Mönchengladbach, Zürich, October 18, 2018

Casting and rolling technology for the production of demanding SBQ steel grades

Shandong Laigang Yongfeng Steel Corporation (YONGFENG), operates as a subsidiary of YONGFENG Group Ltd., based in Dezhou, P.R. China. YONGFENG as a private company has placed an order for two five strands continuous casting machines to SMS Concast and one TMbaR mill from SMS group.

The new equipment will be part of a capacity conversion program, where a new minimill with electric arc furnace (EAF) is intended to replace the existing production facilities with state-of-the-art technology. The new plant will produce 870,000 tpy of a large variety of demanding high-quality SBQ steel grades including bearing steel out of continuous caster CC#1. The continuous caster CC#2 will be dedicated to rebar grades and is aimed to cast 1,000,000 tpy. The 165 mm sq. billets produced will be further transformed into bars by the new TMbaR rolling mill. This includes straight bars with diameters between 8 and 25 millimeters to be rolled at a maximum speed of 45 meters per second and bar-in-coil in diameters ranging from 8 to 32 millimeters to be rolled at a maximum speed of 35 meters per second.

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Contract signing between Mr. Shao Changtao General Manager (Yongfeng Group Ltd.) and Pierpaolo Rivetti, Deputy EVP Sales & Marketing SMS Concast
Tailor-made continuous casting machines for high productivity

The special design of the two continuous casters allows a great flexibility in production planning together with a very high strand productivity in the area of 750 kg/min by means of the proven SMS Concast-developed INVEX® mold. Due to its maximized cooling symmetry INVEX® provides for higher casting speeds allowing the possibility of direct rolling for rebar grades which need a suitable temperature at the hot charge roller table.

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The CONDRIVE is one of the special products that has been included in the new caster design. It’s the newest electric oscillation drive that grants the functionality of mold oscillation without the hydraulic system hassles in terms of maintenance and piping. Its innovative torque drive enables online adjustment of the amplitude, frequency and oscillation profile independently, thus allows optimized settings for every steel grade

Other special features have been implemented to increase the machines safety, productivity and efficiency: cartridge-type mold assembly for higher machine availability, switch between full water and air-mist cooling is performed in seconds for section-independent zones to reduce downtimes, stainless steel piping is considered for machine durability – these are just some examples of the accurate project principles the machines have been designed with.

SMS group´s TMBaR mill (thermomechanical rolling of rebar) - One step ahead

Besides the two five strands continuous caster Yongfeng is going to install a new TMBaR mill with an high-speed rolling area for thermomechanical rolling of rebar, including two six-stand MEERdrive® finishing blocks, cooling and equalizing lines, a high-speed outlet consisting of a two-strand HSD® (High-Speed Delivery) system with dividing shears and pinch roll unit as well as a VCC® (Vertical Compact Coiler) system for coils weighing up to five tons. With SMS group’s TMbaR mill, it is possible to produce fine-grained final products while reducing the content of expensive alloys in the billets.

Thermomechanical rolling is a forming process in which final reduction is carried out within a defined temperature range leading to specific properties of the rolled stock. Thus, sufficient capacity for cooling and equalization has to be provided in the plant design. The lower rolling temperatures (750 to 820 degrees Celsius) require higher rolling forces and consequently wire rod blocks capable of sustaining very high loads. Under these rolling conditions, grain sizes that in conventional rolling would typically range between ASTM 8 and 10 can be improved to ASTM 12 with thermomechanical rolling.

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Handshake after contract signing between Mr. Shao Changtao General Manager (Yongfeng Group Ltd.) and Benjamin Keim, General Manager Long Products SMS group China

Key components of the SMS group TMbaR technology are a loop line with water boxes for controlled cooling and equalizing and a MEERdrive® finishing block. Besides its rigid design, which allows rolling forces so far unattained in the market, the MEERdrive® block is equipped with a single drive which provides the flexibility required to optimally control recrystallization after rolling.

Integrated process control philosophy

Fully integrated PLC for completely automatic operation of the entire plant for both the SMS Concast continuous caster and the TMbaR rolling mill as well as SMS group’s specific process control system for caster (level 2)   integrate metallurgical models and the process control philosophy and production strategy.

Thus, also the most stringent quality issues for the most demanding steel grades can be achieved when combined with a superior mechanical design.

Additionally, the supervision of erection and commissioning will be supplied for the equipment delivered by SMS group.

Right tools for challenging steel grades

With this new investment Yongfeng puts its trust in the long-standing experience of SMS group and its superior technology for challenging steelgrades. It will allow Yongfeng to respond better and faster to new market demands, achieve improved material properties, efficient production and save on alloys and operating costs.

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The high-speed outlet consists of a two-strand HSD® (High-Speed Delivery) system with dividing shears and pinch roll unit as well as a VCC® system