Formation of Austenite in Additively Manufactured and Post-Processed Duplex Stainless Steel Alloys

Iams, A. D.; Keist, Jayme S.; Palmer, Todd

doi:10.1007/s11661-019-05562-w

Cited by 50 publications

(21 citation statements)

References 54 publications

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“…It has been shown that in contrast to the LPBF, DED duplex stainless steel products show a mixture of austenite and ferrite in the as-built condition, with intragranular austenite particles preferentially nucleating on the inclusions [186]. Austenite content increases with the laser energy density.…”

Section: Alloymentioning

confidence: 99%

Additive manufacturing of steels: a review of achievements and challenges

et al. 2020

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Metal additive manufacturing (AM), also known as 3D printing, is a disruptive manufacturing technology in which complex engineering parts are produced in a layer-by-layer manner, using a high-energy heating source and powder, wire or sheet as feeding material. The current paper aims to review the achievements in AM of steels in its ability to obtain superior properties that cannot be achieved through conventional manufacturing routes, thanks to the unique microstructural evolution in AM. The challenges that AM encounters are also reviewed, and suggestions for overcoming these challenges are provided if applicable. We focus on laser powder bed fusion and directed energy deposition as these two methods are currently the most common AM methods to process steels. The main foci are on austenitic stainless steels and maraging/precipitation-hardened (PH) steels, the two so far most widely used classes of steels in AM, before summarising the state-of-the-art of AM of other classes of steels. Our comprehensive review highlights that a wide range of steels can be processed by AM. The unique microstructural features including hierarchical (sub)grains and fine precipitates induced by AM result in enhancements of strength, wear resistance and corrosion resistance of AM steels when compared to their conventional counterparts. Achieving an acceptable ductility and fatigue performance remains a challenge in AM steels. AM also acts as an intrinsic heat treatment, triggering ‘in situ’ phase transformations including tempering and other precipitation phenomena in different grades of steels such as PH steels and tool steels. A thorough discussion of the performance of AM steels as a function of these unique microstructural features is presented in this review.

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Section: Alloymentioning

confidence: 99%

Additive manufacturing of steels: a review of achievements and challenges

et al. 2020

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“…Within the ferritic melt pools acicular grains are found, whereas at the melt pool borders a more allotriomorphic austenite occurs showing austenite side plates 56 . The evolution of Widmanstatten austenite in welding is well known from literature [56][57][58] . It is expected that the microstructure evolves in a similar fashion here.…”

Section: Discussionmentioning

confidence: 99%

Metastable CrMnNi steels processed by laser powder bed fusion: experimental assessment of elementary mechanisms contributing to microstructure, properties and residual stress

Richter

Bartzsch

Scherbring³

et al. 2022

Sci Rep

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The complex thermal history imposed by the laser-based powder bed fusion of metals (PBF-LB/M) process is known to promote the evolution of unique microstructures. In the present study, metastable CrMnNi steels with different nickel contents and, thus, different phase stabilities are manufactured by PBF-LB/M. Results clearly reveal that an adequate choice of materials will allow to tailor mechanical properties as well as residual stress states in the as-built material to eventually redundantize any thermal post-treatment. The chemical differences lead to different phase constitutions in as-built conditions and, thus, affect microstructure evolution and elementary deformation mechanisms upon deformation, i.e., twinning and martensitic transformation. Such alloys designed for additive manufacturing (AM) highlight the possibility to tackle well-known challenges in AM such as limited damage tolerance, porosity and detrimental residual stress states without conducting any post treatments, e.g., stress relieve and hot isostatic pressing. From the perspective of robust design of AM components, indeed it seems to be a very effective approach to adapt the material to the process characteristics of AM.

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“…At higher austenite fractions, austenite also penetrated the ferrite grains in the form of Widmenstätten plates and ultimately formed globular intragranular austenite. In a more detailed description of LMPDED printing of super-DSS, Iams et al [17] found it is possible to achieve 58.3 % austenite fraction with a higher energy rate of 188.7 J.mm -1 . They also reported that, within a single printed part, austenite fraction increased with distance from the substrate: from 55 % at 5-10 mm to 70 % at 20 mm.…”

Section: Introductionmentioning

confidence: 99%