Hot Work Tool Steel Substrates Research Articles

Comparison of Softening Behavior and Abrasive Wear Resistance between Conventionally and Additively Manufactured Tool Steels

Directed energy deposition (DED) is a powerful method for hard‐facing the existing tool components. Herein, three tool steel grades including a newly developed maraging steel (NMS), a cold work tool steel (V4E), and a high boron steel (HBS) are cladded on a hot work tool steel substrate. After tempering, the cladded tool steels are exposed to high temperatures at 600, 700, and 800 °C for 3 h to evaluate their softening resistance. The results show that all three tool steel grades have a significant hardness drop when the softening temperature reaches 700 °C. The investigated NMS has the lowest initial hardness in the tempered state but the best softening resistance. In contrast, HBS has the highest initial hardness but the worst softening resistance among the three steel grades. V4E tool steel has a moderate softening resistance compared to the other two steel grades. The factors contributing to the softening resistance have been discussed. Corresponding conventional tool steels are also adapted as references for comparison. Except for the NMS, the additive manufacturing tool steel samples have a better softening resistance than the conventional counterparts owing to more alloying elements trapped in the matrix. The abrasive wear resistance of the tempered and softened tool steels manufactured by DED and conventional methods is also evaluated and the wear mechanism is discussed. Besides the hardness, the free spacing λ between coarse hard particles is one of the major factors influencing the abrasive wear resistance.

Microstructural and mechanical aspects of laser metal deposited H13 powder for die repair

In this study, the microstructural and mechanical properties of H13 powder deposited via laser metal deposition (LMD) on H13 hot work tool steel substrates were examined. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD) were used to analyze the grain distribution, layer development, and carbide incidence. The mechanical properties were evaluated using Vickers hardness indentations. An α-ferrite matrix consisting of α’-martensite was identified along with a crack-free interface containing Mo- and Cr-rich precipitates between the additive-deposited H13 steel and the substrate. The EBSD results showed a highly consistent combination between the deposition and the substrate, along with a structure consisting of columnar and equiaxial grains resulting from the directional solidification process. Wear resistance tests demonstrated that the H13-deposited region was in a better condition than the substrate was due to the presence of martensite and carbides in the matrix. Finally, the average hardness levels of the substrate and deposition regions were determined to be 213 HV (α-Fe) and 671 HV (α’), respectively. The smooth transition in terms of hardness between the regions also indicated a tendency for lower stress concentrations.

Influence of deposition temperature on microstructure formation of Ti-Al-C-N ceramic coatings prepared via pulsed-DC PACVD

Ti-Al-C-N coatings were deposited on AISI H13 hot work tool steel substrates using PACVD method at deposition temperatures of 350, 425 and 500 °C. The results showed that synthesized nanostructured coatings consist of Ti-rich fcc-(Ti,Al)(C,N) and w-AlN nano-grains as well as an amorphous carbon nitride (a-CNx) phase. Increasing of the deposition temperature from 350 °C to 500 °C enhanced the intensity ratio of Disordered peak (ID) to Graphite peak (IG) from 0.94 to 1.13, respectively which is attributed to the increased graphitization of a-CNx phase. Rising the deposition temperature from 350 °C to 425 °C decreased the crystallite size from 11 to 9 nm, while further temperature increase to 500 °C generated larger crystallites of 13 nm. Layers of 2.33, 1.63 and 2.02 μm thickness were developed at different temperatures of 350, 425 and 500 °C, respectively. This behavior caused by increasing the temperature was originated from two competitive factors; the reduction of growth rate induced by more intense ion sputtering and the increase of growth rate induced by grain growth. Another result obtained by increasing the temperature from 350 °C to 500 °C was noticed as a 40% higher surface roughness due to more intense ion sputtering effect and grain growth. Finally, the highest micro-hardness value was measured as 4240 ± 53 HV0.01 for the coating deposited at 425 °C associated with the smallest crystallite size.

Scratch and indentation adhesion characteristics of multilayered PVD coatings before and after the heat treatment deposited by duplex process

In this research, the adhesion of multilayered nitride coatings produced by cathodic arc physical vapour deposition to hot work tool steel (AISI H13) substrate was evaluated and the effect of heat treatment on mechanical properties of these coatings was studied. Plasma nitriding was carried out as part of a duplex process, prior to physical vapour deposition of TiN-TiAlN or TiN-TiAlN-CrAlN, to improve adhesion of nitride coatings of thicknesses 5 μm and 7 μm, respectively, to the hardened steel substrate. The adhesion strength of the coatings was evaluated by scratch and indentation tests. Experimental results indicated that TiN-TiAlN coatings after annealing treatment possessed the optimum properties, as compared to other coatings. Rockwell indentation tests revealed severe delamination in TiN-TiAlN-CrAlN, whereas TiN-TiAlN coatings experienced microcracks at higher critical loads.

Dry Sliding Wear of Laser-Clad High-Vanadium Crucible Powder Metallurgy (CPM) 3V, 9V, and 15V Tool Steel Coatings

Dry sliding wear of laser-clad high-vanadium Crucible Powder Metallurgy (CPM) 3V, 9V, and 15V tool steel coatings was investigated in “as-clad” and “heat-treated” conditions against cemented WC-6%Co ball, where a hardened wrought AISI H13 hot-work tool steel substrate was used as a baseline for comparison. The 15V coating demonstrated a superior sliding wear resistance; the 9V coating possessed a better sliding wear resistance than the 3V coating, but was inferior to the 15V coating, and all the laser-clad CPM coatings showed a better sliding wear resistance than the hardened H13 substrate. The sliding wear resistances of the 3V and 15V coatings were further improved after double tempering at 540 and 550 °C (corresponding to their respective “secondary hardening”), respectively. By contrast, the sliding wear resistance of the 9V coating after double tempering at 550 °C (beyond its “secondary hardening” temperature) was slightly dropped instead, ascribed to the reduced hardness. The microstructures of the coatings, the morphologies, and chemical compositions of the worn surfaces were studied, revealing that the adhesion and oxidation played important roles in the dry sliding wear, depending upon the hardness of the martensitic matrices of the coatings and the morphologies and amount of (V, Cr)8C7 vanadium carbides dispersed on the matrices.

Characteristics of TiAlCN ceramic coatings prepared via pulsed-DC PACVD, part I: Influence of precursors’ ratio

In this study, titanium aluminium carbonitride (TiAlCN) ceramic coatings with different precursors' ratio of AlCl3/TiCl4 were deposited on H13 hot work tool steel substrates, using pulsed-DC plasma assisted chemical vapor deposition method. The coatings showed a nanocomposite microstructure consisted of fcc-TiAlN and hcp-AlN nanocrystalline grains and an amorphous carbon phase. Increasing the precursors' ratio from 0.5 to 3 led to an increase in Al content from ∼10 to ∼42 at.%. Moreover, with increasing the precursors' ratio, the surface roughness of the coating reduced initially from 21.39 to 14.44 nm, due to the creation of more nuclei of AlN and then it rose up to 18.26 nm. Coating with the precursors' ratio of 0.5 presented the highest microhardness of 3840 HV0.01,due to the less amount of chloride impurity and hcp-AlN phase. The precursors’ ratio of 0.5 resulted in the highest wear resistance and lowest coefficient of friction of around 0.17.

Characterization of TiN Coatings Deposited on H11 Tool Steel by PECVD Method

In this work, TiN nanostructured hard coating was deposited on the quartz and H11 hot work tool steel substrates using by plasma enhanced chemical vapor deposition (PECVD) technique. The process was performed in a hot wall chamber containing Ar, N2, and H2 gases along with TiCl4 vapor for 2 h at the temperature deposition of 470°C. Field emission scanning electron microscopy (FE-SEM) and EDS were used to determine thickness and chemical composition of the coating, respectively. Crystal structure of the coating was investigated by X-ray diffraction (XRD) technique which indicated strong reflections of highly crystalline TiN. This was further confirmed by X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS). Potentiodynamic polarization test in 3.5% NaCl solution and pin-on-disc were used to evaluate the properties of the TiN coating. The results indicate that specimens coated with TiN coating has fine columnar grains and low friction coefficient (about 0.2). Also polarization curve exhibit a 10 times improvement in corrosion resistance compare to uncoated samples. This protection is attributed to formation a dense and adhesive layer of TiN nanostructured hard coating on the H11 substrate.

Tailoring microstructure, mechanical and tribological properties of NiTi thin films by controlling in-situ annealing temperature

Magnetron sputtered near equiatomic NiTi thin films were deposited on Si (100) and hot work tool steel substrates. The deposited thin films were in-situ annealed at four different temperatures viz., 80°C, 305°C, 425°C, and 525°C. The effect of the in-situ annealing temperature on the microstructure of the film, the morphology, as well as mechanical and tribological properties was studied using X-ray diffraction, synchrotron diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, ball-on-disc, scratch test, and three dimensional optical microscopy. The obtained results revealed how the variation of in-situ annealing temperature affects the crystallization, microstructure evolution, as well as mechanical and tribological properties of NiTi thin films.

Investigation of the self-healing sliding wear characteristics of NiTi-based PVD coatings on tool steel

Excellent damping capacity and superelasticity of the bulk NiTi shape memory alloy (SMA) makes it a suitable material of choice for tools in machining process as well as tribological systems. Although thin film of NiTi SMA has a same damping capacity as NiTi bulk alloys, it has a poor mechanical properties and undesirable tribological performance. This study aims at eliminating these application limitations for NiTi thin films. In order to achieve this goal, NiTi thin films were magnetron sputtered as an interlayer between reactively sputtered hard TiCN coatings and hot work tool steel substrates. The microstructure, composition, crystallographic phases, mechanical and tribological properties of the deposited thin films were analyzed by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, ball-on-disc, scratch test, and three dimensional (3D) optical microscopy. It was found that under a specific coating architecture, the superelasticity of NiTi inter-layer can be combined with high hardness and wear resistance of TiCN protective layers. The obtained results revealed that the thickness of NiTi interlayers is an important factor controlling mechanical and tribological performance of bilayer composite coating systems.

Structure and properties of Al2O3 thin films deposited by ALD process

The comprehensive investigation results of the microstructure, mechanical properties and corrosion resistance of the Al2O3 thin films deposited on hot work tool steel substrate are presented in the paper. Aluminium oxide layers were prepared using atomic layer deposition (ALD) method in temperature 150, 225 and 300 °C.The uniform structure of the investigated coatings without any visible delamination was observed as a result of measurements performed with the use of scanning electron microscope. Combined SEM, AES and ToF-SIMS studies confirmed presumed chemical composition of the layers. Despite the very low thickness (∼200 nm) the layers demonstrated an excellent adhesion to the substrate, as well as a high hardness and corrosion resistance. The best mechanical properties and corrosion resistance exhibit the layers deposited at 300 °C.The excellent properties of the ALD thin films make them suitable for various engineering and industrial applications.

Nano-Scale Structure Investigation of Vapour Deposited AlCrSiN Coating Using Transmission Electron Microscope Techniques

Abstract The investigations concerned the structural analysis of the AlCrSiN coating deposited by arc Physical Vapour Deposition method on the X40CrMoV5-1 hot work tool steel substrate. The deposition process was carried out on a device equipped with a technique of lateral, rotating cathodes. The nano/microstructure, phase identification and chemical state of the coating were analysed by high-resolution transmission electron microscopy. It was found that the investigated coatings have nanostructured nature consisting of fine crystallites. The fractographic tests were made using the scanning electron microscope and allow to state, that the coating was deposited uniformly and tightly adhere to the substrate material. In the work is presented the nature of a transition zone between the produced AlCrSiN coating and substrate material.

Wear and Adhesive Failure of Al2O3 Powder Coating Sprayed onto AISI H13 Tool Steel Substrate

In this study, an alumina (Al2O3) ceramic powder was sprayed onto an AISI H13 hot-work tool steel substrate that was subjected to sanding and ultrasonic nanocrystalline surface modification (UNSM) treatment processes. The significance of the UNSM technique on the adhesive failure of the Al2O3 coating and on the hardness of the substrate was investigated. The adhesive failure of the coating sprayed onto sanded and UNSM-treated substrates was investigated by a micro-scratch tester at an incremental load. It was found, based on the obtained results, that the coating sprayed onto the UNSM-treated substrate exhibited a better resistance to adhesive failure in comparison with that of the coating sprayed onto the sanded substrate. Dry friction and wear property of the coatings sprayed onto the sanded and UNSM-treated substrates were assessed by means of a ball-on-disk tribometer against an AISI 52100 steel ball. It was demonstrated that the UNSM technique controllably improved the adhesive failure of the Al2O3 coating, where the critical load was improved by about 31%. Thus, it is expected that the application of the UNSM technique to an AISI H13 tool steel substrate prior to coating may delay the adhesive failure and improve the sticking between the coating and the substrate thanks to the modified and hardened surface.

Characteristics of Hybrid Coating Deposited by PVD and PACVD Process

Deposited on hot work tool steel substrate coating system composed of AlTiCrN film covered by diamond-like carbon (DLC)-based lubricant, was the subject of the studies. The AlTiCrN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. This paper provides an analysis of the microstructure, mechanical and tribological properties. Several surface sensitive techniques and methods, i.e. High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), Raman spectroscopy and ball-on-disk were used to performed study of the coating. TEM investigation shows an amorphous character of DLC layer. It was found that tested AlTiCrN layer has nanostructural character with fine crystallites. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.02-0.04. The investigated coating reveals high wear resistance. The coating demonstrated good adhesion to the substrate.

Characteristics of CrAlSiN+DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

Coating system composed of CrAlSiN film covered by diamond-like carbon (DLC)-based lubricant, deposited on hot work tool steel substrate was the subject of the research. The CrAlSiN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. HRTEM investigation shows an amorphous character of DLC layer. It was found that the tested CrAlSiN layer has a nanostructural character with fine crystallites while their average size is less than 10 nm. Based on the XRD pattern of the CrAlSiN, the occurrence of fcc phase was only observed in the coating, the texture direction 〈3 1 1〉 is perpendicular to the sample surface. Combined SEM, AES and ToF-SIMS studies confirmed assumed chemical composition and layered structure of the coating. The chemical distribution of the elements inside the layers and at the interfaces was analyzed by SEM and AES methods. It was shown that additional CrN layer is present between substrate and CrAlSiN coating. The atomic concentration of the particular elements of DLC and CrAlSiN layer was calculated from the XPS measurements. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05 and 0.07. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate.

Characterization and properties of PVD coatings applied to extrusion dies

The paper presents the research results on the microstructure, mechanical and tribological properties of coatings deposited by cathodic arc evaporation methods on the X40CrMoV5-1 hot work tool steel substrates as well as the possibility to employ the finite element method for evaluation of stresses in the investigated coatings. The tests were carried out on CrAlSiN and CrN coatings. The coatings demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate. The critical load LC2 lies within the range 54–55 N, depending on the coating type. The investigated coatings have the potential to increase the service life of an extrusion die by orders of magnitude as compared with uncoated steel.

Microstructure and Mechanical Properties of PVD Nanoncrystalline Layers

This work presents the research results on the structure and mechanical properties of coatings deposited by PVD methods on the X40CrMoV5-1 hot work tool steel substrates. It was found that tested coatings have nanostructural character with fine crystallites, while their average size fitted within the range 10–15 nm, depending on the coating type. The morphology of the fracture of coatings is characterized by a dense microstructure. The coatings demonstrated good adhesion to the substrate, the latter not only being the effect of interatomic and intermolecular interactions, but also by the transition zone between the coating and the substrate, developed as a result of diffusion and high-energy ion action that caused mixing of the elements in the interface zone and the compression stresses values. The critical load LC2 lies within the range 66–85 N, depending on the coating type. The coatings demonstrate a high hardness (4000 HV).

Microstructure and tribological properties of PVD coatings deposited on the X40CrMoV5-1 steel substrate

This paper presents the investigation results on the microstructure and tribological properties of the AlCrSiN, AlTiCrN and CrN coatings deposited by cathodic arc evaporation method with additional thin low-friction DLC layer on the X40CrMoV5-1 hot work tool steel substrate. As a result of the performed investigations it was found that the coatings reveals a compact structure, without any visible delamination or defects. The morphology of the coating fractures is characterised by a dense structure. Tribological tests were performed in sliding friction conditions using the ball-on-disk method, where a ceramic Al2O3 ball was used as the counterpart. The dry friction coefficient and wear rate of coatings kvc and counterpart kvb were determined. In sliding dry friction conditions, after the break-in time, the friction coefficient for the investigated elements is set in the range between 0.03–0.06 depending on the coating type. The investigated coatings reveals high wear resistance.

Structure and mechanical properties of PVD coatings deposited onto the X40CrMoV5-1 hot work tool steel substrate

This work presents the research results on the structure and mechanical properties of coatings deposited by PVD methods on the X40CrMoV5-1 hot work tool steel substrates. The tests were carried out on CrAlSiN, CrAlSiN+DLC, CrN and WC/a-C:H coatings. It was found that tested coatings have nanostructural character with fine crystallites, while their average size fitted within the range 3–13nm, depending on the coating type. The coatings demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate, the latter not only being the effect of interatomic and intermolecular interactions, but also by the transition zone between the coating and the substrate, developed as a result of diffusion that caused mixing of the elements in the interface zone and the compression stresses values. The critical load LC2 lies within the range 45–55N, depending on the coating type. The coatings demonstrate a high hardness (4000 HV).

Structure, mechanical properties and corrosion resistance of PVD gradient coatings deposited onto the X40CrMoV5-1 hot work tool steel substrate

This paper presents research results on the structure, mechanical properties and corrosion resistance of TiAlN, TiCN and AlSiCrN gradient coatings deposited by PVD methods on the X40CrMoV5-1 steel substrate. The coatings demonstrated columnar structure as well as good adhesion to the substrate, the latter not only being the effect of adhesion but also by the transition zone between the coating and the substrate, developed as a result of diffusion and high-energy ion action that caused mixing of the elements in the interface zone. The critical load LC2 lies within the range of 46-59 N, depending on the coating type.

Structure, mechanical properties and corrosion resistance of nanocomposite coatings deposited by PVD technology onto the X6CrNiMoTi17-12-2 and X40CrMoV5-1 steel substrates

This article presents the research results on the structure and mechanical properties of nanocomposite coatings deposited by PVD methods on the X6CrNiMoTi17-12-2 austenitic steel and X40CrMoV5-1 hot work tool steel substrates. The tests were carried out on TiAlSiN, CrAlSiN and AlTiCrN coatings. It was found that the structure of the PVD coatings consisted of fine crystallites, while their average size fitted within the range 11–25 nm, depending on the coating type. The coatings demonstrated columnar structure and dense cross-sectional morphology as well as good adhesion to the substrate, the latter not only being the effect of adhesion but also by the transition zone between the coating and the substrate, developed as a result of diffusion and high-energy ion action that caused mixing of the elements in the interface zone. The critical load L C2 lies within the range 27–54 N, depending on the coating and substrate type. The coatings demonstrate a high hardness (~40 GPa) and corrosion resistance.