Influence of the L-PBF Process Atmosphere on the Microstructure and Tensile Properties of AISI 318LN Duplex Stainless Steel
Round 1
Reviewer 1 Report
The author's research is interesting. The author has done a lot of work and has also conducted in-depth research on this paper. However, there are some obvious mistakes in this manuscript. And some results were not analyzed. Abstracts and summaries are poorly written. Suggested authors the author rewrite these two parts. I have queries that the author may address before recommending for acceptance. The authors should perhaps consider following points in the revised submission:
Abstract: A poorly written abstract can easily confuse readers. Please check your abstract carefully and suggest rewriting it.
Line 10-11: It's easy to get confused: the nitrogen content plays a major role in microstructure formation. Where the nitrogen content? Is it from the duplex stainless steels or the protective atmospheres? In the abstract, the author then introduces the protective gas nitrogen, so it is easy for readers to have this confuse.
Line 11-12: Duplex stainless steels (DSSs) combine excellent mechanical properties and corrosion resistance due to their austenitic-ferritic microstructure. However, the unique cooling conditions in Laser Powder Bed Fusion (L-PBF) of DSS result in a fully ferritic microstructure. What are the advantages of DSS with fully ferritic microstructure? Is it better than DSS with austenitic-ferritic microstructure or not? Why in here write this sentence? By the way there are DSSs and DSS, which is right? Correct them.
Line 21-22: A positive effect of nitrogen atmosphere compared to argon could not be demonstrated. However, there are not results of the specimens processed under argon atmosphere, how to do the comparison?
Introduction: Line 38: It is right for Duplex stainless steels (DSS)? Check your all content and make sure it is DSSs or DSS.
Line 72: Check the format of this sentence?
Introduction: Some of the important articles on related topics have not been analyzed. For instance: Chen, X., Liu, K., Guo, W., Gangil, N., Siddiquee, A.N., Konovalov, S. The fabrication of NiTi shape memory alloy by selective laser melting: a review (2019) Rapid Prototyping Journal, 25 (8), pp. 1421-1432. DOI: 10.1108/RPJ-11-2018-0292; Toker, G.P., Nematollahi, M., Saghaian, S.E., Baghbaderani, K.S., Benafan, O., Elahinia, M., Karaca, H.E. Shape memory behavior of NiTiHf alloys fabricated by selective laser melting (2020) Scripta Materialia, 178, pp. 361-365. DOI: 10.1016/j.scriptamat.2019.11.056; Yao, T., Wang, Y., Zhu, B., Wei, D., Yang, Y., Han, X. 4D printing and collaborative design of highly flexible shape memory alloy structures: a case study for a metallic robot prototype (2020) Smart Materials and Structures, 30 (1), № 015018. DOI: 10.1088/1361-665X/abcc0a
Materials and Methods: What is the interval in seconds for each layer? what the final sample looks like? It is better to give this information in the part L-PBF processing and specimen production.
Line 153-155: where are the Z-Y-plane and X-Y-plane? The author should add schematic diagrams for better understanding by readers.
Line 179-186: Why use different temperatures (1080℃ and 1150℃)? On what basis did you choose these two temperatures?
Line 191: Where does the tensile test specimen come from? Are the tensile patterns obtained in the horizontal direction of the alloy or in the vertical direction of the alloy?
Results and Discussion: Line 225-226: Further solution annealing did not influence the porosity as it remained nearly constant at 0.09 % ± 0.04 % in the N2_HIP+SA+Q condition. However, after further solution annealing the porosity slightly increased (0.08 % ± 0.03 %). It has an effect on porosity, why the author said not?
In the part 3.1 Influence of process atmosphere on porosity. From the results, we can get the conclusions such as: The L-PBF under argon atmosphere resulted in higher dense specimens than under nitrogen atmosphere. N2_AB specimens tend to have more LOF pores and so on. These are only the results, the author donot explain these results. Why are there such results? For example, why the L-PBF under argon atmosphere resulted in higher dense specimens than under nitrogen atmosphere? The author need give the reason and not the result which get by the test. There are just the results, without discussion.
Conclusion: Line 417: Why is the 5. Conclusions? Where are the part 4? Check it.
There are too many conclusions and too scattered. It is better to summarize the effect of duplex stainless steels under argon and nitrogen protective atmosphere on porosity, structure and properties under the protection of argon and nitrogen.
Author Response
Please see the attachement
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper, the authors investigated the effects of L-PBF process atmosphere on microstructure and tensile properties of AISI 318LN DSS. It is interesting and within the scope of the journal. Some issues need to be addressed before the manuscript is accepted.
- There are some incoherent and long sentences in this paper, and the usage of “the” and “a” also needs to be improved. It is recommended to polish the language. Furthermore, in Section 1, the logic between each paragraph needs to be strengthened and it is recommended to reorganize and rewritten the language.
- In Section 3.1, the authors stated that “It becomes apparent that pores within N2_AB specimens tend to be more irregular formed compared to pores in the Ar_AB specimens”, it is not clear how to get this conclusion from Fig. 4. Furthermore, please supplement more explanations about the variation law of curve in Fig. 4.
The authors stated that “This fact becomes evident when comparing microsections of specimens built under argon and nitrogen protective atmosphere, as shown in Figure 6.”, it is known that the microstructure maybe different for the specimen even with the same post-processing, so how to choose the specimen? Is the selected specimen representative?
- In Section 3.2, the authors stated that “The precipitation of austenite grains along prior grain boundaries after solution annealing and quenching is clearly evident in Figure 10 b) and Figure 11 b)”, it seems not so clear, please add some directions in the related figures.
- In Section 3.3, the authors presented the influence of process atmosphere on nitrogen and argon content, is this part necessary for the whole manuscript?
- Please revise all the formats of the tables.
- In Section 3.4, in Fig. 15, what is the reason for the difference of stress-strain curves? Please supplement more explanations.
- In Section 5, too many conclusion points are listed, and it is recommended to refine and reorganize the conclusion.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
No comments.
