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Two bearing steels, with higher Mn and Si content than GCr15, were refined in 50kg vacuum induction furnace followed by multi-pass rolling to 12mm thick flat on two-high mill. Mechanical properties and microstructures were measured and observed. The results show that higher content of Mn and Si decreases the martensite starting temperature (Ms), which is beneficial to the forming of martensite. The microstructure changes from martensite plus troostite to martensite, leading to higher hardness of steel and improvement of wear resistance. However, the band microstructure is easily formed by increase of Mn and Si, which is harmful to transverse property.

This paper aims at getting a way to obtain the suitable track tension by analyzing a heavy tracked vehicles driving prototype which is consisted of the sprocket and the meshing tracks. First, by analyzing the force state in the driving part in the multi-body dynamics simulation tool: RecurDyn, a critical condition to judge the peel-off of tracks in heavy tracked vehicle is proposed. Second, by comparing the different models built in RecurDyn, an ideal track distribution around the sprocket is obtained and also the relationship between the driving torque and the track tension under that ideal situation is concluded. Third, basing on the data from the simulation, the force state of each track meshed with the sprocket is analyzed, and an assumption about the proportion between each tracks upper and bottom pulling force is proposed.

In this paper, the Urea-SCR system is first introduced; then change of the urea solution concentration under different temperatures with time lapsing is given. Meanwhile, conditions for the urea crystallization are analyzed and SCR converter adaptability is tested under high sulfur environment on engine test bench. As the efficiency of NOx conversion is not significantly reduced after aging and the activity of the catalyst is very little damaged by dense sulfur content in fuel, SCR catalyst is able to adapt to the application of high-sulfur-contained fuel environment in our country.