Weldablity of the Lap Joint between a 5182 Aluminum Alloy and a DP1180 Two-Phase Steel Sheet
- PDF / 2,726,064 Bytes
- 14 Pages / 594 x 792 pts Page_size
- 8 Downloads / 142 Views
WELDABLITY OF THE LAP JOINT BETWEEN A 5182 ALUMINUM ALLOY AND A DP1180 TWO-PHASE STEEL SHEET N. C. Lü,a,1 G. D. Hao,b,2 and Y. T. Wang
UDC 539.4
c,3
The welding process of the lap joint between a 5182 aluminum alloy and a DP1180 two-phase steel sheet (1.2 mm thick) is deeply studied by friction stir welding, defects not revealed, and high-quality welded joints were obtained. The steel plate pressed to 0.2 mm is placed under the aluminum plate. With a large-size friction stir head, the rotational speed was 800 rpm and the welding speed was 50 mm/min, respectively. Many steel particles flaking in the aluminum matrix were distributed in the vicinity of the interface of the weld zone; they were surrounded by a thick layer of an intermetallic compound. This continuous and uniform layer composed of Al4Fe (EDS analysis) was formed at the interface. Keywords: friction stir welding, welded joint, hook defects, intermetallic compound. Introduction. Although the joining format between aluminum and steel is commonly made using butt joints, lap jointa are often applied in automotive industry. Moreover, both types of joint have important practical value in shipbuilding, aviation, petrochemical, vehicle manufacturing and other fields. Aluminum and steel can be easily welded by such welding methods as laser, brazing, MIG, friction stir welding (FSW), etc. [1–5]. Therefire, it is expedient to research lap technology, microstructure and performance of aluminum-steel joint made by FSW. The character of FSW between aluminum and steel lap is as follows: the heat input is small, the performance of the joint is relatively high, the welding process is simple and fast and do not need to add welding materials, while the type of joint is not restricted. Therefore, FSW has been widely concerned by domestic and foreign scholars [6–12]. On account of aluminum-steel dissimilar metals FSW lap in a lot of the previous studies, no defect FSW joints were obtained mostly under the conditions of the high rotation speed, while the joint bonding strength did not exceed 200 MPa. Moreover, the lap interface easily generates too much IMC at high rotation speed. The pre-treatments of steel base metal were performed by many researchers [7–10], for example, the surface of the steel plate was commonly used to galvanizing layer [11] in order to reduce the formation of IMC, on the other hand, the interface of Al-Fe element binding was promoted to increase its bonding strength. The size of the stir tool is a very important process factors in the lap joints,and a smaller size of the stir tool was adopted in previous studies, while it is possible to get better performance of the joints in these cases, but the combined area is too tiny. 1. Optimization of Lap Process Parameters. 1.1. Mixing Head Agitator. In the aluminum-steel FSW lap, metallurgical bonding between aluminum and steel was achieved by a violent agitation of the stirring tool [7–12]. Therefore, the size of the stirring tool in the aluminum-steel FSW is the key process factors, while the diameter and
Data Loading...
