Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion
The combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool du...
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MDPI AG
2023-09-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/13/9/1552 |
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| author | Alessandro Morri Mattia Zanni Lorella Ceschini Alessandro Fortunato Massimo Pellizzari |
| author_facet | Alessandro Morri Mattia Zanni Lorella Ceschini Alessandro Fortunato Massimo Pellizzari |
| author_sort | Alessandro Morri |
| collection | DOAJ |
| description | The combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool duration. Moreover, the suitability of LPBF-manufactured PH-SS in the as-built (AB) condition to be age-hardened through a direct aging (DA) treatment enables a great heat treatment simplification with respect to the traditional solution annealing and aging treatment (SA). However, plastic injection moulding tools experience severe thermal cycles during their service, which can lead to over-aging of PH-SS and thus shorten tool life. Therefore, proper thermal stability is required to ensure adequate tool life and reliability. The aim of the present work is to investigate the aging and over-aging behaviour of a commercially available PH-SS (AMPO M789) manufactured by LPBF in the AB condition and after a solution-annealing treatment in order to evaluate the effect of the heat treatment condition on the microstructure and the aging and over-aging response, aiming at assessing its feasibility for plastic injection moulding applications. The AB microstructure features melt pool borders, oriented martensite grains, and a cellular solidification sub-structure, and was retained during aging and over-aging. On the other hand, a homogeneous and isotropic martensite structure was present after solution annealing and quenching, with no melt pool borders, cellular structure, or oriented grains. The results indicate no significant difference between AB and solution-annealed and quenched specimens in terms of aging and over-aging behaviour and peak hardness (in the range 580–600 HV), despite the considerably different microstructures. Over-aging was attributed to both the coarsening of strengthening precipitates and martensite-to-austenite reversion (up to ~11 vol.%) upon prolonged exposure to high temperature. Based on the results, guidelines to aid the selection of the most suitable heat treatment procedure are proposed. |
| first_indexed | 2024-03-10T22:28:34Z |
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| language | English |
| last_indexed | 2024-03-10T22:28:34Z |
| publishDate | 2023-09-01 |
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| series | Metals |
| spelling | doaj.art-f948d942358d458088dc08aa939dcf5d2023-11-19T11:56:32ZengMDPI AGMetals2075-47012023-09-01139155210.3390/met13091552Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed FusionAlessandro Morri0Mattia Zanni1Lorella Ceschini2Alessandro Fortunato3Massimo Pellizzari4Department of Industrial Engineering (DIN), Alma Mater Studiorum—University of Bologna, Viale Risorgimento 4, 40136 Bologna, ItalyDepartment of Industrial Engineering (DIN), Alma Mater Studiorum—University of Bologna, Viale Risorgimento 4, 40136 Bologna, ItalyDepartment of Industrial Engineering (DIN), Alma Mater Studiorum—University of Bologna, Viale Risorgimento 4, 40136 Bologna, ItalyDepartment of Industrial Engineering (DIN), Alma Mater Studiorum—University of Bologna, Viale Risorgimento 4, 40136 Bologna, ItalyDepartment of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, ItalyThe combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool duration. Moreover, the suitability of LPBF-manufactured PH-SS in the as-built (AB) condition to be age-hardened through a direct aging (DA) treatment enables a great heat treatment simplification with respect to the traditional solution annealing and aging treatment (SA). However, plastic injection moulding tools experience severe thermal cycles during their service, which can lead to over-aging of PH-SS and thus shorten tool life. Therefore, proper thermal stability is required to ensure adequate tool life and reliability. The aim of the present work is to investigate the aging and over-aging behaviour of a commercially available PH-SS (AMPO M789) manufactured by LPBF in the AB condition and after a solution-annealing treatment in order to evaluate the effect of the heat treatment condition on the microstructure and the aging and over-aging response, aiming at assessing its feasibility for plastic injection moulding applications. The AB microstructure features melt pool borders, oriented martensite grains, and a cellular solidification sub-structure, and was retained during aging and over-aging. On the other hand, a homogeneous and isotropic martensite structure was present after solution annealing and quenching, with no melt pool borders, cellular structure, or oriented grains. The results indicate no significant difference between AB and solution-annealed and quenched specimens in terms of aging and over-aging behaviour and peak hardness (in the range 580–600 HV), despite the considerably different microstructures. Over-aging was attributed to both the coarsening of strengthening precipitates and martensite-to-austenite reversion (up to ~11 vol.%) upon prolonged exposure to high temperature. Based on the results, guidelines to aid the selection of the most suitable heat treatment procedure are proposed.https://www.mdpi.com/2075-4701/13/9/1552additive manufacturingprecipitation-hardening stainless steellaser powder bed fusiondirect agingover-aging |
| spellingShingle | Alessandro Morri Mattia Zanni Lorella Ceschini Alessandro Fortunato Massimo Pellizzari Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion Metals additive manufacturing precipitation-hardening stainless steel laser powder bed fusion direct aging over-aging |
| title | Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion |
| title_full | Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion |
| title_fullStr | Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion |
| title_full_unstemmed | Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion |
| title_short | Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion |
| title_sort | aging behaviour of a 12 2cr 10ni 1mo 1ti 0 6al precipitation hardening stainless steel manufactured via laser powder bed fusion |
| topic | additive manufacturing precipitation-hardening stainless steel laser powder bed fusion direct aging over-aging |
| url | https://www.mdpi.com/2075-4701/13/9/1552 |
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