Improve The Mechanics Performance Of The High Strength Grey Cast Iron

The effects of Si/C, Cu Cr element, inoculation on the microstructure and mechanical properties were investigated to improve and stabilize materials properties of Euro diesel and the experiments had been done as producing in the workshop.The results show that the austenite amount is increased and the matrix is strengthened, while improving the Si/C ratio, because the cutting effect of flake graphite on the matrix is minished via graphite amount decreasing and Si strengthens the matrix via solid solution hardening. So the mechanical properties of castings are improved by this way, and ultimate tensile strength reached 336MPa when Si/C ratio was 0.68.Cu element can depress the critical temperature of austenite transformation, refine and increase the pearlite amount of matrix. Because of some amounts of Cr and Sn elements existing in molten iron, the pearlite content of casting matrix was not changed clearly by the addition of Cu. But the pearlite flake spacing was refined obviously, adding up to 0.4% of Cu from 0.2% wt pct. Because the effect of Cu on refining pearlite is finite, Cu content was increased to 0.5%,the pearlite and tensile strength of separated specimen was changed little.The mechanical properties of casting were influenced significantly by the absorption of inoculant alloy which was affected directly by adding method and time. The experiment results indicated it was not beneficial to the absorption that the inoculant alloy was placed in the ladle, the graphite morphology and tensile strength of casting was bad and low produced by this method. The absorption could be improved by adding in the tapping stream, so the graphite morphology and tensile strength were improved. The inoculation effect was best when the adding time was 25 seconds after 1/3 tapping amount. If the adding time increased to 35s, the last inoculant alloy didn't be absorbed because of floating on the surface of molten iron.Operation stability is very important to the product quality in the mass product line. In this article, pre-control, balancing alloys accurately, mechanical controlling alloy adding time etc measurements were taken, the analysis results by shows that the process controllability was improved obviously, the difference between UCL and LCL was decreased from 95MPa to 39MPa.