Effect of Austenitizing Temperature on the Work Hardening Behavior of Air-Hardening Steel LH800

Round 1

Reviewer 1 Report

Reviewer’ s questions/remarks:

The paper concerns the effect of austenitizing temperature on work hardening behavior of the air-hardening steel LH800. The presented results are interesting, however the motivation for undertaking research is not clear. Is it possible to indicate the practical use of research results?

What LH 800 exactly means?

The novelty as well as the motivation for undertaking research are not well clarified. The authors of the publication should clearly present what new discoveries they have made in relation to other researchers. Only papers that bring new information into the research topic are of interest to potential readers.

Author Response

Dear Reviewer:

Thank you very much for your letter and thoughtful comments about our paper (Title: Effect of austenitizing temperature on work hardening behavior of the air-hardening steel LH800).

We have checked the manuscript and revised it according to the comments. If you have any question about this paper, please don’t hesitate to let me know. I have listed some modify the situation as below:

Comments 1: The paper concerns the effect of austenitizing temperature on work hardening behavior of the air-hardening steel LH800. The presented results are interesting, however the motivation for undertaking research is not clear. Is it possible to indicate the practical use of research results?

Response 1. First of all, Thank you very much for your suggestion. the motivation for undertaking research is in order to determine the plastic deformation mechanism of the LH800 steel, so as to obtain air-hardening steel with high strength. It can further expand the scope of application of low-cost high-strength automotive sheets, and can provide guidance for the development of a new generation of automotive steels.

Comments 2: What LH 800 exactly means?

Response 2. LH in LH800 steel comes from the German word "lufthärtenden", That is, the meaning of air-hardening, 800 refers to the tensile strength level of the steel grade. The German Salzgitter Flachstahl GmbH refers to the air-hardening steel produced as LH steel for short.

Comments 3: The novelty as well as the motivation for undertaking research are not well clarified. The authors of the publication should clearly present what new discoveries they have made in relation to other researchers. Only papers that bring new information into the research topic are of interest to potential readers.

Response 3. First of all, Thank you very much for your suggestion. In recent years, the research on air-hardening steel has mainly focused on its microstructure evolution and mechanical properties changes. While very few scholars expanded their research to further study its room temperature deformation mechanism and work hardening behavior characteristics. In this paper, we present the effect of austenitizing temperature on the work hardening behavior of air-hardening steel LH800, and thus, the plastic deformation mechanism of the LH800 steel was determined. Finally, it provides ideas for obtaining high-strength air-hardening steel.

We look forward to your positive response.

Sincerely yours,

Zhen-Li Mi

Author Response File: Author Response.pdf

Reviewer 2 Report

Good work on the analysis of the effect of microstructure on the mechanical behavior under cold work hardening of LH800 air-hardening steel. To change the microstructure, the authors varied the austenitizing temperature, and to analyze the mechanical behavior, the authors used and compared three hardening models, namely Hollomon, DC-J and MC-J. I have only a few comments:

1. Please, provide statistical information on mechanical testing as well as structural measurement. How many tensile specimens of each condition were tested? How many structural elements were measured? The authors do not always provide a confidence interval or standard deviation.

2. Figure 1. A typo, both in the Figure itself and in the Figure caption, namely should be ‘Temperature’ instead ‘Temeprature’

3. English should be polished. For example, authors use different terms, such as ‘as-supplied state’ and ‘delivered state’. In addition, ‘the amplitude of microhardness’ phrase is not very successful.

Author Response

Dear Reviewer:

Thank you very much for your letter and thoughtful comments about our paper (Title: Effect of austenitizing temperature on work hardening behavior of the air-hardening steel LH800).

We have checked the manuscript and revised it according to the comments. If you have any question about this paper, please don’t hesitate to let me know. I have listed some modify the situation as below:

Comments 1: Please, provide statistical information on mechanical testing as well as structural measurement. How many tensile specimens of each condition were tested? How many structural elements were measured? The authors do not always provide a confidence interval or standard deviation.

Response 1. First of all, Thank you very much for your suggestion. Three tensile specimens were tested for each condition, and the average values are reported. Image analyses were performed on at least five numbers of scanning electron microscope micrographs of each set of sample using Image Pro Plus and Photoshop Image processing software to measure volume fraction of the constituent phases and the ferrite grain size, the average values are reported.

Firstly, we used PS software to color the ferrite grain, as shown in Figure 1. There are approximately 70-100 ferrite grains in each condition. And then used IPP software to count the phase proportion and ferrite grain size.

                      (a)                              (b)

 (c)

Fig.1 (a) 750℃; (b) 775℃; (c) 800℃

Comments 2: Figure 1. A typo, both in the Figure itself and in the Figure caption, namely should be ‘Temperature’ instead ‘Temeprature’

Response 2. We have changed “Temeprature” into “Temperature” of Figure 1, The changes in the article are marked in red.

Comments 3: English should be polished. For example, authors use different terms, such as ‘as-supplied state’ and ‘delivered state’. In addition, ‘the amplitude of microhardness’ phrase is not very successful.

Response 3. First of all, Thank you very much for your suggestion. We have unified the terms in this article. The changes in the article are marked in red. We also have invited professional English language experts to polish the entire article. The polished parts are marked in red in this paper.

We look forward to your positive response.

Sincerely yours,

Zhen-Li Mi

Author Response File: Author Response.pdf