Metallography analysis of AISI316L austenitic steel processed via direct energy deposition technology and hot isostatic pressing technology

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A_____%2F24%3AN0000204" target="_blank" >RIV/26722445:_____/24:N0000204 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Metallography analysis of AISI316L austenitic steel processed via direct energy deposition technology and hot isostatic pressing technology

Original language description

Our study aimed to describe microstructural changes associated with the processing of AISI316L powdered austenitic steel by direct energy deposition (DED) in combination with annealing (A), and hot isostatic pressing (HIP). A thick wall plate was prepared by direct energy deposition technology in dimensions of 250x250x35 mm. Annealing of the plate was done at 1090 °C with a holding time of 1 hour in vacuum furnace. HIP was done at 1100 °C, holding time 2 hours, and pressure 100 MPa. Metallography analysis was done by light optical microscopy and scanning electron microscopy in different locations of the plate and extracted samples. Metallography analysis aimed to determine changes in the presence of porosity, inclusions, grain morphologies, chemical homogeneity, and hardness associated with sample heat treatment. Our results show that during the printing of thick wall parts porosity could arise in some regions of the part. A lack of fusion and keyholing [1] type of pores was found in the high of 1/3 of the plate in the Z direction. The Pore's surface was covered with oxide envelopes, see Fig. 1. Annealing of the samples did not affect the presence of porosity. HIP treatment led to the closing of porosity. Their complete closure was then prevented by oxide films on the surface of the pores. The porosity of the plate was about 0.3±0.2 % in the annealed state and about 0.06±0.03 % for HIP-treated samples. The grain shape after the annealing and HIP treatment consisted of polygonal austenitic grains with a random orientation spread in almost all cases and with similar grain sizes in different parts of the evaluated thick plate. The difference in grain size for annealed and HIP-treated samples was not observed. Hardness was about 167±8HV1 for annealed samples and 157±5HV1 for HIPtreated samples. Our results then show that HIP technology is necessary in the case of the application of additively manufactured parts for thick parts used in the energy sector. Its application led to the closing of internal pores and increasing the homogeneity of printed parts. That could lead to an increase in fatigue life, stress corrosion cracking resistance, and creep resistance of thick parts. Our next research will focus on experiments with additively prepared ferrous and nonferrous materials that are in use or are in development for new types of power plants. Poster at Additive 2024 - Additive Manufacturing 2024,12 - 14 June 2024, Hybrid Symposium in Bremen, Berlin (Germany).

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů