Strain-Ageing of Low-Alloyed Multiphase High-Strength Steels
Round 1
Reviewer 1 Report
I feel this is a good paper, with lots of techniques and some nice results but it could do with some reorganisation for clarity. The introduction gets a little confused towards the end so it is not always clear what the message is supposed to be. There is a lot of discussion in the results section and so very little of the preceding work is actually discussed in the discussion section. I feel the research points would be made clearer by moving a lot of these points to the discussion where all the data has already been introduced.
Specific comments
Line 29: is > are
Line 33: light strength > high strength
Line 34: please define AHSS acronym
Line 35: please define TRIPP acronym
Line 36: consider reversing the sentence beginning "By means of..."
Line 42: "Bake hardening steels are once that are increases they yield"
suggest changing to "Bake hardening steels increase their yield"
line 42: himself > itself (actually I think this entire sentence is not really required)
Line 46: Please be consistent with spelling of ageing/aging (from line 27) I believe both are acceptable, but as the rest of the manuscript is written in American English, I suggest going with the US convention of "ageing".
Line 50: Can an outline of the method be given before referring to a specific part of it, ie the holding time.
Line 61: Surrounding > surroundings and He > They (et al.)
Line 63: same again
Line 71: Please explain how this plot gives the activation energy
Line 79: It is unclear what TRIP1 etc refer to at this point, I think outlining the differences in the text would be clearer than referring to a figure caption.
Line 88: Consider reversing sentence beginning "Tensile specimens.."
Paragraph starting at 88: This is quite confused so it need reading a few times to understand what is going on. There is incomplete information as to how the materials are tested - how the strain was measured - were they unloaded or baked at load - what equipment was used etc.
Line 112: Starting "The prestrain..." incomplete sentence.
Line 113: Starting "The choice..." incomplete sentence, to the point that I don't really see how we got to XRD.
Line 117: using BH initialism without defining it, but the bake hardening index has been defined as BH_x so this is confusing.
Line 118: There must be a better way to get this information across, this is confusing as it is. A table perhaps?
Line 150 and figure1 and figure2: Unless there is additional data that is not being plotted, I believe the curve fitted has too many degrees of freedom and so the sigmoid shape is an artefact of this.
Line 164: 5min > 5 min
Line 166: 100min > 100 min
Line 169: For a ageing times > For aging times
Line 170: 60min > 60 min
Figure 3 and 4: overlay text is too small when the important part is the exponent. Also, the arrows almost connect with some of the letters they point from. It is also very hard to see the BH_5 line as it is just made from dots. I am also concerned about the point at 1000 min in BH_0 in fig 3.
Line 195: 60min > 60 min
Figure 13: Annotations crossing the axis and arrows make it difficult to read
Line 292: 24x109 cm-2 > 24x10^9 cm^-2
Line 325: 60min > 60 min
Author Response
please see the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The response of four different TRIP steels to strain ageing, with specific focus on bake hardening, has been studied. A wide range of parameters for the ageing and different characterization methods have been used. The results have provided a good overall picture of the interplay between base alloy chemistry, forming strain and subsequent ageing (paint baking) and their effect on the strength evolution. The manuscript appears to be interesting for some readers and contains adequate experimental data for dissemination to the public. Thus it is recommended for publication, however a few concerns need to be addressed.
The manuscript requires an editorial review and revision to improve its English (typo, sentence structure).
The abstract should be revised to highlight the scope, what has been done (not the details of experiments) and the findings to address the knowledge gap.
Some experiments and new method (new definition for BH effect) and high strain rate properties/tensile have not been presented in the text but strangely appeared in the abstract and conclusion. They must be removed or discussed in the main text.
Conclusion must be revised to match the results and findings (high strain rate, new definition for BH effect).
The authors should discuss and provide scientific justification of the observed results, i.e. why different responses have been observed by these different alloys? (effect of Si, Al contents? effect of carbon content of the intercritical austenite?
The starting material, its processing (cold rolled (and R%), hot rolled) and the details of annealing treatment (intercritical temperature, hold time, bainite formation temperature (isothermal or semi-isothermal), cooling after bainite stage) should be described. Title of the table 1 contains information which is not used in the table (HR, CR)
Some legends does not match with Figure captions (Fig 3 legend indicates TRIP 2, and the legend in Fig 4 indicated TRIP 1, incorrectly)
Authors should explain and show (the analysis method and details) how the time exponent was determined for BH kinetics (for Fig 3 and 4).
Last but not least, what is the main message and implication of these findings for alloy design and industrial practices (forming, processing)?
Author Response
please see the attached file.
Author Response File: Author Response.pdf
