| The high-speed train is important symbol, which are their level of science and technology in the industrial countries and an important indicator of the railway transportation development degree. French high-speed electric trains in April 3, 2007 reached 574.8 km speed test. Had broken 1990 ago when which sets the record of by this country high speed electric locomotive 515.3 kilometers had axle railroad moving velocity world record [1]. After our country railroad passes through six times raises greatly fast, the train speed reached 200 km above the trunk level [2]. Thus, the development of the national economy has provided a better transportation.With the speed enhancement of trains, the tracks and the train is a higher and more stringent performance requirement. Train axles is an important part of its operating parts, and its quality is not only determined the speed of the trains can operate, also directly affects the safety of train transport.Domestic train axles usually manufactured with 40 or 50 steel [3]. However, the carbon steel has poor harden ability. [4] And Section axle dimension and size is larger, usually just to be normalizing to get smaller Flake pearlite organization to process axles. Its synthesis mechanical properties lower performance requirements and are difficult to satisfies the high-speed train on the axle. To solve this problem, taking into account the axle load, failure, and the characteristics and state of stress fracture toughness and other factors, China Railway ASTRI and Chengdu Branch of the China Railway Materials company request axles for materials selection and performance requirements [5], 35CrMo hot-rolled steel is selected to produce seamless steel tubes into super-thick high-speed train axles.After analysis, research, testing and rolling. Pan CHENGGANG Chengdu Seamless Steel Tube Plant produced a batch ofΦ215×72.5mm super-thick steel 35CrMo seamless steel tube satisfied the technical requirements, which supplied to manufacture parts.In this paper, in a briefing on the state of industrial development over the high-speed train axle materials, Analysis of the high-speed train running axial stress and the distribution of the axle load, Security Reserve (fracture toughness) and the reasons for failure and so on. Subsequently, introduction 35CrMo steel alloy principle, correlation physical constants, break tenacity scope and heat treatment characteristic. Afterwards, has carried on the following aspect analysis, the research and the test work with emphasis.Firstly, understood carefully and has analyzedΦ215×72.5mm thick super 35CrMo Seamless Steel metallurgy process, specially hot rolling engineer testing process and rolling production process. Dissected and has analyzed this kind of seamless steel pipe metallurgy quality, had pointed out its larger eccentricity,shortage causes and improvement measures. The analysis and the experiment were carried on to the 35CrMo steel heat treatment craft system.Secondly, conducted in the laboratory has quenched, the tempering engineer testing. After has carried on the metallographic analysis, mechanics performance, SEM and the TEM analysis and the experiment to the sample, had determined best quenching and tempering heat treatment craft parameter, which can satisfy the use technical specification and have excellent fracture toughness and the fine comprehensive mechanics performance. Afterwards, has carried on the quenching and tempering heat treatment to the car axle in Chongqing Big River Mechanical Factory. When processing actual train axle, because still had the section size after the rough machining train axle thick, the weight and aperture is small and so on the characteristics, picked 125kw deep non-standard well type resistance furnace carries on the quenching heating, after it, choice cooling capacity compares the oil strong and may adjust the quenching intensity polymer water-solubility quenching medium cooling to quench [6].Thus, had prevented effectively at the beginning of oil hardening when flushes the fire, flushes the oil easily, to catch fire, to affect workshop working conditions problems and so on. Moreover, overcame the oil insufficient cooling capacity to make the train axle mechanics performance worsen seriously,because of middle the thick-walled tube in place easy to form on the bainite and other non-martensite organization. After 850℃±10℃heats up for 2.5 hours to quench into 13.5% densities in the polymer watery solution to quench, again 575℃±10℃3.5 hours tempering, this kind of high speed hollow train axle has achieved the stipulation technical specification, which manufactured byΦ215×72.5mm 35CrMo steel super thick seamless steel tube.Finally, with a summary of previous work, the author made some proposals to improve 35CrMo steel smelting, rolling craft and the equipment to the super-thick tube and the heat treatment process.
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