Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Article:

 

“Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion”

This is interesting article, however it contains some drawbacks listed below.

Materials and Methods

Line 102: The sintering temperature is missing,

Lines 115 – 116: “…and then mirror-polished up to 1 μm by diamond powder.” This sentence should be modified

Lines 119 – 120: The types of optical microscope, type of EDX spectrometer and parameters of SEM-EDX examinations should be given.

Results and discussion

Figures 2 and 4: What are the black spots? Pores, non-metallic inclusions or something else? It should be explained in the text.

Figure 3. All peaks should be labelled in the figure, not only attributed to FCC phase.

In my opinion, hardness tests results for every condition presented in the manuscript should be given to show how efficient was the heat treatment for mechanical properties. The size of Cu precipitates presented in figure 5 is very big (micrometres) while in 17-4PH steel in condition H900, the Cu-rich precipitates are of tens of nanometres size. Please, give any comment to this issue.

Author Response

The answers are in the pdf file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer Recommendation and Comments for manuscript metals-3428906 with the title: “Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion”, authors: Pietro Forcellese 1,*, Tommaso Mancia 2, Michela Simoncini 3, and Tiziano Bellezze 1,*.

‴ Relevance of the Research. The effects of solution-annealing and aging treatments on the corrosion resistance properties of 17-4 PH stainless steel manufactured by Bound Metal Deposition were studied. Through the studied subject, the manuscript covers the specifics of the Metals journal.

‴ Evaluation of scientific novelty of Research results. The effects of annealing and aging treatments on the corrosion resistance properties of 17-4 PH stainless steel are studied by physical and chemical surface characterization methods. The chemical composition is studied using x-ray diffraction analysis, chemical etching, Cyclic Potentiodinyamic Polarization (CPP), and Open Circuit Potentiometry (OCP) in neutral sodium chloride electrolytes. The study brings new results regarding microstructure and corrosion resistance.

‴ Practical Significance of Research Results. The study is of particular importance for areas of interest such as obtaining metallic materials with superior physico-chemical properties. The effects of heat treatments on the microstructure and corrosion resistance of stainless steel are observed.

‴ Strengths of the Research. The authors use modern methods to characterize the crystal structure and determine the chemical composition of stainless steel.

‴ Weaknesses of the Research. The study fails to explain the relationship between microstructure, EDX analysis and corrosion resistance. There are no OM or EDX analyses for samples 45 and 90.

‴ Citations. Although the manuscript introduces new data on 17-4 stainless steel, the cited references of mostly recent publications (within the last 5 years) account for only 45%. Do not include an excessive number of self-citations (does not exceed 13%). With a total of 31 citations, the manuscript could be improved with recent citations (without self-citations) from the last 5 years.

‴ Overall, the research contains novel scientific findings obtained through the employment of contemporary investigative methods. The data garnered hold significance for specialists in the fields of materials. The work merits publication in the Metals journal upon addressing the comments and responding to the questions.

The main comments that I find useful for improving the quality of the article are presented below:

‴ At first glance, the abstract and keywords should encourage reading and use of the results of this manuscript. With the authors' agreement, these two sections should be rewritten. No scientific or other errors are observed, but refining these sections could greatly improve the impact of the paper.

‴ lines 137 to 141. “Electrochemical Impedance Spectroscopy (EIS) was measured before CPP in the frequency range from 100 kHz to 1 Hz, setting 10 points per decade and a signal amplitude of 10 mV for the measurements. The EIS was done to determine the solution resistance and correct the polarization curves for the ohmic drop.” Please present the results obtained through the EIS and the corresponding comments. Why are these not presented in Results and Discussion?

‴ The results and discussions regarding OM, especially for Figures 2a and 2b, which look similar, need to be much improved. Conclusions expressed only on the bright or dark intent are not sufficient.

‴ lines 244-245. “The microstructure of the BMD samples obtained with Vilella’s etchant and shown in Fig. 4 revealed the presence of oxides, carbides, and inclusions.” The chemical composition cannot be determined by microscopic analysis. For example, why not hydroxides?

‴ Figure 5b shows a different magnification (6250) than figures 5a (6000), 5c (6000) and 5d (6000). Why do all the figures show the same magnification at 10 um!?

‴ Table 2. Adding percentages doesn't get you 100%!? Can a difference of up to 1% change the conclusions of the study? What is the difference up to 100%?

‴ Table 2 shows results only for samples with 0° orientation? Are there also data for 45° and 90° orientations?

‴ Line 330. “(Fig. 5b and Tab. 2)” Table 2 shows the results for samples with 0 orientation and Figure 5b for 45 orientation. If orientation influences corrosion resistance then is the chemical composition also influenced?

‴ The data must be compared accordingly. EDX for 0° with CPP for 0°. EDX for 45° with CPP for 45°. EDX for 90° with CPP for 90°.

‴ Is there EDX data for samples with H900?

‴ Are there OM analyses for samples after corrosion? (without and with H900)

‴ Line 447. “was 0.96 V∙h”. According to figure 9, there is no sample with an area of ​​0.96.

‴ The conclusions are too long.

‴ There are some grammar and typing mistakes.

‴ The authors must revise the entire manuscript.

Author Response

The answers are in the pdf file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer Recommendation and Comments for manuscript metals-3428906 with the title: “Characterization of Microstructure and Localized Corrosion Resistance of Heat-Treated 17-4 PH Stainless Steel Fabricated by Material Extrusion”, authors: Pietro Forcellese 1,*, Tommaso Mancia 2, Michela Simoncini 3, and Tiziano Bellezze 1,*.

The authors make improvements to the manuscript taking into account the reviewer's comments. The authors provide a new and improved version of the manuscript. The manuscript can be considered for publication.

I congratulate the authors for their hard work.