In 1967, in order to further reduce the height of the casting machine, two ultra-low head slab continuous casting machines were built in Germany. One slab continuous casting machine at the Uss/Gary factory centralized the sliding nozzle of the tundish, automatic pouring and mold level control, and bending and straightening with liquid core.

In addition, technologies such as hydraulic driven crystallizer vibration, hydraulic shear machines, and tundish heating have also been developed. American Olson proposed progressive bending straightening technology, while German Mannesmann Company adopted immersion nozzle casting technology. There have also been fully continuous casting steel plants and special-shaped billet casting machines for I-beams.

1970s: Oil Crisis Promotes High Speed Development of Continuous Casting

The energy consumption of the continuous casting process is only about 10% of that of the mold casting and primary rolling process. Therefore, the two global oil crises in the 1970s accelerated the development of continuous casting.

The new continuous casting technologies that emerged during this period include automatic control of mold liquid level, porous immersion nozzle, multi-stage mold, electromagnetic stirring of mold, free guidance of casting billet, secondary cooling dense guide roller and combination roller, soft reduction of casting billet with liquid core, sliding nozzle of tundish, argon blowing of tundish stopper, protection of steel flow in ladle, and induction heating of tundish. During this period, Japan utilized technologies such as vacuum treatment and electromagnetic stirring to produce quasi boiling steel, thereby creating conditions for full continuous casting.

The 1970s was also a decade of accelerated development of continuous casting in China.

Phase 4 (1980-1990s)

The popularization, optimization, and rapid development stage of conventional technologies

By the late 1970s, continuous casting technology had matured, indicating that continuous casting was used in most steel industrial production and could replace mold casting. Promoting continuous casting and increasing the continuous casting ratio is the mainstream in the metallurgical industry. Taking Germany as an example, the continuous casting ratio was 41.3% in 1980, 91.3% in 1990, and 96.3% in 1999. During the same period, it was 6.2%, 23.2%, and 77.6% in China, respectively.

In the 1980s, due to the high construction cost and low efficiency of vertical continuous casting machines, they were gradually replaced by arc type continuous casting machines (crystallizer arc type), and ultra-low head and horizontal continuous casting machines emerged. Low water head, low construction cost, low static pressure of molten steel, and few cracks and defects in the casting billet, but its disadvantage is asymmetric solidification. Ultra low head and horizontal continuous casting machines, including arc continuous casting machines, are not conducive to the removal of inclusions.

With the increasing demand for materials and quality requirements, especially for automotive plates, deep drawn steel, pipelines, ship plates, etc., the demand for clean steel has driven the optimization of continuous casting machines.

The straight arc continuous casting machine, represented by VAI, has gradually become the mainstream model for slab continuous casting, with ultra low head and horizontal continuous casting machines gradually withdrawing from the stage.