Advanced Materials Research Vols. 189-193

Abstract: The inhibition effect of corrosion and scale inhibitor WJF-6 on Q235 steel in simulated seawater circulation cooling water was studied by rotary coupon corrosion tests. And corrosion mechanism of this inhibitor was researched by some electrochemical measurements such as polarized curves and linear polarization, scale inhibition performance of this inhibitor was studied by static anti-scale method. At the same time, the corrosion and scaling influence of concentrated 1,2,3times for corrosion and scale inhibitor WJF-6, used in simulated seawater circulation cooling water, was researched. The results showed that the corrosion inhibitor efficiency reached 91.8% with 75mg/L of the inhibitor with linear velocity of 0.3m/s, and rotation of 72h at 50°C when concentrated multiple was three times. The results of linear polarization showed polarized resistance greatly increase by adding 75mg/L of this kind of inhibitor, its inhibition rate achieved 81.3%. The results of polarized curve revealed the strong polarized area of polarized curve have left shift and anodic polarized curves of electrode reaction was increased in strong polarized area, the basic function of corrosion and scale inhibitor WJF-6 is that the anodic process of electrode reaction were restrained. The effect of concentration multiple on corrosion and scale inhibitor WJF-6 in simulated seawater circulation cooling water showed that the corrosion rate was less than 0.125mm/a of the national standard and when concentrated multiple of simulated seawater circulation cooling water exceeded three times, and scale inhibition rate was more than 90%.

Abstract: Because of the high-speed, high transport capacity, low power consumption and a lot of technical and economic advantages, high-speed rail way are universal importance. High-speed railway with the speed of more than 300k/h has been run in China. But fatigue cracking of wleded bogie structure is markedly increased with increasing the train speed. How to avoid fatigue destroy of wleded bogie structure and ensure the safety of transportation are urgent problems to be soved in engineering. A lot of research works have been done at home and abroad. Comparing with traditional surface engineering method, there are many advantages of ultrasonic impact , for example, simple operation, less power consumption, high efficiency, adapt to a wide range, easy to achieve automate production and so on. It is an effective way to surface strengthening of metallic materials. Plastic flow and grain refinement on the metal surface can be obtained by using ultrasonic impact method, and the residual compressive stress on the surface can also be formed. So the mechanical properties of metal surface can be greatly improved. It is new method used in the area of welded structure, especially in the welded bogie structure. It is a new research direction to research the surface nanocrystallization mechanisium of ultrasonic impact, the effect of ultrasonic impac on the fatigue properties and failure mechanisium of wled joint of bogie.

Abstract: Surface treatment was carried out on the butt joint weldment of 16MnR steel by using the HJ-II-type ultrasonic impact machine. The ultrasonic impact current is 1.2A, the impact amplitude is 30 microns and ultrasonic impacting time is 30min and 60 min,respectively. Fatigue experiment was carried out for both treated specimen and un-treated specimen. The fatigue fracture observed with the scanning electron microscope of 6360LA type. The experimental results show that the fatigue life of the butt joint weldment of 16MnR steel can be significantly improved through the ultrasonic impact treatment. The main reason is that the ultrasonic impact can reduces the stress concentration in the weld toe, decrease the tensile stress, and even change to compressive stress in the weldment, the grain size in the welded joint can be refined. The longer the impact time, the greater increasing range of fatigue life will be. Compared to the sample without treatment, its fatigue life was increased 375.22%, 521.24%, respectively, when the impact time was 30, 60min, respectively.

Abstract: The special thermal effect makes some alterations to nugget morphology during resistance spot welding on unequal-thickness dissimilar steel. Method of nonlinear multiple orthogonal regression assembling design was introduced to design the experiment and investigate the resistance spot welding process. The indexes studied in experiments were nugget diameter and nugget deviation, which were the primary factors affecting the nugget morphology. Furthermore, four process parameters, namely welding current, electrode force, welding current duration and heat-treatment pulse current, and interactions among them were considered as the factors impacting the indexes. The nonlinear multiple regression models about nugget morphology parameters were developed on the basis of optimization. The experimental results showed that there was an effective prediction on nugget size based on the optimized models. The optimization to welding process also can be realized by the analysis to the effects of parameters and interactions.

Abstract: The cemented carbide YG30 and steel 1045 were welded with Co-Fe-C filling alloys with different carbon contents by the tungsten-inert-gas (TIG) arc welding. η phase formation at the welding joints was investigated through scanning electronic microscopy (SEM). The results show that the average composition of η phase is W-25, Fe-22, Co-19, C-24 (mass, %), which is a kind of carbide enriched by Fe, W，and Co. The amount of η phase formed near the interface of YG30 and weld bead is related to the C content in the filling alloy. Namely the amount of η phase decreases with the increasing of the C content in the filling metal. When the C content reaches to 0.8 wt%, no η phase forms. The reason of which is that the added C reduces and/or restrains the resolving of the WC that locates at the interface, so that inhibit the W and C to form η phase with Fe and Co. The existence of large-size η phase near the interface is mainly attributed to the aggregation of small size η phase with the unsolved WC due to the stir of liquid metal, and then growing up.

Abstract: Closed cell polymeric foams are widely used in sport and medical equipments. In this study, an artificial neural network (ANN) based inverse finite element (FE) program has been developed and used to predict the nonlinear material properties of EVA foams with multiple layers. A 2-D parametric FE model was developed and validated against experimental data. Systematic data from FE simulations was used to train and validate the ANN model. The accuracy and validity of the ANN method were assessed based on both blind tests and experimental data. Results showed that the proposed artificial neural network model is robust and efficient in predicating the nonlinear parameters of foam materials.

Abstract: The thermal behavior during electron beam welding on magnesium alloy were analyzed and simulated. According to the thermal effect of the electron-beam-generated keyhole, a mathematic model of rotary Gaussian body heat source with incremental power-density-distribution was developed. This model can be useful for simulating the thermal effect of metal vapor plasma on the surface of the workpiece and the deep-penetrating effect of the electron beam. By the action of thermal model, the characteristics of temperature field during vacuum electron beam welding on AZ61 magnesium alloy were studied by the method of finite element analysis. And then, the influence of welding parameters on the temperature distributions and the weld contours were analyzed. The simulations and experiments showed that the different deep-penetration effects and temperature distributions were achieved with the varying welding energy inputs, and the metal vapor plasma has a significant impact on the weld contour of magnesium alloy.

Abstract: The (Sn-9Zn0.05Ce)xBi solders with different Bi contents were prepared by a new process. The characteristics of solders about microstructure, tensile strength, elongation and microhardness were studied. The results showed that addition Bi can induce acicular or granular Zn-rich precipitated phase in Sn-9Zn0.05Ce solder. To increasing Bi content caused more Zn-rich phase distributed disorderly. When the Bi content was added to 4%, the granular Bi precipitated phase was observable. The tensile strength and hardness of (Sn-9Zn0.05Ce)xBi solder will raise, but elongation descend significantly due to the Bi content increasing. It can be funded that there was a more obvious turning point as w(Bi)=2wt﹪.

Abstract: The effect of electrode force on the weld quality of resistance spot welding monitored using electrode displacement was experimentally studied in this article. The electrode displacement was detected by the grating displacement sensor, and the maximal electrode displacement was obtained by the measurement system. The weld quality was evaluated by the tensile-shear strength of spot welds. Groups of spot welding experiments were performed under different electrode pressure, and the relationship of the maximal electrode displacement and tensile-shear strength in weld lobe was analyzed. The results showed that the relationship between electrode displacement and weld quality is not constant when the electrode force changed.

Abstract: ZL114A was joined by friction stir welding and liquid nitrogen was used to cool the welded joint during the welding process. The Influence of forced cooling on the microstructure and properties of welded jointed was studied. The results show that, when forced cooling is used, the amount of silicon particles in weld nugget zone is larger and the size is more homogeneous, the size of silicon particle in heat-mechanical affected zone is more fine , the grain size of heat affected zone is half of air cooling welded joint and the amount of Al-Si eutectic is smaller than air cooling welded joint. The micro hardness increases after forced cooling is used, the hardness of weld nugget zone is 20Hv higher than air cooling welded joint. The strength of forced cooling welded joint increases 13.6% than air cooling welded joint.