Study of Corrosion Resistance of Hybrid Structure of DP980 Two-Phase Steel and Laser-Welded 6013-T4 Aluminum Alloy

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1.-Table 1 concerning the chemical composition is written in an incorrect way. It should be corrected to the appropriate language.

2.- The data on the chemical composition of the materials used correspond to nominal values but not to real values. The authors should add the actual values of the base materials used in the study as well as the technique used to obtain the data.

3.- The real chemical composition and the technique used must be integrated into 2.1 Material section.

4.- Globally, all images in this document are of poor quality, which makes it impossible to appreciate the information. For example, in Figure 12 the analysis map does not show good resolution.

In addition, the figures do not maintain a proper aspect ratio between the dimensions and text labels. It is highly recommended to correct this observation throughout the document.

 

5.- In section 3.3. Microstructural Analysis of Welded Joints: The authors describe the cracking that occurs in the solidification process in aluminum alloys as well as the constituent mixture. Explain specifically why cracking occurs in this study and how it is related to the welding process.

 

6.- Regarding the microhardness analysis, the evidence is shown on the behavior on the DP 980 steel side, however no change is shown on the effect of the melting process on the aluminum interface. Include this section. 

7.- In figure 13 and 14 indicate de planes in the XDR peaks, authors must improve the artwork.

8.-In the results of conductivity, at 72 hrs there is an increase of pH to 7.08, how this affects the corrosion behavior in the weldments, explain.

Author Response

Dear reviewer I. Thank you for your valuable suggestions for this paper. Your suggestions have greatly improved the quality and level of this paper.

Thanks!

Regards,

• Table 1 concerning the chemical composition is written in an incorrect way. It should be corrected to the appropriate language.

Response: Accept the suggestions of the reviewer. Table 1 has been corrected to the appropriate language.

• The data on the chemical composition of the materials used corresponds to nominal values ​​but not to real values. The authors should add the actual values ​​of the base materials used in the study as well as the technique used to obtain the data.

Response: Accept the suggestions of the reviewer. The real composition of the alloys was described in the results, however, following the reviewer's suggestion, both the real measurement and the way it was performed were added to the materials section.

• The real chemical composition and the technique used must be integrated into 2.1 Material section.

Response: Accept the suggestions of the reviewer. The real composition of the alloys was described in the results, however, following the reviewer's suggestion, both the real measurement and the way it was performed were added to the materials section.

• Globally, all images in this document are of poor quality, which makes it impossible to appreciate the information. For example, in Figure 12 the analysis map does not show good resolution. In addition, the figures do not maintain a proper aspect ratio between the dimensions and text labels. It is highly recommended to correct this observation throughout the document.

Response: Accept the suggestions of the reviewer. The images have been modified for better quality and size as well. In particular, Figure 12 has been modified for better quality and the indication of the element it shows.

• In section 3.3. Microstructural Analysis of Welded Joints: The authors describe the cracking that occurs in the solidification process in aluminum alloys as well as the constituent mixture. Explain specifically why cracking occurs in this study and how it is related to the welding process.

Response: Accept the suggestions of the reviewer. A paragraph has been added highlighting the case shown in Figure 6:

The crack shown in Figure 6 is a typical welding defect. In this case, according to [X, Y], there is an incompatibility of the thermal expansion coefficients between the brittle intermetallics and the aluminum during cooling. This causes the emergence and prop-agation of cracks in the weld region close to the aluminum alloy. This phenomenon is more present in welds with depths greater than 700 μm, as the weld region becomes more fragile due to the formation of intermetallics. As shown in Figure 6, the crack occurred in the weld region, close to the aluminum and, as will be shown, there is the formation of brittle intermetallics that can cause the formation and propagation of cracks [X, Y].

• In the introduction section, the authors must include a robust article about the recent findings of the DP980 two-phase steel and 6013-T4 aluminum alloy.

Response: Thank you for your comments. In fact, this study wanted to focus more on DP980 steel, also doing a study in relation to the height of the bead, drawing 3 lines - at the beginning, in the center and at the end) of the bead towards the aluminum plate. This is due to the fact that the aluminum alloy AA6013-T4 presents several studies in relation to microhardness when welded to steel, for example the study of: Atílio, I.; Braga, V.; de Siqueira, R.H.M.; de Carvalho, S.M.; de Lima, M.S.F. Comparing the weldability of AA6013-T4 aluminium alloy on DP600 dual-phase steel with laser welding and resistance spot welding. J. Braz. Soc. Mech. Sci. 2020, 42, 1 – 12. Therefore, this study was not carried out in this work. This observation was included in the article.

 

• In figure 13 and 14 indicate de planes in the XDR peaks, authors must improve the artwork.

Response: Accept the suggestions of the reviewer. The figure's art has been redone, improving the visualization of the points.

• In the results of conductivity, at 72 hrs there is an increase of pH to 7.08, how this affects the corrosion behavior in the weldments, explain.

Response: Thank you for your comments. If the answer is not sufficient, we are available for further clarification.Taking into account the standard deviation, we cannot state that there was an increase in pH since the first and last measurements are the same, considering the standard deviation. The pH measurements indicate that the environment does not influence the corrosion rate. Even with a slight increase or decrease, throughout the experiment the pH remained close to neutrality, indicating that the experiment did not influence it.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript suffers from significant issues in English grammar, clarity, and repetition. Phrasing is often awkward and long-winded. Thorough professional language editing is required. The discussion of galvanic effects and the potential cathodic protection by aluminum presence is insightful but would benefit from deeper thermodynamic or electrochemical reasoning.

The paper is technically solid and offers original contributions, especially in its use of electrochemical noise analysis with wavelet decomposition to study welded joints. However, major revisions are necessary, particularly in: (i) language clarity and grammar; (ii) improving the focus and interpretive strength of the discussion

Author Response

Dear reviewer II. Thank you for your valuable suggestions for this paper. Your suggestions have greatly improved the quality and level of this paper.

Thanks!

Regards,

 

The manuscript suffers from significant issues in English grammar, clarity, and repetition. Phrasing is often awkward and long-winded. Thorough professional language editing is required. The discussion of galvanic effects and the potential cathodic protection by aluminum presence is insightful but would benefit from deeper thermodynamic or electrochemical reasoning.

The paper is technically solid and offers original contributions, especially in its use of electrochemical noise analysis with wavelet decomposition to study welded joints. However, major revisions are necessary, particularly in: (i) language clarity and grammar; (ii) improving the focus and interpretive strength of the discussion

Response: Thank you for your comments. (i) The entire document has been revised to improve clarity and grammar. (ii) Changes have also been made to the text and images to improve the objectivity of the discussion, as suggested.

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, the authors present a corrosion-resistance analysis of DP980 two-phase steel and 6013-T4 aluminum alloy welded by a laser technique. Although the authors present a robust work with a well-structured experimental section, they must improve the discussion of the results, especially in the electrochemical noise analysis. In my opinion, the manuscript could be accepted for publication after minor corrections.

Below are some specific comments

In the introduction section, the authors must include a robust article about the recent findings of the DP980 two-phase steel and 6013-T4 aluminum alloy.

On page 9, the authors have found failure in experiments 1 to 4 due to multiple causes; however, the test conditions in each experiment are not commented on. The authors must provide the details or remove those experiments and leave only experiment 5. This is because the best parameters of this experiment have been analyzed in this article.

In the microstructural analysis of welded joints section, the authors discuss the microstructure in the Transition Zone (TZ), Refined Zone (RZ), Martensitic Zone (MZ), Base Metal (MB), and Molten Zone (FZ). However, in those images, it is impossible to observe the microstructure that the authors dispute in the manuscript. The authors must provide microstructure images of those macrostructure zones.

In Figure 10 the authors must identify the insets with a), b), etc

In the XRD patterns of Figure 13, the authors must identify each of the phases in these HKL reflections

In Figure 15, 0 the curves of current density and potential must be identified as DP980 steel, Aluminum alloy 6013-T4, etc instead 00h

Figures 15 to 17 must be discussed in the manuscript.

 

Author Response

Dear reviewer III. Thank you for your valuable suggestions for this paper. Your suggestions have greatly improved the quality and level of this paper.

Thanks!

Regards,

 

• In the introduction section, the authors must include a robust article about the recent findings of the DP980 two-phase steel and 6013-T4 aluminum alloy.

Response: Thank you for your comments. (i) The entire document has been revised to improve clarity and grammar. (ii) Changes have also been made to the text and images to improve the objectivity of the discussion, as suggested.

• On page 9, the authors have found failure in experiments 1 to 4 due to multiple causes; however, the test conditions in each experiment are not commented on. The authors must provide the details or remove those experiments and leave only experiment 5. This is because the best parameters of this experiment have been analyzed in this article.

Response: Thank you for your comments. The conditions of the experiments are given in Table 3. The researchers thought it would be a good idea to include all of this data and images from this pre-test as they are results for future research, rather than starting the work with the parameters that provided the best results. If advised, we can remove these results and discuss and leave only the experiment that resulted in a weld without macro defects.

• In the microstructural analysis of welded joints section, the authors discuss the microstructure in the Transition Zone (TZ), Refined Zone (RZ), Martensitic Zone (MZ), Base Metal (MB), and Molten Zone (FZ). However, in those images, it is impossible to observe the microstructure that the authors dispute in the manuscript. The authors must provide microstructure images of those macrostructure zones.

Response: Accept the suggestions of the reviewer. Figure 10 has been added showing micrographs of each zone.

• In Figure 10 the authors must identify the insects with a), b), etc.

Response: Accept the suggestions of the reviewer. The Figure was subdivided into (a) and (b) and its composition explained.

• In the XRD patterns of Figure 13, the authors must identify each of the phases in these HKL reflections.

Response: Accept the suggestions of the reviewer. The art of the Figure has been improved and presented in the form of points the determination of the intermetallics with the highest probability of existing in the diffractograms. In addition, a quantity of noises can be observed in addition to the composition of the Aluminum Alloy and Steel.

• In Figure 15, 0 the curves of current density and potential must be identified as DP980 steel, Aluminum alloy 6013-T4, etc instead 00h.

Response: Accept the suggestions of the reviewer. The names of the Figures were changed as per instructions.

 

• Figures 15 to 17 must be discussed in the manuscript.

Response: Accept the suggestions of the reviewer. Discussions about the mentioned figures have been added

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have attended to most of the corrections and observations indicated, however I consider that in general the quality of all their images is poor compared to other works published in this journal.

This is probably due to the way the images are exported to the template.

To improve the quality of all the images in the document it is highly recommended that they be exported in another high quality format for a better appreciation of the information.

 

Author Response

Thank you for your comments, we agree with the reviewer. All images have been processed and quality improved. We are available for any changes.