Effect of Microstructure Morphology of Q&P Steel on Carbon and Manganese Partitioning and Stability of Retained Austenite
Round 1
Reviewer 1 Report
The manuscript deals with an interesting topic describing influence of the initial microstructure morphology on the following microstructure evolution during Q&P treatment and resulting mechanical properties. The manuscript is well-organized, good-written and the results are worth of publication. I have only some minor comments to the authors.
Please describe what means the term “G” in equation (1).
I can not recognize characteristic microstructures in secondary martensite-retained austenite islands in Fig. 2 a,b due to a low resolution of SEM images. Are they also visible in Fig. 2 c,d? Could you mark these by arrows? If the islands are represented in Fig. 2 c,d by dark areas, could you comment, why the M2/A-islands seems to be larger on micrographs shown in Fig 2a,b, than on micrographs demonstrated in Fig.2c,d and in Fig. 3?
Did you compare the amount of ferrite in Q&P and QQ&P samples after intercritical annealing? As I can see, the later contains less ferrite, which would explain a higher retained austenite percentage in QQ&P sample after partitioning. Please refer this point in discussion.
Other minor remarks:
Abstract, page 1, line 11: “During the intercritical annealing…” instead of “In the intercritical annealing…”.
Abstract, page 1, line22-23: “…increase the homogeneity of carbon…” instead of “increase the homogenous of carbon…”.
Page 2, line 80: “…during the intercritical annealing…” instead of “in the intercritical annealing…”.
Page 2, line 93: “Panalytical” instead of “Panslytical”.
Page 7, line 181: “…during the intercritical annealing…” instead of “in the intercritical annealing…”.
Figure 5 and Figure 6: Please complement the underlines with words “after intercritical annealing and quenching.”, since it’s unclear that the images represent an intermediate state.
Page 12, lines 244-245: “During cold rolling…” instead of “After cold rolling…”.
After a corresponding minor revision I will recommend the manuscript for publishing in MDPI Metals.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this manuscript the partitioning behavior of carbon and manganese in the Q&P and QQ&P samples after intercritical annealing and partitioning was studied. They showed that in the partitioning process, the migration of ferrite-austenite interface and diffusion of manganese can be ignored and also carbon first diffuses from the ferrite grains to the ferrite-austenite interface, and then diffuses in the austenite grains. Moreover, they claimed that in the intercritical annealing, the partitioning of carbon and manganese in the Q&P and the QQ&P samples are occurred, so that the contents of carbon and manganese were significantly higher than those in ferrite. Finally, the effect of these heat treatment cycles on the tensile behavior of the used steel has also been investigated and the results are acceptable.
I think that this manuscript can be interesting for the reader of Metals. Therefore, it can be accepted in this form.
Author Response
Thanks for your considerations and giving us the opportunity to resubmit the revised manuscript to Metals. We appreciate the reviewers’ comments, which are valuable for improving the quality of this manuscript. The manuscript has been revised according to the reviewers’ comments. The changes are highlighted with the color of blue in the “Revised Manuscript” .
Reviewer 3 Report
The article entitled “Effect of microstructures morphology of Q&P steel on carbon 2 and manganese partitioning and stability of retained austenite” is having potential information for publications. The authors have modified the microstructures of cold rolled steel by quenching & partitioning (Q&P), and pre-quenching, quenching & partitioning (QQP) processes. QP and QQP samples produced blocky and lath shaped homogeneous microstructures respectively. The authors have found that QQP samples possessed more retained austenite structures and hence, these samples have produced improved mechanical properties in terms of ductility and for achieving more thermal stability. I can recommend this work in your journal. I have observed the following points which the authors have to address on it.
1. The name of material for modifying the microstructure by QP and QQP is not mentioned in the abstract. It has to be incorporated in first line of abstract.
2. The outcome of results from the tensile test is not incorporated in the abstract. It is suggested to add one line in the abstract.
3. Few more literature are to be added in the introduction part related to QP and QQP of other AHSS.
4. The main objectives of the present study are to be incorporated at the end of introduction part. This is missing in the present form.
5. In equation (1), what is the meaning of G is not mentioned. How it can be find out? Need to be addressed
6. Tensile tests are conducted along rolled direction only? Have the authors accounted an-isotropic parameters?
7. Whether the volume fraction of retained austenite measured from XRD is compared with the results obtained from microstructures or not?
8. Various features observed from TEM results of Figure 3 are to be marked.
9. Work hardening behaviour and strain hardening exponents are to be investigated based on tensile test results of Figure 9. This is missing in present form.
10. Some more outcomes in terms of quantitative results are to be incorporate in the conclusion part
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors have worked based on my previous comments and now, I am recommending to accept the revised version in your journal
