Laser alloying of 316L steel with boron and nickel

Author(s):  
D. Mikołajczak ◽  
M. Kulka ◽  
N. Makuch ◽  
P. Dziarski

Purpose: The aim of the study was to improve the hardness and tribological properties of austenitic 316L steel by laser alloying with boron and nickel. Design/methodology/approach: The relatively low wear resistance of austenitic 316L steel could be improved by an adequate surface treatment. Laser alloying was developed as an alternative for time- and energy-consuming thermo-chemical treatment, e.g. diffusion boriding. In the present study, laser alloying of 316L steel with boron and nickel was carried out as the two-stage process. Firstly, the outer surface of the sample was coated with the paste, consisting of the mixture of boron and nickel powders, blended with a diluted polyvinyl alcohol solution. Second stage consisted in laser re-melting of the paste coating together with the base material. Laser treatment was carried out with the use of the TRUMPF TLF 2600 Turbo CO2 laser. The multiple laser tracks were formed on the surface. The microstructure was observed with the use of an optical microscope (OM) and scanning electron microscope (SEM) Tescan Vega 5135. The phase analysis was carried out by PANalytical EMPYREAN X-ray diffractometer using Cu Ka radiation. Hardness profile was determined along the axis of laser track. Wear resistance was studied using MBT-01 tester. Findings: The use of the adequate laser processing parameters (laser beam power, scanning rate, overlapping) caused that free of cracks and gas pores and the uniform laseralloyed layer in respect of the thickness was produced. In the microstructure, only two zones were observed: laser re-melted zone (MZ) and the substrate. There were no effects of heat treatment below MZ. Heat-affected zone (HAZ) was invisible because the austenitic steel could not be hardened by typical heat treatment (austenitizing and quenching). The produced laser-alloyed layer was characterized by improved hardness and wear resistance compared to the base material. Research limitations/implications: The application of proposed surface treatment in industry will require the appropriate corrosion resistance. In the future research, the corrosion behaviour of the produced layer should be examined and compared to the behaviour of 316L steel without surface layer. Practical implications: The proposed layer could be applied in order to improve the hardness and tribological properties of austenitic steels. Originality/value: This work is related to the new conception of surface treatment of austenitic steels, consisting in laser alloying with boron and some metallic elements.

2018 ◽  
Vol 27 (47) ◽  
pp. 101
Author(s):  
Sandra Arias ◽  
Maryory Gómez ◽  
Esteban Correa ◽  
Félix Echeverría-Echeverría ◽  
Juan Guillermo Castaño

Nickel-Boron autocatalytic coatings are widely used in several industries to improve mechanical properties of materials such as hardness and wear resistance. Tribological properties were evaluated in Ni-B autocatalytic coatings deposited on AISI/SAE 1018 carbon steel before and after a heat treatment at 450 °C for one hour. Tribological tests were carried out by dry sliding, using a load of 5 N and a sliding speed of 0.012 m/s, in a homemade ball-on-disk tribometer, which followed ASTM G99 standard. According to the tribological evaluation, the heat treatments applied to Ni-B coatings improved their tribological performance. This research corroborates that by applying an adequate heat treatment, hardness and wear resistance of Ni-B coatings can be improved significantly.


2018 ◽  
Vol 24 (3) ◽  
pp. 50-54
Author(s):  
Jan Senatorski ◽  
Jan Tacikowski ◽  
Janusz Trojanowski ◽  
Paweł Mączyński

Nitriding of carbon steels does not allow for adequate hardening of the substrate of layers and core required in some applications. Such hardening can be achieved by using further heat treatment. As a result of this heat treatment, the zone of nitrides vanishes and a nitro-carbon martensite structure is formed, additionally hardened by ageing. The carried out tribological tests have shown that subjecting nitrided carbon steel to further hardening treatment significantly improves its wear resistance in comparison to nitrided steel, and the zone of good wear resistance goes deeper.


Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 137-142
Author(s):  
Dagmara TRYBA ◽  
Marcin KOT ◽  
Anna ANTOSZ

Properties of high manganese austenitic cast steel are not satisfactory; therefore, this material should be hardened. Currently, the commonly used method of hardening does not allow eliminating problems related to premature wear of railway frogs. Therefore, many studies have been carried out to find an alternative method to obtain improved wear resistance of such elements. The article presents an analysis of the mechanical and tribological properties of base and hardened, by different methods, high-manganese cast steel applied for turnouts. Tests were performed for three hardening methods: explosive, pressure-rolling, and dynamic impact. The results were compared with the properties of base material after saturation treatment. The conducted tests allowed the determination of hardness profiles of hardened surfaces, as well as the wear resistance and coefficient of friction, and the obtained results are very promising. Hardening by dynamic impact provided much better results in relation to presently used explosive hardening technology.


Tribologia ◽  
2019 ◽  
Vol 288 (6) ◽  
pp. 73-80
Author(s):  
Aleksandra Pertek-Owsianna ◽  
Karolina Wiśniewska-Mleczko ◽  
Adam Piasecki

This paper presents two methods of introducing boron into the surface layer of iron alloys, namely diffusion boronizing by means of the powder method and laser alloying with a TRUMPF TLF 2600 Turbo CO2 gas laser. Amorphous boron was used as the chemical element source. As regards diffusion drilling, the influence of temperature and time on the properties of the layer was tested. During the laser alloying, the influence of the thickness of the boriding paste layer as well as the power and laser beam scanning velocity was determined. How the carbon content in steel and alloying elements in the form of chromium and boron influence the structure of the surface layer was tested. To achieve this object, the following grades of steel were used: C45, C90, 41Cr4, 102Cr6, and HARDOX boron steel. The microhardness and wear resistance of the obtained boron-containing surface layers were tested. A Metaval Carl Zeiss Jena light microscope and a Tescan VEGA 5135 scanning electron microscope, a Zwick 3212B microhardness tester, and an Amsler tribotester were used for the tests. The structure of the diffusion- borided layer consists of the needle-like zone of FeB + Fe2B iron borides about 0.15 mm thick, with a good adhesion to the substrate of the steel subjected to hardening and tempering after the boriding process. After the laser alloying, the structure shows paths with dimensions within: width up to 0.60 mm, depth up to 0.35 mm, containing a melted zone with a eutectic mixture of iron borides and martensite, a heat affected zone with a martensitic-bainitic structure and a steel core. The microhardness of both diffusionborided and laser-borided layers falls within the range of 1000 – 1900 HV0.1, depending on the parameters of the processes. It has been shown that, apart from the structure and thickness of the layer containing boron and microhardness, the frictional wear resistance depends on the state of the steel substrate, i.e. its chemical composition and heat treatment. The results of testing iron alloys in the borided state were compared with those obtained only after the heat treatment.


Author(s):  
S. I. Bogodukhov ◽  
E. S. Kozik ◽  
E. V. Svidenko

Hard alloys are popular materials widely used in the toolmaking industry. Refractory carbides included in their composition make carbide tools very hard (80 to 92 HRA) and heat-resistant (800 to 1000 °С) so as they can be used at cutting speeds several times higher than those used for high-speed steels. However, hard alloys differ from the latter by lower strength (1000 to 1500 MPa) and the absence of impact strength, and this constitutes an urgent problem. We studied the influence of thermal cycling modes on the mechanical and tribological properties of VK8 (WC–8Co) hard alloy used in the manufacture of cutters and cutting inserts for metal working on metal-cutting machines. As the object of study, we selected 5×5×35 mm billets made of VK8 (WC–8Co) alloy manufactured by powder metallurgy methods at Dimitrovgrad Tool Plant. The following criteria were selected for heat treatment mode evaluation: Vickers hardness, flexural strength, and mass wear resistance (as compared to the wear of asreceived samples that were not heat treated). Plates in the initial state and after heat treatment were subjected to abrasion tests. Wear results were evaluated by the change in the mass of plates. Regularities of the influence of various time and temperature conditions of heat treatment on the tribological properties of products made of VK group tungsten hard alloys were determined. An increase in the number of thermal cycling cycles improved such mechanical properties of the VK8 hard alloy as strength and hardness. When repeating the cycles five times, an increase in abrasive wear resistance was obtained compared to the initial nonheat-treated sample. The elemental composition of the VK8 hard alloy changed insignificantly after thermal cycling, only a slight increase in oxygen was observed on the surface of plates. The grain size after thermal cycling increased in comparison with the initial VK8 hard alloy. It was found that VK8 hard alloy thermocyclic treatment leads to a change in the phase composition. X-ray phase analysis showed the presence of a large amount of α-Co with an hcp-type lattice on the surface of a hard alloy and a solid solution of WC in α-Co. A change in the cobalt modification ratio causes a decrease in microstresses. An analysis of the carbide phase structure state showed that the size of crystallites and microstresses changed after thermal cycling. The lattice constant of the cobalt cubic solid solution decreased, which may indicate a decrease in the amount of tungsten carbide and carbon dissolved in it. Statistical processing of experimental results included the calculation of the average value of the mechanical property, its dispersion and standard deviation in the selected confidence interval.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Yuh-Ping Chang ◽  
Jin-Chi Wang ◽  
Jeng-Haur Horng ◽  
Li-Ming Chu ◽  
Yih-Chyun Hwang

The technology of composite heat treatment is used popularly for low friction and wear resistance of drive elements. A large number of papers about the heat treatment technology had been proposed. Especially, the nitride treatment has been used widely for the purpose of wear resistance and low friction in the industry. Therefore, the self-developed vertical ball/disk friction tester with the measurement system was used to study the effects of nitride on the tribological properties of the low carbon alloy steel—SCM415— in this study. The experiments were conducted under dry and severe wear conditions. The variations of friction coefficient and surface magnetization were simultaneously recorded during dynamic friction process. After each test, the microstructures of the wear particles were observed and analyzed under a SEM, and the depth of wear track is measured by means of a surface tester. According to the experimental results, the wear resistance of the specimens with carburizing-nitride is significantly larger than the case of nitride-carburizing. Moreover, the surface magnetization was especially larger for the case of nitride-carburizing. As a result, the wear particles always stay in the interfaces and the wear mechanism becomes complex. Therefore, it is necessary to put nitride after carburizing for the composite heat treatments.


Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3232 ◽  
Author(s):  
Jan Medricky ◽  
Frantisek Lukac ◽  
Stefan Csaki ◽  
Sarka Houdkova ◽  
Maria Barbosa ◽  
...  

Ceramic Al2O3-ZrO2-SiO2 coatings with near eutectic composition were plasma sprayed using hybrid water stabilized plasma torch (WSP-H). The as-sprayed coatings possessed fully amorphous microstructure which can be transformed to nanocrystalline by further heat treatment. The amorphous/crystalline content ratio and the crystallite sizes can be controlled by a specific choice of heat treatment conditions, subsequently leading to significant changes in the microstructure and mechanical properties of the coatings, such as hardness or wear resistance. In this study, two advanced methods of surface heat treatment were realized by plasma jet or by high energy laser heating. As opposed to the traditional furnace treatments, inducing homogeneous changes throughout the material, both approaches lead to a formation of gradient microstructure within the coatings; from dominantly amorphous at the substrate–coating interface vicinity to fully nanocrystalline near its surface. The processes can also be applied for large-scale applications and do not induce detrimental changes to the underlying substrate materials. The respective mechanical response was evaluated by measuring coating hardness profile and wear resistance. For some of the heat treatment conditions, an increase in the coating microhardness by factor up to 1.8 was observed, as well as improvement of wear resistance behaviour up to 6.5 times. The phase composition changes were analysed by X-ray diffraction and the microstructure was investigated by scanning electron microscopy.


2006 ◽  
Vol 129 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Ping Huang ◽  
Rong Liu ◽  
Xijia Wu ◽  
Matthew X. Yao

The chemical composition of Stellite® 21 alloy was modified by doubling the molybdenum (Mo) content for enhanced corrosion and wear resistance. The specimens were fabricated using a casting technique. Half of the specimens experienced a heat treatment at 1050°C for an hour. The microstructure and phase analyses of the specimens were conducted using electron scanning microscopy and X-ray diffraction. The mechanical properties of the specimens were determined in terms of the ASTM Standard Test Method for Tension Testing of Metallic Materials (E8-96). The mechanical behaviors of individual phases in the specimen materials were investigated using a nano-indentation technique. The wear resistance of the specimens was evaluated on a ball-on-disk tribometer. The experimental results revealed that the increased Mo content had significant effects on the mechanical and tribological properties of the low-carbon Stellite® alloy and the heat treatment also influenced these properties.


2016 ◽  
Vol 291 ◽  
pp. 292-313 ◽  
Author(s):  
M. Kulka ◽  
D. Mikolajczak ◽  
N. Makuch ◽  
P. Dziarski ◽  
A. Miklaszewski

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