With the continuous growth of the world economy and energy consumption, natural gas, as high-quality and efficient energy, is widely used in various fields. The consumption of LNG (liquefied natural gas) in China is now increasing at a rate of 10% per year and small in LNG volume. It is convenient for economic and reliable long-distance transportation and is stored in the normal pressure LNG storage tank. However, the LNG storage tank is a composite multilayer structure, the inner tank is welded by the 9%Ni steel plate, the concrete close to the inner tank is made of low-temperature steel, and the outer concrete is made of ordinary steel, HRB355, and HRB400. Therefore, low-temperature reinforcement for inner concrete requires not only high strength and good toughness at low temperature but also high resistance to defects.
According to the characteristics of water cooling technology of low-temperature steel bar, the Anhui University of Technology scholars use the field measured data and combine the theoretical analysis to obtain the convective heat transfer coefficient in the water cooling process of different sizes of low-temperature steel bars. The cooling process of low-temperature steel bar was studied by MSC Marc finite element software and field trial production. The effects of technological parameters such as cooling water flow rate, final rolling temperature and water penetration time on the temperature field and microstructure evolution of low-temperature steel bar were studied. The simulation results show that: When the cooling water flow rate is 120m3/h, the core of the steel bar begins to have a pearlite transformation. When the cooling water flow rate is 400m3/h, there is no ferrite transformation in the core of the steel bar. When the cooling water flow rate is 160 ~ 200m3/h, the microstructure obtained is acicular.