China made the world's largest seamless integral stainless steel ring forging

On March 12, the world's largest seamless integral stainless steel ring forging was successfully rolled by using the metal building forming technology developed by the Institute of metals, Chinese Academy of Sciences.

According to the Institute of metals, Chinese Academy of Sciences, the ring has a diameter of 15.6 meters and a weight of 150 tons. For the first time, it has realized the hierarchical construction and forming of 100 tons of metal billets. It is also the largest diameter and weight forged stainless steel ring in the world.

With the entrustment and support of CNNC, the Institute of metals, Chinese Academy of Sciences has set up an industry university research team and developed a 15.6m diameter ring forging in Shandong YILAITE Heavy Industry Co., Ltd. with the application of TISCO's high-purity continuous casting slab. Its characteristics are no weld on the whole, high degree of homogenization and good microstructure uniformity. The giant ring will be applied to the fourth generation nuclear power units in China, and its successful development will effectively guarantee the implementation of major equipment in China's nuclear industry.

As the core component of the fourth generation nuclear power unit in China, the support ring is not only the boundary and safety barrier of the pressure vessel, but also the "backbone" of the whole reactor vessel, which bears 7000 tons of weight in structure. In the past, this kind of heavy forgings were manufactured by multi-stage billet welding in foreign countries, which not only has long processing cycle and high cost, but also has weak material structure and performance at weld position, which has hidden danger to the operation of nuclear power units.

After more than ten years of hard work, the researchers of Institute of metals, Chinese Academy of sciences have developed the original metal construction forming technology, revealed the healing mechanism and microstructure evolution mechanism of the construction interface, broke through the limitation of the idea of "making large from large" for large forgings, developed a series of key technologies such as surface activation, vacuum sealing, multi-directional forging, hierarchical construction, integral ring rolling, and completely eliminated the multi-layer defects The interface between the metals makes the position of the interface between the support ring forging and the base metal completely consistent in composition, microstructure and properties, realizing the new processing and manufacturing of "small to large", greatly improving the quality and reducing the manufacturing cost.

The technology has been evaluated by many academicians and experts as a transformative innovation in the field of large component manufacturing, and has been applied in hydropower, wind power, nuclear power and other fields. It has played an important role in promoting the rapid development of high-end equipment in China and ensuring the independent and controllable core materials of major equipment.