Currently, high-speed trains work under various atmospheric environments, and the bogie as a key component suffers serious corrosion. To investigate the corrosion behavior of bogies in industrial atmospheric environments, the periodic immersion wet/dry cyclic corrosion test for SMA490BW steel and automatic metal active gas (MAG) welded joints used for bogies was conducted in the present work. Corrosion weight loss rate, structure, and composition of rust layers as well as electrochemistry parameters were investigated. The results showed that the corrosion weight loss rate decreased with increasing corrosion time; furthermore, the corrosion weight loss rate of the welded joints was lower than that of SMA490BW steel. The XRD results showed that the rust layers formed on SMA490BW steel and its welded joints were mainly composed of α-FeOOH, γ-FeOOH, Fe2O3, and Fe3O4. The observation of surface morphology indicated that the rust layers of the welded joints were much denser and had a much finer microstructure compared with those of SMA490BW steel. After corrosion for 150 h, the corrosion potential of the welded joints with rust layers was higher than that of SMA490BW steel. In short, the welded joints exhibited better corrosion resistance than SMA490BW steel because of the higher content of alloy elements, as shown in this work.

Keywords: plasma-MIG hybrid welding process; residual stress; welding deformation; bogie frame Abstract. The residual stress and welding deformation were measured for the bogie frame steel plate SMA490BW butt joint welded by using the plasma-MIG hybrid welding process and the general MAG welding process respectively, as well as in different groove angle conditions. The results indicate that the plasma-MAG hybrid welding can effectively reduce the residual stress and the welding deformation compared with the classic MAG welding. With the decrease of groove angles, the residual stress and welding deformation reduced accordingly. From the angle of reducing the residual stress and the deformation, the plasma-MAG hybrid welding process should be adopted in the way of narrow groove.

The transfer device is widely used in the industrial production line, and the different production lines have different requirements for the equipment control system. In the paper, a smart transfer device control system based on the S120 and PLC was developed for a production line with two different products, and it can transfer each product in different mode. The system uses the master-slave control mode，which PC is upper computer and the S7-300 PLC is lower computer. The data exchange between PLC and S120 is achieved by Profibus, and the data between PLC and PC is exchanged by Ethernet. The system is equipped with Human Machine Interface, which can meet the requirements of high precision control of the transfer device, and solve the complex problem of multi-parameter control and multi-function control. The result of field debugging verified that the system is stable, easy to operate, and has strong practicability.

Microstructures of SMA490BW weathering steel welded joints are investigated. Tensile tests, impact tests and bending tests of joints were carried out to investigate the mechanical properties from the test temperature of 0°C to-40°C. And the fatigue properties of jonits at-40° C and 0°C are discussed in the article. Fracture surface of impact joints of different temperautre are observed. Well-formed welded joint has been obtained by MIG welding method. There are no cracks and other weld defects are found in the joints. In the temperature range of 0-40 °C, all the tensile specimens are broken at the base metal, and the tensile strength increases with the decreasing temperature. Impact toughness of weld decreases with the decreasing temperature. Fracture mode of base material transforms into quasi-cleavage fracture by the dimple mode at-40°C. Cleavage fracture surface is observed of the weld at the temperature of 0°C and-40°C. Cracks and other surface defects are not found in the bending test of the weld at the temperature of-40°C.