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As one of the quenched and tempered steels, 40Cr steel is often used to manufacture the shaft in heavy-duty trucks. To adjust the working environment of the heavy-duty machines, 40Cr steel should have high impact property. In this study, different tempering cooling mediums were treated as critical influence on improving impact property of the steel. After heated under 520°C tempering temperature, the samples of 40Cr were cooled in air, oil and water, respectively. The experiments were carried out through charpy impact, metallographical and SEM analysis. The results has shown that 40Cr steel of high impact property and fine microstructure can be obtained when water is used for the tempering cooling medium.

The effect of different tempering temperatures on microstructure and impact property of 20CrMnTi steel has been studied on Zwick/roell Amsler PKP 450 pendulum machine, SU-8020 scanning electron microscope (SEM) and optical microscope. The results shows that the impact property of 20CrMnTi steel is dramatically improved after high-temperature tempering. However, the minimum value occurs when it was tempered at 350°C because of low-temperature tempering brittlement at this degree. The SEM fracture morphology was typical dimples after high temperature tempering, and the type of fracture was ductile fracture; the type of cleavage characteristic and quasi cleavage characteristic were generated on the fracture morphology at low-temperature and medium-temperature tempering respectively, and the type of fracture was brittle.

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.

Building external sun-shading is an important building energy efficiency measure in hot-humid areas. Integrated photovoltaic sun shading, which is of energy saving as well as power production, is one method with great potential for sustainable development of building. This paper extends the external sun-shading modules design and explores the BIPV design possibilities in the area by discussing the combined building skin strategy in hot-humid areas, photovoltaic external sun-shading modules layout and the micro-structure technical analysis. The model is optimized and the specific application in construction is determined through the software simulation of solar radiation shading, indoor illumination effects and photovoltaic shading .The reasonable combination of photovoltaic sun-shading modules and the battery arrangement with different light transmission rate enrich the possibility of the building skin space in architectural heat shielding and aesthetic design.