Site specific control of crystallographic grain orientation through electron beam additive manufacturing

Materials Science and Technology - Tập 31 Số 8 - Trang 931-938 - 2015
Ryan Dehoff1,2, Michael M. Kirka1,2, William J. Sames3,4, Hassina Bilheux5, Anton S. Tremsin6, Larry Lowe1,2, S. S. Babu7,8,9
1Manufacturing Demonstration Facility, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
2Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
3Department of Nuclear Engineering, Texas A&M University, College Station, TX, USA
4Manufacturing Demonstration Facility, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Nuclear Engineering, Texas A&M University, College Station, TX, USA
5Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
6Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA, USA
7Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, TN, USA
8Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
9Manufacturing Demonstration Facility, Oak Ridge National Laboratory, Oak Ridge, TN, USA

Tóm tắt

Site specific control of the crystallographic orientation of grains within metal components has been unachievable before the advent of metals additive manufacturing (AM) technologies. To demonstrate the capability, the growth of highly misoriented micron scale grains outlining the letters D, O and E, through the thickness of a 25·4 mm tall bulk block comprised of primarily columnar [001] oriented grains made of the nickel base superalloy Inconel 718 was promoted. To accomplish this, electron beam scan strategies were developed based on principles of columnar to equiaxed transitions during solidification. Through changes in scan strategy, the electron beam heat source can rapidly change between point and line heat source modes to promote steady state and/or transient thermal gradients and liquid/solid interface velocity. With this approach, an equiaxed solidification in the regions bounding the letters D, O and E was achieved. The through thickness existence of the equiaxed grain structure outlining the letters within a highly columnar [001] oriented bulk was confirmed through characterizing the bulk specimen with energy selective neutron radiography and confirming with an electron backscatter detection. Ultimately, this demonstration promotes the ability to build metal components with site specific control on crystallographic orientation of grains using the electron beam melting process.

Từ khóa


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Materials Science and Technology

Tập 31 Số 8

931-938

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