Non-metallic Inclusions in HSLA Steel–Origin, Detection and Refractory Systems to improve Cleanness
HSLA steels need extremely low levels of tramp elements like P, S, H and Ot. During tapping the steel is de-oxidized with aluminum and in the secondary metallurgy sulphur (<10 ppm) and hydrogen (<1 ppm) are extracted. After tank degassing the steel is strongly Ca-treated by wire feeding to form CaS instead of MnS.Non-metallic inclusions in the steel and centre segregation with MnS are sinks for hydrogen which result in HIC (Hydrogen Induced Cracking). Therefore these steels ask for excellent oxide cleanness and S-contents of<10 ppm. Macro inclusions of > 50 μm are harmful for the product. These large inclusions are seldom and difficult to be detected. Small inclusions of<15 μm do no harm to the product. The origin of non-metallic inclusions is, roughly spoken, one third each of de-oxidation-/re-oxidation products, refractory and casting powder. Slag carry-over is mainly avoided by sensitive electronic devices.Slag covers and shrouding systems of the steel stream during the transfer of metal between ladle, tundish and mold are effective to avoid reoxidation. Systems to control the flow of steel in tundish and mold favor the floatation of inclusions and their even distribution in the strand.
Extra low contents of P,S and H. Extraction metallurgy Ca-treatment control of slag carry-over shrouding flow control separation of inclusions inspection systems.
DETTELA Heiko KLENNER Gerald CAPPEL Juergen WUENNENBERG Klaus
RHI-AG, 115007 Lianoing, Bayuquan, PR China RHI-AG, 1100 Vienna, Austria Cappel Stahl Consulting, 40667 Meerbusch, Germany steel consulting, 47249 Duisburg, Germany
国际会议
The 6th International Conference on High Strength Low Alloy Steels(第六届高强度低合金钢国际会议HSLA Steels2011)
北京
英文
389-395
2011-05-31（万方平台首次上网日期，不代表论文的发表时间）