Surface Modification Of Tool Steel Research Articles

Duplex surface modification of tool steel - deposition of a WN film and subsequent electron-beam modification

In this study, we demonstrate a combined treatment technique of R18 high-speed tool steel comprising deposition of a WN coating followed by electron-beam surface treatment (EBT). In order to understand the influence of the deposited WN coating on the resultant structure and properties, an uncoated specimen was directly electron-beam treated under the same EBT technological conditions. The structure of the specimens was studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The microhardness was also investigated. The phase composition consisted of a double phase structure of Fe and M6C carbides in both cases. The microstructure was significantly finer in the case of an EBT of the steel with WN coating, leading to a much higher microhardness in comparison with the case without WN.

Ytterbium impulse laser for surface modification of tool steel with B4C-Al powders

The paper deals with a new application solution of Ytterbium Picosecond Pulsed Fiber Laser for surface modification of 3Kh2V8F hot-work tool steel (the analog of AISI H21 steel). Surface modification was conducted by B4C-Al powders from preplaced pastes followed by laser heating. The ratio of B4C-Al powders was taken as 5/1 by weight and the paste thickness was approximately 1 mm. Laser treatment was conducted according to the following parameters: 1070 nm of wavelength, 100 W of power, 1 mJ of pulse energy, 100 ns pulse duration, pulse frequency range from 50 kHz to 90 kHz. Several tracks with different widths were obtained as a result of treatment depending on velocity of the laser move. EDS analysis showed that B4C particles were not completely dissolved in the weld beads. However, an enhanced concentration of boron (8-12 wt.%) was revealed in the vicinity of B4C particles. The aluminum concentration was low (up to 0.79 wt.%) on the surface of the weld beads.

Surface modification of tool steel by using EDM green powder metallurgy electrodes

Electro-discharge machining (EDM) is mostly used for machining difficult-to-cut materials which are difficult to machine by conventional machining processes. In recent years, EDM is also used for surface modification. This work aims to investigate the phenomenon of surface modification of tool steel Calmax (Uddeholm) by EDM process using Cu-ZrO2 powder metallurgy green compact electrode. Results show that the higher Material Transfer Rate of 46.5 mgr/min is achieved on the combination of Ip=9A and Ton=25 μs. The effect of peak current and pulse duration on the material transfer rate and surface roughness (Ra and Rz) was investigated. Machined surfaces were characterized by scanning electron microscopy (SEM).

Surface modification of tool steel by cathodic cage TiN deposition

ABSTRACT The aim of this work is to investigate the effect of titanium nitride coating for various treatment times (0.5–4 h) by cathodic cage plasma deposition (CCPD) on surface properties of AISI D6 tool steel. The obtained results depict micrometric-sized TiN film deposition under all processing condition with improved surface hardness and corrosion resistance. Raman and EDS analysis are used to calculate N/Ti ratios for stoichiometric calculations of samples. This study depicts that the surface properties of tool steel can be effectively improved by TiN film deposition using CCPD, with low processing time, low processing temperature and better uniformity, as compared to conventional techniques. Additionally, the problems associated with the conventional TiN films such as pores and voids are eliminated. This technique is compatible with industrial-scale applications, and thus results from this study are expected to be beneficial for the surface engineering industry.

Elevated temperature plasma nitriding and effects on electrochemical properties of steel

Abstract Surface modification of tool steel had been performed by utilizing plasma nitriding at elevated temperature by varying the exposure time. The nitrided steel had shown significantly enhanced corrosion resistance properties. X-ray diffraction (XRD) had revealed the presence of FexN (x = 2–3, 4) in the surface modified microstructure after nitriding. In an environment of NaCl potentiodynamic polarization and impedance (EIS) tests of steel with and without nitriding had been performed. Both these tests had shown the improved resistance to corrosion of the steel after nitriding.

Surface modification of tool steel by electrical discharge machining with molybdenum powder mixed in dielectric fluid

Research works in electrical discharge machining (EDM) with powder suspended in dielectric fluid indicate significant gains in process stability and surface roughness improvement of EDMachined components. Powder-mixed EDM (PMEDM) process is also investigated in order to obtain a resolidified layer (recast layer), which acts as a kind of coating, having superior mechanical properties to the base material. Molybdenum (Mo), commonly used as an alloying element in steels, in solid solution or in the form of various carbides, provides high resistance to wear, corrosion, and high hardness. However, as reported in literature, there are technological gaps in the use of molybdenum as an additive powder in PMEDM process. The influences of different sizes of fine Mo powder particles (˂5 and ˂15 μm) suspended in dielectric fluid in several EDM finishing regimes and machining times were investigated regarding AISI H13 tool steel surface modification. Samples were evaluated in terms of hardness, chemical composition, and microstructure using optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), nanoindentation, and X-ray diffraction (XRD). Results showed an enrichment of the modified surface layer (recast layer) with Mo, in which the formation of phases of Fe-Mo and Mo x C and also the presence of Mo in solid solution were observed, resulting in a four times fold hardness increase in comparison with the metal matrix. Best results were obtained with 1-A discharge current and less than 15-μm particle size, with the formation of a Mo-enriched, 14-GPa hardness uniform modified layer, with a constant thickness of 5 μm free of pores and microcracks. Machining times did not affect the characteristics of resolidified layer (recast layer). This work provides PMEDM process referential parameters to the use of Mo as a material for providing better surface mechanical properties.

Laser Surface Modification of Tool Steel for Semi-Solid Steel Forming

This paper presents an analysis of the effect of CO2 laser processing parameters on the surface modification and heat treatment of steels. The CO2 laser and sample movement process parameters are presented. The controlled operation of these in conjunction with each other is required to obtain better surface hardness and structure. H13 tool steel samples were rotated at high speeds to keep exposure times below 0.3s. Laser processed samples were analysed using EDX spectroscopy, optical microscopy, Vickers and Martens micro-hardness testing, and X-ray diffraction (XRD). Results show how the hardness profile through the surface is related to the laser treatment and resultant microstructures. Increased surface hardness was noted due to a complete microstructural transformation to an amorphous state in the glazed samples. The usefulness of such coatings on tool steels, in conjunction with other thermal barriers, for the forming of semi-solid steel alloys is presented.

Nano structured surface modification of tool steel and its beneficial effects in mechanical properties

The industrial beneficial effects of nano-structured surface modification of tool steel (SKD 61) have been studying. Ultrasonic cold forging technology (UCFT) is one of severe plastic deformations for the improvement of mechanical properties by making nano-structure on surface. The basic mechanism of UCFT and experimental device for treatment of trimmer knives (SKD 61) are presented. Test results of UCFT treated knives in cold steel milling line and analysis why the improved service life is achieved are explained.

Surface modification of tool steel by MOS2 powder shooting

This paper describes surface modification of tool steel by MoS2 powder shooting technology and the lubricating ability of such MoS2 shot tool steel for metal-forming applications. This method introduces a MoS2 shot layer of approximately 1.5μm into the surface of the tool steel by shooting MoS2 powder with pressurized air. Friction measurements indicated that the friction properties of such MoS2 shot tool could be remarkably improved. Ring compression tests were performed to measure the lubricating ability of the MoS2 shot tool during large deformation processes, which indicated a lower coefficient of friction compared to the case of no lubrication. Consequently, the surface roughness of compressed ring and the seizure between tool and ring could be improved.

N-ion implantation assisted by preparative and closing implantation for surface modification of tool steel

The study aims at investigating the effect of auxiliary preparative and closing implantations in hardened tool steels on surface tribology modification. Samples of a martensitic tool steel, SKD11, are triply implanted with ions of N or Ar at higher energies, N at the normal energy, and N, BF and CO 2 at lower energies. The ion implantations result in dramatic increases of hardness and wear resistance to the samples in comparison with single N-ion implantation and double ion implantation. Analysis of ion depth profiles and surface compositions and microstructures is performed to reveal the mechanisms. It can be concluded that the improvement of the mechanical properties can be attributed to the deepening in the ion penetration and the forming of compound covers at the near surface region.