热芯大压下轧制连铸坯再加热时的组织遗传性

 热芯大压下轧制工艺在改善连铸坯内部缩孔、疏松缺陷的同时,可以破碎粗大的铸态组织,并通过影响再加热奥氏体化后的组织来影响最终产品的组织和性能。为了研究热芯大压下轧制后的铸坯再加热过程的组织演变,选用微合金钢和中碳钢2种具有代表性的钢种为研究对象,采用炼钢-连铸-轧制一体化试验,研究了热芯大压下轧制对连铸坯显微组织及再加热后奥氏体组织形貌的影响。研究结果表明,热芯大压下轧制可改善铸态组织,获得均匀细小的室温组织。对于中碳钢,热芯轧制获得的细小组织经再加热后无法继续保持,与无形变的坯料相比,再加热后的奥氏体晶粒反而更加粗大;而对于微合金钢,由于第二相粒子的钉扎作用,热芯大压下轧制获得的细小组织经再加热后可继续保持。

Microstructure inheritance of continuous casting steel deformed by hot-core heavy reduction rolling technology during reheating process

The Hot-core Heavy Reduction Rolling(HHR2) technology can break the coarse as-cast microstructure and affect the microstructure and properties of the final product by affecting the morphology of austenite after reheating,as well as improving the internal shrinkage cavity and porosity of the continuous casting steel. Two typical sheets of steel,microalloyed steel and medium carbon steel were selected as the research objects. The effects of HHR2 technology on the microstructure of continuous casting steel and the austenitic morphology after reheating were studied by the integrated pilot experiment of steelmaking,continuous casting and rolling. The results show that the as-cast microstructure can be improved and fine microstructure can be obtained at room temperature by HHR2 technology. For medium carbon steel,the fine microstructure obtained by HHR2 technology cannot keep fine after reheating,and the austenite grain size after reheating is larger than that of the non-deformed casting steel. However,for the microalloyed steel,the fine microstructure obtained by HHR2 technology can be maintained after reheating due to the nailing effect of the second phase particles.