Comparison of Modified Johnson–Cook Model and Strain–Compensated Arrhenius Constitutive Model for 5CrNiMoV Steel during Compression around Austenitic Temperature

Round 1

Reviewer 1 Report

The authors Compared the Modified Johnson-Cook and Strain-Compensated Arrhenius Constitutive Models for 5CrNiMoV Steel during Compression around Austenitic Temperature. The paper is well-written and interesting for readers about materials constitutive equations. The paper can be accepted after some minor revisions below.

1) There should be an experimental setup image, and also specimen image for proof.

2) Section 3.1. True stress-strain curves and microstructures should be separated as "True stress-strain curves" and "microstructures".

3) In Figure 2, the demostration data as 700C, 0.05 s_1, and others should be given in different places. It is not suitable to show them on the stress-strain curves.

4) There should be some indicators of the microstructural changes (like twinning, precipitation hardening, etc) in Figures 3 and 4.

5) There should be some quantitative results in the summary section.

 

Author Response

Reviewer #1

Comment #1

There should be an experimental setup image, and also a specimen image for proof.

Response: The authors are grateful to the reviewer for pointing out this in notice. In the revised manuscript, the experimental setup image and specimen image have been added in Figure 1b.

 

Comment #2

Section 3.1. Ture stress-strain curves and microstructures should be separated as ‘True stress-strain curves’ and ‘microstructures’.

Response: Thanks for the reviewer’s suggestion. Sections 3.1 has been separated as ‘3.1. True stress-strain curves of the 5CrNiMoV steel’ and ‘3.2. Microstructures of the 5CrNiMoV steel after compression’ in the revised manuscript. Now section3 consists of five parts i.e. part 1(True stress-strain curves of the 5CrNiMoV steel), part 2(Microstructures of the 5CrNiMoV steel after compression), part 3(Modified Johnson-Cook model), part4 (Strain-compensated Arrhenius model) and part 5(Evaluation of the constitutive models).

 

Comment #3

In Figure 2, the demonstration data, 700C, 0.05S_1, and others should be given in different places. It is not suitable to show them on the stress-strain curves.

Response: The authors are thankful to the reviewer for providing valuable suggestions. Figure 2, Figure 10 and Figure 11 have been revised according to the reviewer’s suggestions.

 

Comments #4

There should be some indicators of the microstructural changes (like twinning, precipitation hardening, etc) in Figure 3 and 4.

Response: Yes, some indicators including ‘continuous strip’, ‘recrystallized grains’, ‘coarsened grains’ and ‘fine recrystallized grains’ have been added in Figure 3 and Figure 4.

 

Comments #5

There should be some quantitative results in the summary section.

Response: Thanks for the reviewer’s suggestion. Some quantitative results were added in the summary section of the revised manuscript. For example, ‘The unbiased AARE values were 6.82 and 5.71 for MJC model and SCA model, respectively, which implied the SCA model has higher accuracy than the MJC model.’, ‘The MJC and SCA models are suitable to predict the thermomechanical behavior of 5CrNiMoV steel when the flow stress lower than 200 Mpa. For a higher flow stress state, the SCA model is more preferred.’.

Reviewer 2 Report

The abstract is little bit confusion as there are limited details on quantitative information : “is at a relatively lower level.”..” predicted and measured values seems to expand.” More accurate information should eb provided. Otherwise seems both models to have some degree of predictability but not possible to use them as validation !

The English should be massively improved as there it was found numerous issue “process are always attracted so much” this is just an example and everywhere it was found the same

The sample preparation of SEM and BSE were very briefly presented and difficult to replicate – please provide better details of each step used in order to reproduce it

What does means this “For specimens without external stress” from where come this external stress here ?

This part “Alloy element diffusion… more complicated.” Should be endorsed by some citation as the authors do not have provided evidence

Why was used these citation in “effect on the flow stress [12,27,32],” as long as they are your results !

Why the authors used different scale for images from Figures 2 – now it make difficulty to compare the results !

The figures 3, 4 are inconsistent with what authors claims as not clear details about grains and other particularities !

The conclusion are very qualitative and rather  they should indicate more quantitative details !

Author Response

Reviewer #2

Comment #1

The abstract is little bit confusion as there are limited details on quantitative information: ’is at a relatively lower level’, ‘predicted and measured values seems to expand’. More accurate information should be provided. Otherwise seems both models to have some degree of predictability but not possible to use them as validation.

Response: The authors are thankful to the reviewer for asking this question. Yes, we completely agree with the reviewer’s point of view that the abstract and the conclusions lack quantitative information. Some quantitative results have been added to the abstract and the summary.

 

Comment #2

The English should be massively improved as there it was found numerous issue ‘process are always attracted so much’ this is just an example and everywhere it was found the same.

Response: The authors are thankful to the reviewer for pointing out the grammar error. Please accept our apologies for the same. In the revised manuscript the errors are corrected.

 

Comment #3

What does mean for ‘For specimens without external stress’ from where come this external stress here?

Response: The authors are grateful to the reviewer for this question. For metals with phase transformation, temperature, phase transformation and strain/stress can influence each other. For example, the increase or decrease of temperature can cause a phase transformation, also the external stress has a significant effect on the phase transformation process, especially for the phase transformation velocity and the start/finish point. There is no external stress for testing the Ac1 and Ac3 temperatures at different heating rates. In the manuscript, ‘For specimens without external stress, the temperature is the main driving force of phase transformation, the heating rate is a major factor affecting the phase transformation kinetics…..’, was used to identify the deformation temperatures 750 ºC and 700 ºC are below the Ac3.

 

Comment #4

This part ‘Alloy element diffusion … more complicate’ should be endorsed by some citation as the authors do not have provided evidence.

Response: Thanks for the reviewer’s suggestion. The authors did not provide any evidence about this issue, and citations have been added in the revised manuscript (W. D. Callister. Materials science and engineering an introduction, John Wiley & Sons, Inc Press, 2007).

 

Comment #5

Why was used these citation in ‘effect on the flow stress[12, 27,32]’, as long as they are your results.

Response: The authors are grateful to the reviewer for bringing this in author’s consideration. In the revised manuscript, this sentence is corrected in this form ‘It can be seen the deformation temperature and strain rate have a significant effect on the flow stress, similar results have also been reported by other scholars [12,27,32], despite above or below Ac3 temperature’.

 

Comment #6

Why the authors used different scale for images from Figure 2, now it make difficulty to compare the results.

Response: The authors are thankful to the reviewer for asking this question. Figure 2, Figure 10 and Figure 11 used different scales in the manuscript.  Measured and calculated true stress-strain curves of 5CrNiMoV steel at different temperatures and strain rates were shown in the above figures. In order to make the curve distribution more uniform, we choose different scales on the Y-axis. Moreover, other scholars also use different scales in the stress-strain curves. (X. He, Z. Yu, X. Lai, A method to predict flow stress considering dynamic recrystallization during hot deformation, Comput. Mater. Sci. 44 (2008) 760-764. O. Sabokpa, A. Zarei-Hanzaki, H.R. Abedi, N. Haghdadi, Artificial neural network modeling to predict the high temperature flow behavior of an AZ81 magnesium alloy, Mater. Des. 39 (2012) 390-396.)

 

Comment #7

The figures 3, 4 are inconsistent with what authors claims as not clear details about grains and other particularities.

Response: Thanks for the reviewer’s suggestion. The contents corresponding to Figure 3 and Figure 4 have been corrected. i.e. ‘If the effect of stress/strain-induced austenite decomposition can be ignored, the microstructure of the 5CrNiMoV steel should be martensite after cooling, no precipitation occurred in this process.’.

 

Comment #8

The conclusion are very qualitative and rather they should indicate more quantitative details.

Response: The authors are grateful to the reviewer for pointing out this question. More quantitative results have been added to the revised manuscript. For example, ‘The MJC model has a good accuracy close to the reference conditions (0.001 s^-1 and 700 ºC). With the increase of compression temperature or increase of strain rate, the discrepancy between the MJC predicted flow stress and the measured flow stress expanded gradually, especially when the true strain was larger than 0.6’.

Round 2

Reviewer 2 Report

The authors responded well to my questions therefore I suggest acceptance.