This paper introduces the producing process of high cleanliness gear steel SAE8620H(/％,0.18～0.22 C,0.20～0.30 Si,0.60～0.80 Mn,≤0.015 P,≤0.003 S,0.40～0.50 Cr,0.020～0.040 Al,some Mo、Ni)with BOF→LF→RH→CCM.By controlling the end point of the converter[％C]0.06～0.12,[％P]≤0.012,adding 1.0～1.3 kg/t Al to deoxidize and synthesizing refining residue to wash out steel,LF produces high basicity slag R=5.0～8.0,slag refining(/％,52～56 CaO,6～10 SiO2,3～8MgO,26～33 Al2O3,≤0.8 FeO+MnO),RH high vacuum ≤67 Pa holding time of more than 15 min,feeding Ca line denaturing treatment,continuous casting superheat of 15～25 ℃,using tundish alkaline covering agent and low-carbon gear steel special protective slag protection casting,M+F electromagnetic stirring and other technological measures,finished products[％P]≤0.015,[％S]≤0.005,[N]≤45×10-6,[H]≤1.3 × 10-6,T[O]≤12 × 10-6,the average value of 7.6 × 10-6,rolled steel test results show that all kinds of non-metallic inclusions in steel ≤1.0,meet the quality requirements of high cleanliness gear steel,product quality is better than the product standard ASTM A304.
维普
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