• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.10a
• /
• pp.166-173
• /
• 1996

There are kinds of materials for protective heat shield, i.e.Zn-coated steel, AI-coated steel and aluminum alloy sheets. This study compare formability, corrosion resistance, heat protectability, weight, and cost of these materials for heat protective shield. Generally aluminum alloy sheets are less formable than steel sheets, but A1100 alloy sheet shows almost same press quality of steel parts, using the press dies which producing steel parts. The heat shields using aluminum alloy sheet and steel sheet show almost same heat protectibility. It is the conclusion that Zn-coated merit, and AI-coated steel sheet and aluminum alloy sheet can be used to protect functional corrosion in severely corrosive market area. The material cost of AI-coated steel sheet and aluminum alloy sheet for a mid-size car is almost same, so aluminum alloy sheet is more recommendable in the point of weight reduction of vehicle.

• Journal of Welding and Joining
• /
• v.15 no.4
• /
• pp.42-62
• /
• 1997

Resistance spot welding has been widely used in the sheet metal joining processes because of its high productivity and convenience. Recently, automobile industries are trying to replace partly steel sheets with aluminum alloy sheets. Among currently produced aluminum alloys, Al alloy sheets of Al-Mg-Si(6000 series) are being tested. Especially, 6000 series are the most probable substitute in view of strength and weldability. In this paper, an attempt was made to apply resistance spot welding to joining of dissimilar sheet metals (KS6383+SCPZn or KS6383+SHCP). An effort was made to balance heating rate in the Al alloy with that in the steel sheets by increasing electrode tip diameter. Although resistance spot welding of Al alloy sheet and sheet metals does not produce desirable nugget, it proved to have reasonable strength if optimal weld condition is found by tensile-shear strength and fatigue life test. Since spot weld joints in automobile are always experiencing repeated load, spot welding methodology proposed in this paper is found to be not suitable to automobile body manufacturing.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.6
• /
• pp.64-76
• /
• 1997

This paper deals with development of brackets by using aluminum alloy sheets which is indispensable for weight reduction of autobody. The press formability of aluminum alloy sheet is estimated by means of tensile test, V bending test, sample manufacturing test and photograph of microstructure. The results show that the elongation, strength, work hardening exponent, plastic anisotropy coefficient of Al 6***series are better than those of Al 5***series, but for general press formability, Al 5***series are better than Al 6***series due to lower yield strength. Since most of mechanical properties of aluminum sheet are generally inferior to those of cold-rolled steel sheet, shape fixability and press formability of aluminum sheet are very poor. For making components of autobody by use of die for steel sheet application, it is essential that die should be nodified for least bending and stretching. With the modified die for aluminum, it could be possible to make brackets, the component of autobody. Microstructure of Al 5***series has fine grain and small the 2nd phase and that of Al 6***series has relatively coarse grain. Therefore, it seems that fine grain and small the 2nd phase of Al 5***series is one of the factor of lower yield strength, resistance to stamping work, formation of Luder's line.

• Transactions of Materials Processing
• /
• v.18 no.5
• /
• pp.416-421
• /
• 2009

The applications of the aluminum alloy sheets to the auto-body panels are dramatically increasing for weight reduction of the automobiles. However, low formability of the aluminum alloy sheet compared to the steel sheet can be obstacles in tool manufacturing processes. Therefore, many of yield criteria for the anisotropic materials such as the aluminum alloy sheet have been observed. In this study, the biaxial tensile test and FLD test for the aluminum alloy sheet are performed. The results are compared with Hill's 1948 and Hill's 1990 models by means of theoretical predictions. Finite element analysis was also performed using the proposed method for the real panel.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.164-167
• /
• 2009

The applications of the aluminum alloy sheets to the auto-body panels are dramatically increasing for weight reduction of the automobiles. However, low formability of the aluminum alloy sheet compare to the steel sheet can be obstacles in tool manufacturing process. Therefore, much of yield criteria for the anisotropic material such as the aluminum alloy sheet have been observed. In this study, the biaxial tensile test and FLD test for the aluminum alloy sheet are performed. The results are compared with Hill's 1948 and Hill's 1990 model by means of theoretical predictions. Finite element analysis also performed using the proposed method for the real panel.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.08a
• /
• pp.83-90
• /
• 2004

The drawbead is one of the most important factors in sheet metal forming for automotive parts. So clarifying the friction characteristics between sheets and drawbead is essential to improve the formability of sheet metal. Therefore in this study, drawbead friction test was performed at various panels(cold rolled steel sheets, galvanized steel sheets, electrogalvanized coating steel sheets, electrogalvanized Zn-Fe alloy steel sheets and aluminum alloy steel sheets). Circular shape bead has been used for the test. The results show that friction and drawing characteristics were mainly influenced by the nature of zinc coating.

• Journal of Welding and Joining
• /
• v.19 no.4
• /
• pp.379-383
• /
• 2001

Resistance spot welding has been widely used in the sheet metal joining processes because of low cost, high productivity and convenience. Recently, automobile and aerospace industries are trying to replace partly steel sheets with aluminum alloy sheets. But in the case of dissimilar materials, to apply resistance spot welding has been known to be very difficult owing to the effect of melting temperature. On this study, an effort was made to apply spot welding of dissimilar sheet metals, 2024 aluminum alloy and zinc coated steel sheet, evaluate the spot weld quality with tensile-shear strength test and nondestructive evaluation technique, C-scan image methodology. In this study results, as the current below 11 kA, melting of materials is not achieved well. Also as the current exceeds to 13.5 kA, the more spatters happen at welded zone and tensile-shear strength lowered. So, the feasibility of C-scan image technique proposed in the study is found to be suitable evaluation method for resistance spot weldability.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.401-404
• /
• 2009

The purpose of this study is investigating the joint characteristics of advanced high strength steel DP780 and Al5052 alloy sheet in the clinching process. It is difficult to join the advanced high strength steel with light-weight materials like aluminum alloy, because of low formability of DP780. The defects of clinching joint such as necking of the upper sheet, cracks of the lower sheet and no interlocking were occurred by different ductility between advanced high strength steel and aluminum alloy. The clinching conditions should be optimized to interlock without any defects. In this study, the effect of process parameters of clinching process on joinability of advanced high strength steel with Al5052 alloy was investigated by using FE-analysis. From the result of FE-analysis, the clearance between clinching punch and die, die depth and the shape of die cavity mainly affected the joinability of advanced high strength steel with Al5052 alloy.

• Journal of Welding and Joining
• /
• v.12 no.4
• /
• pp.127-140
• /
• 1994

Resistance spot welding has been widely used in the sheet metal joining processes because of its high productivity and convenience. In the resistance spot welding processes the size of molten nugget is a criterion to assess weld quality. Many research have founded on measuring weld nugget size at the same time monitoring welding process parameters such as dynamic resistance and electrode movement. With increasing demand of energy saving, many efforts were made to employ aluminum alloys that are lighter than steel and have relatively equivalent strength to steel in the automobile industry. In this paper, spot weldability of aluminum alloys for various welding conditions were examined by series of experiments. One of the 6000 series (Mg-Si) aluminum alloy, 6383-T4 was chosen, which is currently considered as a substitute for the galvanized steel. Dynamic resistance, electrode movement and corresponding nugget size were observed and compared to the case of steel. Finally, resistance spot welding of dissimilar material (galvanized steel-aluminum alloy) was attempted.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.2
• /
• pp.74-80
• /
• 1998

An extensive corrosion study was initiated by galvalume steel sheet manufacturing company to clarify the corrosion behavior of zinc and zinc-alloy coated automotive sheet steel in out panel and electrical application. Since the early 1980's the use of zinc and aluminum alloy coated steel for vehicular corrosion protection has increased drastically. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel sheet has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.