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Based on the three-dimensional field of molten pool and twin-roll strip casting experiments, this work verified the cracking mechanism of the strip by establishing mathematical model and rolling experiments. The results showed that due to the instability of the thermophysical field of the molten pool and the inconsistency of kiss curve height, the newly solidified strip will undergo incompatible deformation through the rolling. The stress concentration will appear around the large reduction area and then form slip bands. When plastic strain exceeds the limit of the metal, the oblique cracks will appear in the slip bands periodically or completely penetrate the strip. In addition, tensile cracks could also be produced by incompatible deformation. Therefore, keeping the uniformity and stability of the thermal physical field in molten pool is the key factor to restrain cracks.

Based on CAFE theory and KGT model, the twin-roll strip casting mathematical model was established to solve the dendrite growth and solidification of T2 copper alloy in the molten pool. The influence mechanism of casting temperature, heat transfer, and other technological conditions on the microstructure of strip was analyzed. The results showed that the liquid metal formed 35 µm chilling layer after touching the rollers, and the layer was consisted of a high number of small and equiaxed crystals. Then some grains would appear close to the newly chilling layer, and grow toward the core of molten pool competitively. The dominant grains mainly grew along the 〈001〉 orientation into columnar crystals, and the rest grains that grew out of alignment were eliminated gradually. The number of grains declined, and the radius of columnar grains became coarsening. The Kiss point is a key factor for solidification structure, and the lower location of the Kiss point could limit the growth spaces of columnar crystals, which refined the grains.

The Beijing-Tianjin-Hebei-Shandong Region (BTHS Region) is a crucial area for China to achieve synergy between pollution reduction and carbon emissions reduction. The demand for coordinated emissions reduction through source control measures such as energy transition and industrial restructuring are becoming increasingly necessary owing to the limited emissions reductions potential of end-of-pipe control measures. An assessment of the emissions reductions potential through strengthening the end-of-pipe control in the BTHS Region, as well as the environmental and health co-benefits from accelerated energy transition and industrial restructuring, was conducted using scenario simulation analysis based on the REACH model. The results showed that the rapid implementation of the best available end-of-pipe control technologies in the BTHS Region would result in 3.3 μg·m -3 reduction in PM 2.5 concentration in 2035, but this would not be sufficient to achieve the PM 2.5 concentration control targets. Accelerating the energy transition and the industrial restructuring are necessary for the BTHS Region to achieve air quality standards, which would reduce the PM 2.5 concentrations by 6.3 μg·m -3 in 2035. The environmental and health co-benefits brought by the accelerated transition could partially or entirely offset the additional socio-economic cost (compared to that of the current policy efforts) of approximately 0.9%-2.5% of the total regional GDP in achieving the PM 2.5 concentration control target paid by the four provinces.