Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint...
Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6N01 alloy welds. Aluminum alloy plate of 2.0mm in thickness with filler metal bar was welded by twin beam Nd:YAG laser facility (total power:5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 l/min was used. The defocusing distance is kept at 0 mm. At travel speeds of 3 to 9 m/min and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.
Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6N01 alloy welds. Aluminum alloy plate of 2.0mm in thickness with filler metal bar was welded by twin beam Nd:YAG laser facility (total power:5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 l/min was used. The defocusing distance is kept at 0 mm. At travel speeds of 3 to 9 m/min and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.
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가설 설정
1) By increasing travel speed, the width of soft HAZ decreases greatly. Especially when travel speed was 18m/min, the width decreased to about 1/5 of plate thickness.
2) Hardness of weld metal was increased by increasing the content of Cu or Ni in filler metal. Particularly, when Cu and Zr were added to the Al-12Si filler metal, the hardness of weld metal was higher than 120 Hv, though base metal hardness was about HvlOO.
3) The value of DAS decreased greatly by the increase in travel speed. However, the influence of addition of alloying elements has not been confirmed.
제안 방법
To investigate mechanical properties of the specimens, hardness test and tensile test were conducted. To study the metallurgical changes, macrostructures across the welded joint were observed and dendrite arm spacing (DAS) were measured.
To investigate mechanical properties of the specimens, hardness test and tensile test were conducted. To study the metallurgical changes, macrostructures across the welded joint were observed and dendrite arm spacing (DAS) were measured.
대상 데이터
Therefore, it was decided initially to improve the joint strength by hardening the weld metal. Magnesium and silicon containing aluminium alloy A6N01 was used as base metal. It can be easily extruded to form complex cross sections and has good corrosion resistance.
데이터처리
In order to consider the strengthening effect of alloying element in the welded joint, weld bead area was measured from the tracing of weld metal macrostructure. The dilution of the element in the weld metal zone was calculated using computer image analysis. From this result, the average content of alloying elements in weld metal is calculated by assuming uniform dissolution.
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