Based on 200 t BOF-LF-RH-CC slab metallurgical process to produce 10CrNi3Mo steel

silicon-calcium cored wire and calcium-magnesium composite cored wire are injected respectively into liquid steel to modify inclusions

and the slabs are rolled to 35 mm plates with 4 300 mm heavy plate rolling mill then to carried out heat treatment. The inclusions of test steel are analyzed quantitatively and qualitatively by means of SPEED

SEM & EDS and INCA etc. The obtained main performance is that the number of inclusions per unit area is reduced by about 40% and the average distance is nearly doubled after modification. Combined with the Charpy impact test results

it is concluded that the inclusion deformation treatment is obviously improve to the impact toughness

especially the low-temperature impact toughness.