Influences of superheat and cooling intensity on macrostructure and macrosegregation of duplex stainless steel studied by thermal simulation

The influences of superheat and cooling intensity on macrostructure and macrosegregation of one new kind duplex stainless steel (DSS) were studied. Thermal simulation equipment was applied to prepare samples, which could reproduce the industrial processes of DSS manufactured by a vertical continuous slab caster. Macrostructure and macrosegregation were analyzed using the digital single lens reflex and laser-induced breakdown spectroscope (LIBSOPA-200), respectively. The percentage of both chill zone and center equiaxed zone increases with the superheat decreasing, while that of the columnar zone decreases. There is only equiaxed grain existing as the superheat is 10 and 20 degrees C. The lower the superheat is, the coarser the gain size is. High cooling intensity in mold could remarkably decrease the chill zone length and refine the grains in chill zone and center equiaxed zone. The influences of cooling intensity on macrosegregation are greater than those of superheat. The macrosegregation of Si, Mn and Cr is slightly dependent on superheat, while that of Cu, Mo and Ni changes greatly with superheat increasing.

Automated summary

The influences of superheat and cooling intensity on the macrostructure and macrosegregation of a new kind of duplex stainless steel were studied. Lower superheat led to coarser grain size, while higher cooling intensity had a greater impact on macrosegregation than superheat. In addition, the macrosegregation of certain elements such as Cu, Mo and Ni changed significantly with increasing superheat.