Based on the “Iiron and steel generic technology innovation center”, “The high strength sheet steel heat treatment line transformation” project with the joint effort of RAL and Ansteel has successfully mass produced S32101 ultra wide duplex stainless steel with the thickness of 8~40mm and width of 1500~3700mm. The steel plate enjoys stable performance and good flatness. The mass production of this product serves as an affirmation of NEU’s technology in “key equipment for large size high performance special steel plate heat treatment”. It is also a major breakthrough in the localization, autonomization of China’s third generation key equipment material for nuclear power, which has filled a gap in terms of width both at home and abroad.
▲Chart 1 roller hearth heat treatment furnace and quenching machine equipment
▲Chart 2 Production Process of Steel Plat
The “high strength sheet steel heat treatment lineproject”was launched in February, 2016. RAL was responsible for the equipment of high temperature roller hearth heat treatment furnace and multi-function roller quenching machine, as well as the development, supply and adjustment of the control system of the whole production line. To guarantee the supply of ultra wide steel plate used in key engineering equipment in China, the team members of the project worked hard and made scientific arrangements, and they had finished the design, manufacture, installation and oven baking in just 5 and half months, and began the trial run of the heat load. So far they have carried out the solution treatment on the ultra wide duplex stainless steel plate with the maximum width of 3700mm and thickness of 14mm.
Due to the features of corrosion resistance, long fatigue life, good yield strength and economy, S32101 has been widely used in the construction of equipment and structure in medium corrosion environment such as third generation nuclear power plant. But this type of steel is poor in plasticity, so there is great difficulty in its processing, and it poses extremely high demand for the heat treatment equipment and processing control technology. The high-temperature roller hearth furnace and roller quenching machine are the key equipment for heat treatment production. The technique developed by RAL for this project can be used for the production of special steel plate with a maximum width of 4000mm in high temperature(MAX.1200℃), high heating precision( ≤±5℃）, high surface quality and high flatness. In this way, the shortage of high quality heat treatment equipment for the high-end steel products such as ultra wide special stainless steel and nickel base alloy is solved.
Attachment: Domestic and International Supply of Wide Duplex Stainless Steel and Its Applications
Nowadays, the steady supply of wide duplex stainless steel used for nuclear power overseas is 3100 mm in width. In China, the central research institute of State Power Investment Corporation(SPIC) had successfully developed S32101 duplex stainless steel plate with a width of 3.5 meters in April, but it was only trial production with a small batch. In CAP1400 modular construction, if we can substitute the 2.6m steel with 3.6m steel in blending, a single nuclear power plant would save 300 meters in seam welding. For the best welder at present, he can finish 10 meters of seam welding in a day, which means saving 30 days in project schedule, and saving another 28 days in the follow-up ultrasonic wave scanning and penetrate testing stage. In this way, the manufacture cycle of the structural module in a single nuclear power unit can be shortened by almost 2 months, and the economic benefit brought by one day’s shortening of the cycle equals to 10.32 million. At the same time, fewer welding seams will reduce the risk of seeping or leaking during their service life, and greatly reduced the workload of checking-up. So the labor cost will be greatly reduced and the safety margin of the nuclear power plant will be improved. Prior to its localization, the ultra wide duplex stainless steel relied on imports and it was very expensive. The localization will reduce the cost of duplex stainless steel, which will directly reduce the construction cost of nuclear power plants.