The Influence Of Electromagnetic Stirring On The Quality Of 1Cr13 Martensitic Stainless Ingot

Martensitic stainless steel have the feature of high strength and good corrosion resistance,etc.Among them 1Cr13 martensitic stainless steel is mainly used as in the production of higher toughness and impact load of parts,such as cutting tool,blades,hydraulic press valve,structure frame,bolt,etc.But the center loose,cracks and other defects appeared easily in the billet,which bring difficulties to the subsequent thermal processing.The purpose of this paper is to test and analysis the quality in 160x160 mm 1Cr13 martensitic stainless steel continuous cast slab of a domestic metallurgical enterprises,then analysising the influence on continuous cast slab under different final stirring position and different stirring intensity.In the laboratory,we carried out the experimental study for 1Crl3 martensitic stainless steel with EMS.Investigation the effect of electromagnetic stirring on the solidification behavior of martensitic stainless steel.Then we analysis of the formation mechanism of 1Cr13 martensitic stainless steel center crack and study the influence of nickel element on the refinement of martensitic stainless steel.The main conclusions show:(1)At the same frequency,the magnetic flux density increased with an increase in stirring current;magnetic flux density varied with location,on the edge and center longitudinal cross section,magnetic flux density at the center held the biggest,and reduce with the direction to the center;the minimum was at the center point of the cross section;(2)There has been a large number of straight-growing columnar dendrite in martensitic stainless steel without EMS,the proportion of center equiaxed grain is only 10%,grain size is about 121.5?m.With EMS,columnar dendrite significantly reduced,the proportion of center equiaxed grain is add to 38%,and grain size is become small comparing without EMS.At 250A/12Hz stirred parameters,grain size refined to 65.8?m,which bring about better quality of the center slab.(3)Grain boundary of casting have inclusions,precipitation of MnS weaken the strength of grain boundary.Under the action of peritectic transformation and the solidification shrinkage stress,fragile grain boundary generate fracture and lead to center crack.Under the electromagnetic stirring,element distribution become more uniform and reduce inclusions aggregating at the grain boundary,the center crack gap of ingot become more smaller.The developing columnar crystals disappeared,mainly the oval one crystal axis.(4)At 250A/12Hz stirred parameters while add 1.5%nickel element,the solidification structure of 1Cr13 martensitic stainless steel has been significantly improved.Without adding nickel element,the grain size is 65.8?m.When we add nickel element,the grain size is 35.6?m,grain size refined,which is contributes to the grain refinement strengthening.It reduces the generation of the center cracks,which is lead to improving for the slab quality.