Enhancing Wear Resistance of Selective Laser Melted Parts: Influence of Energy Density

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Y. Yang ◽  
Y. Zhu ◽  
H. Yang
Keyword(s):  
Wear Resistance ◽  
Energy Density ◽  
Process Parameters ◽  
High Hardness ◽  
Scanning Speed ◽  
Cellular Structures ◽  
Wear Rates ◽  
Scratch Tests ◽  
Hatch Spacing ◽  
Metal Additive

Abstract Selective laser melting (SLM) is a rapidly developing metal additive manufacturing technology. SLM process parameters have a direct impact on the microstructure of parts, which further affect wear behaviors. Increasing the wear resistance by tailoring process parameters, instead of postprocessing, is crucial for enhancing surface properties of the SLM-fabricated parts with complicated structures. In this study, 316L stainless steel samples were fabricated using different energy densities by varying hatch spacing and scanning speed. The relative density and hardness were measured, and the microstructures were examined. The wear resistance was evaluated by performing scratch tests. Results show that high hardness was found in the bottom region of the samples by small hatch spacings and the highest hardness of 302.8 ± 4.3 HV was measured in the sample by a hatch spacing of 10 μm. With the increase of energy density from 178 to 533 J/mm3 by reducing hatch spacing, the fraction of cellular structures decreases and columnar structures are more likely to be aligned in a relatively constant tilted angle from the build direction, which significantly improve the ability to resist slipping and deformation, indicated by 90.1%, 45.0%, and 15.7% reductions in wear rates under 1, 3, and 5 N, respectively. With the increase of energy density from 182 to 545 J/mm3 by reducing the scanning speed, the number of cellular structures increases but pores also form, which negatively affects wear resistance.

Research on Warpage of Polystyrene in Selective Laser Sintering

2010 ◽  
Vol 43 ◽  
pp. 578-582 ◽  
Author(s):  
C.Y. Wang ◽  
Q. Dong ◽  
X.X. Shen
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Laser Power ◽  
Selective Laser Sintering ◽  
Scanning Speed ◽  
Laser Sintering ◽  
Main Process ◽  
Influence Of Process Parameters ◽  
Temperature Changes ◽  
Hatch Spacing

Warpage is a crucial factor to accuracy of sintering part in selective laser sintering (SLS) process. In this paper, The influence of process parameters on warpage when sintering polystyrene(PS) materials in SLS are investigated. The laser power, scanning speed, hatch spacing, layer thickness as well as temperature of powder are considered as the main process parameters. The results showed that warpage increases with the increase of hatch space. Contary to it, warpage decreases with the increase of laser power. Warpage decreases with the increase of layer thickness between 0.16~0.18mm and changes little with increase of the thickness. Warpage increases along with the increase of scanning speed but decreases when the speed is over about 2000mm/s. When the temperature changes between 82°C-86°C, warpage decreases little with the increase of temperature. But further increase of temperature leads to warpage decreasing sharply when the temperature changes between 86°C-90°C.

Optimization of parameters for SLS of WC-Co

2017 ◽  
Vol 23 (6) ◽  
pp. 1202-1211 ◽  
Author(s):  
Sanjay Kumar ◽  
Aleksander Czekanski
Keyword(s):  
Energy Density ◽  
Process Parameters ◽  
Laser Power ◽  
Laser Energy ◽  
Beam Diameter ◽  
Content Type ◽  
Powder Bed ◽  
Scan Speed ◽  
New Equation ◽  
Hatch Spacing

Purpose WC-Co is a well-known material for conventional tooling but is not yet commercially available for additive manufacturing. Processing it by selective laser sintering (SLS) will pave the way for its commercialization and adoption. Design/methodology/approach It is intended to optimize process parameters (laser power, hatch spacing, scan speed) by fabricating a bigger part (minimum size of 10 mm diameter and 5 mm height). Microstructural analysis, EDX and hardness testing is used to study effects of process parameters. Optimized parameter is ascertained after fabricating 49 samples in preliminary experiment, 27 samples in pre-final experiment and 9 samples in final experiment. Findings Higher laser power gives rise to cracks and depletion of cobalt while higher scan speed increases porosity. Higher hatch spacing is responsible for delamination and displacement of parts. Optimized parameters are 270 W laser power, 500 mm/s scan speed, 0.04 mm layer thickness, 0.04 mm hatch spacing (resulting in energy density of 216 J/mm3) and 200°C powder bed temperature. A part comprising of small hole of 2 mm diameter, thin cylindrical pin of 0.5 mm diameter and thin wall of 2 mm width bent up to 30° angle to the base plate is fabricated. In order to calculate laser energy density, a new equation is introduced which takes into account both beam diameter and hatch spacing unlike old equation does. In order to calculate laser energy density, a new equation is formulated which takes into account both beam diameter and hatch spacing unlike old equation does. WC was not completely melted as intended giving rise to partial melting-type binding mechanism. This justified the name SLS for process in place of SLM (Selective Laser Melting). Research limitations/implications Using all possible combination of parameters plus heating the part bed to maximum shows limitation of state-of-the-art commercial powder bed fusion machine for shaping hardmetal consisting of high amount of WC (83 wt. per cent). Practical implications The research shows that microfeatures could be fabricated using WC-Co which will herald renewed interest in investigating hardmetals using SLS for manufacturing complex hard tools, molds and wear-resistance parts. Originality/value This is the first time micro features are successfully fabricated using WC-Co without post-processing (infiltration, machining) and without the help of additional binding material (such as Cu, Ni, Fe).

scholarly journals Investigation into Microstructure, Wear Resistance in Air and NaCl Solution of AlCrCoNiFeCTax High-Entropy Alloy Coatings Fabricated by Laser Cladding

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 358
Author(s):  
Peng Zhao ◽  
Jun Li ◽  
Ruyan Lei ◽  
Baige Yuan ◽  
Manman Xia ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
High Hardness ◽  
Atomic Radius ◽  
High Entropy Alloy ◽  
Dispersion Strengthening ◽  
Nacl Solution ◽  
High Entropy ◽  
Wear Rates ◽  
Significant Difference

AlCrCoNiFeCTax (x = 0, 0.5 and 1.0) high-entropy alloys coatings were synthesized on 45# steel by laser cladding. The microstructural evolution of the coatings with the change in x was analyzed in detail. The effect of Ta content on the wear behaviors of the coatings at different circumstances (in air and 3.5 wt.% NaCl solution) was especially highlighted. The microstructure presented the following change: equiaxed BCC (Body Centered Cubic) grains + fine MC (carbide, M = Al, Cr, Co and Ni) particles (x = 0) → equiaxed BCC grains + coarse TaC blocks + fine TaC particles (x = 0.5) → flower-like BCC grains + coarse TaC blocks + eutecticum (BCC + TaC) (x = 1.0). The average microhardness of the coatings demonstrated an upward tendency with increasing x due to the combination of the stronger solid solution and dispersion strengthening from the significant difference in atomic radius between Ta and Fe and the formation of TaC with an extremely high hardness. The wear rates of the coatings were gradually reduced both in air and in NaCl solution along with the increase in Ta content, which were lower than those of the substrate. The wear rates of the coatings with x = 0.5 and 1.0 in NaCl solution were slightly reduced by about 17% and 12% when compared with those in air. However, the values of the substrate and the coating without Ta in NaCl solution were sharply enhanced by 191% and 123% when compared with those in air. This indicated that the introduction of Ta contributed to the improvement in wear resistance both in air and in NaCl solution.

Review and Prospect of the Influence of Laser Cladding Process Parameters on the Properties of Die Cladding Layer

2020 ◽  
Vol 990 ◽  
pp. 67-72 ◽  
Author(s):  
Bin Han ◽  
Hui Wang ◽  
Jia Yi Lin ◽  
Xi Hao Liu
Keyword(s):  
Laser Cladding ◽  
Process Parameters ◽  
Laser Power ◽  
High Hardness ◽  
Scanning Speed ◽  
Production Costs ◽  
High Wear Resistance ◽  
Cladding Layer ◽  
Laser Cladding Process ◽  
Development Direction

Laser cladding technology is widely used in the surface modification of parts due to its excellent properties such as high hardness, high wear resistance and corrosion resistance. Extends the life of these parts under normal use conditions, greatly reducing production costs. In this paper, the influence of different parameters such as laser cladding process parameters—laser power and scanning speed, and their interaction on the performance of mold cladding layer is discussed, and the future development direction of laser cladding technology in mold is prospected.

scholarly journals A Comparative Study in the Tribological Behavior of DLC Coatings Deposited by HiPIMS Technology with Positive Pulses

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174 ◽  
Author(s):  
Jose A. García ◽  
Pedro J. Rivero ◽  
Eneko Barba ◽  
Ivan Fernández ◽  
Jose A. Santiago ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Tribological Behavior ◽  
High Hardness ◽  
Scratch Test ◽  
Low Friction ◽  
Dlc Coatings ◽  
Useful Life ◽  
Scratch Tests ◽  
Deposition Techniques

During the last few decades, diamond-like carbon (DLC) coatings were widely used for tribological applications, being an effective tool for improving the performance and the useful life of different machining tools. Despite its excellent properties, among which stand out a high hardness, a very low friction coefficient, and even an excellent wear resistance, one of the main drawbacks which limits its corresponding industrial applicability is the resultant adhesion in comparison with other commercially available deposition techniques. In this work, it is reported the tribological results of a scratch test, wear resistance, and nanoindentation of ta-C and WC:C DLC coatings deposited by means of a novel high-power impulse magnetron sputtering (HiPIMS) technology with “positive pulses”. The coatings were deposited on 1.2379 tool steel which is of a high interest due to its great and wide industrial applicability. Finally, experimental results showed a considerable improvement in the tribological properties such as wear resistance and adhesion of both types of DLC coatings. In addition, it was also observed that the role of doping with W enables a significant enhancement on the adhesion for extremely high critical loads in the scratch tests.

scholarly journals Influence of Combined Mechanical Processes on Tribological Properties of Tool Steels Vanadis 8 and Vancron 40 With a Similar Hardness

2021 ◽  
Vol 7 ◽  
Author(s):  
Daniel Toboła ◽  
Aneta Łętocha
Keyword(s):  
Wear Resistance ◽  
Hard Turning ◽  
High Hardness ◽  
High Wear Resistance ◽  
Tool Steels ◽  
Wear Rates ◽  
Resistance Surface ◽  
Slide Burnishing ◽  
Gas Quenching ◽  
Vacuum Furnaces

Surface integrity is important factor for components exposed to wear, like cold working tools, which need to possess high hardness combined with high wear resistance. Surface treatments such as grinding, hard turning, and hard turning with slide burnishing have been developed for its improvement. Vancron 40 and Vanadis 8 tool steels, of different chemical composition and different types and amounts of carbides, were now investigated. Heat treatment was carried out in vacuum furnaces with gas quenching to hardness of Vancron 64 ± 1 HRC and of Vanadis 65 ± 1 HRC. 3D topography, optical and scanning electron microscopy, X-ray diffraction and ball-on-disc tribological tests against Al2O3 and 100Cr6 balls as counterparts were used to examine wear and friction. For both steels, the lowest values of dynamic frictions and wear rates against Al2O3 counterbodies were achieved after sequential process of hard turning with slide burnishing with a burnishing force of 180 N. For alumina balls, the increase of wear resistance, achieved after hard turning plus burnishing in comparison to grinding exceeds 50 and 60%, respectively for Vanadis 8 and Vancron 40 steels.

scholarly journals Effect of SLM Processing Parameters on Microstructures and Mechanical Properties of Al0.5CoCrFeNi High Entropy Alloys

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 292 ◽  
Author(s):  
Kun Sun ◽  
Weixiang Peng ◽  
Longlong Yang ◽  
Liang Fang
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Process Parameters ◽  
Laser Power ◽  
Scanning Speed ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Hatch Spacing

Selective laser melting (SLM) to fabricate Al0.5CoCrFeNi high entropy alloys with pre-mixed powders was studied in this paper. The influences of process parameters including laser power, scanning speed, and hatch spacing on the relative density of high-entropy alloys (HEAs) were investigated. A relative density of 99.92% can be achieved by optimizing the SLM process parameters with laser power 320 W, scanning speed 800 mm/s, and hatch spacing of 60 μm, respectively. Moreover, the microstructure of the HEAs was also studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD). It was found that the microstructure of the HEAs was only composed of face-centered cubic and body-centered cubic phases, without complex intermetallic compounds. The mechanical properties of the HEAs were also characterized. At ambient temperature, the alloys had a high yield strength of about 609 MPa, tensile strength about 878 MPa, and hardness about 270 HV. Through a comparison with the corresponding alloys fabricated by vacuum induction melting, it can be concluded that the high entropy alloys fabricated by SLM had fine microstructures and improved mechanical properties.

scholarly journals The Influence of Selective Laser Melting Process Parameters on the Property of TiAlN/TiN Multilayer Coating on the 316L Steel

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 377 ◽  
Author(s):  
Yueling Lyu ◽  
Jingwei Wang ◽  
Yulin Wan ◽  
Yangzhi Chen
Keyword(s):  
Selective Laser Melting ◽  
Process Parameters ◽  
Laser Power ◽  
Orthogonal Experiment ◽  
Multilayer Coating ◽  
Melting Process ◽  
Scanning Speed ◽  
Laser Melting ◽  
Wear Rates ◽  
Comprehensive Property

Selective laser melting (SLM) is an important advanced additive manufacturing technology. The existing SLM products cannot fully meet the requirements of high-precision and strength of the mechanical component because of their defects. The TiAlN/TiN multilayer coating can improve the surface property of SLM products. The present work aims to explore the influences of different process parameters of SLM on the property of TiAlN/TiN multilayer coating plating on the 361L specimen and the mechanism of these influences. Taking laser power, scanning speed, and scanning space as factors, an orthogonal experiment was designed. The TiAlN/TiN multilayer coating specimens can be obtained by plating on the 361L specimen, fabricated by the process parameters of SLM on the orthogonal experiment. The surface topographies and properties of TiAlN/TiN multilayer coating were tested, the influences of SLM process parameters on TiAlN/TiN multilayer coating were analyzed, and the optimal process parameter was obtained. The electron microscope images revealed that the surface morphology of TiAlN/TiN multilayer coating plating on the SLM specimen was relatively flat, and there were some macro-particles in different sizes and pin holes dispersed on it. The thickness of the TiAlN/TiN multilayer coating was 2.77–3.29 μm. The microhardness value of coating SLM specimen was more than four times that of the uncoated SLM specimen and the wear rates of the uncoated specimen were 2–4 times that of the corresponding coating specimen. The comprehensive analysis shows that the laser power had the greatest influence on the comprehensive property of the coating. The primary cause of the influence of SLM process parameters on the properties of the TiAlN/TiN multilayer coating was preliminarily discussed. When the laser power was 170 W, the scanning speed was 1,100 mm/s, and the scanning space was 0.08mm, the TiAlN/TiN multilayer coating plating on the SLM specimen had the best comprehensive property.

scholarly journals A New Plasma Surface Alloying to Improve the Wear Resistance of the Metallic Card Clothing

2019 ◽  
Vol 9 (9) ◽  
pp. 1849 ◽  
Author(s):  
Dongbo Wei ◽  
Fengkun Li ◽  
Shuqin Li ◽  
Xiaohu Chen ◽  
Feng Ding ◽  
...  
Keyword(s):  
Wear Resistance ◽  
High Hardness ◽  
Surface Alloying ◽  
Plasma Surface ◽  
Wear Rates ◽  
Before And After ◽  
Glow Plasma ◽  
Surface Morphologies ◽  
And Diffusion ◽  
Plasma Surface Alloying

A new surface strengthening process: Plasma surface chromizing was implemented on the metallic card clothing to improve its wear resistance based on double glow plasma surface metallurgy technology. A chromizing coating was prepared in the process, which consisted of a deposited layer and diffusion layer. The surface morphologies, microstructure, phase composition, and hardness were analyzed in detail. The friction behaviors of the metallic card clothing before and after plasma surface alloying were comparatively analyzed under various sliding speeds at room temperature. The results showed that: 1. The chromizing coating on the surface of metallic card clothing was dense and homogeneous without defects, and the metallic card clothing still maintained its integrity and sharpness. 2. The chromizing coating consist of [Fe,Cr], Cr, Cr23C6, and Cr7C3, which contribute to the high hardness. 3. The average microhardness of metallic card clothing increased from 365.4 HV0.05 to 564.9 HV0.05 after plasma surface chromizing. Nano hardness of the chromizing coating was approximately 1.87 times than the metallic card clothing. 4. At various sliding velocities of 2 m/min, 4 m/min, and 6 m/min, the specific wear rates of metallic card clothing were 16.38, 9.06 and 6.26 × 10−4·mm3·N−1·m−1, and the specific wear rates of metallic card clothing after plasma surface chromizing were 2.91, 3.30, and 2.95 × 10−4·mm3·N−1·m−1. Furthermore, the wear mechanism of the chromizing coating gradually changed from adhesive wear to abrasive wear as the sliding velocity increased. The results indicate that the wear resistance of metallic card clothing was improved obviously after plasma surface chromizing.

Caracteristics of TiN Coating Films for Large Sizes Prepared by Arc Ion Plating

2012 ◽  
Vol 706-709 ◽  
pp. 2589-2595
Author(s):  
Kyeong Cheol Baek ◽  
Chan Yeol Seo ◽  
Ki Bok Heo ◽  
Yang Soo Kim ◽  
Dong Joo Yoon ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Partial Pressure ◽  
Process Parameters ◽  
High Hardness ◽  
Hard Coatings ◽  
Tin Coating ◽  
Adhesion Properties ◽  
Arc Ion Plating ◽  
Ion Plating ◽  
Industrial Manufacture

Arc ion plating (AIP) is one of the most attractive physical vapour deposition (PVD) method for the industrial manufacture of TiN coatings, owing to a high degree of ionization in the target material and convenient control of the process parameters. The important characteristic of hard coating is the adhesion strength between the coating layer and the substrate. The coating will be subjected to various loads, such as mechanical, thermal load, etc., in practical applications. Therefore, for more than a decade, Ti-based hard coatings have been applied to tools, dies, and mechanical parts because of the enhance lifetime and performance. It is focus on the attractive properties such as high hardness, good wear, and chemical stability. In the present study, TiN monolayer film was prepared at various N2 partial pressures and current by the AIP technique in SACM645 material. The correlation between microstructure and properties of the TiN coating was comparatively investigated by XRD, FE-SEM and AFM. These study carried steadily out improve the adhesion properties and wear resistance of Ti-based coating using pre-treatment of the substrate, insertion of an interlayer, application of multi-layers and adjustment of the process parameters. The main phase FCC TiN displayed (200) orientation in the film with the highest N2partial pressure. The (111) orientation was observed with decreasing N2partial pressure. The (200) and (111) textures in the film which was treated 80A arc current were found to be competitive orientations, however stronger arc treated the (200) texture was increased. The multilayer TiN films has possessed high hardness (up to 42Nm) and the best wear resistance among the specimens. These features were attributed to the presence of dense microstructures that were mainly composed of TiN phase around 5.16㎛ thickness, HF1 adhesion and Ra 35㎚ surface roughness

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