| Vibration welding is a technology through inputting mechanical vibration to improve the overall quality of welded joints in the welding process by vibration and composite effect in welding heat process. Vibration welding can reduce the residual stress of welded joints, refining grain, improving the mechanical properties of joints. While improving the joint quality, it can also shorten production cycle in some extent and reduce production costs but take no additional contamination.Vibration welding can be divided into low-frequency mechanical vibration method, high-frequency ultrasonic vibrations method, electromagnetic stirring and vibration method according to different local oscillator. Ultrasonic vibration electroslag welding is the focus of this study. Using kinetic energy of ultrasonic is instead of mechanical vibration to optimize the properties of electroslag welding joint. Electroslag welding ultrasonic vibration exciter is transformed by ultrasonic impacting eliminate stress implement. The contact of exciter coupled with the surface of welded steel plate at 45°. Ultrasonic which spread in the plate by standing waves, shear waves, surface waves and other different delivery methods will reach the weld pool area to get optimized effect of vibration.In this study, it completes butt welding tests of electroslag welding and different ultrasonic vibration amplitude of electroslag welding tests to 90mm thick plate of Q460E steel to find the relevance of field energy parameters, welding parameters and the quality of joint, which is provided by Baoshan Iron & Steel Co. Ltd. On the basis of the above test, it can establish a new and engineering utility process and specification by the most effective field optimization technology through further experimental research. It completes three different processes and the mechanism analysis of improvement the performance of electroslag welding joint. The feasibility of engineering application is also taken into considered in the items.There are three test parameters that should be taken in to ultrasonic welding and the vibration frequency is 27.6kHz, the ultrasonic transducer according to the amplitude given, respectively,30μm,43μm and 60μm. Taking into account that the effect of ultrasonic associated with the exciter contact distance, it should be focused on the impact properties of heat affected zone at -20℃under conditions of the length of the test plate limited. Therefore, cutting the impact of sampling specimens by the way of dense sampling on the test board, no longer consider the lateral bending test.The test used to measure the welded hardness of the Q10, Q11 and Q12 by the Vickers hardness to observe the influence of ultrasonic vibration parameters and welding parameters to the joint cross-section on hardness distribution.Observed from the hardness distribution map, the hardness of heat-affected zone and weld center increases with growing heat input, due to the difference between heat input. The distance between the hardest part of welding area to the most soft part of parental metal is about 10mm.The area of the hardest part will be wide with the heat increasing but the distribution characteristics are similar. From Statistics of hardness, we can conclude that the hardness of vibration electroslag welding have little to do with modes of vibration and vibration parameters. However, the hardness of the highest and lowest heat input has little correlation. Overall is belonging to discrete distribution.It is showed that:In the conditions of ultrasonic interference, the impact value of welds at -20℃is greater than 27J, achieving the desired requirements. When using a large amplitude (60μm), impact value of heat affected zone which close to the upper area of ultrasonic exciter coupling point is greater than 27J too. Although, the average impact test of majority region is greater than 27J, but there are a group of date (three impact specimens) discrete highly, estimated that concerning with superimposed ultrasonic echo effect "beat" in small-scale rigid body. This stack can cause the amplitude of the double, can also cause times decrease to zero (the formation of vibration, "Pitch"), which may lead to the impact of discrete values. And the reason of the impact decline may be is the amplitude too large.We observed the metallographic organization of weld and heat affected zone from most specimen. Despite the area has a clear choice, when we select the similar geometric position it is difficult to achieve quantitative results because of the complexity of the welding. |
PDF Full Text Request