Engineers in China are producing ultra-thin stainless steel sheets that once cost as much as gold to import – breaking a previous reliance on other countries to provide the product.
Tsingtuo Group announced it had successfully rolled out “steel foil” of just 0.015mm (0.0006 inch) thickness, equal to a quarter of the thickness of a sheet of paper or one-third that of a strand of human hair. stainless uses
Their “hand-torn steel” was the thinnest possible in the world, the privately held firm claimed in a post on their official WeChat social media page last month.
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China’s creation of a domestic industry for high-end ultra-thin stainless steel sheets – called steel foil when they are less than 0.05mm thick – began only a few years ago.
Despite China being the largest producer of steel worldwide, foil production used to be dominated by Japan, Germany, and the United States, from whom China had to import at a high premium.
The per gram cost was roughly the same as that of gold, according to state media reports.
Steel production in China has been focused on low to mid-end products, according to an analysis done last year by China Merchants Securities.
But in less than a decade, the country has gone from buyer to producer of high-end steel foils, thanks to huge state investments in technological innovation.
In 2020, state-owned Taiyuan Iron and Steel Company (Tisco) became the first Chinese company to roll out 0.015mm steel foil, which domestic media reports said was the thinnest in the world.
Now Tsingtuo – which only rolled out its first 0.05mm thin foil in 2021 – has also started mass production, boosting the domestic sector.
In its post, Tsingtuo also claimed it was the first stainless steel foil produced in China using only domestic equipment.
Steel foil, called “hand-torn steel” in China because of its ability to rip like paper, is used in a vast array of products – including cutting-edge foldable phones.
For instance, one of the biggest challenges in producing affordable, high-quality foldable phones is the folding screen.
Liao Xi, head of research and development at Tisco, said ultra-thin steel foil was key.
The use of thin steel foil could increase the lifespan of such smartphones from 50,000 to 300,000 folds, Liao told Chinese network CGTN.
Earlier this year, Tisco began mass producing steel foil for delivery to domestic companies. The foil will be used for hi-tech products, including flexible OLED screens for smartphones, according to China’s official People’s Daily.
In the first two years after Tisco began producing their 0.02mm foil, the company experienced a revenue growth of 80 per cent. In the first quarter of 2020, their exports increased by 70 per cent year on year, according to Science Times.
According to Tisco, when a tonne of stainless steel is turned into foil, it can be sold at a profit of 300 to 500 per cent more than the cost of stainless steel before processing.
Last year, the Asia-Pacific region – namely China, Japan and India – dominated the stainless steel foil market, and was “the most lucrative region”, according to an analysis by the market research company Transparency Market Research.
Steel foil has a broad range of applications, including aerospace components, chips and circuits, thermal insulation, pipelines, solar panels, industrial processing equipment and surgical equipment.
Aerospace components where foil is used include hydraulic tubing, high-pressure seals and nozzles, according to the US-based Ulbrich Stainless Steels & Special Metals.
The foil – usually in sheets measuring 600mm across – is produced through a process of “cold rolling”. This involves very long stainless steel sheets being passed through a series of rolling machines under high pressure, with the finished product then wound up in coils.
“No other country” is able to mass produce super thin steel sheets that are also 600mm wide, Liao told state media.
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In the early days of Tisco’s development of ultra-thin foil, the sheets would sometimes break after slipping on the rolling machines. It took the company several trial runs to perfect the production system, state broadcaster CCTV reported.
In 2018, after two years of development and over 700 trials, Tisco announced that it had successfully rolled out the country’s first 0.02mm foil.
Import prices were halved as the country began to meet demand domestically, according to China Daily.
“We are among the few companies in the world capable of producing soft steel foil of 0.02mm or thinner,” Wang Tianxiang, steel foil production manager at Tisco, told the state-backed paper.
Liao said a small reduction in thickness from 0.02mm to 0.015mm could “enhance battery capacity by 17 per cent”, CGTN reported.
Different grades of stainless steel foil, made of alloys with varying combinations of iron with other metals, are used in different industries.
HZW Technology, another Chinese steel foil maker, said the material is lightweight and flexible but strong, with higher resistance to high temperatures and corrosion than aluminium and copper foil.
In China, steel foil wider than 600mm is also used in thermal insulation for buildings, as the sheets can trap heat in the winter and keep it outside in the summer, HZW said.
HZW also listed a wide array of other uses for different grades of steel foil, including the production of engines, farming equipment, cars, kitchen appliances, and petroleum refining equipment.
Duan Haojie, director of Tisco research and development, told Chinese news site The Paper they would continue trying to make thinner steel foils.
carbon steel sheet metal “We can probably reach 0.012mm,” he said.