragmentation and dispersal carbide grains, depending on the ultrasonic frequency and amplitude of vibration and the nature of ultrasonic waves introduced into welding bath.An important problem that has been pursued was that of possible defects that may occur in plating by the welding process. As shown in Figure 5 a, the plating by welding without ultrasonic activation may occur a lot of porosities, in particular in the heat affected zone and  in the filler material, which may be dangerous because they can become areas which accumulates hydrogen atomic leading to the appearance of microcracks and even cracks, or which accumulate sulfide hydrogen leading to a decrease in the corrosion resistance. When planting in an ultrasonic field (Figure 5, b) porosities disappear almost completely and from the heat affected zone and deposited layer and this is possible because the extensive phenomenon appears - compression that is subject the welding bath under the action of ultra-sound, allowing the removal of porosities to the surface of the deposited layer.In Figure 6 we see a large number of porosities, and in case of depositing the second layer of filler material, especially in the first layer in contrast with the plating by welding in the ultrasonic field (Figure 7) where the porosities almost completely disappear near the demar-cation line between base material - layer 1 of filler ma-terial and some porosities remain attached to the demar-cation line between layer 1 - layer 2, probably due to improper cleaning after deposition of layer 1 of filler material.CONCLUSIONS– the action of ultrasounds at a tension -compression in the solidification process leads to fragmentation of the carbide grains and their dissipation according to ultrasound frequency and vibration amplitude but also according to the nature of ultrasonic waves in-troduced into welding bath;– at plating in ultrasonic field, defects of porosity type disappeared completely and the cracking tendencies are no longer manifest in the demarcation line be-tween filler material - base material.REFRENCES[1]  Gh. Amza, D. Dobrotă, Metalurgija, 52 (2013) 1, 83-86. [2]  D. Dobrotă, Gh. Amza, Metalurgija, 52 (2013) 1, 87-89. [3] R. Kažys, A. Voleišis, B. Voleišienė, Ultragarsas (Ultra-sound), 63 (2008) 2, 7-17.[4]   A. Siddiq, E. Ghassemieh, Mechanics of Materials, 40 (2008) 12, 982-1000.[5]  Shin-ichi Matsuoka, Hisashi Imai, Journal of Materials Processing Technology, 209 (2009) 2, 954-960.Note:  The responsible translator for English language is S.C. PURTRAD S.R.L., Targu Jiu, Romania  a bFigure 5  Appearance of porosities in case of plating by welding: a – at welding without ultrasonic activation; b – at welding in ultrasonic field, in conditions:  f = 35 797 / Hz; A = 70,5 / μm; Is = 240 / A; vs=45,7 / cm/min; zoom 100x, attach Nital 2%Figure 6  Appearance of porosities at plating by welding without ultrasonic activation and deposition of two layersFigure 7  Appearance of porosities in a piece plated by welding in ultrasonic field, in conditions: f = 35 797 / Hz; A = 70,5 / μm; Is = 240 / A; vs = 45,7 / cm/min

Influence of use of ultrasound on metallographic structure of plated pieces by welding in ultrasonic field

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