Characterization of Microstructural Damage and Failure Mechanisms in C45E Structural Steel under Compressive Load

Round 1

Reviewer 1 Report

The authors of this manuscript reported an experimental study on the microstructural damage and failure mechanisms of C45E structural steel under compressive load. The structural evolution of ferrite and pearlite phases in C45E structural steel under different compressive loads and their role in the process of structural damage were carefully analysed and studied by means of optical microscope and scanning electron microscope. The critical role of pearlite colonies in the development of microstructural damage was demonstrated. The reported results are new and novel for a comprehensive understanding of failure mechanism of the material. I suggest that the manuscript can be accepted for publication after a minor revision.

1. In page 6: “The size of ferrite grains is 8 (according to the ASTM E112), which corresponds to a mean size of 22 μm as for the perlite colony is 6, which is equivalent to a mean size of 44 μm.”. Please check whether the data for the “mean size” is correct.
2. What is “microcracs”? Do the authors mean “microcracks”?
3. In page 13: “The material properties and flow curve are given in Chapter 2.”. Where is Chapter 2 in the manuscript?
4. In Figure 20: “Radius R” should be rewritten as “Radius r”.
5. Where is the tensile stress in Figure 19? Is it the “circumferential stress”? The symbolic definition of stress variables in the manuscript is very confusing and needs to be rewritten.

Author Response

Many thanks for the careful review of the paper and stated comments of the manuscript. The responses to your comments are provided in a .doc file attached.

Reviewer 2 Report

The authors present a very detailed work analysing the evolution of damage for increasing levels of strain during uppseting process. The work is based on microscopy observations and supported by FE analyses.

Overall, it is interesting and has great potential. However, it requires improvement before being publised.

The main comments are as follows:

1) Please, clearly state the previous works that were focussed on the evolution of damage under compressive conditions. Stress the novelty of your research.

2) Include standard deviation in Table 2.

3) Avoid speculation. Sometimes, it looks like the authors provide statements that are not fully supported by observations (e.g., the 45º observations in some features). They MAY be right, but in such a case they should mention that the observations are general (i.e., in many places of the specimens), and not particular in certain points.

3) Explain Zone A in Table 3

4) Indicate that the equivalent stress in equation (3) is Von Misses stress.

5) Review English. There is room for improvement.

6) The introduction mentions some studies and comments about cyclic loading and damage. This is a bit confusing, as there is evidence that in such cyclic conditions intrusions, extrusion amd int-ext pairs play a key role.

7) Correct the typos and style issues. There are many along the text. Examples:

a) when you use i.e do not put it directly within the text, use brackets.

b) line 41, eliminate the comma after "which"

c) line 60, eliminate comma after "and"

d) line 102, use compression instead pressure

e) line 116, occur instead occurs.

f) line 142, symbol missed for the strain

g) Table 1, indicate Fe "balance"

h) line 162, strain under maximum load instead of ultimate strain

i) line 249, whose instead of which.

j) Figure 8a, marc C is missed

k) line 306. Is it necessary to say "under the action the tensile stress"? Is it the only mechanism for that flow? (Poisson?)

l) incluede reference for the FE software

m) Figure 20, correct legend

n) line 436, Figure 22, not 21

o) line 49, strain, not stain.

etc.

Author Response

Many thanks for the careful review of the paper and stated comments of the manuscript. The responses to your comments are provided in a .doc file attached.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The paper can now be published.

Notice that legend in Figure 20 has some lines missed.