**9. Casting and Solidification**

The solidification of a metal is a complex and gradual process that is difficult to control. Niaz et al. [33] reported numerical predictions of the Horizontal Single Belt Casting (HSBC) process, which avoids multiple hot-rolling steps by directly producing a thin sheet. Results from an experimental rig were compared with findings from a CFD model, and the latter was applied to study non-uniformity and other undesired conditions, as well as means to address these, e.g., by appropriate design of the metal feeding system.

Precipitation behavior of inclusions was studied by both Wang et al. [34] and Li et al. [35], the former for titanium nitride (TiN) during solidification and the latter for chromium spinels in stainless steel slags. A systematic study was made to clarify the mechanism of TiN precipitation to guide the development of ultra-high strength grade steels. The stability of chromium in stainless steel slag was found to have a positive correlation with spinel particle size and a negative correlation with the calcium content of the spinel. However, both groups of authors stress that further experimental work and theoretical analysis are needed to understand the precipitation behavior of the inclusions to improve the quality of the finished steel.

#### **10. Rolling**

Most steel products are manufactured by hot rolling, because it is one of the most efficient plastic-forming processes. On the basis of comparative studies on the temperature distribution during hot plate rolling and rod rolling, Hwang [36] concluded that the temperature distribution and variation of a rod during shape rolling are different from those of a plate during flat rolling. The higher variation in effective stress of the rod along the circumferential direction induces a higher temperature difference of the rod. The same author [37] also investigated the effect of roll design on the strain distribution of the flat surface, lateral spreading, and the strain inhomogeneity of a flat-rolled wire, proposing a new strategy for fabricating high-quality flat-rolled wires through a cambered roll of a small radius.

Hu et al. [38] developed an optimization model for hot rolling based on the time-of-use (TOU) electricity pricing using a genetic algorithm. Jumps between adjacent slabs in width, hardness, and thickness were avoided by including penalties in the objective function. The method was verified on batch results from the hot rolling of 240 slabs of different sizes and was demonstrated to reduce the cost of power required for rolling.

Chen et al. [39] found that the hot working ability of a nickel-based GH4698 alloy markedly decreased under lower temperatures and higher strain rates in isothermal compressions: this alloy is extremely sensitive to thermal processing parameters and cracking may easily occur. An Arrhenius model was used to estimate the flow stresses and profiles for processing under various thermal conditions.

**Funding:** There is no funding support.

**Conflicts of Interest:** The authors declare no conflict of interest.
