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Sun W.-L.,Agricultural University of Hebei | Sun W.-L.,Light Metal of Alloy Material Engineering Center in Hebei Province | Li Y.,Agricultural University of Hebei | An G.,Agricultural University of Hebei | Cheng Y.,Agricultural University of Hebei
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

To improve the mechanical properties of the 35CrMoA steel, unconventional treatment methods of improving the heating temperature and salt bath quenching can be adopted for simple workpieces. The Mo content in the steel has a significant effect on the workpiece mechanical properties after quenching. The effects of Mo content on the metallographic structure and mechanical properties after quenching were studied by means of direct reading spectroscopic chemical composition analysis, SEM fracture microstructure observation, mechanical property testing, hardness testing and metallographic analysis. The results showed that the Mo content greatly affects the toughness properties of the 35CrMoA steel workpiece after heat treatment, and using the higher range of CNS about the Mo content can guarantee the workpiece impact toughness. For the 35CrMoA steel with lower Mo content, processes of high temperature heating and salt bath quenching are unsuited. Source


Li Y.,Agricultural University of Hebei | Sun W.-H.,Agricultural University of Hebei | Sun W.-H.,Light Metal of Alloy Material Engineering Center in Hebei Province | Cheng Y.,Agricultural University of Hebei | An G.,Agricultural University of Hebei
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

The hot rolled seamless pipes is made by Q345B steel at high temperature, it cracks along the radial direction during the process of enlarging hole. The chemical composition, microstructure, fracture morphology and mechanical properties of the Q345B raw materials, the finished pipe and cracked pipe were analyzed by using OM, SEM, BDS and direct reading spectrometric etc. Experimental result showed that in the hot rolled process the cracks of steel surface could not heal because of high temperature oxidation and reside in seamless pipes. When the hole was further enlarged, the extension of cracks would destroy the seamless pipes. It could be concluded that the main causes of steel pipe cracking was residual longitudinal capillary crack in the seamless steel pipe, and non-metallic inclusions in the seamless steel pipe played a supporting role. Source


Wang H.-Q.,Agricultural University of Hebei | Wang H.-Q.,Light Metal of Alloy Material Engineering Center in Hebei Province | Sun W.-L.,Agricultural University of Hebei | Sun W.-L.,Light Metal of Alloy Material Engineering Center in Hebei Province | Xing Y.-Q.,Agricultural University of Hebei
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

ZrN film was made on aluminium alloys surface by mid frequency reactive magnetron sputtering process. The influences of nitrogen flow rate, sputtering time and temperature on the deposition rate and properties were studied. The experimental result showed that the corrosion properties of ZrN film would increase with the increase of nitrogen flow rate. When the nitrogen flow rate reached 15 seem, the corrosion properties were turned down. The adhesion of ZrN film would increase with the increase of the deposition time and the temperature, and when the time reached 30 min and the temperature was 100°C, the maximum deposition value could be obtained. The film thickness was proportional to the deposition time. When the thickness increased, the color of film from light yellow became yellow and golden. As the thickness was more than 70 nm, the color became dark. Source


Xing Y.-Q.,Agricultural University of Hebei | Wang H.-Q.,Agricultural University of Hebei | Wang H.-Q.,Light Metal of Alloy Material Engineering Center in Hebei Province | Sun W.-L.,Agricultural University of Hebei | Sun W.-L.,Light Metal of Alloy Material Engineering Center in Hebei Province
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

Failure analysis on the automobile swing was carried out by means of SEM and OM to find the reason of automobile swing fracture. According to chemical composition, macroscopic and microscopic test, the quality problems were decided inside a failure workpiece. Analysis results showed that the fracture source belonged to the ductile fracture which was in the swing corner. The main reasons were as follows. The first was the high temperature when formed the austenite structure process, resulting in some widmanstatten structures. The second was that there were more MnS inclusions along the rolling direction, which made the transverse ductility to be lower and caused to the automobile swing fracture. Therefore, the steelmaking process should be improved such as to reduce the temperature of austenite forming process, and to improve the transverse ductility of the HP295 steel, which could make the steel more purified. Source


Wang H.-Q.,Agricultural University of Hebei | Wang H.-Q.,Light Metal of Alloy Material Engineering Center in Hebei Province | Sun W.-H.,Agricultural University of Hebei | Sun W.-H.,Light Metal of Alloy Material Engineering Center in Hebei Province | Xing Y.-Q.,Agricultural University of Hebei
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2012

According to the method of chemical composition analysis, metallographic examination and hardness test, the fracturing reason of 40Cr steel of dacromet bolt was analyzed. The result showed that there were excessive phosphorus element that is easily to form Fe 3P, resulting in the cold brittleness. After the heat treatment there would be more carbides in the microstructure. According to the second standard level of JB/T 8837-2000 undissolved carbides (1~3 pass), it was evaluated 5 level and did not meet the requirements. So much carbides would reduce the carbon concentration, resulting in the decrease of the intensity. According to the national standard of GB/T 1231-2006, 40Cr material hardness was tested by the 8.8S standard. The test result indicated that the hardness value was greater than that of the national standard. It could be concluded that the main reasons which caused the 40Cr bolt fracture were the excessive phosphorus element, the more carbides in the microstructure and the greater hardness than the national standard. Source

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