Research on Non-metallic Inclusion Behavior of Q195 Rectangular Billet

Q195 steel is mainly used for strip production.In order to reduce the cost,the LF refining process is removed on the basis of the original process 80 t converter→argon blowing→LF→continuous casting.In order to ensure the slab quality does not affect the product performance,the composition and source of the non-metallic inclusions in the slab are analyzed by tracer method,metallographic,oxygen and nitrogen test,large sample electrolysis and scanning electron.After argon blowing[O]in the steel is up to 226×10^-6,[N]is 33×10^-6;For different heats,[O]in the tail billet is up to 251×10^-6,and[N]is 37×10^-6.The contents of micro-inclusions and large inclusions are high,and-MnO composite inclusions and-CaO composite inclusions are present in the slab.Therefore,a stable casting process is necessary,and the tundish structure shall be modified to improve the flow field to prevent slag entraping,hhile protection pouring shall be strengthen to reduce the occurrence of secondary oxidation.