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Programme nominated for the Innovation of the Year Steelie Award 2023

Fe-Ni-based alloy wide and heavy plates are in large-scale demand from the rapidly developing worldwide photovoltaic (PV) industry and are designed to solve constraints, such as limited product size, low production efficiency, low qualification rate of ultrasonic tests, low yield and so on.

Compared with the currently widely used die casting and non-commonly used vertical continuous casting processes, in 2022, TISCO originally put forward innovative schemes, i.e. alloy N08810 being cast to 200mm large slabs with wide vertical bending continuous casting and vacuum sealing welding bonding to thickness
400mm billets process, and then rolled into 97mm of thickness wide heavy plate with unit weight of 13 tonnes; as well as alloy N08120 being cast to 200mm large slabs with wide vertical bending continuous casting process, and then rolled into 67mm wide heavy plate with unit weight of 8 tonnes.

In both schemes, the plate weight and width enjoy a leading position globally. The innovative solutions reduce the number of welds in poly-crystal silicon reactors, cut the consumption of expensive welding materials, lower the emissions during welding, and realise the short-process manufacturing of Fe-Ni-based alloy wide heavy plates.

The energy consumption per tonne of steel and the emission intensity to air are reduced by about 9% respectively. Within 2 years of mass production, nearly 20,000 tonnes of wide heavy plates were delivered to more than 100 poly-crystal silicon reactors, which produced poly-crystal silicon for the PV industry that reduced CO2 emissions by about 1 billion tonnes per annum compared with coal-fired power generation industry.

Compared with the die casting process, the new schemes improve yield by about 18%, the qualification rate by about 46%, and shorten the product delivery cycle from nearly 3 months to less than 2 months. The traditional operation time of the die-casting process applied by other suppliers is generally about 100 days due to the life limit of the ingot mould, while the innovative process scheme can realise quasi-continuous operation.

The Fe-Ni-based alloy wide heavy plate produced with the new scheme has better ultrasonic test results, improved high-temperature performance and more uniform grain size.

Besides being widely used in poly-crystal silicon reactors in the PV industry, the plates have also been applied extensively in chemical and environmental protection industries, such as PVC reactors and metallurgical waste acid regenerative roasters. The project has achieved outstanding social and economic benefits and contributed considerably to sustainable development.