Improving Steel Processing for Better Engines

[Guest_Jim_*]

There has been a great interest for a long time now to make cars more efficient and one way this is being achieved is by downsizing the engine. This can be a tricky tactic though, because the pressures and temperatures the engine components must endure increase. To continue downsizing and increasing engine power, harder steels must be made and researchers at Karlsruhe Institute of Technology have recently found a more efficient means of making such a steel.

Low-alloy steels contain less than five mass percent of metals other than iron and can be made to have a hard surface with a soft core. One way to process these steels is low-pressure carbonitration, which enriches the surface with carbon and nitrogen at temperatures between 800 and 1050 ºC, but at low pressure. The low pressure is necessary to limit surface oxidation but it also has the effect of making a more consistent hardness profile. Normally this process uses ammonia as a nitrogen donor and a carbon donor like ethyne or propane, but the KIT researchers found they could replace these two gases with just one. Methylamine (CH₃NH₂) and dimethylamine ((CH₃)₂NH₂) can both supply the carbon and nitrogen, which simplifies and accelerates the process. This is because the carbon and nitrogen are able to enter the material in parallel, and methylamine can also be used at higher temperatures, speeding up the process even more. Plus the gas is used better, so less is needed.

Now the researchers are working on optimizing the process and then bringing the process out of the lab and to the pilot scale.

Source: Karlsruhe Institute of Technology

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