In 2005, Hyundai Steel became the first company in South Korea to develop anti- seismic steel with high-strength, energy absorption and shock resistance. The recent successful development of the world’s first refractory anti-seismic steel was another landmark achievement. The Arc Furnace Development team will continue to pioneer new frontiers.
Steel serves as the foundation of many industries including automobiles, construction and machineries. Thanks to its wide ranging applications, there is constant demand for new steel materials with desirable properties. Rebars and section steels, which are used in construction, are important in ensuring safety. Recently, there has been an increase in natural disasters including earthquakes. This makes the development of steel capable of withstanding external shocks a must for international steel companies. The focus is not just on increasing strength but also on developing advanced products which reduce slippage or prevent rust. Hyundai Steel has been striving to develop new steel materials and products which can make ever higher skyscrapers, which are also stronger and safer.
High-strength advanced steel materials
High-strength anti-seismic section steel
Section with reduced yield ratio* for increased seismic resistance
Refractory anti-seismic section steel
Multi-purpose section steel with reduced yield ratio and enhanced heat resistance
High-strength anti-seismic rebar
Reinforced rebar with high plasticity* for strong seismic performance
Cryogenic rebar
Rebars created to minimize brittle fracture* in extremely low temperature
* Yield ratio: A ratio calculated by dividing yield strength (the stress at which a specific amount of plastic deformation is produced) by tensile strength (a measurement of the force required to pull something to the point where it breaks). High yield ratio means high resistance to deformation.
* Plasticity: A non-reversible change of shape in response to applied forces.
* Brittle fracture: The sudden, very rapid cracking of materials under stress with little plastic deformation.
For value beyond iron
Q. Internal steel companies are competing fiercely through M&As. What is the latest in steel materials research?
Leading steel companies have wide-ranging products in their portfolios. This is because it has become important to meet wide-ranging customer demands in terms of thickness, size, shape and strength. At the moment, increasing strength and multi-purpose functionality are the two main trends in R&D. Higher strength section steel can make higher skyscrapers possible at reduced cost. In terms of functionalities, anti-seismic, refractory and cryogenic steels for special applications have become important.
Q. What are the types of advanced products that the Electric Arc Furnace Development team has recently developed?
Electric arc furnace is used to manufacture section steels and rebars, which are used for construction application. We developed refractory anti-seismic section steel and cryogenic rebar certified for LNG storage tanks, which won the grand award of 2019 from the company.
Since ”Engineering the future beyond steel” is the company’s vision, we are striving to create materials that go beyond the conventional image of steel that people have.
Q. It is well-known that Hyundai Steel is a leader in the anti-seismic steel market but it has a new ”refractory” property, what is it?
For a long time South Korea was a country which had little reason to concern itself about earthquakes. However, this all changed with the strong earthquake which took place in Gyeongju in 2016. Rebars and steel beams are the bones of buildings and should stay hidden but these were exposed during this earthquake.
The earthquake demonstrated that structural collapse is a real danger but greater damage is generally caused by fire. Fire can lead to suffocation and also weakening of steel structure. We realized that there was a need for the development of steel material which is strong enough to withstand earthquakes and that is also resistant to fire. The refractory anti-seismic section steel we developed is the world’s first and has a maximum load of 355MPa. It can withstand up to 36kg of weight per 1mm and maintain more than 67% of its yield strength at temperatures of up to 600℃, reducing the chance of the building collapsing. The yield strength of conventional steel products generally falls below 30% when they are heated beyond 350℃.
We began R&D for refractory anti-seismic steel in 2016 as a leader in the government funded ”Industrial Materials Core Technology Development project”. The project is scheduled to be completed by 2020 and we are working to develop larger-sized 420MPa class refractory anti-seismic steel products before the end of 2019. As buildings are becoming taller and larger, the use of refractory seismic steel not only improves safety but reduces the use of insulation materials and construction time, which in turn leads to reductions in cost.
Q. What is cryogenic rebar? It sounds like it has a special application.
When we began development in 2016, the supply of cryogenic rebars was 100% dependent on import from ArcelorMittal, the world’s largest steel maker. Cryogenic rebars are used for the external walls, of LNG tanks which are made of concrete and rebar. When there is a leak in an LNG tank, the external wall is exposed to -190℃ LNG which could lead to the brittle fracture of rebars in the external walls.
Our market research revealed that a rapid growth in LNGtank construction was underway and we decided that the development of cryogenic rebar had the potential for significant profit and market opportunity worldwide.
We struggled at first when we began the development work. We experimented with metallographic methods, trying to keep the use of alloy at a minimum and to control the microstructure. After a lot of trial and error, we were able to successfully produce Cryogenic rebars for LNG tank, and happily won an internal award for this achievement. The cryogenic rebar we developed is capable of withstanding -165℃ before brittle fracture, while thresholds for conventional cryogenic rebars is -40℃. Currently, the demand for cryogenic rebars is limited to LNG tanks. We plan to make an effort to pioneer new applications in building construction in extremely cold regions.
Q. What is the biggest challenge in developing new materials? Any special considerations?
The construction industry has a conservative attitude toward new materials because unimaginable losses could be incurred when a building collapsed for example. New materials also need to be cost competitive to be used widely. Furthermore, it is also important for construction companies to have a good understanding of the factory as well. As a result, it is a big challenge to win the support of construction companies even if a new material is developed successfully. Hyundai Steel began development of anti-seismic steel in 2004 and launched an antiseismic steel brand ‘H CORE’ in 2018. We are working hard to market our H CORE products to consumers and construction companies who are unfamiliar with anti-seismic steel products.
Standard certification for new materials takes a significant amount of time. If the product has never been manufactured in the country, the manufacturer needs to study certification methods. We designed jig for extreme low temperature testing and traveled to Luxemburg where the one and only testing center capable of carrying out the cryogenic rebar test is located. It is not enough to develop good materials with improved properties but one must also predict industry trends and focus on the development of materials that could be commercialized in the future.
Q. What kind of new projects is the Electric Arc Furnace Development team preparing to take on?
Our current priority is completing the development of 420MPa class refractory anti-seismic section steel. Developing section steel for maritime application is also a top priority. We are focusing on making it capable of withstanding low temperatures and repeated shocks from ocean waves. We are aiming to achieve multiple desirable properties in the product and to make a leapfrog improvement to achieve over 1GPa in strength. It might take some time but we want to eventually develop new materials that will give us first mover advantage.
