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http://www.youtube.com/watch?v=rCfV5TCjIl0[/youtube]
Pretty neat stuff actually. 1.2 GPa of tensile strength for sheets is impressive. I did some digging around on Nippon Steel's site since they developed the steel for Nissan. I'm not sure what alloys are being used in the steel, but the structure of the metal is what's being controlled tightly to produce such a high tensile strength. The new steel falls under NS's dual phase category which is basically changing the micro-structure by applying specific cooling techniques during a controlled hot roll. NS started using dual phase micro-structures in oil pipelines years ago, it just looks like they were able to scale it down to the thinner 1.6mm thickness of the sheet steel. The NS data sheet lists dual phase sheet metal's primary uses for energy absorbing items such as bumpers and structures.
The only thing I'm missing here is how this steel is lighter. I know more advanced steels can be lighter than less refined steels, so without knowing what alloy additives are in the steel, it's really hard to know just exactly why this steel is lighter than more traditional steels. It's more than likely chromium as that's always a safe bet to see put into steel. I saw one of their high tensile pipe steels had 23% chromium in it. But to put it in perspective, NS's data sheets don't list different mass specs for rolls based on type of steel. The mass differences are based on sheet thickness.
James is correct on the rust issue. Iron is going to rust no matter what. You can add all the carbon and chromium you want to iron when you're making steel, but it's going to rust. You can dip it in zinc, but that will eventually wear away and you'll get rust. Auto makers have gotten really good at developing coating techniques to fully protect the steel to reduce rust. If you're asking this because of older Datsun and Nissan tendency to rust, that was due to poor protection techniques. I mean, who uses a body filler that allows moisture in so it can sit next to the metal?
Bubba, who knows how this will impact price. Nippon Steel doesn't list their price per coil, but they probably do pricing based on contracted quantities. So as Nissan rolls more of this steel into their production line, the price on their end will go down. And since it can be used on existing tool and dies, Nissan doesn't have to pay to re-tool. More than likely, the end price points won't budge much. But we'll see on that.
I would love to see some of this stuff make it into older cars, but let's be realistic there :P
