Application of 310S Austenitic Stainless Steel in Nuclear Power
As a clean and efficient power generation method, nuclear power has become an important strategic carrier to meet the national electricity demand, optimize the energy structure, ensure energy security, and promote sustainable economic development.
At the same time, it is also an effective way to reduce environmental pollution and achieve economic and ecological development. In recent years, my country’s nuclear power has developed rapidly, and the nuclear power equipment in use has continued to operate safely and stably. The annual cumulative power generation has increased by 6.6% over the previous year.
However, the development and utilization of nuclear power has brought huge social and economic benefits, as well as many safety issues. After the Fukushima nuclear accident, South Korea attached great importance to nuclear safety issues. The treatment method of high-level radioactive waste has become an important issue that needs to be solved urgently in the utilization of nuclear power, and it is also a key factor related to the sustainable power generation of nuclear energy.
The world-recognized and most reasonable radioactive waste disposal method is to conduct geological treatment of the solidified radioactive waste obtained after the solidification of the radioactive waste, so as to separate the high-level radioactive waste from the human living environment stably for a long time. Minimize or eliminate the impact of high-level radioactive waste on nature and humans.
The high-level waste storage tank is a special container for storing the solidified high-level waste. Vitrification of high-level radioactive waste is a treatment method developed earlier. It has been used in practical projects for more than 30 years, and the technology is relatively mature. It has been widely used in developed countries such as France, the United Kingdom, the United States, and Japan. my country is still in the experimental research stage, and the storage tank is made of 310S austenitic stainless steel.
In the actual welding of the tank body, it was found that the grains in the coarse grained zone of the welding heat affected zone (CGHAZ) were severely rough. This results in lower impact toughness, lower crack propagation work and higher brittle transition temperature of austenitic stainless steel CGHAZ. There will also be stress concentration, especially when the grain size is not uniform, which can easily limit the use and application of austenitic stainless steel.
Methods for Inhibiting Grain Growth in Heat-Affected Zone of Welds
At present, in practical industrial applications, there are three main methods for suppressing particle growth in the heat-affected zone of welds.
One is to adjust the welding process, that is, reduce the welding current and increase the welding speed to reduce the grain size of the welding heat affected zone, but this method greatly reduces the welding quality and welding efficiency.
The second is the phase change, that is, through heat treatment, the heat-affected wound of the weld undergoes a phase change and transforms into a phase with a relatively small particle size. Since the 310S austenitic stainless steel is completely austenitic from normal temperature to solid phase, there is no phase transformation, so the microstructure cannot be adjusted by the transformation method.
Third, alloying elements are added on the basis of the base metal, so that the second phase particles and fine particles are precipitated at the interface, which plays a role in fixing the grain boundaries. Therefore, it hinders the movement of grain boundaries. This method has strong applicability and obvious inhibitory effect. 310S austenitic stainless steel is a high chromium-nickel full austenitic stainless steel containing 25% Cr and up to 20% Ni, which maintains corrosion resistance and mechanical properties.
the waste storage tank mainly adopts the 310S austenitic system
Therefore, the waste storage tank mainly adopts the 310S austenitic system. Stainless steel. At present, the main grade of 310S steel of Baosteel Group and Taiyuan Iron and Steel Group in China is 06Cr25Ni20, and the US ASTM and UNS standard grades are 310S and S31008 respectively. The Korean KS standard grade is STS310S, and the EU BSEM standard grade. 1.4845 and Australian AS standard grades.