Microstructure and Wear Resistance of WC and High Chromium Cast Iron Hardfacing Layers

Round 1

Reviewer 1 Report

Dear Authors,

I read Your article and found it interesting. The subject of shaping the material properties by applying WC or HCCI welding layers is very interesting and results which You show are valuable. Unfortunately, the way the results are presented and the language in which the article was written makes it impossible to understand and appreciate it.

There are many language and grammar mistakes in Your manuscript. I strongly suggest to make the language verification.

I propose to use “base material” rather than “substrate” or “matrix”.

Title is about only one type of layer but in article two are described.

Abstract:

There is a typo in page 1, line 11 –in “microstructure”.

Add “and” between SEM and X-ray.

Remove “And” from line 12 and 15.

As “mechanical properties” are plural change “was” to “were” in line 13.

In abstract You use abbreviations which are not explained.

What mean: “is contribute to improves”?

Introduction:

Line 37: marteries?

High chromium cast iron is named HCCI in abstract but HHCI in Introduction.

Line 41: “low carbide steel” – steel with small amount of carbides or carbon?

Last sentence of Introduction should be rewritten.

Introduction chapter is very poor. Literature review is chaotic and written with the use of poor language. There has to be “a story” to show the purpose of doing such research and to show other researchers ideas. In addition, only 10 references are connected to this chapter and most of them are from 2013-2015. This show that literature survey wasn’t very accurate.

Experimental:

The first and second sentences have no verbs. The language in chapter 2 is tragic and although I can guess what these sentences mean, they are incorrect and make it difficult to understand the content.

Which welding process was used? Welding rod was only the consumable or the consumable electrode? Was it covered? How the maximum temperature of welding cycle was measured?

I understand that for wear tests the specimen has to be 30x30mm but I cannot understand how You have surfaced such a small sample manually and achieved 3-5mm thickness layer on 3mm thickness base material. Were there any additional elements, plates, setup or fixings?

Line 54: morphology was polished?

What was the name of profilometer?

I have written “Zwick-Roell Sclerometer” in Scholar but till now there is not even one article with this name. Write what type of hardness measurements was carried out and write the parameters for used for this measure.

Line 62: change “form” to “from”

Results:

Language in this chapter is also very poor.

I am a little bit confused – You write that the hardness in 4b and photos with wear profiles in 6e-g were made at high temperature? You have been imaging the samples in SEM and they were 800C during it?  If so, You have to write it clearly and write about the equipment for it. If not (what I expect more) correct your description of the experiment and the description of the results.

Unify the font in Figures.

In figure 3 photos a,c and b,d looks like they have different magnifications but the scale is drawn the same.

Figure 4a. Distance is 0 at the face of the surface layer? If so, why we can see “-100” distance on a scale? Write clearly where is base material and where is a welded layer. Additionally, all samples had the same thickness after welding? The scheme shows a 300microm layer for all samples but in line 51 You wrote something else. Here we can see that Vickers hardness was used but we still don’t know the applied force and time.

You write in line 98 that hardness decreases because of pores but earlier You write about pore only in WC layer.

Figure 5. What is RT? Use consequently the same colour and shape for WC and HCCI in all Figures.

Caption of Figure 6 is very messy. Rewrite it. In fig. 6e what the little arrows show? What temperature is “high temperature”?

Discussion

Caption of Figure 8 is too short. You have to write sth about a-d.

When You write “heating” You mean welding? Write it clearly in caption, figure and in text. My first thought was that you describe what happens when the temperature rises during the wear test.

Here also (line 161) You write about pores in both layers but on a basis of the figure of only WC layer.

Conclusions

“the hardness of WC welding layer decrease with the formations of Fe3W3C particles,” -> which results allow such a conclusion to be drawn?

There is no contribution between authors given while two of authors are in acknowledgements. Authors thank themselves?

Author Response

Reviewer 1

1. There are many language and grammar mistakes in Your manuscript. I strongly suggest to make the language verification.I propose to use “base material” rather than “substrate” or “matrix”.Title is about only one type of layer but in article two are described.

Reply: The language of manuscript have been improved though the whole test. The “base material” was corrected to “matrix” in the manuscript. Furthermore, the tile was changed to “Microstructure and wear resistance of WC and high chromium cast iron hardfacing layers” in the revised manuscript.

2. Abstract: There is a typo in page 1, line 11 –in “microstructure” Add “and” between SEM and X-ray. Remove “And” from line 12 and 15. As “mechanical properties” are plural change “was” to “were” in line 13. In abstract You use abbreviations which are not explained. What mean: “is contribute to improves”?

Reply: The abstract of this paper has been revised intensively. We remove the experimental details and the abbreviations were carefully defined. The revised absract highlights the two contributions of present research (1) develope an experimental method to evaluate the three-body wear resistance at high temperatures; (2) figure out the microstructual cause for the improved high-temperature properties of WC hardfacing layer.

3. Line 37: marteries?

High chromium cast iron is named HCCI in abstract but HHCI in Introduction.

Line 41: “low carbide steel” – steel with small amount of carbides or carbon?

Last sentence of Introduction should be rewritten.

Introduction chapter is very poor. Literature review is chaotic and written with the use of poor language. There has to be “a story” to show the purpose of doing such research and to show other researchers ideas. In addition, only 10 references are connected to this chapter and most of them are from 2013-2015. This show that literature survey wasn’t very accurate.

Reply: The language mistakes in the Introduction part have been revised. Almost the whole introduction part have been rewritten. The logic is clear in the present version. Furthermore, the references from 2015-2020 were chosen to support the current investigation.

4. The first and second sentences have no verbs. The language in chapter 2 is tragic and although I can guess what these sentences mean, they are incorrect and make it difficult to understand the content.Which welding process was used? Welding rod was only the consumable or the consumable electrode? Was it covered? How the maximum temperature of welding cycle was measured?

I understand that for wear tests the specimen has to be 30x30mm but I cannot understand how You have surfaced such a small sample manually and achieved 3-5mm thickness layer on 3mm thickness base material. Were there any additional elements, plates, setup or fixings?

I have written “Zwick-Roell Sclerometer” in Scholar but till now there is not even one article with this name. Write what type of hardness measurements was carried out and write the parameters for used for this measure.

Reply: the language have been polished in this part. The specimens were prepared by the company. They are not convenient to tell the authors the detail preparation process of the specimen.

The 30*30*3-5mm specimens were prepared from the claded Q235 plate by wire cutting. Then the surface was polished by the grinding machine.

5. I am a little bit confused – You write that the hardness in 4b and photos with wear profiles in 6e-g were made at high temperature? You have been imaging the samples in SEM and they were 800C during it?  If so, You have to write it clearly and write about the equipment for it. If not (what I expect more) correct your description of the experiment and the description of the results.In figure 3 photos a,c and b,d looks like they have different magnifications but the scale is drawn the same.

Reply: In the revised version of manuscript. The results have been carefully exposed. And the description was revised according the the comments.

The authors have check the oringal data, the four figures in Fig. 3 have the same magnification. Therefore the scale is drawn the same in the manuscript. However, it should be noted that the Fig.3a and Fig.3c are Second electron image, while Fig. 3b and Fig. 3d are backscattered electron image. They have different contrast.  

6. Figure 4a. Distance is 0 at the face of the surface layer? If so, why we can see “-100” distance on a scale? Write clearly where is base material and where is a welded layer. Additionally, all samples had the same thickness after welding? The scheme shows a 300microm layer for all samples but in line 51 You wrote something else. Here we can see that Vickers hardness was used but we still don’t know the applied force and time.

Reply: in the experment part, we write that “The force selected for Vickers microhardness measurement is 200 mN, and the holding time is 10 s.” 

In the Figure 4 of the revised manuscript. We also present the indentations of the welding layers. Five measureent were conducted to obtaineed one data point. During th micro-hardness measurement, we first make the interface parallel to the x direction of the moving stage. Then the position of interface was determined by the indentors.    

Figure 4. The hardness of welding layer at room and high temperatures: (a)&(b) the indentations on the WC and HCCI hardfacing layers; (c) the Vickers hardness changes from welding layer to matrix; (d) the high temperature HRC hardness of both the welding layer.

7 Caption of Figure 8 is too short. You have to write sth about a-d.

Reply: The caption of Figure 8 has been revised to “Schematic diagram showing the formation process of the Fe₃W₃C phase: (a) the dissolution of WC, (b) the diffusion of W, C, and F atoms in liquid, (c) formation of Fe₃W₃C, (d) the formation of WC.” according to the comments.

8 Conclusions

“the hardness of WC welding layer decrease with the formations of Fe3W3C particles,” -> which results allow such a conclusion to be drawn?

Reply: in the revised version the conclusions have been rewriten.

“(1) The WC and HCCI hardfacing layers were prepared on the Q235 matrix. The welding layers have higher hardness than the matrix.

(2) The Fe₃W₃C is the dominant phase in the WC welding layer.

(3) The abrasive wear resistance of WC welding layer is better than that of the HCCI welding layer, especially at high temperatures. “

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the attached Word file.

1. The paper is really about the combined effects of corrosion and wear, particularly the results at 800^oC.
2. The English needs to be improved.

Comments for author File: Comments.pdf

Author Response

Reviewer 2

1. This paper is perfectly understandable, but the standard of English is very low. I will suggest a very fewcorrections, but the paper needs to be edited by somebody with excellent English.

Reply: the language of this paper have been improved greatly through the paper.

2. Line 14. HCCI needs to be defined in the Abstract.

Line 16. Should read: “the anti-oxidation properties of Fe3W3C contributed to the improved …”

Reply: The authors have revised the Abstract. In the new version, the abstract becomes:

“The WC and high chromium cast iron (HCCI) welding layer were prepared on the Q235 low carbon steel by hardfacing technique in order to improve the high-temperature performances. The microstructure and mechanical properties of the welding layer were investigated. It is found that Fe₃W₃C is the major strengthening phase of the WC welding layer. Furthermore, a high-temperature three-body abrasive wear experiment was designed and conducted on the welding layers. The results show that the wear resistance of WC welding layer is much better than that of the HCCI welding layer at both room and high temperatures. During the high-temperature abrasive wear process, the Fe₃W₃C phase can effectively strengthen the matrix and hence contribute to improved wear resistance.” 

3. Lines 24 and 27. The addition of a layer does not “improve” the “surface properties” (wear resistance)of the steel itself. The successful addition of a wear resistant layer is however dependent on how well the layer bonds to the steel. The sentence needs to be re-written so that it is clear that it is the properties of the added layer that is being assessed (for both WC and HCCI), including its bond with the  To be fair to the authors, this is clearly expressed in the rest of the paper - except for lines 31 and 32 (see comments below). Lines 31 and 32. You make the same mistake here. The “hardness of low carbide steel” does not increase. The hardness increase is due to the addition of an additional layer of a different material.

Lines 41 and 42. You have it correct here it was the wear resistance of the welding layers (not the steel) that was investigated.

Reply: the authors agree with the reviewer that the materials we investigated are not low carbon steel by the new composite formed by hardfacing. Therefore, every sentence in the introduction part has been revised in order to make the paper clear.

Furthermore, the bonding properties of the surfacing layer is key for the hardfacing technique. However, we don’t pay our attention to the interfacial properties in this paper.

4. I am not familiar with this test. The average reader may also be in the same position and needs to knowmore.

(1). Is the feed rate of abrasive material (alumina) not an important variable?

(2). The specimen must also have been weighed earlier. Was this first weighing before or after the pre-grinding?

(3). Presumably the alumina particles become embedded in the counter-grinding material.

Reply: The feed rate is an important variable. We are conducting more investigations on this setup.

The first weighing was conducted after pre-grinding.

Yes, the wedge-shape opening of the upper specimen can help the alumina particles participate in the abrasive wear. However, more investigation will be conducted on this method.  

5. Line 107 and Figure 5(b). What are the units of 1/ΔV?

Line 111, Figure 6. Were the wear profiles more or less independent of position on the circumference (angle theta in polar co-ordinates)? The amount of wear does vary with radius (there are grooves) particularly at the high temperature of 800 deg. C.

Line 130 paragraph. No mention is made of the oxide scales earlier, but surely they play a very important role at 800 deg. C, where corrosion and wear are occurring together? This needs to be reflected in the title of the paper. Your main conclusion about the “anti-oxidation” properties of the WC layer are determined by resistance to oxidation (corrosion) of the “WC layer”.

Reply: In Table 3 of the revised manuscript, we define the unit of 1/ΔV is 1/mm³_.

The profile of the abrasive trace (Fig. 5) is indeed should be presented in polar coordinates. The distance in the Figure is the r in the polar coordinates. Therefore, the amount of wear around the whole trace varies with the radius. During the calculation, we assume that the grooves is perfect around the trace and use an integral method to get the whole volume loss. Four measurements were used to get a data.

The authors agree with reviewer that corrosion and wear are occurring together at the temperature of 800 ^oC. However, we believe that the previous conclusion about the “anti-oxidation” contribution of Fe3W3C phase is not solid. Therefore, we corrected this conclusion in the revised manuscript.  

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript under the title “Microstructure and wear resistance of WC welding layer” discusses the SEM, XRD analyses, and mechanical properties (at room and elevated temperatures) of WC and HCCI welded layers. The findings are somehow novel, but I am not able to read and catch the text in the manuscript because the current paper has severe English flaws. The sentences are not written correctly. Besides, punctuation and helping verbs need significant attention from the authors. Therefore, I will recommend the following major modifications:

1. The most important thing, please define abbreviation before using it.
2. Please redefine your findings in the abstract as I didn’t observe any deterministic outcomes.
3. In the introduction section, please elaborate on the novelty of the current manuscript and emphasize why you carried out this study?
4. There is a massive confusion between the two terminologies: (a) HCCL and (b) HCCI.
5. Please combine the result and discussion sections as it will create confusion for the readers. Another thing, please define the text and then display images in the results and discussion section—besides, elaborate results in detail. All the graphical work is fine.
6. Please redefine the conclusion section as no quantitative information is found. For instance, if the hardness of the WC weld layer is decreasing, how much it has reduced?!
7. Please take assistance from a native English speaker, in writing the manuscript based on the results presented.

All the above comments are for the benefits of the authors to produce a well-understandable manuscript.

Regards,

Reviewer.

Author Response

Reviewer 3

1. The findings are somehow novel, but I am not able to read and catch the text in the manuscript because the current paper has severe English flaws. The sentences are not written correctly. Besides, punctuation and helping verbs need significant attention from the authors.

Reply: the lauguage have been improved greatly through the whole test in the revised manuscript.

2. The most important thing, please define abbreviation before using it.

Reply: all the the abbreviation have been defined before using.

3. Please redefine your findings in the abstract as I didn’t observe any deterministic outcomes.

Reply: The abstract has been rewriten in the reivsed manuscript.

the revised abstract:

“The WC and high chromium cast iron (HCCI) welding layer were prepared on the Q235 low carbon steel by hardfacing technique in order to improve the high-temperature performances. The microstructure and mechanical properties of the welding layer were investigated. It is found that Fe₃W₃C is the major strengthening phase of the WC welding layer. Furthermore, high-temperature three-body abrasive wear experiment was designed and conducted on the welding layers. The results show that the wear resistance of WC welding layer is much better than that of the HCCI welding layer at both room and high temperatures. During the high-temperature abrasive wear process, the Fe₃W₃C phase can effectively strengthen the matrix and hence contribute to improved wear resistance.”

The revised absract highlights the two contributions of present research (1) develope an experimental method to evaluate the three-body wear resistance at high temperatures; (2) figure out the microstructual cause for the improved high-temperature properties of WC hardfacing layer.

4. In the introduction section, please elaborate on the novelty of the current manuscript and emphasize why you carried out this study?

Reply: in the revised Introduction, we claim that:

“it is expected that the WC contained surfacing layer can also be applied to the workpieces that service at high temperatures. However, compared to the room-temperature properties[1][1], the high-temperature properties of WC welding layer have received less attention in the literature.

In this study, the WC welding layer and high chromium cast iron (HCCI) welding layer were fabricated on a low carbon steel matrix (Q235) by continuous multiple-layer surfacing technique. The microstructure of the welding layers was investigated. The hardness of the welding layers was measured at room and high temperatures. Furthermore, a three-body abrasive wear resistance test setup was designed to evaluate the wear properties of the welding layer at high temperatures.”

5. Please combine the result and discussion sections as it will create confusion for the readers. Another thing, please define the text and then display images in the results and discussion section—besides, elaborate results in detail. All the graphical work is fine.

Please redefine the conclusion section as no quantitative information is found. For instance, if the hardness of the WC weld layer is decreasing, how much it has reduced?!

Reply: the results, discussion, and conclusions have been revised intensively in the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors,

the manuscript is much better now and quality of language is enough to understand the content.

Discussion should be connected with introduction or with other literature sources to compare Your results with other ones. In addition, introduction is too general. In results Vickers and HRC values are given. It is not  supported by data from the methodology. Hardness measurements at high temperatures are not very common so give standard, reference source with methodology description or write it by yourself. Write "welded layer", not "welding layer".

Author Response

Reply: This is a letter paper, therefore we try to avoid some unnecessary discussions in the manuscript. In this revised manuscript, the hardness test methodology were introduced “The force selected for Vickers microhardness measurement was 200 mN, and the holding time was 10 s. The high-temperature hardness tests were conducted in a ARCHIMEDES tester (HRN/T150) protected by high purity argon atmosphere. ” 

The “welding layer” was corrected to “welded layer” through the manuscript.

Reviewer 2 Report

The authors have done a reasonable job with their revision of the paper.

At the high temperature the authors use volume of material worn away as the measure of the amount of wear, because they claim the amount of oxidation would materially affect the weight change.  However they do not quantify the influence of corrosion on the wear measurement at high temperature.  How significant is the influence of corrosion?  The volume lost roughly doubled, (from Table 3) but that was probably mainly due to the loss of hardness (strength) with temperature (Figure 4(d)).  Perhaps oxygen was not readily able to enter the zone where wear was occurring, but then again the authors do imply that oxidation affected the results.  I will leave it to the authors to clear up this point.

Please see the attached file for some minor comments.  I really would like to see the exess zeros removed from Figure 5, by changing the units on the axes.

Abstract: Stick to the past tense.
Line 35: “worn” not “wore”
Line 45: Wear properties were also evaluated at room temperature?
Line 56: “constituents” not “constitutions”.
Line 67: You have not addressed the question of the flow rate of the abrasive alumina powder,
Line 85: “peaks…belong” not “peaks…belongs”
Line 89: The word “two” is redundant
Line 95: mainly Fe3W3C
Figure 5 must be revised. The x- and y-axes should both be in mm and microns respectively. It is not good to have all those zeros.
Line 183: “Fe” not “F” atoms

Comments for author File: Comments.pdf

Author Response

Reply: The authors believe that corrosion should occur at high temperatures. But to be honest, more efforts are required to quantify the respective contribution of wear and corrosion.

Figure 5 has been corrected in the revised manuscript. And all the typos have been revised.   

Reviewer 3 Report

All the modifications have been implemented. We recommend their acceptance for publication.  

Author Response

Thanks

Round 3

Reviewer 1 Report

Dear Authors,

in my opinion the revisions You have made are enough to publish the article.