Study on Non-metallic Inclusions in Q420 Steel

For analyzing the composition and distribution of inclusion in the steel ingot,the experimental samples of the Q420 steel were sampled at the locations of the riser,the top of the ingot,the middle and bottom of the mold cast ingot.The result showed that the inclusion index was between 2.09 and 4.98(pron/mm2),the microscopic inclusions in the middle of ingot is less than other parts.The content of large inclusions in the ingot were between 5.7 and 22.5 mg/10 kg,which composed mainly by SiO2,Al2O3 and a little Na2O and K2O.The large sized inclusions were mainly from the mold slag used during pouring and its content in the bottom of the ingot is much higher than that in the other parts.