Abstract: The rapidly solidified butt welding of small diameter bars with size of φ2.5 mm TA2 and 0Cr18Ni9Ti was conducted by a micro-type capacitor discharge welding machine.The joint microstructure and joining mechanism were investigated,and mechanical properties of joint were tested.The results show that the butt welding of TA2 and 0Cr18Ni9Ti bars can be realized by capacitor discharge welding method,the microstructure of the nugget is fine and the features are obviously characterized by rapid solidification.Due to instant welding and the welding process performed is in a split second,the formations of brittle intermetallics TiFe₂ and TiFe were avoided effectively.Micro cracking is the main welding defect,which appears at the side of 0Cr18Ni9Ti and permeats to the centre of nugget.The optimized welding parameters are:welding voltage is 195 V,capacitance is 9 900 μF,and pole pressure is 15 N.At this condition,the tensile strength of joint can reach to 480 MPa.