关键词: 25Mn钢环件, 离心铸造, 热辗扩, 织构, 铸辗成形

Abstract: The centrifugal casting and hot rolling for large-scale 25Mn ring in industries are performed based on casting-rolling forming technology, and then hardening and tempering is conducted. By means of optical microscope, scanning electron microscope and electron backscatter diffraction technique, the microstructure and micro-texture are analyzed. The mechanical properties are also examined by tensile and Charpy impact tests. The results show that the rolled ring possesses precise geometrical dimension and uniform microstructure, but with a few irregularity grains in several areas. The textures are mainly brass-R {111}<112> along <110>//ND and Goss{110}<001> with orientation density of 6.0, leading to sound mechanical properties except for lower plasticity. The mechanisms of tensile and impact fracture are the coexistence of cleavage and dimple. After heat treatment, the comprehensive mechanical properties are enhanced due to fine and dispersed carbide particle precipitated during tempering. The proportion of high-angle boundary is 3/4 in fine and uniform grains. The textural development indicate Goss texture gradually gather and transform towards to {110}<110> along ξ-orientation, resulting to evidently enhance in plasticity. The dimple fracture plays a dominant role during tensile and impact. This investigation reveal it is feasible to fabricate 25Mn large-scale ring directly from centrifugal casting blank by hot ring rolling, and achieve the dual-purpose of forming and modification for ring components.

Key words: 25Mn steel ring, casting-rolling forming, centrifugal casting, hot ring rolling, texture