'SPOT FRICTION WELDBONDING' FOR SHEET ALUMINUM JOINING--Paper 17

摘要

Spot friction welding (SFW), a novel variant of the "linear" friction stir welding (FSW) process without transverse movement, creates a strong, spot lap-weld without bulk melting. This paper studies the feasibility of SFW with adhesive, also called "spot friction weld-bonding". Aluminum 6111-T4 coupons, 25 mm x 100 mm with two different thicknesses, 0.9 mm and 1.0 mm, were used for producing SFW specimens in a lap-shear configuration with and without an one-component (heat curing) structural epoxy adhesive. Lap-shear strength was determined for samples with un-cured and cured adhesive. The strengths of joints with uncured adhesive, with measurable strength at the shortest joining time (0.6 sec), was 0.88 kN lap-shear load to failure. Strength increased with longer joining time. The maximum load to failure value of samples with uncured adhesive was 2.1 kN with a joining time of 1.1 sec. Maximum load to failure value of samples without adhesive was 3.0 kN with a 1.0 sec joining time. Comparison of the strength of the sample with uncured adhesive to the sample with no adhesive shows a lower value, however, the strength is higher than Japanese Industrial Standard (JIS) and comparable to resistance spot welded joints and self-piercing riveted joints without adhesive. Cured spot friction weldbonding samples had lap-shear load to failure exceeding 7 kN, which is equivalent to the aluminum coupon strength with the same thickness and width. Light micrographs and scanning electron micrographs confirmed the adhesive had been completely expelled or squeezed-out of the joint during the joining process at an early stage (0.6 sec). For this study, even without process optimization in this study to achieve the highest strength, the feasibility of spot friction weld-bonding was successfully demonstrated.