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6578 |
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Wednesday, June 10, 2020, Hall G1 11:50 AM New Processes |
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Laser assisted cold spray deposition of high strength steels |
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Luke Brewer* / The University of Alabama, USA Dallin Barton / The University of Alabama, USA Venkata Bhattiprolu/ The University of Alabama, USA Clio Batali/ The University of Alabama, AL Gregory Thompson/ The University of Alabama, AL |
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This talk will present recent developments in the application of laser assisted cold spray (LACS) deposition to high strength, ferritic steels, and in particular alloys HY-80 and 4340. While austenitic stainless steels are readily deposited by the cold spray technique, much less work has been reported on the cold spray deposition of ferritic steels. Some recent reports have demonstrated the feasibility of cold spray of high strength ferritic-martensitic steels. To improve the performance of cold spray for these materials, we are combining a VRC generation III high pressure cold spray system with a Laserlines LDM4000 4 kW infrared laser (940 nm wavelength) to deposit gas atomized steel powders. This LACS approach was able to successfully deposit 4340 steel using helium as the carrier gas. The deposition efficiency increased systematically, from 45 to 70 percent, with increasing surface temperature from 500 to 950°C. We have also measured similar improvement in deposition using LACS for the oxide dispersion strengthened alloy Fe-8Ni-1Zr. In LACS-deposited 4340 steel, the substrate-interface quality is quite good and the porosity of LACS-deposited steel is <1%. An increase in ferrite grain size for deposition temperatures above the A3 temperature (>800°C) was measured for this alloy. In addition, microscale areas of oxidation were present, and they increased with increasing surface temperature. Similar measurements on HY-80 steel will be discussed, as will simulations of the LACS process using finite volume element techniques. |