60Si2Mn半固态浆料的制备和流变轧制的组织形貌

以弹簧钢（60Si2Mn)为研究对象，采用电磁搅拌的方式制备半固态浆料，研究了搅拌参数对半固态浆料组织形貌的影响；同时对半固态浆料进行了流变轧制，观察和分析了半固态浆料在轧制过程中的组织演变及轧制产品可能存在的组织缺陷。结果表明：在变温连续搅拌条件下，随着搅拌时间的延长，半固态浆料的固相率提高，初生固相颗粒的直径减小，组织更均匀；经过1道次的轧制，半固态浆料中的液相从固相颗粒间挤出，流向轧件的表面，大部分固相集中在轧件的中心，产生宏观偏析现象，提高固相率可减小偏析程度。此外，轧件中还可能出现缩孔、分层组织等缺陷。

THE MICROSTRUCTURAL MORPHOLOGY OF SEMI-SOLID STEEL 60Si2Mn DURING FABRICATION AND RHEO-ROLLING

The semi-solid slurry of spring steel (60Si2Mn) was fabricated by electromagnetic stirring, and the influence of stirring parameters on the microstructural morphology of the slurry was studied. Subsequently, the semi-solid slurry was rheo--rolled, its microstructural evolution and the possible microstructural defects were analyzed. The results show that with the stirring time prolonging under the condition of temperature-changing arid continuously stirring, the solid fraction increases, the diameter of primary solid phase decreases and the homogeneity of rnicrostructure increases. After the semi-solid slurry was rolled one pass, the entrapped liquid phases are squeezed out and flow to the surface of rolled product, but the solid phases mainly concentrate in the center, resulting in macrosegregation. Increasing the solid fraction can reduce this segregation. Moreover, the shrinkage cavity and laminal microstructure appear in the rolled product.