Study On The Ingot Casting Quality In YISCO

With the development of equipment manufacturing industry in our country,the demand for large size and small batch steel ingot is increasing.There are problems about ingots quality,utilization rate of steel ingot and ultrasonic testing qualified rate in the products of Yonggang Iron and Steel CO.LTD(YISCO).The low utilization rate and ultrasonic testing qualified rate can be mainly caused by the quality of ingot.It's essential to increase utilization rate of steel ingot and ultrasonic testing qualified rate,thus the economic benefit of enterprise can be improved by controlling ingot quality.Based on the statistical analysis of YISCO ingot quality problems,and the analysis of Some defects,the further calculation,measurement and analysis on the related factors of utilization rate and ultrasonic testing qualified rate was made.The optimizations and solutions about ingot mould structure,auxiliary materials and pouring processe have been put forward.The following conclusions can be got from the analysis.(1)The quality problem of steel ingot is caused by the following reasons.steel ingot surface exists crack and rimhole,it accounts for 13.04%.The ultrasonic testing is not pass,it accounts for 63.04%,micro cracks accounts for 60% of it,porosity and shrinkage cavity accounts for 28% of it,intensive defect accounts for 12% of it.Ingot end has slag,it accounts for 6.52%.(2)The mould taper is generally small,the 6.8 tons should be increased to between 4.5% to 5.0%,10.3 tons should be increased to 3.0%.The height-diameter ratio is basically reasonable,the 6.8 and 10.3 tons,is too high,6.8 tons should be reduced to between 2.6 to 2.8,10.3 tons should be reduced to between 2.5 to 2.7.The hat capacity ratio of all kinds of mould is too high,should be reduced to between 8% and 10%.(3)The thermal insulation property of part of insulation board is bad.The melting rate of part of casting powder is slow.(4)The molten steel superheat should be reduced.The pouring speed should be reduced,the feeding time should be increased.(5)By means of infrared temperature measurement,establishing the relationship between the surface temperature of ingot mould and internal solidification of steel ingot,and judging the internal quality of steel ingot by the temperature change.After taking the above measures,the quality of steel ingot had been improved,eventually,utilization rate of steel ingot increased from 80% to 86%,ultrasonic testing qualified rate increased from 88% to 95%,two data both reach the high level of industry.