Review Reports

Round 1

Reviewer 1 Report

In this manuscript, the macroscopic molten pool heat transfer model  and the microscopic  phase field model are combined to establish a cross-scale model to simulate the shape  change of the molten pool and the evolution of the dendrite morphology of the TC4 alloy  during the WLAM process, through the molten pool model calculation and analysis of  the change law of the molten pool temperature, morphology and solidification parameters, a physical model of the coupled macro/microorganism synergistic response, simulating the microstructure evolution process in different regions of  the melt pool, and  quantitatively analyzes the effects of laser power, laser scanning rate and other process parameters on the dendrite morphology.

The paper is well-written and could be published after major revision.

The first sentence in the abstract is too long” A cross-scale model of macro-micro coupling was established for the laser fuse additive  manufacturing process of TC4 titanium alloy, which reproduced the dynamic evolution process of  the molten pool shape, revealed the temperature change law in the molten pool, and simulated the  microstructure and morphology of different regions of the molten pool, the effects of process parameters (laser power, scanning speed) on the growth morphology of dendrites during solidification were quantitatively analyzed.”

Why the authors used semicolon before “After solidification, an asymmetrically distributed  equiaxed  grain structure is formed at the upper part of the molten pool, the bottom of the molten  pool is slender columnar crystals, the  columnar-to-equiaxed transition  (CET)  occurs in the middle  of the molten pool”

USE small sentences.

Strength the introduction by: prediction of laser cutting parameters for polymethylmethacrylate sheets using random vector functional link network integrated with equilibrium optimizer; improving laser cutting quality of polymethylmethacrylate sheet: experimental investigation and optimization; surface quality measures analysis and optimization on machining titanium alloy using co2 based laser beam drilling process; experimental investigation on laser cutting of pmma sheets: effects of process factors on kerf characteristics; modeling of the transient temperature field during laser heating and others.

The following article is very important: Tribological performance of gradient Ag-multilayer graphene/TC4 alloy self-lubricating composites prepared by laser additive manufacturing.

What are the mechanical properties of the used material?

What are the boundary conditions used in Figure 2?

A deep discussion should be added to “dendrite growth morphology at different locations of molten pool”.

In figure 11, P1-P6 must be defined.

Physical parameters of the main TC4 alloys used in the simulation must be supported by a reference.

“The power and scanning speed of laser  determines the temperature and size of the  molten pool, it controls the structure and morphology of the melt after solidification, and  is  closely related to the generation of micro-segregation, inclusions, micro-cracks and  porosity in the structure, which will ultimately affect the mechanical properties and  corrosion resistance of the molded parts” too long sentence.

Add a sketch of the cutting process.

It is better to measure the chemical composition of the material, if possible.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper investigated the macro molten pool heat transfer model combined with microscopic phase field model to establish a multi-scale model, simulation of TC4 alloy laser fuse to add material in the manufacturing process. These results have highly scientific values and very useful for the development of laser cladding.

Figure 2 (a) shows that the Z-axis is perpendicular to the laser irradiation plane, however the R(t) and G(t) in L158 can't  be find any formula for the Z-axis ( the depth direction).

It should be included that the equations calculated for the R(t) and G(t) in the Z-axis.

Is the G(t) temperature gradient in the Z-axis?  Please specify whether the G(t) is the temperature distribution in the planar direction (X-Y axis) or in the depth direction (Z-axis ).

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript entitled “metals-1720411-v1” dealing with AM has been reviewed. The paper has been nicely written but needs significant improvement. Please follow my comments.

1. Suggest providing a reference for Table 1. Where should you find this information?
2. Provide more discussion and fundamental relation for figure 4 b.
3. Add some quantitative results to the abstract.
4. Laser fused is not the correct terminology. Please refer to ASTM 52900 for correct terminology.
5. Try to you DED for the presented work. This reflects your work and is understandable for the reader.
6. Add more detail to the conclusion.
7. Additive manufacturing has many advantages over the conventional manufacturing method which can be highlighted in your paper. Please read the following article and add to the introduction to show the experimental application of additive manufacturing and the advantage of this process over conventional manufacturing like machining. “Additive manufacturing a powerful tool for the aerospace industry”
8. Please update the introduction with the new publications in the field. Authors are encouraged to read and add the following new papers in the field.

• High-cycle fatigue properties of curved-surface AlSi10Mg parts fabricated by powder bed fusion additive manufacturing
• Proposal of design rules for improving the accuracy of selective laser melting (SLM) manufacturing using benchmarks parts
• Fatigue life optimization for 17-4Ph steel produced by selective laser melting

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Accept in present form

Author Response

Thanks for the positive comments.

Reviewer 3 Report

The paper is ready to publish. 

Author Response

Thanks for the positive comments.