Although China is the world’s largest steel producer, foil production was once dominated by Japan, Germany, and the United States, and China had to import it from these countries at a high premium.
The cost per gram was about the same as gold, state media reported.
According to an analysis conducted by China Merchants Securities last year, China’s steel production is concentrated in low- to mid-priced products.
But thanks to huge national investments in technological innovation, the country has transformed from a purchaser to a producer of high-grade steel foil in less than a decade.
In 2020, state-owned Taiyuan Steel Corporation (Tisco) became the first Chinese company to roll out 0.015mm steel foil. According to domestic media reports, it is the world’s thinnest.
Currently, Qingtan, which just rolled out its first 0.05mm thin foil in 2021, has also started mass production, boosting its domestic sector.
In its post, Qingtao also claimed that this is the first stainless steel foil manufactured in China using only domestic equipment.
Steel foil, known in China as “hand-pulled steel” for its ability to tear like paper, is used in a wide range of products, including cutting-edge flip phones.
For example, one of the biggest challenges in producing an affordable, high-quality foldable phone is the foldable screen.
Liao Shi, Tisco’s head of research and development, said ultra-thin steel foil is the key.
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The use of thin steel foil could extend the lifespan of such smartphones from 50,000 to 300,000 cycles, Liao told Chinese network CGTN.
Earlier this year, Tisco began mass production of steel foil for delivery to domestic companies. According to China’s state-run People’s Daily, the foil will be used in high-tech products such as flexible OLED screens for smartphones.
In the first two years after Tisco began producing 0.02mm foil, the company experienced an 80% increase in revenue. According to Science Times, its exports increased by 70% year-on-year in the first quarter of 2020.
According to Tisco, a ton of stainless steel processed into foil can be sold at a profit of 300 to 500 percent more than the cost of the raw stainless steel.
Last year, the Asia-Pacific region – China, Japan and India – dominated the stainless steel foil market and was the “most lucrative region”, according to an analysis by market research firm Transparency Market Research.
Steel foil is used in a wide range of applications, including aerospace components, chips and circuits, insulation, pipelines, solar panels, industrial processing equipment, and surgical equipment.
Aerospace parts where the foil is used include hydraulic tubing, high-pressure seals and nozzles, according to U.S.-based Ulbrich Stainless Steels & Special Metals.
Typically, 600 mm wide sheet foils are produced through the process of ‘cold rolling’. This involves passing a very long sheet of stainless steel through a series of rolling mills under high pressure and winding the finished product into coils.
“There is no other country” that can mass-produce ultra-thin steel sheets with a width of 600 mm, Liao told state media.
In the early days of Tisco’s development of ultra-thin foil, the sheet sometimes slipped and broke on the rolling mill. State broadcaster CCTV reported that the company needed several trials to perfect its production system.
In 2018, after two years of development and over 700 tests, Tisco announced that it had successfully deployed Japan’s first 0.02mm foil.
According to China Daily, import prices have halved as China has started meeting domestic demand.
“We are one of the few companies in the world that can produce mild steel foil with a thickness of less than 0.02 mm,” Tisco’s steel foil production manager Wang Tianxiang told the state newspaper.
According to a report by CGTN, Liao said that slightly thinning the thickness from 0.02mm to 0.015mm could “increase battery capacity by 17%.”
Different grades of stainless steel foil, made from alloys of various combinations of iron and other metals, are used in different industries.
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Another Chinese steel foil manufacturer, HZW Technology, said the material is lightweight, flexible yet strong, and more resistant to high temperatures and corrosion than aluminum or copper foil.
In China, steel foils over 600mm wide are also used for building insulation, with the sheets able to trap heat in the winter and keep it outside in the summer, HZW said.
HZW also listed a wide range of other uses for its various grades of steel foil, including the manufacture of engines, agricultural machinery, automobiles, kitchen equipment, and oil refinery equipment.
Duan Haojie, Tisco’s research and development director, told Chinese news site The Paper that the company will continue to strive to produce thinner steel foil.
“We can probably get to 0.012mm,” he said.