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  • Yanmei Li 1,*,
  • Yonghao Cui 1 and
  • Chen Xu 2
  • et al.

Reviewer 1: Ali Ercetin Reviewer 2: Inesh Kenzhina Reviewer 3: Chandan Pandey Reviewer 4: Anonymous

Round 1

Reviewer 1 Report

The study is about the effects of simulated post-welding heat treatment PWHT on the microstructure and mechanical properties of 2.25Cr1Mo0.25V steel for a hydrogenation reactor.

The technically applied methods and the findings obtained are at a sufficient level.

However, in order for the current study to contribute to science better, it is recommended to extract the content of mechanical properties and to revise the manuscript again based on changes and developments in the microstructure.

Point 1: In introduction section, at first paragraph:

The beginning of the manuscript and the problem definition are well done. However, it is recommended that the statements be supplemented with more references. Thus, it can be understood from the reader's point of view that the problem is not a single reference source but a more general problem. In addition, the introduction needs to be expanded.

The same situation can be seen at the beginning of second paragraph of introduction section.

As an example: “Steel is usually strengthened using two methods to improve its mechanical properties at high temperatures. One method utilizes the solid solution of Cr and Mo to strengthen the matrix. The other method forms fine precipitates produced by adding micro-alloying elements such as V, Nb, and Ti; these consist of a cubic crystal structure of type MX and can effectively hinder the dislocation movement”.

This sentence includes two methods. It will be better to support one of the method with different references.

Point 2: Some sentences do not include references. The sentences in 3rd and 4th paragraphs of introduction section.

“This heat treatment ……….. repairs (generally considering two repairs)”

“One of the difficulties ……. steel after SPWHT”

Point 3: Materials and Methods section includes author guidelines of the Journal.

Please check the first, second and third paragraphs of the Materials and Methods section.

Point 4: The paper presents the new formations and changes in the microstructure very well after detailed research on microstructure by SEM, TEM analysis and tests.

However, the fact that the mechanical properties are adversely affected as a result of the application of the SPWHT method calls into question the necessity of the SPWHT method applied to the 2.25Cr1Mo0.25V steel.

Is SPWHT applied 2.25Cr1Mo0.25V steel still usable in hydrogenation reactor or hydrogen-bearing heavy wall pressure vessels in the petrochemical industry?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The article considers the change in the properties of steel 2.25X1M0.25V of great thickness after external influences. The authors use a fairly large number of research methods for data analysis and interpretation, which indicates their qualifications and skills. In general, this line of research is very important not only from a scientific point of view, but also from a practical one in view of the prospects of the data obtained. The article corresponds to the subject of the declared journal and can be accepted for publication after the authors answer a number of questions that the reviewer had during a detailed analysis of the data presented.

1. The visual series of images presented in the article should be combined with each other for a better perception of the observed changes, as well as understanding the effects of the formation of a defective structure as a result of external influences.

2. The presented SEM images clearly show the formation of a grain structure near the boundaries of which carbide inclusions are formed, the authors should pay attention to this, and also provide mapping data or the elemental composition of these areas.

3. Data on the chemical composition of the selected sample for research should be brought to a unified style in the accuracy class.

4. When describing the effects of Mo segregation on the change in strength properties, the authors should pay more attention to the change in these strength properties, taking into account the precipitation of carbide compounds.

5. The strength measurement data presented in Table 2 should be given in the format of the value and measurement error. In this form, the presented data confuse readers and do not allow drawing correct conclusions about the properties of the material.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Review report on the topic ‘Effects of Simulated PWHT on the Microstructure and Mechanical Properties of 2.25Cr1Mo0.25V Steel for a Hydrogenation Reactor’. The work is presented well. The comments to improve the quality of the manuscript are listed below:

 

  1. Please omit the unnecessary information and add the key conclusion of the work at the end of the abstract section. In present, the conclusion section is very lengthy.
  2. Please add a separate section to discuss the novelty of the work.
  3. The introduction section is presented roughly. Add more references and try to make a bridge between current and previously published work: https://doi.org/10.1007/s11665-022-06747-y; https://doi.org/10.1016/j.optlastec.2021.107610.
  4. What was NT condition?
  5. Add the microstructure and mechanical properties of the as-received plate.
  6. The impact energy was evaluated at -30 C, why? The material is mainly used for the high-temp application. Hence in such conditions, impact testing at a negative temperature is meaning less.
  7. Add the image of the impact and tensile tested specimen before and after a fracture.
  8. The term PWHT is confusing. Generally, that term is used for the welded sample if we heat it just after welding. Please change the notations of the heat treatment.
  9. Add EDS spectra of the particles. Also mention the grain size and particle size.
  10. In the EPMA study, add technical discussion related to the elemental map.
  11. In Fig. 5, mark the location of dimples, voids and cleavage areas and also provide the technical discussion. Also add the image of the fractured specimen and tensile test results in a separate table: https://doi.org/10.1016/j.engfailanal.2017.05.025.
  12. Shorten the length of the conclusion section. 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

I list my remarks below:

1.    The introduction is too short and contains only 5 references. Considering that post-weld heat treatment of steel is a popular scientific problem the authors should better highlight the state of the art and the novelty of this study.
2.    The authors wrote in the introduction part that “The SPWHT for large thickness 2.25Cr1Mo0.25V steel is divided into the minimum simulated post weld heat treatment (Min.SPWHT: 705°C for 8 h) and the maximum post weld heat treatment system (Max.SPWHT: 705°C for 32 h).” How these parameters have been established? No reference is given, no scientific background of the heat treatment.
3.    “12Cr2Mo1V (R)” What this “R” stands for?
4.    “Previous studies mainly examined the changes in the mechanical properties of the steel after SPWHT(…)” What studies? Please add the reference.
5.    Materials and methods contain three paragraphs that are simple template of the journal.
6.    The authors investigate the post-weld heat treatment. The question is where is the welding process in this entire paper?? How we can examine the effect of PWHT by referring to the results to the normalized steel?
7.    Microstructural analysis. “Generally, the normalized structure of the steel is granular bainite, which is composed of bainite ferrite and an M-A component; the M-A component will decompose into ferrite and carbide after tempering.” With all due respect, the authors did not show any grainy microstructure that can support this statement or the reference. The observations of the grainy microstructure should be an obligatory part of this study.
8.    There are two sections entitled “3.2. Microstructural analysis”.
9.    Element distribution. “The effect of the SPWHT on the distribution of the main alloy elements of Cr, Mo, and V was studied by EPMA (Figure 3).”. Figure 3 does not contain the distribution of Vanadium.
10.    Element distribution. “Mo existed almost exclusively in the carbides in the grain boundary; this showed that the carbides precipitated after SPWHT were mainly Cr-rich carbides with less Mo-rich carbides.” This statement overstates the results: what was the composition of these carbides and how do we know that there are no other precipitates that contain Cr and Mo?
11.    Add the error bar to figure 4b. “thermoplastic curve”?
12.    What are the differences between these 9 photos in figure 5? What was the fracture character and how SPWHT affected it?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have well addressed the comments. There is no additional comments.

Reviewer 2 Report

The authors answered all questions, the article can be accepted for publication.

Reviewer 4 Report

The authors have improved the paper. I recommend the publication.