Determination of Corrosion Resistance of High-Silicon Ductile Iron Alloyed with Nb

Round 1

Reviewer 1 Report

This manuscript is devoted to the study of corrosion resistance of high-silicon ductile iron alloyed with niobium. The work is of great practical importance for industry, since corrosion is one of the main problems of metallurgical and other industries where metal structures, equipment and other devices are used. The determination of the corrosion resistance of materials and the development of new methods of corrosion protection can reduce the cost of repair and replacement of equipment, as well as ensure a more durable and safe use of metal products. Thus, the results of this work can be used to improve the technological processes of industry and increase its efficiency.

I believe that the article is well written and should be published in Metals magazine, but before accepting it for publication, it is necessary to make a number of adjustments to the work:

1. There is no micrograph E in Figures 2 and 7, although the caption and the text of the article refer to 5 micrographs of various samples.

2. Figure 7 has a caption that is not in place.

3. Figure 12 in the caption also lacks information about micrography E.

4. It is not entirely clear how the alloying additive niobium affects the ductility and wear resistance of cast iron. It should be clarified.

5. It is not clear from the text of the article how homogeneous the resulting alloy is and what is the distribution of the alloying element in it?

6. Has the effect of the pores formed on the quality of the resulting alloy been evaluated?

7. I would like to see the goals of further research in the conclusions.

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Reviewer 2 Report

In the paper entitled “Determination of corrosion resistance of high silicon ductile iron alloyed with Nb” Authors present studies which concern the impact of Nb introduced in amount to approx. 1 wt.% on microstructure and selected usable properties of ductile cast iron in the as-cast state. Although the problems presented in the manuscript are not completely novel and in particular, in a lot of presented aspects, the impact of Nb addition is well understood in the foundry technology of ductile cast irons, it should be appreciated the Authors work and the creation of a comprehensive study on the influence of Nb on the possibility of shaping the usable properties of ductile cast iron. Moreover, the whole presentation is very clear and the discussion of research results is proper for the considered problem additionally is very well connected with results obtained by other researchers. In particular, some conclusions from obtained results are interesting and constitute a new approach to the problem of the influence of Nb in ductile cast iron. Therefore I think the paper will be interesting for Readers. Summing in my opinion the paper could be published after the following comments are addressed. Detailed comments are given below:

#1: In a lot of places in the manuscript, the Authors forget to use the proper definition of concentration unit i.e. wt. %. For example in the Abstract is “In this study, the effect of Nb on the microstructural characteristics, hardness, and corrosion resistance of high-silicon ductile cast iron (HSDI)-3.6% Si was investigated. Samples from different castings with 0-0.9% Nb were obtained and compared to a commercial ductile iron.” And should be: (…) ductile cast iron (HSDI)-3.6 wt.% Si (…) castings with 0-0.9 wt.% Nb were obtained (…) and so on in the whole manuscript.

#2: In a lot of places in the manuscript, the Authors forget to use subscripts for some chemical compounds for example H2SO4 presented on page 3, row 131. Please check this in the whole manuscript.    

#3: In Table 1 besides Nb is a lack of other carbide-forming elements such as Cr, V and mainly Mo which is often added to the similar to studied SiMo ductile iron. I think in the presented studies the concentration of Mo was very low but this info is necessary to put, for example in Table 1.

#4: On page 2, rows from 69 to 88, the Authors mentioned the refinement in ductile cast iron as a result of the addition of Nb and the creation of NbC. Have You observed in your studies some refinement in ductile cast iron after Nb addition compared to the state U-HSDI i.e. without Nb? I suggest adding a suitable comment in section 3.2.

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Reviewer 3 Report

Interesting work, very well designed in the part concerning mechanical properties and structural tests. The part related to corrosion tests seems "poor" against this background.

For people who deal with corrosion and corrosion tests on a daily basis and who are familiar with the Gamry system, the mpy unit is unambiguous, for others maybe less. It is good to define it as "mills per year".

The authors state that the corrosion tests were carried out in the potential range of -1000 mV to 1000 mV. The attached drawings show that the tests were carried out in this range, but with regard to the corrosion potential, it should be clearly indicated.

The potential on the x-axis is given in Volts, while the caption on the axis suggests mV.

To determine the corrosion rate using the potentiodynamic polarization method, it was enough to perform measurements in the Tafel range.

 

 

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