Rolling And Quality Analysis Of 35CrMo Steel Ultra-Wall Seamless Tube For High Speed Train Axle

High-speed train is an important symbol, which indicates the level of science and technology in industrial countries and an important indicator of the degree of the railway transportation development. French high-speed electric trains on April 3, 2007 reached 574.8 km speed test. This broke 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. After it was raised for six times, The train speed has reached 200 km above the trunk level. Thus, the development of the national economy has provided a better transportation.With the increament of trains, speed is a higher and more stringent performance were required for. Train axles is an important part of its operating parts, and its quality not only determines the speed of the trains which can operate, also directly affects the safety of train transport.Domestic train axles are usually manufactured with 40 or 50 steel. However, the carbon steel has poor hardening ability. And the section dimension of axle are large, usually just to be normalizing to get smaller Flake pearlite organization to process axles. Its synthesis mechanical properties and lower performance requirements are difficult to satisfy for 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, 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 ofΦ215mm×72.5mm super-thick steel 35CrMo seamless steel tube which satisfied the technical requirements and were supplied to manufactures.This paper briefly summarized the state of industrial development over the high-speed train axle materials and analyzed 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, 35CrMo steel alloy principle, correlation physical constants, break tenacity scope and heat treatment characteristic are introduced. Afterwards, the analysis, research and test work for rolling craft of 35CrMo steel ultra-wall seamless tube were carried out. Finally, the 35CrMo steel ultra-wall seamless tube with diameter wall ratio of 2.97 was produced which has never been reported in domestic.TheΦ215mm×72.5mm thick super 35CrMo Seamless Steel metallurgy process, specially hot rolling engineer testing process and rolling production process was carefully analyzed Based on the defailed analysis of this kind of seamless steel pipe metallurgy quality, its larger eccentricity,shortage causes and improvement measures were pointed out. The analysis and the experiment were carried out in a 35CrMo steel heat treatment craft system.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.