mohammadreza khanzadeh

This study investigates the corrosion behavior and microstructural changes of Cu/Al/Cu three-layer tubes after post-weld heat treatment in the explosive welding process. The heat treatment was performed by varying the temperature. Polarization tests and electrochemical impedance spectroscopy were employed to examine the corrosion behavior of the weld zone. Additionally, metallographic examination using optical microscopy (OM) and scanning electron microscopy (SEM) was conducted to study the microstructure. The electrochemical impedance spectroscopy results showed that the value of “n” in the heat-treated sample at 300°C and explosion load of 2.8 had a lower value compared to the heat-treated sample at 300°C and explosion load of 3.2, indicating higher corrosion current in the heat-treated sample at 300°C and explosion load of 2.8, leading to a decrease in charge transfer resistance. By comparing the heat-treated samples at 300°C and explosion load of 2.8 with the ones heat-treated at 400°C and explosion load of 2.8, with variable annealing temperature and constant annealing time, the sample heat-treated at 400°C exhibited a higher value of n (0.77), while the heat-treated sample at 300°C and explosion load of 2.8 had a lower value of n (0.69), attributed to the increase in annealing temperature and the decrease in stored energy in the joint.

In the present study, the effect of thermal treatment on the corrosion behavior and microstructure changes of two-layer stainless-304-Cu sheet steel sheets after the explosive welding process has been investigated. Explosive welding has been done in parallel with an explosive layer of 46 and 63 µm and a stop distance of 2-3 mm. After explosive welding, the heat treatment process was carried out at 350 and 450 ° C for 8 and 16 hours. Explosive welding with an explosive load and variable stop distance. From the results of the electrochemical impedance test, it can be seen that the n number in the heat treatment sample at 350 ° C and 8 hours is less than the heat treatment sample at 450 ° C and 8 hours, and as a result, the corrosion current in the heat treatment sample The temperature is 350 ° C and the time is 8 hours, which reduces the load transfer resistance. By comparing the heat treatment samples at 350 ° C and 8 hours and the heat treatment at 450 ° C and the time of 8 hours with varying aniline temperature, the annealing time is constant and the heat treatment sample at 450 ° C and time 8 The hour with more annealing temperature has a value of n (0.80), followed by heat treatment at 350 ° C and 8 hours (n = 0.66), due to annealing temperature and reduced energy storage In the chapter.

In this study, the corrosion behavior and microstructural variations of two-layer sheets consisting of 304 stainless steel copper have been investigated after the explosive welding process. Explosive welding is carried out by variable explosive charges and changing the distance between the sheets. To investigate the corrosion behavior of the welding zone, dynamic potential polarization and electrochemical impedance imaging were used. Besides, to perform microstructural analysis, metallographic tests using an optical microscope and scanning electron microscope (SEM) were employed. In addition, micro-hardness is considered to investigate the effect of shock waves caused by the explosion. The results showed that the sample with an explosive thickness of 79 mm has the highest interface hardness (HV 549) due to the high thickness of the explosive layer and standoff distance (3 mm). Also, the polarization test results indicated that the lowest corrosion rate corresponds to the sample with an explosive charge thickness of 79 mm and a standoff distance of 2 mm, and the highest corrosion rate was related to the sample with a 46-mm explosive charge thickness and standoff distance of 3 mm. Based on the results obtained from the electrochemical impedance spectroscopy, It can be concluded that by increasing the amount of copper in the locally frozen melt of the samples, the intensity of corrosion caused by the galvanic cell increases.

In the present study, the corrosion behavior and microstructural changes of 5000 series aluminum and copper sheets after the explosive welding process have been investigated. Explosive welding is performed with a fixed stop interval and change of explosive load. Dynamic potential polarization tests and electrochemical impedance spectroscopy, light microscopy, and scanning electron microscopy were used. The results of TOEFL polarization curves show that the lowest corrosion velocity was related to the sample with an explosive load of 1.5 and the highest corrosion velocity was related to the sample with an explosive load of 2.5. The corrosion resistance of a sample with an explosive load of 2.5 is less than that of a sample with an explosive load of 1.5 due to more severe plastic deformation at the joint. The metallographic results show a wave-vortexing of the joint due to the increase in the explosive charge. The results of the impedance test in welded samples showed that the value of n (experimental power parameter) decreased with wave-vortexing of the joint and the sample with 2.5 explosive load had the highest corrosion rate. Based on the results of scanning electron microscopy, it was observed that with an increasing explosive charge, the thickness of the local melting layer gradually increases.

In this research, continius cooling behavior of 1.2304 cold work tool steel was investigated by dilatometry tests. All samples heat treated in vacuum furnace, then quenched with nitrogen gas in different cooling rates. The results showed that ferrite - perlite, bainite and martensite phase transformatios occurred in 596-713 °C, 360-468 °C,253-268 °C, respectively. CCT diagram of steel has been drawn after analysis of dilatometric curves.Morever by cryogenic treatment, martensitic finish temperature was determined at -87 °C.

Experimental tests were carried out to explosively clad solution annealed Inconel 718 super alloy on quench-tempered AISI H13 hot tool steel. Experimental tests were carried out using various stand-off distances and explosive ratios. Various interface geometries were obtained from these experiments. Experiments were carried out with Ammatol explosive mixture. In this study, the integrity of the bond interface was examined by the shear test. The micro hardness profiles at the interface for all samples were performed. Metallographic inspections of the bond interfaces were also carried out. The shape of interface fell roughly into two classes, wavy or wavy with some vortex shedding. In some case, a gradual change in wavelength along the direction of welding was observed which was due to a change in impact angle following plate contacts. Hardness was increased with stand-off distance and explosive ratio. Shear strength was found to be functions of interface morphology and wave amplitude.