Numerical and Experimental Investigation of the Heat Input Effect on the Mechanical Properties and Microstructure of Dissimilar Weld Joints of 690-MPa QT and TMCP Steel
Round 1
Reviewer 1 Report
An experimental campaign carried out to investigate the microstructure after welding dissimilar steels using different heat input is presented. The paper contains also the description of a finite element analysis of the welding process, but the discussion of this part is very synthetic compared to the very careful description of the final microstructure, which was studied using image analysis software. Moreover, the microhardness profiles are provided which can give an idea of the mechanical behavior but do not represent a mechanical characterization of the material. For this reason, if the paper is maintained in the present form the title should be modified to : ‘Investigation of the heat input effect in the microstructure of dissimilar…’.
The English language has to be improved, especially in the abstract, which is hardly understandable and do not provide a clear description of the paper content. Some other inaccuracies are distributed throughout the text, giving the appearance of deficient care in preparing the manuscript.
The novelty content of the paper is fair: a very careful experimental characterization of the joint is presented, which can be of interest for the technical community, but represent a marginal step forward. Different would have been the impact of the paper if the authors had better discussed and documented the finite element modelling of the welding operation.
My suggestion to ask for major revisions. In the revision the authors could follow a statement, probably coming from a previous revision of the paper, that accidentally was left in the text (page 10 row 296) which verbatim quotes: ‘…Authors should discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted’.
In the revision a better discussion of the correlation between numerical and experimental analysis must be provided. In particular, the authors should describe, how the latent heat of fusion is implemented in the model.
A better description of the experimental device used to measure the solidification process is also necessary.
Author Response
Article: metals-454102
Title: Numerical and Experimental Investigation of the Heat Input Effect in the Mechanical and Microstructure of Dissimilar Weld Joint of 690 MPa QT and TMCP Steel.
Author: Francois Miterand Njock Bayock
Dear Reviewer,
The response to the reviewer’s comments of “Numerical and Experimental Investigation of the Heat Input Effect in the Mechanical and Microstructure of Dissimilar Weld Joint of 690 MPa QT and TMCP Steel”.
Point1:
The English language has to be improved, especially in the abstract, which is hardly understandable and do not provide a clear description of the paper content. Some other inaccuracies are distributed throughout the text, giving the appearance of deficient care in preparing the manuscript. Response 1
I have provided the response for point 1
Point 2:
My suggestion to ask for major revisions. In the revision the authors could follow a statement, probably coming from a previous revision of the paper, that accidentally was left in the text (page 10 row 296) which verbatim quotes: ‘…Authors should discuss the results and how they can be interpreted in perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted’
Response 2
I have provided the response for point 2. The corrections were made
Point 3:
In the revision a better discussion of the correlation between numerical and experimental analysis must be provided. In particular, the authors should describe, how the latent heat of fusion is implemented in the model.
Response 3
I have provided the response of point 3 in the introduction (It is writing in red)
Column 39, line 25
Point 4:
A better description of the experimental device used to measure the solidification process is also necessary.
Response 4
Some illustrations have been presented in the material and methods section. (Column 17, Line 48)
Best regards,
Reviewer 2 Report
Its an intteresting study about dissimilar welding of high strength steels.
However the reviewer is not a native English speaking person, the language needs serious improvement, there are sentences very hard to understand.
Generally:
- The choise of filler must be emphasized it has a lot less YS / TS than the base materials.
- Figures need improvement, the font sizes are very different and small, hard to read.
- Some unit are given (for the simulation i guess) not in the commonly used way for welding.
e.g. welding speed 3.71 mm/s can be set maybe for a robot (0.01 mm/s accuracy is high even for a robot), hovewer an average 22 cm /min (which is basically the same) can be made with everything. There is also J/mm then kJ/mm...etc.
-Some technical testing; bending charpy, tensile test ...would be great...at least qualify the joint parts according the present data as acceptable / not acceptable joints (joint parts)
- Also for the conclusion part, the simulation is mentioned, as it has different outcome as the measured T8-5 values. Then the model needs to be improved ! --> therefore should not be in this manuscript, or is there some other result for which it needs to be presented in this manuscript? Then it should be given also in the conclusion part. Also please emphasize where a welding engineer (whih I am) can use this research data, give suggestions for possible usage, window of application....etc.
I made my detailed remarks, questions, comments in the manuscript_with_reviewers_comments
With corrections the manuscript might fulfill the publication criteriia in Metals.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
The response to the reviewer’s comments of “Numerical and Experimental Investigation of the Heat Input Effect in the Mechanical and Microstructure of Dissimilar Weld Joint of 690 MPa QT and TMCP Steel”.
Point1:
The choice of filler must be emphasized it has a lot less YS / TS than the base materials.
Response 1
I have provided the response for point 1 in red (column 55 line 50)
Point 2: Figures need improvement, the font sizes are very different and small, hard to read.
Response 2
I have provided the response for point 2 in red
Point 3: - Some unit are given (for the simulation i guess) not in the commonly used way for welding.
Response 3
I have provided the response for point 3 in red
Point 4: Also for the conclusion part, the simulation is mentioned, as it has different outcome as the measured T8-5 values. Then the model needs to be improved ! --> therefore should not be in this manuscript, or is there some other result for which it needs to be presented in this manuscript? Then it should be given also in the conclusion part. Also please emphasize where a welding engineer (which I am) can use this research data, give suggestions for possible usage, window of application....etc.
Response 4
I have provided the response for this point. You can see it in the introduction, abstract, and in the conclusion (In red).
Best regards,
Round 2
Reviewer 1 Report
the paper has been improved, not all the questions have been answered in detail but the paper has been improved to a level suitable for publication
Author Response
Thank you!
Best regards.
Reviewer 2 Report
The manuscript was improved significantly from the initial state, the corrections and answers to my questions were adequate, but one:
"The choice of filler must be emphasized it has a lot less YS / TS than the base materials."
I have provided the response for point 1 in red (column 55 line 50)
line 50 "HAZ of different HSSs is of practical interest [11,12]. Researchers usually give primary attention to the"
"Line 8-91 "Table 2 shows the chemical composition of the 88 filler metal determined after the evaluation of the equivalent carbon. This equivalent carbon has been 89 identified on the base of the chemical compositions of the base materials." Last sentence is not clear please rephrase.
Where there any other filler within the required YS class, was only the CE the choice of filler? Please emphasize where such choice will be interesting some examples.
Some other small remarks:
- Fig 5-8 does not needs to be separated, a common scale bar and legend could save a lot of space (also there is no info on the right side of these images you can crop it.
Fig 17. is the area in nm2 not in µm2?
- Fig 18. measured along how many lines? Where exactly? average values? +- std dev? what is the stdev. of the base materials? it looks like te 10 kJ/cm specimen has smaller HAZ?
I think with minor corrections the manuscript will satisfy the publication criteria in Metals.
Author Response
Article: metals-454102
Title: Numerical and Experimental Investigation of the Heat Input Effect in the Mechanical and Microstructure of Dissimilar Weld Joint of 690 MPa QT and TMCP Steel.
Author: Francois Miterand Njock Bayock
Dear Editor,
The response to the reviewer comments of “Numerical and Experimental Investigation of the Heat Input Effect in the Mechanical and Microstructure of Dissimilar Weld Joint of 690 MPa QT and TMCP Steel”.
Reviewer.
"The choice of filler must be emphasized it has a lot less YS / TS than the base materials."
Corrected.
The choice of the filler wire depends of the YS/TS of the base and the shieling gas used. Inside the base material, we already have a chemical composition. So, we can easily evaluate the carbon equivalent of both base materials. It was applied 3 heat input parameters to weld the second pass. 10kJ/cm, 14kJ/cm, and 17kJ/cm. the required filler wire to weld the two base materials is 16834-A G 69 6 M21 Mn4ni1,5CrMo. (720 (YS), 780 (TS), min 17 (A). The YS/TS) are a little less than the base material, but it was applied for undermatched weld.Some other small remarks:
- Fig 5-8 does not needs to be separated, a common scale bar and legend could save a lot of space (also there is no info on the right side of these images you can crop it.
Corrected
Fig 17. is the area in nm2 not in µm2?
Corrected
- Fig 18. Measured along how many lines? Where exactly? average values? +- std dev? what is the stdev. of the base materials? it looks like te 10 kJ/cm specimen has smaller HAZ?
Corrected
They were three samples, and it had made one-line measurement for every sample. 2 mm from the top of the sample. The hardness of the base material for S690QT= 270 HV, and S690TMCP= 290 HV. In the Figure, some deviations were observed in the figure. The percentage were evaluated in the comparative analysis of the data.
Best regards.
