Effects of Pressure on Microstructure and Residual Stresses during Hot Isostatic Pressing Post Treatment of AISI M50 Produced by Laser Powder-Bed Fusion

Round 1

Reviewer 1 Report

Dear Authors,

 

The paper can be accepted in presented form. No criticism. I appreciate this paper.

 

Best regards

Rev

Author Response

Dear Reviewer,

Great thanks for your feedback!

Best regards,

Siyuan

Reviewer 2 Report

The paper concerns the novel and interesting problem of the effect of pressure during HIP post treatment with integrated quenching on the microstructure evolution and residual stresses of high alloyed steel AISI  M50 fabricated by LPBF. The results presented in the manuscript are well documented and interpreted. References are appropriate to the subject. In my opinion the manuscript can be accepted for publications in Metals.

Author Response

Dear Reviewer,

Great thanks for your feedback and comments.

Best regards,

Siyuan

Reviewer 3 Report

In this paper, the authors study the effects of isostatic pressure on microstructure evolution and residual stresses using laser-powered bed fusion. The key result of the paper is that hot isostatic pressing delays recrystallization causing residual stresses that are compressive.

The paper is well-written, clearly presented and is a good fit for this journal.

A few minor comments:

1. There are some formatting issues, with "mm³", written as "mm3". Please correct these.
2. Elemental names such as ytterbium should be lower case first letter, not "Ytterbium" unless used at the start of a sentence.
3. Figure 4 is confusing. What do the squares in the graph mean?
4. "SEM" is not defined in the text, please add it.
5. In the conclusions, the last sentence is not meant to be there. Please remove.

Author Response

Dear reviewer,

Great thanks for your feedback and comments.

Following revision has been made according to your comments:

1. "mm3" is changed to "mm³" in line 87,90 and 271
2. The first letter of element name now is in lower case (line 83).
3. Squares in figure 4 are actually micrograph of the cross section. And these squares have been removed.
4. SEM now is defined in line 126
5. Last sentence now is deleted.

 

Best regards

Siyuan

Reviewer 4 Report

Comments for authors in the attachment.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Great thanks for your feedback and comments.

Following edition has been made according to your comments:

1. The porosity is determined by image analysis and the shape is not considered since the pores are mostly spherical.  A supplement is wrote in line 134-137. (The relationship between pores and mechanical properties is mentioned in point 2)
2. Thank you for the two very inspiring literatures. The second literature which describes how pores influences the fracture micromechanisms is cited as [24] and discussed in line 303. However, the first paper is more related to anisotropy and fine grains, which is not involved in the main discussion of this paper. But it is a great hint for the paper that I am working with.
3. I totally agree with your suggestion that the hardness is an important property that should be discussed. Due to the time limitation (revision should be uploaded in 5 days), the hardness measurement for the samples in this paper is hard to be achieved. And actually,  now we are working with another paper, where the hardness will be discussed much more in detail.
4. As mentioned in point 3, the microhardness and hardness along the building direction will be discussed much more in detail in another paper that now we are working with.

Great thanks again for your effort.

Best regards

Siyuan

Reviewer 5 Report

Thank you for submitting this work to metals.
Below a few comments on how I think you can improve this manuscript.

Comments on style:
-MDPI will ask you for all email addresses
-check the last sentence of the manuscript - this seems to still be coming from the MDPI template
-do a language edit and check for typos, I found quite a few

Manuscript:
-present quantitative results in abstract
-Introduction: HIP can actually also be used for AM under your definition (https://www.mdpi.com/2075-4701/10/5/613) maybe an interesting detail to add
-Fig. 2 you can include the temp in the figure - I know it is in the text, but most people just look at the figures briefly
-Fig. 4 no need for the micrographs - or am I missing anything? They look very similar

This is a sound paper - make sure the language is fine, that is currently my biggest concern - the rest looks good

Author Response

Dear reviewer,

Great thanks for your feedback and comments.

The edition in the new version has been made accordingly:

Comments on style:

• All the email addresses have been added
• The last sentence of the manuscript is deleted.
• The typos have been checked and corrected.

 Manuscript:

• Quantitative results are presented in abstract
• The corresponding paper is cited in discussion part in line 311
• The temperature is included in figure 2.
• The micrographs are removed in figure 4.

Great thanks again for your valuable comments and effort.

Best regards,

Siyuan

Round 2

Reviewer 4 Report

Accept.