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Steel 3D printing literature review

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This literature review is to support the ongoing project: Open-source metal 3-D printer - Gerald C. Anzalone, Chenlong Zhang, Bas Wijnen, Paul G. Sanders and Joshua M. Pearce, “Low-Cost Open-Source 3-D Metal PrintingIEEE Access, 1, pp.803-810, (2013). doi: 10.1109/ACCESS.2013.2293018 open access preprint


Weld Based 3D Printing Systems[edit]

  1. Building three-dimensional objects by deposition of molten metal droplets[1]
    Abstract:
    Purpose – The purpose of this paper is to determine conditions under which good metallurgical bonding was achieved in 3D objects formed by depositing tin droplets layer by layer. Design/methodology/approach – Molten tin droplets (0.18-0.75mm diameter) were deposited using a pneumatic droplet generator on an aluminum substrate. The primary parameters varied in experiments were those found to most affect bonding between droplets on different layers: droplet temperature (varied from 250 to 3258C) and substrate temperature (varied from 100 to 1908C). Droplet generation frequency was kept low enough (1-10 Hz) that each layer of droplets solidified and cooled down before another molten droplet impinged on it. Findings – In this paper, a one dimensional heat transfer model was used to predict the minimum droplet and substrate temperatures required to remelt a thin layer of the substrate and ensure good bonding of impinging droplets. Cross-sections through samples confirmed that increasing either the droplet temperature or the substrate temperature to the predicted remelting region produces good bonding between deposition layers. Originality/value – This paper used a practical model to provide reasonable prediction of conditions for droplet fusion which is essential to droplet- based manufacturing. The feasibility of fabricating 3D metal objects by deposition of molten metal droplets has been well demonstrated.
    Notes:
  2. Rapid Manufacturing of Metallic Objects[2]
    Abstract:
    • Purpose – The purpose of this paper is to review additive and/or subtractive manufacturing methods for metallic objects and their gradual evolution from prototyping tools to rapid manufacture of actual parts. #*Design/methodology/approach – Various existing rapid manufacturing (RM) methods have been classified into six groups, namely, CNC machining laminated manufacturing, powder-bed technologies, deposition technologies, hybrid technologies and rapid casting technologies and discussed in detail. The RM methods have been further classified, based on criteria such as material, raw material form, energy source, etc. The process capabilities springing from these classifications are captured in the form of a table, which acts as a database.
    • Findings – Due to the approximation in RM in exchange for total automation, a variety of multi-faceted and hybrid approaches has to be adopted. This study helps in choosing the appropriate RM process among these myriad technologies.
    • Originality/value – This review facilitates identification of appropriate RM process for a given situation and sets the framework for design for RM.
  3. Electromagnetically confined weld-based additive manufacturing[3]
    Abstract:
    Due to the cost advantage, weld-based Additive Manufacturing (AM) is suitable for directly fabricating large metallic parts. One of challenges for weld-based Additive Manufacturing is to build overhanging structure or tilt structure at a large slant angle, because liquid metal on the boundary would flow down by gravity due to lack of sufficient support. In the present work, electromagnetically confined weld-based Additive Manufacturing is developed to solve this problem. In the process, liquid metal is confined and semi- levitated by the Lorentz force exerted by magnetic field and thus the flow of liquid metal is restricted. Experiments and numerical simulations are performed to investigate the effect mechanism of electromagnetic confinement. Experimental results verify that the flow-down or collapse of liquid metal is impeded by electromagnetic confinement. With specific welding parameters, the maximum tilt angle of successful building increases from 50° to 60° when imposing electromagnetic confinement.
    Notes:
  4. Rapid prototyping of metal parts by three-dimensional welding[4]
    Abstract:
    Three-dimensional welding has the ability to produce strong, fully dense metal parts in layers. Adaptation of a weld cladding technique has enabled the production of parts wider than normally possible from single beads. However, high heat inputs during welding could affect part quality. Simple temperature control techniques help improve surface finish. A number of parts were made incorporating temperature control. Results show that, although improvements have been made, corresponding time penalties can have a significant influence on build time. Descriptions of the welding system and temperature control technique are included as well as the surface measurement and residual stress assessment techniques used. Results of temperature versus time, surface finish versus temperature and temperature versus residual stress are presented and discussed.
    Notes:
  5. Rapid prototyping and rapid tooling - the key enablers to rapid manufacturing[5]
    Abstract:
    Rapid manufacturing is a new mode of operation that can greatly improve the competitive position of companies adopting it. The key enabling technologies of rapid manufacturing are rapid prototyping (RP) and rapid tooling (RT). This paper classifies the existing RP processes and briefly describes those with actual or potential commercial impact. The paper then discusses five important RP applications: building functional prototypes
    Notes:

Effect of Process Parameters[edit]

  1. A Closed Loop Welding Controller for a Rapid Manufacturing Process[6]
    Abstract:
    The aim of this paper is to investigate on the closed loop welding controller of a rapid manufacturing Shaped Metal Deposition (SMD) process. SMD was developed and patented by Rolls-Royce in order to produce mechanical parts directly from a CAD model. The paper describes a deep investigation upon the welding dynamics and parameters in order to develop an SMD automatic controller. An SMD plant has been set up as described in the paper, and some experimental work pieces have been produced. On the basis of the experiences acquired, some basic control laws have been carried out, and a closed loop controller has been implemented, using image processing and a video feedback control. The experimental results reported confirm the validity of the proposed strategy.
    Notes:
  2. Controllable Parameters on Cold-wire Gas Tungsten Arc Weld Bead Geometry[7]
    Abstract:
    Multi-layer Gas Tungsten Arc Welding (GTAW) is widely used for refurbishing plastic injection molds. This welding process can provide the high quality weld that is required for molds that will be subject to high temperatures and pressures during production. This refurbishing weld process is currently performed manually, which exposes the welders to poor working conditions. GTA welding is a tedious and time consuming process when compared to other welding processes. The advantages of automating this process are two-fold: removing workers from arduous working conditions, and decreasing production cycle time by increasing the deposition rate through robotic control. The purpose of this study was to investigate the e↵ects of controllable welding parameters on weld bead geometry for standard welding operating ranges when refurbishing plastic injection molds. Another aim was to determine and predict the sensitivity and response, respectively, of base metal orientation on bead geometry. Remanufactured molds require the removal of tool steel, which can be achieved with current CNC machining technology. However, automating the addition tool steel is di cult achieve due to the inherent complexity of the GTA welding process. The work presented in this thesis is an integral component for simplifying the mold remanufacture process by eliminating the guesswork in choosing optimal welding parameters. Through the means of experimental design and statistical analysis, relationships were developed between welding parameters and their e↵ects on bead height, bead width, penetration, heat a↵ected zone (HAZ) depth and HAZ width. The regression models were capable of predicting responses in bead geometry within 1 millimeter in variation. The resulting regression models can be extended to cold wire GTA welding applications that require high deposition rates and the capabilities of predicting bead geometry for various base metal orientations.
    Notes:
  3. Effect of the electrode to work angle, filler diameter and shielding gas type on weld geometry of HQ 103 steel joints produced by robotic GMAW[8]
    Abstract:
    GMAW (Gas Metal Arc Welding) is an arc welding process which is widely used in industry to join the metals. We investigated the effect of varying welding parameters on the bead geometry in robotic GMA welds of HQ130 steel having 5 mm thickness. The chosen parameters for this study were the electrode to work angle (Φ), filler diameter (d) and shielding gas type (S.G). Different samples obtained by employing electrode to work angle of 65°, 75° and 85°, filler diameter of 0.8, 1, 1.2 mm. The main recommended gases for this filler material type were Ar, He and CO2 gas. Having finished the welding process, the depths of penetration were measured for specimens and the relationship between parameters and penetration of weld were studied. The results clearly illustrated that in- creasing of electrode to work angle increases the depth of penetration while increasing in filler diameter results in decreasing the weld penetration. In addition, the highest penetration was observed for CO2 shielding gas.
    Notes:
    • Different electrode work angles (65, 75, 85 degrees) were studied to determine the effect of penetration along with filler diameter and shielding gas
    • lowest depth of penetration was seen at 65 degrees because the applied heat perareas of the weld decreased the further the welder was from 90 degrees
  4. The effect of process parameters on penetration in gas metal arc welding processes[9]
    Abstract:
    In this study, the effects of various welding parameters on welding penetration in Erdemir 6842 steel having 2.5 mm thickness welded by robotic gas metal arc welding were investigated. The welding current, arc voltage and welding speed were chosen as variable parameters. The depths of penetration were measured for each specimen after the welding operations and the effects of these parameters on penetration were researched. The welding currents were chosen as 95, 105, 115 A, arc voltages were chosen as 22, 24, and 26 V and the welding speeds were chosen as 40, 60 and 80 cm/min for all experiments. As a result of this study, it was obvious that increasing welding current increased the depth of penetration. In addition, arc voltage is another parameter in incrimination of penetration. However, its effect is not as much as current’s. The highest penetration was observed in 60 cm/min welding current.
    Notes:
    • Compared penetration vs. welding speed and penetration vs. weld current and penetration vs. arc voltage. Used symbols on each graph to differentiate lines based upon the value of a third variable (arc voltage or weld current)
    • Depth of penetration increases linearly with welding current. Arc voltage and welding speed also causes increases to a lesser effect.
  5. A study on relationship between process variables and bead penetration for robotic CO2 arc welding[10]
    Abstract:
    Generally the robotic arc welding process involves sophisticated sensing and control techniques applied to various process variables. One of the major important tasks in the robotic CO2 arc welding process is to understand interrelationship between process variables and bead penetration and subsequently develop the mathematical models to predict the desired bead penetration.
    To achieve the objectives, partial-penetration and single-pass welds were fabricated in 12 mm SS400 plate by using four different process variables. The experimental results were employed to develop the curvilinear and linear equations, and find the process control algorithms for the CO2 arc welding process. Mathematical models developed can predict the bead penetration with reasonable accuracy. The process control algorithms developed will be useful for identifying the various problems that result from the CO2 arc welding process, and establishing criteria for effective joint design.
    Notes:
    • The effect of welding variables on bead geometry described using theoretical studies of heat flow, empirical methods, the tolerance box approach, mathematical models
    • These models have shown that mathematical models, derived from experimental results, can accuratly predict bead geometry. Mathematical models also predict that weld current has the greatest effect
    • Developed a mathematical model to describe welding process: variables (4): arc voltage, welding current, welding speed, welding angle
    • Weld thickness determined by cutting welds mid-length, profile project used to measure bead penetration
    • Plotted welding current (A) vs. bead penetration and each line on the graph represents a different weld speed, weld angle, voltage
    • Tested each plot with a curvilinear and liner equ.
    • Also derived linear and curvilinear equations using statistical methods
  6. The Effects of Process Variables on the Weld Deposit Area of Submerged Arc Welds[11]
    Abstract:
    The results of bead-on-plate submerged arc welding experiments are presented to determine the effects of pro- cess variables on the weld deposit area at a constant heat input of 3 kj/mm. It is found that the deposit area is a function of the welding current, welding voltage, welding speed, electrode polarity, elec- trode diameter and electrode extension. In general, welds made using direct current electrode negative (DCEN) polarity, a small-diameter electrode, long elec- trode extension, high welding current, low welding voltage and a high welding speed have large deposit areas. The weld deposit area is, however, not affected significantly by the power source or the flux type used in this investigation.
    Notes
    • Study recommends using response surface analysis to understand the relationship between welding parameters
    • Also suggest using both RSA and GA (genetic algorithm)

Statistical Models and Methods[edit]

  1. Statistical modeling and computer programs for optimization of the electron beam welding of stainless steel[12]
    Abstract:
    A statistical analysis of the electron beam welding of stainless steel samples was done using multi-response statistical techniques. A model is created which includes the values of the distance between the electron gun and both the focusing plane of the beam and the sample surface as parameters. The response at work surfaces for the welding depth and width for variable beam power, welding speed, and the above two distances, determining the position of the beam focus towards the sample surface can be found. These predicted results coincide with the existing experimental experience in this technique. Computer procedures for the choice of operating conditions under some criteria for obtaining special parameters of the seam and for acquiring optimal weld parameters are also presented. It is possible to predict the geometrical characteristics of the seam when working in some chosen limited region of the welding parameters.
    Notes:
  2. Optimization on selective laser sintering of metallic powder via design of experiments method[13]
    Abstract
    • Purpose – The objective of this study is to investigate the effect of various parameters on rapid prototyping parts for processes of sintering metallic powder by using Nd:YAG laser via the design of experiments (DOE) method.
    • Design/methodology/approach – Experiments based on the DOE method were utilized to determine an optimal parameter setting for achieving a minimum amount of porosities in specimens during the selective laser sintering (SLS) process. Analysis of variance (ANOVA) was further conducted to identify significant factors.
    • Findings – A regression model predicting percentages of porosities under various conditions was developed when the traditional Taguchi's approach failed to identify a feasible model due to strong interactions of controlled factors. The significant factors to the process were identified by ANOVA.
    • Research limitations/implications – Four controlled factors including pulse frequencies and pulse durations of laser beams, times of strikes of a pulse applying on a single laser spot and particle sizes of the powder base material had significant influence on the sintering process. Future investigation planned to be carried out for achieving multiple quality targets such as the hardness and the density for 3D parts.
    • Originality/value – The implementation of the DOE method provided a systematic approach to identify an optimal parameter setting of the SLS process; thus, the efficiency of designing optimal parameters was greatly improved. This approach could be easily extended to 3D cases by just including additional parameters into the design. Additionally, utilization of the normality analysis on the residual data ensured that the selected model was adequate and extracted all applicable information from the experimental data.
    Notes:
    • Use a square pattern for their weld curves
  3. Statistical modeling and computer programs for optimization of the electron beam welding of stainless steel[14]
    Abstract:
    A statistical analysis of the electron beam welding of stainless steel samples was done using multiresponse statistical techniques. A model is created which includes the values of the distance between the electron gun and both the focusing plane of the beam and the sample surface as parameters. The response at work surfaces for the welding depth and width for variable beam power, welding speed, and the above two distances, determining the position of the beam focus towards the sample surface can be found. These predicted results coincide with the existing experimental experience in this technique. Computer procedures for the choice of operating conditions under some criteria for obtaining special parameters of the seam and for acquiring optimal weld parameters are also presented. It is possible to predict the geometrical characteristics of the seam when working in some chosen limited region of the welding parameters.
    Notes:
    • Inputs: Welding velocity (v), focusing current of the beam (zo), distance between the lens and sample surface (zp), beam power (p)
    • Response: Weld width (B), weld depth (H)
    • Used response surfaces, power vs. velocity w. contours representing weld thickness or depth. Each graph had constant z parameters.
    • Response surface for depth & thickness can be overlaid to find region of optimal weld geometry
    • Also used desirability functions which I don't understand – can be used in situations were more than one property is desired (ie. Thin welds and low variability)
  4. A study on fiber laser micro-spot welding of thin stainless steel using response surface methodology and simulated annealing approach[15]
    Abstract:
    This study analyzed variations of shear strength that depend on the fiber laser process during micro-spot welding of AISI 304 stainless thin sheets. A preliminary study used ANSYS results to obtain initial process condi- tions. The experimental plan was based on a Taguchi orthog- onal array table. A hybrid method that includes the response surface methodology (RSM)- and back propagation neural network (BPNN)- integrated simulated annealing algorithm (SAA) is proposed to search for an optimal parameter setting of the micro-spot welding process. In addition, an analysis of variance was implemented to identify significant factors influencing the micro-spot welding process parameters, which was also used to compare the results of BPNN- integrated SAA with the RSM approach. The results show that the RSM and BPNN/SAA methods are both effective tools for the optimization of micro-spot welding process parameters. A confirmation experiment was also conducted in order to validate the optimal welding process parameter values.
    Notes:
    • Uses response surfaces to determine optimum weld parameters
    • In-depth description & tables showing analysis methodology
  5. Weld deposition-based rapid prototyping: a preliminary study[16]
    Abstract:
    At the present time, the most widely used commercial rapid prototyping (RP) processes are based on polymeric materials, such as plastics or photocurable resins. While these prototype products adequately meet the requirements for ‘‘form’’ and ‘‘fit’’, they are only very infrequently able to provide any ‘‘function’’ capability. This is especially true when considering metallic products. Laser sintering of metal powers has been studied and is currently being developed into a viable process. However, laser sintering requires expensive equipment and a high price form of starting material. A possibly more economical alternative is offered by the use of weld deposition processing. Research at the University of Kentucky has allowed the development of a dedicated control technology, including slicing/planning, system implementation and post-processing for RP using gas metal arc welding as the deposition process. The metal transfer control system is used to control the size and frequency of the droplets in order to improve the deposition accuracy. The component to be prototyped is specified by CAD surfaces or a solid model in standard IGES format. An integrated and user-friendly environment has been developed to slice the part, plan the deposition parameters, and control the deposition process. In this system, the deposition parameters, and control the deposition process. In this system, the deposition parameters, including the travel speed, touch angle, welding current, and arc voltage, are variably controlled to achieve the required density and three-dimensional geometry. This system, together with its operation, is destroyed and examples of several complex-shaped components produced are illustrated.
    Notes:

Mechanical Properties[edit]

  1. Microstructure and Performance Characteristics of Parts Produced via GMAW Surfacing Rapid Forming[17]
    Abstract:
    The new metal-cored wires with Fe-Si-Mn-Ti-B microalloyed series were prepared to meet demands of GMAW surfacing rapid forming technology. The microstructure and performance characteristics of parts produced with them are both investigated. Its continuous metallographic microstructure along the deposition height direction shows obvious layered characteristic due to the special thermal cycles and cooling conditions. The microhardness values of intermediate sections of the part are higher than those of surface sections, which closely relates to their microstructure. The tensile strength, yield strength and broken elongation percentage of the part are 575MPa, 530 MPa and 10.14%, respectively. The fracture mechanism of the part belongs to quasi-cleavage crack. Therefore, the self-made metal cored wires are acceptable for forming some structure parts.
    Notes:
  2. The mechanical effects of deposition patterns on welding-based layered manufacturing[18]
    Abstract:
    This paper presents a finite element (FE)-based three-dimensional analysis to study the structural effects of deposition patterns in welding-based layered manufacturing (LM). A commercial finite element software ANSYS is used to simulate the deposition incorporat- ing a double ellipsoidal heat source, material addition, and temperature-dependent material properties. Simulations carried out with various deposition sequences revealed that the thermal and structural effects on the workpiece are different for different patterns. The sequence starting from outside and ending at the centre is identified as the one which produces minimum warpage.
    Notes:
  3. The Effects of Process Variables on the Weld Deposit Area of Submerged Arc Welds[19]
    Abstract:
    The results of bead-on-plate submerged arc welding experiments are presented to determine the effects of pro- cess variables on the weld deposit area at a constant heat input of 3 kj/mm. It is found that the deposit area is a function of the welding current, welding voltage, welding speed, electrode polarity, elec- trode diameter and electrode extension. In general, welds made using direct current electrode negative (DCEN) polarity, a small-diameter electrode, long elec- trode extension, high welding current, low welding voltage and a high welding speed have large deposit areas. The weld deposit area is, however, not affected significantly by the power source or the flux type used in this investigation.
  4. Effects of Interpass Idle Time on Thermal Stresses in Multipass Multilayer Weld-Based Rapid Prototyping[20]
    Abstract:
    Interpass idle time is an important parameter affecting the thermal stress distribution in weld-based rapid prototyping. In this paper, the effects of interpass idle time on thermal stresses in multipass multilayer weld-based rapid prototyping are investigated using numerical simulation. Meanwhile the single-layer weld-based rapid prototyping experi- ment is carried out, and the residual stresses are measured in the blind-hole method. The variation trend of calculated residual stresses agrees with that of experimental measure- ments. The research results indicate that there exist stress release effects of rear pass on fore passes and that of rear layer on fore layers. The interpass and interlayer stresses and residual stresses are significantly dependent on interpass idle time. The residual stresses of deposition workpiece decrease with the increase of interpass idle time, whereas the interpass and interlayer stresses on the central line of substrate increase with the increase of interpass idle time.
    Notes:

Thermal Behavior[edit]

  1. A 3D dynamic analysis of thermal behavior during single-pass multi-layer weld-based rapid prototyping[21]
    Abstract:
    Weld-based rapid prototyping enables the capacity of forming 3D complex parts. In rapid prototyping there exists the particular thermal cycling, being repeatedly heated at the same place, which is the basic cause of complex thermal stress. In this paper experiments are carried out to investigate the thermal characters of single-pass ten-layer deposition. Meanwhile a 3D transient heat transfer numerical sim- ulation with temperature-dependent material properties is conducted to investigate temperature field evolution, thermal cycling character, temperature gradient and the effects of depositing directions on the thermal process of single-pass ten-layer rapid prototyping. The calculated results match the exper- imental measurements well. The research results show that the heat diffusion condition of molten pool becomes worse as the depositing height increases. With other parameters being constant, the heat diffu- sion condition can be significantly improved by optimizing the depositing directions. The heat diffusion condition of component with the same depositing directions is better than reverse directions.
    Notes:

References[edit]

  1. M. Fang, S. Chandra, and C. B. Park, “Building three-dimensional objects by deposition of molten metal droplets,” Rapid Prototyping Journal, vol. 14, no. 1, pp. 44–52, 2008.
  2. K. P. Karunakaran, A. Bernard, S. Suryakuman, L. Dembinski, and G. Taillandier, “Rapid Manufacturing of Metallic Objects,” Rapid Prototyping Journal, vol. 18, no. 4, pp. 264–280, 2012.
  3. X. W. Bai, H. O. Zhang, and G. L. Wang, “Electromagnetically confined weld-based additive manufacturing,” Proceedings of the Seventeenth CIRP Conference on Electro Physical and Chemical Machining, vol. 6, pp. 515–520, 2013.
  4. J. Spencer, P. Dickens, and C. Wykes, “Rapid prototyping of metal parts by three-dimensional welding,” Proceedings of the Institution of Mechanical Engineers, vol. 212, no. 3, p. 175.
  5. D. T. Pham and S. S. Dimov, “Rapid prototyping and rapid tooling - the key enablers to rapid manufacturing ,” Proceedings of the INstitution of Mechanical Engineers, vol. 217, pp. 1–23, 2003.
  6. G. Spampinato, G. Muscato, and L. Cantelli, “A Closed Loop Welding Controller for a Rapid Manufacturing Process.”
  7. V. Stefanovski, “Controllable Parameters on Cold-wire Gas Tungsten Arc Weld Bead Geometry,” Masters, University of Waterloo, Waterloo, Ontario, Canada, 2012.
  8. H. R. Ghazvinloo, A. Honarbakhsh-Raouf, and N. Shadfar, “Effect of the electrode to work angle, filler diameter and shielding gas type on weld geometry of HQ 103 steel joints produced by robotic GMAW,” Indian Journal of Science and Technology, vol. 3, no. 1, Jan. 2010.
  9. E. Karadeniz, U. Ozsarac, and C. Yildiz, “The effect of process parameters on penetration in gas metal arc welding processes,” Materials and Design, vol. 28, pp. 649–656, 2007.
  10. I. . Kim, J. . Son, J. . Kim, and O. . Kim, “H. R. Ghazvinloo, A. Honarbakhsh-Raouf, and N. Shadfar, “Effect of the electrode to work angle, filler diameter and shielding gas type on weld geometry of HQ 103 steel joints produced by robotic GMAW,” Indian Journal of Science and Technology, vol. 3, no. 1, Jan. 2010.
  11. L. . Yang, R. . Chandel, and M. . Bibby, “The effects of Process Variables on the Weld Deposit Area of Submerged Arc Welds,” Welding Research Supplement, pp. 12–18, Jan. 1993.
  12. E. Koleva, “Statistical modeling and computer programs for optimization of the electron beam welding of stainless steel,” Vacuum, vol. 62, no. 2–3, pp. 151–157, Jun. 2001.
  13. H.-T. Liao and J.-R. Shie, “Optimization on selective laser sintering of metallic powder via design of experiments method,” Rapid Prototyping Journa, vol. 13, no. 3, pp. 156 – 162, 2007.
  14. E. Koleva, “Statistical modeling and computer programs for optimization of the electron beam welding of stainless steel,” Vacuum, vol. 62, no. 2–3, pp. 151–157, Jun. 2001.
  15. H.-T. Liao and Z.-W. Chen, “A study on fiber laser micro-spot welding of thin stainless steel using response surface methodology and simulated annealing approach,” International Journal of Advanced Manufacturing Technology, vol. 67, pp. 1015–1025, 2013.
  16. Y. Zhang, Y. Chen, P. LI, and A. T. Male, “Weld deposition-based rapid prototyping: a preliminary study,” Journal of Materials Processing Technology, vol. 135, pp. 347–357, 2003.
  17. S. Zhu, C. Li, C. Shen, and Y. Liang, “Microstructure and Performance Characteristics of Parts Produced via GMAW Surfacing Rapid Forming,” Advanced Materials Research, vol. 97–101, pp. 4024–4027, 2010.
  18. R. Mufti, H. Fawad, and M. Mughal, “The mechanical effects of deposition patterns on welding-based layered manufacturing ,” Journal of Engineering Manufacturing, vol. 221, no. B, pp. 1499–1508, 2007.
  19. L. . Yang, R. . Chandel, and M. . Bibby, “The effects of Process Variables on the Weld Deposit Area of Submerged Arc Welds,” Welding Research Supplement, pp. 12–18, Jan. 1993.
  20. G. Zhang, Z. Yin, and L. Wu, “Effects of Interpass Idle Time on Thermal Stresses in Multipass Multilayer Weld-Based Rapid Prototyping,” Journal of Manufacturing Science and Engineering, vol. 135, 2013.
  21. H. Zhao and G. Zhang, “A 3D dynamic analysis of thermal behavior during single-pass multi-layer weld-based rapid prototyping,” Journal of Materials Processing Technology, vol. 211, pp. 488–495, 2011.