Trend of Metal 3D Printing by WeldingJae-Gyu Byun* and Sang-Myung Cho** , † *Dept. of Materials System Engineering, Graduate School, Pukyong National University, Busan 48513, Korea **Dept. of Materials System Engineering, Pukyong National University, Busan 48513, Korea † Corresponding author : pnwcho@pknu.ac.kr (Received June 14, 2016 ; Revised July 13, 2016 ; Accepted July 29, 2016) AbstractMetal AM(Additive Manufacturing) has been steadily developed and that is classified into two method. PBF(Powder Bed Fusion) deposited in the bed by the laser or electron beam as a heat source of the powder material and DED(Directed Energy Deposition) deposited by varied heat source of powder and solid filler material. In the developed countries has been applying high productivity process of solid filler metal based DED method to the aerospace and defense sectors. The price of the powder material is quite expensive compared to the solid filler metal. A study on DED method that is based on a solid filler metal is increasing significantly although was low accuracy and degree of freedom.

Recently, with automobile body weight reduction trend, aluminium alloy sheets are introduced to automotive moving parts such as hood, trunk, and tailgate. Researches about joining technologies on aluminium alloy sheet are necessary. However aluminium alloy has many troubles with spot weldability. In this study, we evaluate effects of electrode face radius and electrode force on weldability of resistance spot welding of aluminium alloy 6061. The two electrode face radius conditions showed the same acceptable welding current rage to produce acceptable spot welding quality. However, high electrode force showed larger welding current process window than low electrode force in resistance spot welding of aluminium alloy 6061

Recent developing tendency of nuclear power plant are studied by searching of NDSL, KIPRIS, Science Direct and so on. Welding materials such as low alloyed steels, stainless steels, nickel-based alloys, zirconium alloy and welding methods such as narrow gap welding, laser beam welding, friction stir welding, overlay welding are investigated.

Aluminium alloy sheets are being utilized in automotive parts such as hood, trunk, and tailgate. However, the spot welding of aluminium alloy has many problems, such as electrode sticking and expulsion, and therefore research on the resistance spot welding of aluminium alloy sheets is necessary. In this study, we evaluated the effects of electrode face thickness on the resistance spot weldability of aluminium alloy 6061. The two electrode face thickness conditions were compared, and the electrode face thickness was determined to be an important process variable that affected the spot weldability of aluminium alloy 6061.

In this study, the welding quality prediction model with high reliability was developed for the 980 MPa grade TRIP steel with minimum conditions in resistance spot welding process using response surface methodology. The welding time and welding current were selected as the important parameters. The welding quality was predicted by deriving four parameters including tensile shear strength, nugget size, expulsion, and button fracture. The experiment was carried out by using the central composite design. Then, the regression equation derived using the result data was analyzed and the effect of the independent variable on the objective function was analyzed by ANOVA. The welding time had a very small effect on tensile shear strength and nugget, but welding current had a dominant effect on the two properties. Also, the reliability of the derived regression model equation is verified by R correlation coefficient and experiments.