Advanced Materials Research Vols. 881-883

Abstract: 40Cr is a kind of steel that is often used for semiaxis in heavy duty trucks, therefore high impact property of 40Cr steel is requested to adjust the heavy-duty machines working environment. In this study, the samples of 40Cr steel were heated under normal tempering temperature and quenched in air, water and oil, respectively. The experiments were carried out through charpy impact and microhardness analysis. It was indicated by experiments that water was more helpful to receive higher impact toughness as the tempering cooling medium than air and oil. At the same time, the intensity and hardness of 40Cr steel were enough to meet the heavy-duty machine semiaxis requirements.

Abstract: The effect of different composition ratio of ZnAlMg coatings on the corrosion resistance of dual phase steel sheet was experimental studied. The results of neutral salt spray test and corrosion products analysis showed that the three kinds of ZnAlMg coatings have different rust resistance performance. Both the Zn6Al3Mg and Zn13.5Al1.5Mg coatings have high corrosion resistance than the pure Zn coating. The Zn13.5Al1.5Mg coating has better anticorrosion performance than the Zn6Al3Mg coating.

Abstract: The inhibition effects of A-Mo inhibitor on corrosion of carbon steel in 55% LiBr solution were investigated using cyclic potentiodynamic polarization curves EIS experiments, Mott-Schottky analysis, SEM, EDAX and XRD methods. The results revealed that A-Mo inhibitor was capable of inhibiting the corrosion of carbon steel in 55%LiBr solution, exhibiting high inhibition efficiencies around 99.7%. A-Mo inhibitor promoted the formation of a protective passive film composed of Fe, Mo and O elements. The passive film improved the electrochemistry performance and enhanced corrosion resistance of carbon steel.

Abstract: In view of the requirements of the heat treatment on low alloy steel large hammer head formation of gradient performance, mainly study the effect of austenitizing temperature on the alloy mechanical properties and organizational . The results show that: austenitizing temperatures have little effection on the experimental alloys hardness but have great effection on toughness. At the austenitizing temperature 820°C, the experimental alloy obtained the high hardness and low toughness by quenching, and obtained high toughness and low hardness by normalizing; The quenched microstructure of the experimental alloy is mainly lath martensite; the microstructure after normalizing is pearlite + a small amount of ferrite.

Abstract: The hardness of P91 for HP loop pipes was lower than required in standard in a power plant which has run for about 35,000 hours. The experiments about Metallographic and conventional mechanical properties were done in this paper. The results show that the metallographic of P91 with low hardness was abnormal, creep damage was not found, and mechanical properties were poor.So the HP loop pipe with low hardness cant continue to be used safely.After re-heat treatment for HP loop pipe with low hardness,the results about metallographic and mechanical tests show that the performance of the pipe is good,and can continue to be used.

Abstract: In this paper, two processes for V-Ti magnetite smelting were introduced, the processes respectively are the conventional blast furnace-BOF process and the high-profile rotary hearth furnace direct reduction technology. The two kinds of processes were introduced briefly, and the problems of the two processes in the production of V-Ti magnetite were analysed. The blast furnace-BOF process with the relatively perfect, large output, high energy efficiency can't make full use of Ti in the mineral resources, in this way, the resource was wasted and the environmental were polluted, and the existence of Ti in slag can also bring a series of problems in blast furnace production. Rotary hearth furnace direct reduction technology has the advantages of high reduction temperature, low product price, flexible selection for raw materials and reducing agent, while the large scale of equipment brings a series of problems to the production and design.

Abstract: SSM 356-T6 aluminium alloys generally present low weldability by fusion methods because of the sensitivity to weld solidification cracking, porosities, change microstructure in weld zone and other defects in the fusion zone. Diffusion bonding can be deployed successfully with aluminium alloys. This paper presents the technique to conserve the globular weld structure of SSM 356-T6 aluminium alloy. The effect of joining parameters on the microstructure and mechanical properties of diffusion bonding butt joints of semi-solid metal 356-T6 aluminium alloy were investigated by conditions as follows: contact pressure at 0.4, 0.9, 1.8, 2.4 and 2.7 MPa, for 3 hours holding time and temperature at 495°C under argon atmosphere at 4 liters per minute. The results showed that condition used contact pressure 2.4 MPa, with 3 hours holding time and temperature at 495°C, under argon atmosphere provided. The highest joint strength reaching to 182.2 MPa, which had joint efficiency of 61.34 percents compared with base material. In addition, microstructure in welded zone after welding is still in globular structure, but the grain size was increased when the higher bonding temperature was used. The results of this investigation have shown that an average hardness is around 121.2 HV.

Abstract: Aiming to the corrosion prevention of 16MnR steel surface in the light aggregate concrete, the paper applies a kind of corrosion prevention system composed of layered coating. It utilizes measurement methods such as field emission scanning electron microscopy and energy disperse spectroscopy to study the corrosion and change process of this kind of coating system in the surface of 16MnR steel in the environment of light aggregate concrete and make the evaluation on its effect of corrosion protection. The experiment result indicates that due to its mechanical masking function, the layered coating system can effectively restrain immersion of the corrosive medium in early corrosion period so as to protect the metallic matrix. With the deepening of the corrosion, the nanometer Zn particle has the function of cathodic protection on the metallic matrix, effectively enhancing the comprehensive corrosion protection ability of the coating system.

Abstract: Based on the cellular automata (CAs) method of Moore neighbor type, a model of simulation for grain growth processes in magnesium alloy heat affected zone of laser melt injection was established. The results show that the grain growth process can be simulated very well by the CAs method, the shapes of grains tend to be hexagonal, the small grain is annexed by large grains, the grain growth index can be obtained as 0.42, and the topological feature reflected by the established model is accord with the physical mechanism of the grain growth. The cellular automaton (CA) method is proved to be a simple and effective approach for the grain growth simulation.

Abstract: The present study was conducted to investigate the effect of heat treatment on the aging and mechanical behavior of Al-Cu-Mg-Li-Zr , Al-Mg-Si and and Al-Mg-Zn alloys (8090 , 6082 and 7075). The effect of cold work after solution treatment, aging parameters (time and temperature) on the microstructure and mechanical properties were studied. Attempts are made to determine the combined effect of cold work and aging treatment on the hardness, UTS and microstructure for these alloys. By study the impact of different heat treatments for Al-Mg-Si alloys (6082), Al-Cu-Mg-Li-Zr (8090) and Al-Mg-Zn (7075) aluminum alloys on the hardness and mechanical properties, it is possible to determine conditions necessary to achieve better mechanical properties and the maximum levels of hardness and values corresponding to those considered suitable for commercial applications of these alloys.Design of Experiment (DOE) method in Minitab is used to measure the impact of various factors and how they relate. Correlation between the hardness and different metallurgical factors for these alloys at both quantitative and qualitative are investigated and analysed. A statistical design of experiments (DOE) approach using fractional factorial design was applied to determine the influence of controlling variables of cold work and heat treatment parameters and any interactions between them on the hardness of the above alloys. A mathematical model is developed to relate the alloy hardness with the different metallurgical parameters to acquire an understanding of the effects of these variables and their interactions on the hardness of wrought Al-alloys. It is noticed that cold work, following solution treatment, accelerates the precipitation rate leading to a rise in strength