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The MIDAS Technique for Detection of Macroscopic Inclusions in CC‐Material: Fundamentals and Practical Applications
Author(s) -
Jacobi Hatto F.
Publication year - 2005
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.200506061
Subject(s) - ladle , materials science , metallurgy , ultrasonic testing , ultrasonic sensor , continuous casting , non metallic inclusions , microstructure , welding , recrystallization (geology) , mechanical engineering , engineering , acoustics , paleontology , physics , biology
In this paper twelve years of experience with MIDAS (Mannesmann Inclusion Detection by Analysing Surfboards) testing for macroscopic cleanness of continuously cast steel is reviewed. MIDAS has replaced the previous slime extraction method, which was technically competitive, but too time‐consuming and costly. MIDAS is indispensible for operational trials in the steelworks. The results correlate with quality demands of the final product. The main feature of MIDAS is the flat cross‐rolling procedure transverse to the casting direction. The microstructure of the steel is grain refined by recrystallization. The inclusions are rolled flat, which is advantageous for the ultrasonic inspection. The ultrasonic frequency is 10 MHz and the scanning steps are Δx = Δy = 1 mm. A test plate of dimensions 400 mm x 300 mm is thus scanned within 15 min. MIDAS‐test results in combination with metallographic and EDX‐analysis of the macro‐inclusions enabled a deeper understanding of the fundamentals of ladle metallurgy, metal‐slag reactions, emulsification, agglomeration and coagulation, reoxidation, fluid flow pattern, precipitation and separation. On the basis of MIDAS results CC machines have been revamped and ladle metallurgical facilities and processes optimized. Steel grades with high cleanness demands, e.g. mechanical tubing, HIC line pipe, roller bearing steel, as well as automotive sheet can be produced at lower cost and higher yield to the satisfaction of the customers.