局部锻造和形变热处理工艺对高锰钢辙叉组织及力学性能的影响

Influence of local forging and deformation heat treatment process on microstructure and mechanical properties for Hadfield steel frogs

利用铸造技术将高锰钢辙叉在服役过程中最易发生失效位置处的心轨和翼轨加高30 mm,并通过高温形变热处理工艺对辙叉加高区域进行压下变形,使其与未加高区域平齐。随后对高锰钢辙叉分别进行立即水韧、回炉于1100℃保温7 min后水韧和回炉于1100℃保温25 min后水韧3种不同的工艺处理。对3种不同状态的辙叉的变形区和未变形区组织进行观察,并对其相应力学性能进行测试,结果表明:经局部锻造和形变热处理后的辙叉的变形区的组织明显细化,且力学性能显著提高。在研究的3种变形状态的高锰钢辙叉中,变形后回炉于1100℃保温7 min后水韧的辙叉的变形区顶部性能的提高幅度最明显,其抗拉强度达到986 MPa,伸长率达到51.1%,较辙叉的未变形区域分别提高了34.1%和46.8%。

The core rail and wing rail at the position where the Hadfield steel frog was most likely to fail during the service process were increased by 30 mm by casting technology,and the elevated area of frog was depressed and deformed by the high temperature deformation heat treatment process to make it match the height of the unelevated area.Then,the Hadfield steel frogs were treated by three different processes:immediate water toughening,water toughening after returning to furnace and holding at 1100℃for 7 min,and water toughening after returning to furnace and holding at 1100℃for 25 min.Furthermore,the microstructures for deformed and undeformed areas of the frogs in the three different states were observed,and their corresponding mechanical properties were tested.Results show that the microstructure of the deformed areas for frogsafter local forging and deformation heat treatment is obviously refined,and the mechanical properties are significantly improved.For the studied hadfield steel frogs in the three deformation states,the frogs with water toughening after returing to furnace and holding at 1100℃for 7 min after deformation have the most obvious performance improvement at the top of the deformed area with the tensile strength of 986 MPa and the elongation of 51.1%.Compared with the undeformed area for frogs,they are increased by 34.1%and 46.8%,respectively.