Optimization and improvement of hot rolling performance of deep drawing steel S20A
A certain steel plant uses molten iron+scrap steel→ultra-high power EBT electric furnace smelting→LF furnace refining→RH furnace vacuum treatment→continuous casting of 180×220 square billets→continuous step furnace heating→650 continuous rolling unit to produce S20A deep drawn steel.Through a reasonable ratio of molten iron and scrap steel,and after LF furnace refining and RH furnace vacuum treatment,the P element content is controlled within 0.010%and the S element content is controlled within 0.005%,the level of non-metallic inclusions is controlled within 1.0 for Class A,within 0.5 for Class B and D inclusions,and 0 for Class C.By increasing the heating temperature of the billet,the starting rolling temperature can be increased from 1 100℃to above 1 200℃,and the final rolling speed can be increased from 6.1m/s to 7.2m/s.During the rolling process,the final rolling temper-ature can be increased from around 850℃to around 950℃.After rolling,the cooling speed of the rolled piece is re-duced by preheating the roller conveyor and covering the cooling bed with an insulation cover.There is no significant change in the tensile strength,elongation after fracture,and impact energy of the steel,and the actual grain size has changed from level 10 to level 8.The final produced round steel can meet the needs of the next step of deep process-ing.
deep drawing steelEBT electric furnace smeltingpuritymechanical propertygrain size
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