PNNL R & D ShAPE process to improve the application of automotive magnesium alloy parts
According to foreign media reports, the U.S. Department of energy's Pacific Northwest National Laboratory (Pacific Northwest National Laboratory, PNNL) developed a new extrusion technology (extrusion process) - assisted extrusion processing and shear (Shear-Assisted Processing and Extrusion, ShAPE), this technology is helpful to the automotive industry with magnesium alloy production structure, enhance the feasibility of the scheme.. because without the use of rare earth metals, can reduce the material cost. At the same time, the new technology also improves the structure properties of the material.
"The battle between steel and aluminum" or evolved into "steel, aluminum, magnesium, melee""
Improve fuel economy has become one of the major enterprises of the major target in the near future, because from the 2025 corporate average fuel economy (Corporate Average Fuel Economy, CAFE) the implementation of standards has been getting closer. Therefore, lightweight has become the preferred, half car prices for new lightweight materials, improve the fuel economy of the vehicle. To meet the requirements of the CAFE standard.
In the automotive industry, once fired the "battle of steel vs. aluminum", and now developed a new extrusion forming method (method of extrusion), or will make the magnesium material also joined the competition
In all metal structure, magnesium is 75% lighter than steel, 33% lighter than aluminum, is the fourth most common elements on earth, it ranks just behind the iron, silicon and oxygen three elements. Although the magnesium material is light and natural abundance (natural abundance) is large, but the car is difficult to magnesium alloy used in automobile parts, because of the use of the material with dysprosium (dysprosium), PR (praseodymium) and ytterbium (ytterbium) and other rare earth elements (rare-earth, elements) to enhance its strength.
Shearing assisted processing and extrusion
Engineers and materials scientists in the US Department of energy said that during the extrusion process of magnesium alloy by rotating mechanical friction and heat, the material softening, and then press it into the mold, making magnesium alloy bar and groove pipe, magnesium (magnesium channels). With the traditional type extrusion machine is different, the resistance heater technology no configuration scheme of energy consumption.
The team design of industrial processing and auxiliary shear extrusion machine and carry out a test run. The research team used the machine, using extrusion technology made of thin-walled circular tubes, with a maximum diameter of 2 inches, the raw material used for the mg Al Zn alloys AZ91 and ZK60A.
Chief researcher and Mechanical Engineer Scott Whalen said: "in the shear assisted processing and extrusion process, we obtained a highly refined metal micro structure, in some cases, even produce characteristic of nano structure. The higher the speed per minute, the particle is smaller, the higher the hardness of pipe production, its ductility (ductile) or (pliable) has better flexibility. In addition, the team can control the crystal structure of metal in the direction of the magnesium alloy energy absorption, making it comparable to aluminum"
Magnesium alloy billets with extremely soft state into the mold, and the rotating force of linear force due to the ShAPE process is applied at the same time. Therefore, compared with the traditional extrusion process, only the original 1/10 force to the raw material into the mold.
As the extrusion pressure is substantially reduced, if the technology is adopted, the enterprise will be able to enable small production machinery to reduce capital expenditure (capital expenditures) and operating costs
"Unlike industrial extruders, the ShAPE equipment provided by us eliminates the need to place bulky heaters around the magnesium alloy billets," Whalen said"
Magnesium material for realizing lightweight of automobile
According to the U.S. Department of energy report, magnesium components now accounts for only 1% of the total weight of conventional vehicles, and ShAPE machine, or to change the situation.
Whalen said: "many car companies without the use of magnesium alloy structure, there are two main reasons: the price and properties of magnesium material. At present, the manufacturer uses low cost aluminum production bumper and other components. If the process of our party, can strengthen the material properties of magnesium material, used to replace the use of aluminum, and no to add rare earth elements will not increase the cost"
Magna is working with PNNL to develop a low cost magnesium parts made of. The company developed the test of large pipe production facilities in Detroit, also provide authorization license PNNL ShAPE technology.