电渣板坯热模压成形工艺研究

Research on Die Pressing Process of Electroslag Casting Slab

提出了一种将X型叶片板坯化拓扑变换后电渣熔铸,压模设计、模压及热处理实现板坯逆向拓扑变换为曲面水轮机叶片的新工艺。叶片通过板坯化拓扑变换后电渣熔铸可解决其直接电渣熔铸充型难的问题,板坯结晶器法兰处施加耐热弹性材料可解决叶片板坯铸造应力大的问题,在板坯极点对应的压模处预置定位柱及复式模压可解决定位精度要求高的问题。与模压相伴的热处理工艺可以在低能耗下同时实现形状与性能要求。通过该工艺生产的电渣熔铸模压叶片有化学成分均匀、组织致密、晶粒细化、无超标缺陷、夹杂物少而弥散等优点。参比砂铸叶片样件的生产过程,电渣熔铸模压叶片,具有环保效果好、造型快捷、样件力学性能高等优点;参比砂铸叶片样件,其冲击韧性提升了约30%,其他力学性能指标全方位改善。参比等厚钢板模压叶片工艺方案,电渣熔铸模压叶片成形工艺方案可大大降低生产成本,提高生产效率。

A new process of slab topological transformation of X-shaped blade followed by melting and casting,die design, die pressing and heat treatment to achieve the reverse topological transformation of the slab into curved hydraulic turbine blade was proposed. Electroslag melting and casting after slab topology transformation can solve the problem of direct electroslag melting and filling difficultly of the casting. The problem of casting stress was solved by applying heat-resistant elastic material to the flange of slab mold.Presetting the positioning column at the pressing die corresponding to the slab pole and multiple pressing can solve the problem of high positioning accuracy requirements. The heat treatment process accompanying with the hot forming can achieve the shape and performance requirements at the same time with low energy consumption. The electroslag melting and casting molded blade produced by this process had the advantages of homogeneous chemical composition, compact structure, grain refinement, no defects exceeding standard,fewer inclusions. Compared with the production process of sand casting blade sample, the electroslag melting and casting molded blade had the advantages of good environmental protection, fast molding, high metal utilization and high mechanical properties of the sample. Compared with samples of the reference sand casting blade, the new technology blades have increased their impact toughness by about 30%, and other mechanical performance indexes improved comprehensively, the mechanical properties of the blades and so on were much better than that of the sample sand casting one. This method can greatly reduce the costs in comparison with equal thickness steel plate hot forming method, and improve the productive efficiency.