The Research On Microstructure And Mechanical Propertiese Of Welding Junction Of Air-cooled Bainitic Frog Steel

Frog is the position that destroyed most seriously in the railway line. All around the world, most countries use high-manganese steel as the frog steel. Although this steel has the maxi merit that it is safe and reliable, there are many problems such as lower-density, lower-hardness, lower-welding property, ephemeral age and slighter-burden. So, the whole world scientists develop technology to improve the properties of high-manganese steel. Although the using effect has been improved, the fundamental problems still exist.In order to satisfy the high-speed development in economics of our country, to accomplish railway conveyance trend to high-speed and extensive-burden and to develop super-line track on the railway line, the hardwearing frog material must has favorable welding property when it is joined to the track At present, the high-manganese frog steel can't fulfill these requirement. So, it is the preoccupation to exploit a frog that has high-strength, high-toughness, high-hardness and super performance after it has been welded.According to a new type of frog made of granular bainitic steel, the properties of the frog are better than high-manganese steel frog. According to its high- strength, high- toughness, high-hardness and good welding property, this new type air-cooled bainitic steel attracts the attention of the pursuers that study the railway material. The article's aim is to find the welding technology and heat-treat technology that can make the junction has the accordant microstructure and mechanical property with the parent metal.By a great deal of experiments and analysis, the article investigates the microstructure and mechanical properties of the junction got by flash butt welding and manual arc welding separately. The finding of investigation is that the junction is granular bainitic structure and the mechanical properties of welding joint are tensional strength 1036 Mpa, impact toughnessσ_k 42.8 J/cm~2, hardness HRC38. All these made the junction come up to the standard of Ministry of Railways.