Mechanical properties and defects in friction stir welded acrylonitrile butadiene styrene polymer

Abstract

In this research work, a butt joint between acrylonitrile butadiene styrene (ABS) sheets was made using Friction stir welding (FSW). Polymers such as ABS have great potential to be used as body parts in automotive industries because of their high strength-to-weight ratio. In the aerospace industry, polymers are preferred over metals as they can retain their properties at low temperatures and their light weight reduces fuel consumption. The objective of this research work was to investigate mechanical properties and defect characterization in weldments. Maximum weld strength achieved was 19.4 MPa which is 61% of the base material at a rotational speed of 224 r/min, travel speed of 50 mm/min, external heating temperature of 45°C, and shoulder diameter of 16 mm. The images of macro and microstructure from an optical microscope and scanning electron microscope, respectively, showed that in FSW of ABS polymer defects were mainly formed on the retreating side of the weld nugget, unlike FSW of metals having it on the advancing side. Only two experiments out of L18 experiments showed tunneling defect, i.e., Experiment no. 8 and Experiment no. 10 and four experiments showed undercutting defect, i.e., Experiment no. 6, 9, 12, and 18. By performing the Vickers microhardness test it was observed that the hardest region formed in and around the weld nugget.