First Welding CompanyFrantisek Kolenic1 Electron Beam Welding of Die- Cast Aluminum Alloy components for Automotive Industry by Frantisek KOLENIC by Frantisek KOLENIC First Welding Company, Bratislava First Welding Company, Bratislava Slovak Republic

First Welding CompanyFrantisek Kolenic2 Content of the presentation 1. Introduction of the First Welding Company 1. Introduction of the First Welding Company 2. Analysis of the welding problem 2. Analysis of the welding problem 3. Requirements for welded joint 3. Requirements for welded joint 4. Selection of welding method 4. Selection of welding method 5. Welding technology 5. Welding technology 6. Welding equipments for mass production 6. Welding equipments for mass production 7. EB welding of heat exchangers for trucks 7. EB welding of heat exchangers for trucks Conclusions Conclusions

First Welding CompanyFrantisek Kolenic3 PRVÁ ZVÁRAČSKÁ, a.s. (First Welding Company, Inc.) Type of company: Research, Production, Consultancy, SME. Type of company: Research, Production, Consultancy, SME. Founded in Founded in Number of employees: 86. Number of employees: 86. Main activities: R&D – laser, electron beam and plasma welding and allied technologies for industrial use, High production arc welding technologies. R&D – laser, electron beam and plasma welding and allied technologies for industrial use, High production arc welding technologies. Products – Electron beam welding equipment, Single-purpose welding equipment, Vibration equipment for residual stress reduction, Development of the welding technologies. Products – Electron beam welding equipment, Single-purpose welding equipment, Vibration equipment for residual stress reduction, Development of the welding technologies. Services - Electron beam welding and surfacing, Laser processing of materials (welding, quenching, cutting, surfacing), Plasma cutting, Soldering. Services - Electron beam welding and surfacing, Laser processing of materials (welding, quenching, cutting, surfacing), Plasma cutting, Soldering. Comprehensive services in repair of power engineering parts. Comprehensive services in repair of power engineering parts. Expertise activities – in the field of welding technologies, welded constructions. Expertise activities – in the field of welding technologies, welded constructions. Certification – personnel in welding and NDT. Certification – personnel in welding and NDT.

First Welding Company Frantisek Kolenic 4 Introduction Welding of die-cast aluminum alloy components is a complex problem. Welding of die-cast aluminum alloy components is a complex problem. In industrial praxis we can find sufficient demands for such welding. In industrial praxis we can find sufficient demands for such welding. One of the examples are heat exchangers of independent heating and cooling of passenger’s cars and trucks. One of the examples are heat exchangers of independent heating and cooling of passenger’s cars and trucks. Due to the complicated shape of the main body they can not be dye casted in one step. Due to the complicated shape of the main body they can not be dye casted in one step. They usually consist of two or more die-casted parts which must be tightly connected by welding. They usually consist of two or more die-casted parts which must be tightly connected by welding.

First Welding CompanyFrantisek Kolenic5 Analysis of the problem Problems of welding of dye casted aluminum alloys by high energy density sources may be in general characterized by the following way: Problems of welding of dye casted aluminum alloys by high energy density sources may be in general characterized by the following way: Occurrence of surface layer of aluminium oxide, Occurrence of surface layer of aluminium oxide, high thermal conductivity of parent metal, high thermal conductivity of parent metal, high thermal expansivity coefficient, high thermal expansivity coefficient, wide interval of alloy solidification, wide interval of alloy solidification, hydrogen content in alloy. hydrogen content in alloy.

First Welding CompanyFrantisek Kolenic6 Requirements for welded joint Smooth surface formation of the weld bead without excess over the welded surface and fall-through below this surface down to 0.2 mm, Smooth surface formation of the weld bead without excess over the welded surface and fall-through below this surface down to 0.2 mm, minimum 2 mm penetration depth, minimum 2 mm penetration depth, vacuum tight joint with minimum porosity, vacuum tight joint with minimum porosity, less than 0.2 % spoiled welds. less than 0.2 % spoiled welds.

First Welding CompanyFrantisek Kolenic7 Entry conditions Positive Positive The aluminium alloy AlSi10 with conventional 10 % Si and other admixtures on max. 0.5 % level with total Al 88.6 % content represents a typical alloy for die casting. It is characterised especially by very good penetration, tightness and resistance to hot crack formation. From the viewpoint of weldability higher Si content in the alloy is favourable especially if filler metal is not used. The aluminium alloy AlSi10 with conventional 10 % Si and other admixtures on max. 0.5 % level with total Al 88.6 % content represents a typical alloy for die casting. It is characterised especially by very good penetration, tightness and resistance to hot crack formation. From the viewpoint of weldability higher Si content in the alloy is favourable especially if filler metal is not used.

First Welding CompanyFrantisek Kolenic8 Entry conditions Negative: Negative: Different width of welding gap (0-0,8 mm), Different width of welding gap (0-0,8 mm), cleaning is done only by washing in ecological solutions which do not assure perfect purity of weld edges and the weld edges are not otherwise cleaned either mechanically or electrolytically, cleaning is done only by washing in ecological solutions which do not assure perfect purity of weld edges and the weld edges are not otherwise cleaned either mechanically or electrolytically, surface layer of aluminium oxides, which is formed immediately at contact with the air exhibits porous character and hence it can contain water vapours from the air. If it is not removed it can induce especially pore and crack formation in the weld, surface layer of aluminium oxides, which is formed immediately at contact with the air exhibits porous character and hence it can contain water vapours from the air. If it is not removed it can induce especially pore and crack formation in the weld, the time between production of weldments and the time of welding differs from 1 day up to 10 weeks, the time between production of weldments and the time of welding differs from 1 day up to 10 weeks, in some castings pores and other defects are present near the weld edge. Those can be opened during welding. in some castings pores and other defects are present near the weld edge. Those can be opened during welding.

First Welding CompanyFrantisek Kolenic9 Selection of welding method LaserElectron beam Welding equipmentCO 2 laser – fast axial flow 5 kW – Mod TEMoo EB machine VUZ EZ kW Welding power kW3,20,75 – 1,4 Accelerating voltage kV42 Welding current mA10 up to 32 Welding speed mm.s up to 60 Rotary beam motion Ø mm 0,2 Frequency kHz7,5 Focus1 mm below the surfaceOn the surface Active gas and its pressure Pa Ar Number of passes1 up to 4

First Welding CompanyFrantisek Kolenic10 Examination of the weld properties The examination of the weld properties have been done as follows: The examination of the weld properties have been done as follows: - the specimens were cut by cross cuts (2 cuts from each weld) on which the structure was examined metallographically, - the specimens were cut by cross cuts (2 cuts from each weld) on which the structure was examined metallographically, - the specimens 10 mm in length have been cut along the central axis of the weld. The number and size of pores was analysed on prepared surfaces at 20 fold magnification. The number and size of pores was studied in dependence on welding speed and the number of passes for laser beam and electron beam welding processes. - the specimens 10 mm in length have been cut along the central axis of the weld. The number and size of pores was analysed on prepared surfaces at 20 fold magnification. The number and size of pores was studied in dependence on welding speed and the number of passes for laser beam and electron beam welding processes. - micro cracks were studied on macro etches metallographically. - micro cracks were studied on macro etches metallographically.

First Welding CompanyFrantisek Kolenic11 Experimental Results-Laser Welding macrographs The first run The second run The third run The fourth run

First Welding CompanyFrantisek Kolenic12 Experimental Results-EB Welding macrographs The first run The second run The third run The fourth run

First Welding CompanyFrantisek Kolenic13 Experimental Results-Laser Welding

First Welding Company Experimental Results-EB Welding macrographs.14 Weld bead formation using electron beam technology

First Welding CompanyFrantisek Kolenic15 Results of the experiments The results have proved that the size and number of pores in laser beam welding is in principle higher than in electron beam welding. The results have proved that the size and number of pores in laser beam welding is in principle higher than in electron beam welding. In laser beam welding the number and size of pores only little changes with welding speed and with the number of passes. It seems that the smaller pores only agglomerate into larger pores with increasing number of passes. In laser beam welding the number and size of pores only little changes with welding speed and with the number of passes. It seems that the smaller pores only agglomerate into larger pores with increasing number of passes. In electron beam welding on the contrary to laser beam welding the susceptibility to pore formation is expressively decreased with increasing number of passes. Pore formation is eliminated at three - four passes. In electron beam welding on the contrary to laser beam welding the susceptibility to pore formation is expressively decreased with increasing number of passes. Pore formation is eliminated at three - four passes. The results have clearly proved better suitability of electron beam welding. The results have clearly proved better suitability of electron beam welding. This might be due to vacuum where the escape of gases from the weld is supported by low pressure. On the contrary in laser beam welding the pressure of shielding gas on the surface of weld pool acts contrarily whereas also the humidity of the atmosphere can enhance pore formation. This might be due to vacuum where the escape of gases from the weld is supported by low pressure. On the contrary in laser beam welding the pressure of shielding gas on the surface of weld pool acts contrarily whereas also the humidity of the atmosphere can enhance pore formation.

First Welding CompanyFrantisek Kolenic16 Welding Equipments for Mass Production For mass production welding of aluminium heat exchangers two single-purpose welding have been developed. For mass production welding of aluminium heat exchangers two single-purpose welding have been developed. Both equipments consist of the same welding source, electron beam gun and auxiliary sources with the following characteristics: Both equipments consist of the same welding source, electron beam gun and auxiliary sources with the following characteristics: Accelerating voltage30 – 60 kV Accelerating voltage30 – 60 kV Max. power6 kW Max. power6 kW Ripple of acc. Voltage± 1,5 % Ripple of acc. Voltage± 1,5 % Max. deflection of the beam± 7° Max. deflection of the beam± 7° Beam oscilation frequency0 – 10 kHz Beam oscilation frequency0 – 10 kHz Electron beam guntriode with LaB6 cathode Electron beam guntriode with LaB6 cathode

First Welding Company Frantisek Kolenic.17 High Production Electron Beam Welding Machine EB ZH-2

First Welding CompanyFrantisek Kolenic18 High Production Electron Beam Welding Machine EB ZH-2

First Welding CompanyFrantisek Kolenic19 Conclusions In the selection process of welding technology laser and electron beam welding processes were verified. From the viewpoint of porosity and bead formation electron beam welding has unambiguously been proved as more convenient. In the selection process of welding technology laser and electron beam welding processes were verified. From the viewpoint of porosity and bead formation electron beam welding has unambiguously been proved as more convenient. In service of welding equipments with two concepts of handling of weldments the concept at which the weldments are transferred from the magazine chambers in the welding chamber with the whole magazine in the number of 8 pcs has been proved as more convenient. In service of welding equipments with two concepts of handling of weldments the concept at which the weldments are transferred from the magazine chambers in the welding chamber with the whole magazine in the number of 8 pcs has been proved as more convenient. Vacuum-tight welded joints without inhomogeneities were fabricated by employing electron beam welding with the technique of multiple passes of electron beam welding. Different welding parameters were applied for individual passes assuring the full penetration of welded joint. Vacuum-tight welded joints without inhomogeneities were fabricated by employing electron beam welding with the technique of multiple passes of electron beam welding. Different welding parameters were applied for individual passes assuring the full penetration of welded joint. The last pass of the beam was destined for achieving a uniform surface formation of the weld bead. The last pass of the beam was destined for achieving a uniform surface formation of the weld bead.