The prevention of surface damage is an important aspect during the production process of continuous cast products, since the deletion of these defects is associated with high costs. An economical production of high quality products therefore requires an optimal production process. This assumes better knowledge of mechanisms that lead to crack initiation – which represents a main goal of this research field.
Since 2007, research programs regarding surface crack phenomena stand in the focus of several K1-MET projects, Comet-K2 projects and company collaborations.
Amongst the efficient production of high quality products a special focus lays on the digitalisation of the continuous casting process. The goal is an online defect-risk model, which predicts the susceptibility for casting defects to appear and automatically adjusts the casting parameters to less critical conditions in order to prevent damage of the material.
Several experimental facilities and software products are used to deal with variable projects regarding the surface quality of casted and rolled products. A special focus lays on the IMC-B test. It presents a unique benchmark experiment which is used for investigations of the susceptibility to surface crack formation under continuous casting conditions. The definition of critical and non-critical testing parameters enable the steel producer to avoid or support conditions in the continuous casting machine in order to prevent surface cracks on the semifinished product. This saves costs, process capabilities and lowers the risk for a non-detected defect on a finished hot rolled product.
BHM – DOI 10.1007/s00501-019-00902-0
Our working group has 25 years of experience in research on “hot tearing” in continuous casting of steels. The phenomenon of hot tearing was – and is still today – investigated in collaboration with several company partners, among them Primetals Technologies and voestalpine Stahl.
The so-called “Submerged Split-Chill Tensile” – test is a unique experiment for the in-situ simulation of hot tearing. Based on experimental results and comprehensive investigations on cast slabs, hot tearing was identified as a segregation phenomenon. Thus, research on micro-segregation was intensified during the last years by applying state-of-the-art thermodynamics.
Our concept of hot tearing analysis includes
- the numerical analysis of solidification in casting machines,
- the metallographic characterization of hot tears and hot tear segregations in cast semis,
- the analysis of micro-segregation for even high-alloyed steel grades
- and finally the experimental characterization of deformation limits for nearly all conceivable steel grades.
This combination of methods is worldwide unique.
Experimental und numerical investigations on hot tearing during continuous casting of steel
Hot tear segregations as quality decisive factor for advanced steel grades