【作者】 裘荣鹏；

【导师】 许鸿吉；

【作者基本信息】 大连交通大学 ， 材料加工工程， 2005， 硕士

【摘要】 高速与重载是当今世界铁路的两大发展趋势,而要实现高速和重载,必须建设跨区间超长无缝线路。本文在查阅大量国内外文献的基础上,运用光镜、透射电镜和扫描电镜等金相试验手段和拉伸、冲击、显微硬度等力学性能试验,对高锰钢辙叉与钢轨闪光对焊接头的显微组织形态、硬度分布和力学性能进行了研究和分析。其研究成果为我国实现高锰钢辙又与钢轨的无缝连接提供了一定的理论依据,具有十分重要的实际工程意义。 试验结果表明:闪光对焊接头ZGMn13高锰钢侧热影响区组织为单一的奥氏体组织,没有碳化物析出,其晶粒度明显小于母材;U71Mn钢轨侧过热区组织为晶粒较粗大的珠光体和少量铁素体,正火区为晶粒细小的珠光体组织,有些地方还有少量晶粒更加细小的索氏体组织。 高锰钢辙叉与钢轨闪光对焊接头的硬度分布:钢轨侧硬度较高,但热影响区硬度分布波动较大,正火区硬度较高,过热区和不完全重结晶区的硬度偏低;高锰钢侧硬度较低,分布较均匀;轨底堆焊层硬度介于高锰钢侧硬度值和钢轨侧硬度值之间。 高锰钢辙叉与钢轨闪光对焊接头的抗拉强度达钢轨母材的60%左右;冲击韧性值也在钢轨母材冲击值的60%以上,其接头力学性能接近或达到了国外加过渡层闪光对焊接头力学性能的水平。断口扫描显示闪光对焊接头拉伸和冲击试验断口为解理+准解理,以准解理为主,具有良好的塑性和冲击韧性。更多还原

【Abstract】 High-speed and over-loaned are the main targets of the modern railway. To achieve these two targets, building super long no-seam rail line is necessary. In this paper, the mechanical properties and microstructure of flash butt welding joint of the austentic manganese steel frog and the track steel had been researched by the metallographical examination, TEM, SEM and tensile, impact and hardness test. Its result has the very important practice meaning.The results showed that the microstructure of the HAZ was consisted of granular austenite in the austentic manganese steel side, but no carbide precipitates. The microstructure of the coarse grained zone is consisted of coarse pearlite and little ferrite in the track steel side; the microstructure of the granular grained zone is consisted of granular pearlite and little granular sorbite.Hardness test showed that the hardness of HAZ of the track steel was higher than the hardness of HAZ of austentic manganese steel, but it was not uniform on whole HAZ, the hardness of the granular grained zone was higher than the hardness of coarse grained zone and the inadequacy re-crystal zone. But the hardness is uniform on the HAZ of austentic manganese steel side. The hardness of buildup welding layer on the rail bottom is higher than the hardness of austentic manganese steel, but it is lower than the hardness of track steel.The tensile strength of flash butt welding joint is about 60% of the tensile strength of the track steel, and the impact toughness of the flash butt welding joint is above 60% of the impact toughness of the track steel. The properties of the flash butt welding joint achieved the level of the foreign experiment results. It can meet the requests of the correlation technology condition. The scanning electron microscope test showed that the fracture of the flash butt welding joint was cleavage fracture and quasi-cleavage fracture. The flash butt welding joint has good plastic and impact toughness.更多还原