铸件厚度及退火处理对蠕墨铸铁切削加工性能的影响

Effect of Annealing Heat Treatment and Casting Thickness on Milling Performance of Compacted Graphite Iron

以发动机缸体材料蠕墨铸铁RuT450为研究对象,通过监测其铣削加工过程中的切削力、切削温度及已加工表面粗糙度的变化,结合微观组织及力学性能演变分析其对切削性能的影响。研究表明,铸造厚度不同,材料的微观组织和力学性能不同;切削力是石墨含量、蠕化率、残余应力、硬度、抗拉强度等性能指标的综合反映,切削热则与切削力密切相关;在保证强度指标的前提下,退火处理有助于降低铣削加工时的切削温度,对适度厚度的工件还可以降低切削力。在相对低速铣削时,退火处理可有效提高工件的加工表面质量;在保证满足表面质量的前提下,去应力退火后可以适当提升切削速度,提高蠕墨铸铁加工效率。

The cutting force,cutting temperature and the machined surface roughness during milling compacted graphite cast iron RuT450 from the engine cylinder are investigated,the influences on machinability are analyzed in conjunction with the evolution of microstructure and mechanical properties.The results show that the microstructure and mechanical properties of the materials vary with casting thickness.Cutting force is a comprehensive reflection of graphite content,vermicular rate,residual stress,hardness,tensile strength,and other performance indicators.Cutting heat generation is closely related to cutting force.Under the premise of ensuring the strength index,annealing is beneficial for lowering the cutting temperature during milling and can also reduce the cutting force for a certain workpiece thickness.Annealing can significantly improve the surface quality of a workpiece when milling at relatively low speeds.After stress relief annealing,the cutting speed can be properly improved to increase machining efficiency of compacted graphite iron under the premise of ensuring surface quality.