Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel
Round 1
Reviewer 1 Report
Manuscript Number: Metals 657500
Title: Study on the Corrosion Characteristics in H2S Environments of X80 Pipeline Steel Submerged Arc Welded Joint
The research work has major points to be considered for publication after major revision. The title is complicated it should be made simple. Emphasizing the novelty of the present study should be taken seriously. Reference in experimental procedures and few sections (3.1, 3.2.1, 3.2.3, and 3.2.4) in results and discussion must be done. Add few more studies for microstructure analysis. Uniform format in references section should be made. Major English is mandatory.
Line 52 – What is M/A constituents?
Line 68 - What is microstructure and micro-morphologies observations exactly mean?
Line 69 - Why instrument name is in capital?
Line 73 - What does “step of 0.5â—¦/min” mean? Is this the correct way to mention 0.5â—¦/min? Explain.
Line 74 - Instrument name, model and other specifications.
Line 76 – Change spelling for experiment
Line 78-79 - The samples were polished to 800# metallographic grade by grade with metallographic sandpaper. What does 800# mean? Can describe in more appropriate way. Refer papers.
Line 85 - Details about software ZSimpWin like version, company name and so on.
Line 93 – Meaning of M/A islands. Add more points with suitable references.
Line 97 - Should “0.2” in HV 0.2 be in lowercase? Verify.
Line 101 - In Figure 1c and 1d marking should be made more clearly visible.
Line 106 – Why in Open “circuit” Potential (OCP) “circuit” is in Small letter?
Line 128 – Write equation number
Line 148 - Check legend font size of figure 6a.
Line 155 - Why is there an apostrophe on samples? Why mackinawite is in capital letter in line numbers 155, 159, 160?
Line 167-169 - Explain why four-prismatic written twice? State the necessity.
Line 176 - Write full stop after studies.
Line 179-180 – Figure 7. Don’t write metal/zone (BM, WM, CGHAZ and FGHAZ) twice. Caption given in a, b, c, and d is enough.
Line 181 - In Table 2 where is the unit for metals elements?
Line 185 - Different immersion time or only for 96 h? Verify and explain the statement in section 3.2.3. Where is the left side scale?
Line 186 - Check the subsection number. It is “3.2.4”.
Line 194 – 203 – Reframe the sentences as it is not clear to understand.
Line 204 - Add more points in section 4.
Author Response
Dear reviewer:
Thank you very much for your comments for our manuscript. They are all valuable and very helpful for revising and improving our manuscript, as well as the important guiding significance to our research. We have studied comments carefully and made corrections, as follows:
The research work has major points to be considered for publication after major revision. The title is complicated it should be made simple. Emphasizing the novelty of the present study should be taken seriously. Reference in experimental procedures and few sections (3.1, 3.2.1, 3.2.3, and 3.2.4) in results and discussion must be done. Add few more studies for microstructure analysis. Uniform format in references section should be made. Major English is mandatory.Response: Thank you very much for your good advice. We have simplified the title to “Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel”.
We have added more studies for microstructure analysis.
In 2.2 (Line 74), we added “The micro-hardness distribution in the welded joints was determined by a HXD-1000TMC micro-hardness instrument (HXD-1000TMC, Xian Weixin Testing Equipment Co. LTD, China) with a load charge of 200 g for15 s”. ( Zhang G.A, 2009).
In 2.3 (Line 78), we added “The electrochemical experiments were performed using Autolab (Aut84886, Shanghai Walong Instrument Co. LTD, China) with a two-component cell, Pt gauze counter electrode, and saturated calomel electrode (SCE) of +0.241 VSHE as reference electrode”. ( Zhao Wei, 2016).
In 3.1 (Line 94), we added “The microstructure of WM is mainly acicular ferrite (AF) with fine grains, where AF is nucleated within austenite grain”. ( Zhang G.A, 2009)
In 3.2.2 (Line 133), we added “the phenomenon is related to the phase transformation and diffusion of corrosion products”.(Bai Pengpeng, 2015).
In 3.2.3 (Line 183), we added “There are many holes in the corrosion products formed on the surface of the CGHAZ, which can significantly affect the corrosion resistance”. ( Zhao Wei, 2016).
In 3.2.3 (Line 186), we added “It is anticipated that cracks could be extended along the direction of external forces due to the holes”. ( Alizadeh M, 2013).
In 3.2.4, we added “The differences in OCP can introduce the galvanic corrosion.” ( Huang F, 2010) Line 204.
In addition, We have asked the professional revision personnel to make the modification.
Line 52 – What is M/A constituents?Response: Thank you for your comment. M/A constituents is the abbreviation of martenstite/austensite constituents, as is shown in Line 40, which can be viewed as second phase (L.W. Wang, 2004), and it is one of the important microstructures for low carbon low alloyed steels. The M/A constituents can present thin film-like, rod-like, dot-like and granular. It commonly exists between the parallel ferrite laths, in the ferrite matrix, in the prior austenite grain boundaries (X.W. Chen).
Line 68 - What is microstructure and micro-morphologies observations exactly meanResponse: Thank you for your comment. Microstructure observation was for the various zones of the welded joints and the micro-morphologies observations was for corrosion product film formed on the steel surface. We have realized that microstructural and micro-morphologies observations are not suitable for the title of this paragraph. Microstructure and Micro-Morphologies of Corrosion Product Observations are suitable topics, as is shown in the revised manuscript.
Line 69 - Why instrument name is in capital?Response: Thank you for your good suggestion. The reason why instrument name is in capital is that it is proper nouns.
Line 73 - What does “step of 0.5â—¦/min” mean? Is this the correct way to mention 0.5â—¦/min? Explain.Response: Thank you for reminding us that it is a mistake. The 0.5 °/min was changed to be 0.5 degree/min, as is shown in the revised manuscript.
Line 74 - Instrument name, model and other specifications.Response: Thank you for your good advice. We have added the information of model, manufacturer, and so on, like (SEM, JSM-6480LA, Shenzhen Kaiyu Technology Co. LTD, Japan) and (XRD, DX-2700, Dandong Haoyuan Instrument Co. LTD, China).
Line 76 –Change spelling for experimentResponse: Thank you for your good suggestion. We have corrected it.
Line 78-79 - The samples were polished to 800# metallographic grade by grade with metallographic sandpaper. What does 800# mean? Can describe in more appropriate way. Refer papers.Response: Thank you for your comment. The specimens were ground using an 800 grit emery paper, then cleaned sequentially with acetone, alcohol, and distilled water. It is a better statement.
Line 85 - Details about software ZSimpWin like version, company name and so on.Response: Thank you for your comment. We have added the details of the software as ZSimpWin (Echem Software Version 3.21), which can be seen in the revised manuscript.
Line 93 – Meaning of M/A islands. Add more points with suitable references.Response: Thank you for your good suggestion. To keep the narrative consistent, the M/A islands was changed to be M/A constituents. M/A constituents is a common structure in high strength steels, which has been introduced in the manuscript.
Line 97 - Should “0.2” in HV 0.2 be in lowercase? Verify.Response: Thank you for your good advice. 0.2 means that the load charge is 200g (0.2kg), as is shown in the section 2.2. To avoid ambiguity, we deleted the 0.2 and the meaning of the figures is not changed any more. The modified figure is as follows:
Line 101 - In Figure 1c and 1d marking should be made more clearly visible.
Response: Thank you for your good suggestion. We have adjusted the contrast and brightness of the picture. The modified figure is as follows
Line 106 – Why in Open “circuit” Potential (OCP) “circuit” is in Small letter?
Response: Thank you for your good advice. It is our mistakes; we have corrected it to Open Circuit Potential
Line 128 – Write equation numberResponse: Thank you for reminding us that it is the wrong description. We have added the equation number.
(1)
Line 148 - Check legend font size of figure 6a.Response: Thank you for your comment. We have checked legend font size of figure 6a. The modified figure is as follows
Line 155 - Why is there an apostrophe on samples? Why mackinawite is in capital letter in line numbers 155, 159, 160?Response: Thank you for your good suggestion. It is our mistakes. We have changed the statement to “the surface of all samples” and changed the Mackinawite to small letter.
Line 167-169 - Explain why four-prismatic written twice? State the necessity.Response: Thank you for reminding us of this mistake. We have corrected it to “The appearance of the corrosion products on the surface of the WM presented a four-prismatic shape”.
Line 176 - Write full stop after studies.Response: Thank you for reminding us that it is wrong. We have added full stop.
Line 179-180 – Figure 7. Don’t write metal/zone (BM, WM, CGHAZ and FGHAZ) twice. Caption given in a, b, c, and d is enough.Response: Thank you for your comment. We have corrected it to Figure 7. SEM of the corrosion products produced on the surface of the (a) BM; (b) WM; (c) CGHAZ and (d) FGHAZ after immersion for 96h.
Line 181 - In Table 2 where is the unit for metals elements?Response: Thank you for your good suggestion. The unit is indicated in the Table. For the second and the third rows, the unit is atom percent and it is abbreviated to at %. For the fourth row, it is a ratio of the atom percent between Fe and S. Because the units of the three rows are different, they cannot be displayed in the title.
Line 185 - Different immersion time or only for 96 h? Verify and explain the statement in section 3.2.3. Where is the left side scale?Response: Thank you for your good suggestion. According to the comments of reviewer 2, “Figure 8: It is very little informative. I propose to remove it and comment the data only in the text.”, We have removed Figure 8 and comment the data only in the text.
Line 186 - Check the subsection number. It is “3.2.4”.Response: Thank you for your comment. We have corrected it to 3.2.4.
Line 194 – 203 – Reframe the sentences as it is not clear to understand.Response: Thank you for your good advice. Significant differences in H2S corrosion resistance exists between the FGHAZ and CGHAZ because of microstructure differences. The microstructure of FGHAZ is mainly PF with a fine grain size and the corrosion products are most closely arranged, the corrosion resistance is the best, even better than that of BM. The CGHAZ shows a large number of coarse non-equilibrium microstructures. The differences in OCP can introduce the galvanic corrosion. The CGHAZ can be preferentially attacked, which leads to the CGHAZ having the lowest Rct and the loosest corrosion product film. Therefore, the CGHAZ is considered to be the weak zone of corrosion resistance of welded joints. This is a clearer expression.
Line 204 - Add more points in section 4.Response: Thank you for your comment. We have added 2 new conclusions in section 4, as:
The WM showed the highest hardness and the HAZ near the BM showed the lowest hardness in the welded joints. The CGHAZ showed the lowest open circuit potential indicating that it will be attacked preferentially when the welded joints is immersed in the electrolyte as a whole.
Reviewer 2 Report
The manuscript describes microstructure and corrosion properties of a weld zone of X80 steel. It is logically structured and the presented results are sufficiently useful for publication in Metals. Below, some minor remarks and recommendations are given:
Line 76-85: It would be helpful if the experimental setup is explained in detail. What electrodes were used? What potentiostat? Line 78: The dimension is given in mm, not mm3. You would need to give the sample volume (200 mm3) to be able to use this unit. Table 2: Standard deviations are missing. What was the error of the measurement? The number of digits should reflect it. Figure 8: It is very little informative. I propose to remove it and comment the data only in the text. Line 187-192: No proof of the proposed mechanism is given. I am not sure this paragraph is useful in any way. Line 193-203: This is an important part of the paper. Please, try to re-phrase it to make it easier to understand.
The English needs to be somewhat improved. There are formulations and expressions that are difficult to understand. Some of them are listed below, but there are many more in the text.
Line 30: Better use hydrogen induced cracking than hydrogen induced crack. Line 37: „… can embrittle …“ Line 38: „… thus leading to …“ Line 41-43: Maybe better to say „… a layer of sulfide corrosion products can be gradually formed on the surface of pipeline steel and its compact structure reduces the corrosion rate …“? Line 47: „… to make the welded joint more …“ Line 53: … coarsening of the microstructure… Table 1: The authors mean „alloy composition“, not „alloy content“, right? What technique was used for the chemical analysis? Line 74: „…micro-hardness instrument which the loading …“. Please, re-phrase. Line 76: „Electrochemical Experiments“ Line 78-79: „… polished to 800# metallographic grade by grade with metallographic sandpaper…“. The sentence in not correctly written in English. Please, re-phrase. Line 80: The authors probably want to write „… the H2S was …“, not „… the H2S should be …“. Line 107: “… solution saturated with H2S …” instead of “… solution with saturated H2S …“. Line 168-169: „a four-prismatic or a four-prismatic shape“. Line 194: “Therefore, the corrosion resistance of BM and WM are approximate …”. The authors probably want to say that it is similar. Line 200: “The coarsening of …” instead of “The coarsen of …”.Author Response
Dear Reviewer #2:
Thank you very much for your comments for our manuscript. They are all valuable and very helpful for revising and improving our manuscript, as well as the important guiding significance to our research. We have studied comments carefully and made corrections, as follows:
Line 76-85: It would be helpful if the experimental setup is explained in detail. What electrodes were used? What potentiostat?Response: Thank you for your good suggestion. We have added the details as “The electrochemical experiments were performed using Autolab (Aut84886, Shanghai Walong Instrument Co. LTD, China) with a two-component cell, Pt gauze counter electrode, and saturated calomel electrode (SCE) of +0.241 VSHE as the reference electrode”.
Line 78: The dimension is given in mm, not mm3. You would need to give the sample volume (200 mm3) to be able to use this unit.Response: Thank you for your comment. We have changed it to “a rectangular shape with dimensions 10 mm × 10 mm × 2 mm dimension”.
Table 2: Standard deviations are missing. What was the error of the measurement? The number of digits should reflect it.Response: We have added the standard deviations in Table 2, as follows:
Table 2. Corresponding EDS results of corrosion products produced on the surface of the BM, WM, CGHAZ and FGHAZ after immersion for 96 h. (the content in parentheses is the standard deviations)
|
|
BM |
WM |
CGHAZ |
FGHAZ |
|
Fe (at %) |
44.82 (1.21) |
46.83 (1.26) |
45.12 (1.15) |
45.83 (1.28) |
|
S (at %) |
55.18 (1.21) |
53.17 (1.26) |
54.88 (1.15) |
54.17 (1.28) |
|
Fe/S |
1.23 (0.11) |
1.14 (0.13) |
1.22 (0.09) |
1.18 (0.15) |
Figure 8: It is very little informative. I propose to remove it and comment the data only in the text.
Response: Thank you for your comment. We have removed Figure 8 and comment the data only in the text.
Line 187-192: No proof of the proposed mechanism is given. I am not sure this paragraph is useful in any way.Response: Thank you for your advice. This paragraph does not meet the title, we have deleted it.
Line 193-203: This is an important part of the paper. Please, try to re-phrase it to make it easier to understand.Response: Thank you for your good suggestion. We have rewritten the paragraph. “Significant differences in H2S corrosion resistance exists between the FGHAZ and CGHAZ because of microstructure differences. The microstructure of FGHAZ is mainly PF with a fine grain size and the corrosion products are most closely arranged, the corrosion resistance is the best, even better than that of BM. The CGHAZ shows a large number of coarse non-equilibrium microstructures. The differences in OCP can introduce the galvanic corrosion. The CGHAZ can be preferentially attacked, which leads to the CGHAZ having the lowest Rct and the loosest corrosion product film. Therefore, the CGHAZ is considered to be the weak zone of corrosion resistance of welded joints”.
The English needs to be somewhat improved.Response: Thank you for your comment. We have asked the professional revision person to make the modification.
Line 30: Better use hydrogen induced cracking than hydrogen induced crack.Response: Thank you for your advice. We have corrected the phrasal errors to “hydrogen induced cracking”
Line 37: „… can embrittle …“Response: Thank you for your comment. The statement is not appropriate. We have changed to “accelerating the corrosion rate of welded joints and causing them to become much more susceptible to dangerous ruptures” is more suitable.
Line 38: „… thus leading to …Response: Thank you for your good suggestion. The sentence is redundant. We've removed it.
Line 41-43: Maybe better to say „… a layer of sulfide corrosion products can be gradually formed on the surface of pipeline steel and its compact structure reduces the corrosion rate …Response: Thank you for your comment. The sentence is rather lengthy. We have corrected it to “a layer of sulfide corrosion product film can be gradually formed on the surface of pipeline steel， and its compact structure are conducive to reducing the corrosion rate”.
line 47: „… to make the welded joint more …Response: Thank you for your comment. The statement is not appropriate. “accelerating the corrosion rate of welded joints and causing them to become more susceptible to dangerous ruptures” is more fluent.
Line 53: … coarsening of the microstructure…Response: Thank you for your advice. “the coarsening of the microstructure increases the corrosion resistance of welded joints”. Table 1: The authors mean „alloy composition“, not „alloy content“, right? What technique was used for the chemical analysisResponse: “Table 1. The alloy composition of the BM and WM. (wt.%)” have been corrected. Plasma spectrum analyzer was used for the chemical analysis.
line74: „…micro-hardness instrument which the loading …“. Please, re-phraseResponse: Thank you for your advice. We have corrected it to “The micro-hardness distribution in the welded joints was determined by a micro-hardness instrument (HXD-1000TMC, Xian Weixin Testing Equipment Co. LTD, China) with a load charge of 200g for 15s”.
Line 76:Electrochemical ExperimentResponse: Thank you for your good suggestion. Electrochemical experiments have been corrected.
Line 78-79: „… polished to 800# metallographic grade by grade with metallographic sandpaper…“. The sentence in not correctly written in English. Please, re-phrase.Response: Thank you for reminding us that it is wrong. We have corrected it to “The specimens were ground using an 800 grit emery paper, cleaned sequentially with acetone, alcohol, and distilled water”.
Line 80: The authors probably want to write „… the H2S was …“, not „… the H2S should be …“.Response: Thank you for reminding us that it is wrong. “the solution was purged with H2S for 24 h, and H2S flow was maintained during the test duration.” We have corrected it.
Line 107: “… solution saturated with H2S …” instead of “… solution with saturated H2S …“.Response: Thank you for your advice. We've changed the order
Line 168-169: „a four-prismatic or a four-prismatic shape“.Response: Thank you for your good suggestion. We've removed the extra " a four-prismatic "
18.Line 194: “Therefore, the corrosion resistance of BM and WM are approximate …”. The authors probably want to say that it is similar.
Response: Thank you for reminding us that it is wrong. “the corrosion resistance of BM and WM are similar” have been corrected.
Line 200: “The coarsening of …” instead of “The coarsen of …”.Response: Thank you for your comment. The sentence has been rewritten as "The CGHAZ shows a large number of coarse non-equilibrium microstructure."
Round 2
Reviewer 1 Report
Reviewers' comments:
The authors revised the manuscript according to the reviewers' comments.
So that I recommended this manuscript accept for publication in metals.
