The 3rd UK-China Steel Research Forum

Materials World magazine
,
1 Sep 2014
Steel with hydrogeninduced cracks<br>© Uwe Aranas

At the 3rd UK–China Steel Research Forum, Eoin Redahan found out about next-generation materials.  

The HIsarna process
Tata Steel is looking at a ton of ways to improve its products. The industrial behemoth is using powder metallurgy to make a highstrength yet highly formable steel, an abrasion-resistant steel for railways, and graded materials for better durability.

Perhaps the most interesting of Tata’s projects is the HIsarna pilot plant in IJmuiden, the Netherlands. The HIsarna process is said to enable the use of lower-grade materials in the ironmaking process. According to the company, coal and fine ore can be put directly into the ironmaking furnace, thereby eliminating two energy-hungry raw material processing stages – the production of coke from coal and the agglomeration of fine ore.

ODS steels
Oxide-dispersion strengthened (ODS) steels put their faces where other materials fear to clad – inside nuclear reactors. According to academic research and a fair dollop of hype, ODS steels boast hightemperature creep strength and excellent resistance to irradiation damage. To make these materials, researchers add aluminium, zirconium, titanium, yttrium or other nanoparticles to the steel, depending on the material characteristics required.

These nanoparticles are dissolved into a steel matrix using processes such as hot isostatic pressing and hot forging. According to the University of Oxford’s Professor Chris Grovenor, these steels have highly refined microstructures. However, he said industry has been slow to build on ODS research. ‘At some stage, industry has to be brave enough to make 10t of a material with these properties.’

Creeping, cracking hydrogen
Hydrogen embrittlement is another area that receives significant attention. High-strength steels tend to crack and fracture when exposed to hydrogen during processing or in corrosive environments, such as the sea. While steel professionals have known about this meddlesome mechanism for more than a century, they have struggled to control it.

Professor Harry Bhadeshia, of the University of Cambridge, explained, ‘Strong steels all suffer from hydrogen [embrittlement]. Any fool can make a strong material, but a better fool can make a strong material that resists hydrogen, fatigue and corrosion.’

The key, he said, is to create a material that stops hydrogen moving within the steel. ‘Aluminium atoms act as traps for the hydrogen atoms. It renders it immobile.’ Armed with this knowledge, Bhadeshia and his colleagues are developing aluminium-doped pipes for oil wells. Titanium carbides can also be used to trap hydrogen. The material chosen depends on the task at hand. As Professor Alan Cocks, of the University of Oxford, noted, ‘By treating steel in different ways, you can trap hydrogen in different ways.’  

Steel in numbers
69.3 million tonnes – China’s crude steel production in June 2014

1.04 million tonnes – the UK’s crude steel production during the same month

1.6bln tonnes of crude steel produced in 2013. The corresponding total in 1970 was 595Mt

70% of steel is manufactured using the blast furnace basic oxygen furnace route

200 steel-related researchers work for Tata Steel in the UK

4 China is the UK’s fourth largest scientific partner

Statistics taken from speakers’ presentations and the World Steel Association