High- and ultra high-strength steels attain their strength from the precipitation of inter-metallic compounds, primarily the element of nickel (15-25%) or the secondary elements such as cobalt, molybdenum, and titanium. These low carbon steels, also called maraging steels, are known for superior strength without the loss of malleability.
In 2000, UltraLight Steel Auto Suspensions (ULSAS) undertook a study in the automotive industry to see how high- and ultra high-strength steel use in suspensions affected mass and cost savings. The results showed there was no compromise in quality of the product and significant mass reduction.
Automakers use these high-strength steels for parts such as:
• Twistbeam
• Strut and Links
• Pillars
• Crankshaft and Gears
Since these steels are light weight, the automobile industry can benefit from reducing the mass of its product to increase the fuel efficiency targets without compromising safety. Also, these steels are moderately corrosion resistant and resist hydrogen embrittlement, increasing the life expectance of these parts.
In order to create such high quality steels, steelmakers must monitor the inclusions present within the steel mix continuously. The high quality standards demand instrumentation that can perform under harsh circumstances and still produce accurate results. Aspex has responded to this demand with its Personal Scanning Electron Microscope (PSEM) and Metal Quality Analyzer (MQA) software.
The MQA uses the electron beam backscatter to scan areas of known inclusions, saving time by only further testing those areas where the backscatter is dark enough to show the presences of inclusions. The MQA then analyzes the size, shape, and elemental composition of the particles, all within the steel line, letting the manufacturer adjust the steel mix before it reaches the final stages of production.
By maintaining the strict process control needed to produce high- and ultra high-strength steels, the steelmakers provide the foundation for the automotive industry to mold these steels into quality products. Some companies, such as Ford, are redesigning their automotives to better protect passengers and increase fuel efficiency.
The Aspex PSEM with MQA software allows steelmakers to produce quality steel products by using advanced analysis of steel inclusions under strict inclusion-controlled circumstances. These steel products allow automakers to design light weight, high-strength parts, insuring passenger safety and quality automotives for their consumers. The MQA helps prevent costly remelts and consumable consumption by allowing the manufacturer to quickly and accurately adjust the steel mix, directly from the shop floor.
Aspex, http://www.aspexcorp.com/industries/metals.html
Wikipedia, http://en.wikipedia.org/wiki/Maraging_steel
American Iron and Steel Insitute, http://www.steel.org/AM/Template.cfm?Section=Press_Releases14&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=29425
Ford, http://media.ford.com/images/10031/Boron.pdf
