The Effects of Post-processing in Additively Manufactured 316L Stainless Steels
- PDF / 5,984,151 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 13 Downloads / 220 Views
ADDITIVE manufacturing (AM) is a process in which material is deposited layer by layer to build up a three-dimensional object.[1,2] This facilitates or enables the rapid production of prototype geometries and complex morphologies, making AM an attractive process for the production of low volume parts and novel complex shapes. Additive manufacturing can be used on a variety of materials including polymers, ceramics, and metals, and includes many different manufacturing techniques.[1–6] The current study is on AM builds of 316L stainless steel made by laser powder bed fusion. The 316 family of stainless steel alloys exhibits excellent corrosion resistance, particularly in seawater, and the 316L variant has enhanced welding characteristics due to a reduced carbon content.[7] Corrosion studies of 316L fabricated through powder
R.W. FONDA, D.J. ROWENHORST, C.R. FENG, K.E. KNIPLING, SCOTT OLIG, ADELINA NTIROS, and ROY RAYNE are with the US Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, DC 20375. Contact e-mail: [email protected] A.J. LEVINSON is now with the Piscataway High School, 100 Behmer Rd., Piscataway, NJ 08854. BETH STILES is with Vision Point Systems, Incorporated, 3951 Pender Drive, Suite 115, Fairfax, VA 22030. Manuscript submitted August 5, 2020, and accepted September 20, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
metallurgy[8,9] reveal a lower corrosion resistance of these sintered materials primarily due to the residual porosity, which is linked to an increase in crevice corrosion taking place in the pores. The corrosion behavior of AM 316L is, however, more complex.[10] While some authors[11–13] observe an improvement in the corrosion behavior of AM components over conventional cast or wrought material, many others[14–21] report a degradation in those properties due to cracks, oxides, and porosity present in the microstructure[16,18,22] or inhomogeneous solute distributions and non-equilibrium microstructures formed during the AM processing.[17] In addition, the surface finish is shown to affect the corrosion rate. Kuznetsov et al.[23] found that machining the surface exposes a higher level of porosity, causing an increase in the pitting and crevice corrosion rates. They concluded that the pitting corrosion develops on surface and subsurface steel pores, so the corrosion damage largely depends on the quality of the exposed surface and on thermal treatment. Post-processing of AM builds can substantially change their characteristic microstructural features and properties. One of the most common post-processing techniques is hot isostatic pressing (HIP), which can substantially decrease the porosity in the build, reduce the chemical segregation and directionality from solidification, and produce a uniform microstructure. Conventional heat treatments (without an applied stress) can also provide similar benefits by reducing the chemical
segregation and directionality from solidification and modifying pore morphologies and distributions, which can lead to improved corrosion and fatig
Data Loading...
