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为了优化氮微合金化钢HRB500E的连铸冷却配水工艺,保证铸坯质量,采用Gleeble-1500D热模拟试验机测定了铸坯的高温力学性能,并对试样断口组织形貌进行了显微观察与分析,讨论了其在不同温度区间的断裂机理。研究表明:在应变速率为1.4×10-3/s时,铸坯第Ⅲ脆性温度区间出现在675~750℃,脆断主要原因是铁素体在奥氏体晶界析出、晶界处Mn S的偏析和大量V(C,N)的析出;铸坯未出现第Ⅱ脆性温度区,在1 000℃左右断裂方式为穿晶断裂;第Ⅰ脆性温度区在1 300℃以上,断裂方式为晶间断裂,主要原因是O,S,P在晶界富集促进形成液膜。
In order to optimize the continuous casting cooling water distribution technology of nitrogen microalloyed steel HRB500E and ensure the slab quality, the high temperature mechanical properties of the slab were measured by Gleeble-1500D thermal simulation testing machine, and the microstructure of the fracture surface was observed microscopically With the analysis and discussion of its fracture mechanism in different temperature range. The results show that when the strain rate is 1.4 × 10-3 / s, brittle fracture occurs in the range of 675-750 ℃ during brittle fracture. The main reason of brittle fracture is that ferrite precipitates at austenite grain boundaries and Mn S segregation and a large number of V (C, N) precipitation; slab does not appear the second brittle temperature zone, the fracture mode at about 1 000 ℃ transgranular fracture; Ⅰ brittle temperature zone above 1300 ℃, the fracture mode Intergranular fracture, the main reason is O, S, P in the grain boundary enrichment to promote the formation of liquid film.