Study On Widmanstatten Structure In Microalloying Steel Of Q460E

Braking system is an important part of railway rolling stock, it has direct impact on train running performance and security. To ensure safety, reliability, weatherability and service life of the brake beam system which is the important parts of truck brake in the cold, heat, high humidity areas, an urgent need of systematically studying the microstructure and influence mechanism of the widmanstatten in micro-alloyed Q460E steel for manufacturing brake beam, and further proposes the method to prevent and eliminate widmanstatten in micro-alloyed Q460E steel.In this dissertation, the existence and formation mechanism of widmanstatten structure in Q460E micro-alloyed steel used for stock break was comprehensively studied. The widmanstatten structure was created by six series of simulation with a total of thirty sub-programs in which the structure generation process was modeled. Using the macro and micro analysis as well as the quantitative micro-technology analysis, the microstructure component of Q460E micro-alloyed steel at the condition of normalizing and tempering process was confirmed to be ferrite, pearlite and widmanstatten. No bainite structure was found in this research. The formation mechanism and the morphology of widmanstatten structure were studied in Q460E micro-alloyed steel at different normalizing temperature. With the quantitative analysis of mechanical property, it was found that the low-temperature impact absorbed energy KV2 (-40℃) decreased steppedly with the increase of widmanstatten fraction in Q460E micro-alloyed. Finally the method for preventing and eliminating the widmanstatten structure was proposed. This method was able to provide basic theory for enacting the metallographic examination graph spectrum of widmanstatten structure as well as the interrelated technical standard and manufacture control of train brake beam production.