High Speed Steel Research Articles

Tool wear and burr formation during drilling of aluminum alloy 7075 in dry and with cutting fluid

Aluminum alloy 7075 (Al 7075) has been widely used in aerospace and automotive industries to replace heavier alloys. This is because of its superior properties of high specific strength, high corrosion resistance, good formability, recyclability and low fabrication cost. However, the ductility and heat generation during drilling Al 7075 often produces a burr at the entrance and exit of the workpiece surface. This research investigates the effect of cutting speeds and drilling conditions on the burr formation of Al 7075. Drilling was performed in dry and with conventional cutting fluid using 6.0 mm high speed steel drills with cutting speeds of 22, 44 and 66 m/min at a constant feed rate of 0.15 mm/rev. The use of cutting fluid in drilling Al 7075 caused lower tool wear by 42%, 38% and 30%, respectively, at 22, 44 and 66 m/min, compared to dry drilling. As for burr formation, drilling with cutting fluid on average resulted in 20% lower burr root width and 10% lower burr height than dry drilling for all cutting speeds. This study indicated that drilling Al 7075 using the cutting speed of 44 m/min with cutting fluid is beneficial as it resulted in the least tool wear and minimum burr formation.

Austempering of PM HSS ASP2030 for improved fracture toughness

This study presents the fracture toughness improvement of the powder metallurgical high speed steel ASP2030 by replacing the martensitic matrix with a bainitic one. For this purpose, the fracture toughness of the steel is compared in both the austempered and marquenched states. The heat treatment of the samples was carried out by austenitizing in the range of 1150–1185 °C followed by either austempering at 235 °C or marquenching processes. Triple tempering at 560 °C for 2 h was also performed on all specimens. Fracture toughness measurements were performed on circumferentially notched tensile specimens. The microstructural features of the specimens were investigated using X-ray diffraction, optical and electron microscopy, and electron backscatter analysis. The results showed that the fracture toughness is sensitive to small changes in austenitizing temperature at both heat treatment conditions. By increasing the austenitizing temperature from 1150 to 1170 °C, the fracture toughness increases and then decreases with a further increase in temperature to 1185 °C. The results suggest that the changes in fracture toughness are due to the simultaneous effects of the volume fraction of undissolved carbides and the lattice microstrain values at different austenitizing temperatures. It can be concluded that the fracture toughness increases when the martensitic matrix is replaced by a bainitic structure. This improvement is related to finer bainitic laths width and also to the larger spacing between the particles of the undissolved carbides.

Numerical simulation and experimental study on production of high-speed steel powder by high-frequency induction melting gas atomization

A new method (electrode induction gas atomization, EIGA) of producing high-speed steel powder was preliminarily studied by a combination of numerical simulation and experiment. Based on COMSOL Multiphysics® software, the effect of various parameters including coil angle, output frequency and power of the electrical source on flux density, induced current, temperature field and phase field was simulated. Meanwhile, the experiment was carried out on the EIGA device to produce high-speed steel powder. The results of FEM simulation indicate that when the coil angle is 30°, there is the highest thermal efficiency on the electrode cone, and the induced current and temperature will increase as the output frequency and power of the electrical source increase. In addition, the powder experimentally obtained by the EIGA method exhibits good particle sphericity regardless of the size, with a median diameter (D50) of 71.4 μm and a low oxygen content of 81 μg/g. The phase composition of the powder is mainly composed of γ-Fe and α-Fe structures and MC-type carbides. Due to the faster cooling rate, a solidification microstructure consists of fine cellular crystals and dendrites, and no coarse eutectic carbide network is observed, also confirmed by EDX elemental mapping.

Induction of residual compressive stresses in the sub-surface by the adjustment of the micromilling process and the tool´s cutting edge

Additional to the conventional requirements for the component quality, the residual stress state of the sub-surface is becoming increasingly important as it affects the fatigue and wear behaviour of the component. First results indicate that micromilling allows the induction of high residual compressive stresses to increase the component's service life. Therefore, a specific design of the micromilling process with regard to the process parameters (feed per tooth and depth of cut), the use of cooling lubricant as well as the tool's cutting edge aimed for the controlled induction of residual compressive stresses in a hardened high-speed steel is presented.

Machining performance of protruded textured high-speed steel cutting tool under dry turning operation

AISI 316 L stainless steel is one of the difficult material to machine by traditional machining process due to its low thermal conductivity and high ductility properties which can cause high tool wear and high cutting forces. This can be addressed while using cutting fluid, however, cutting fluid causes severe environmental pollution while disposal. In recent studies, the usage of surface textures on cutting tools exhibited an improved machining performance without cutting fluids. The present work made an attempt to fabricate positive (protruded) surface textures on HSS cutting tool rake face and study its effect on the machining performance of AISI 316L stainless steel under dry machining. The surface textures are fabricated using the reverse-electro discharge machining process. In the present work, the effect of texture parameters such as texture density, texture height and diameter on the machining performance parameters like cutting forces, flank wear and machined surface quality of the machined workpiece are studied. The results indicated that a positive (protruded) surface textured cutting tool exhibits better machining performance as compared to the un-textured cutting tool. In addition, among the texture parameters, texture height has a significant effect on machining performance. Moreover, textured tool with a combination of 150 µm texture diameter, 5% texture density and 300 µm texture height shown better machining performance. It has also been observed that tool life is improved up to 110% as compared to un-textured tool.

Effect of Phase and Elemental Composition, Structure and Texture of Multilayer Coatings Based on Ticn and Tinbcn on Electrochemical Behavior of High-Speed Steel in 3% Nacl Solution

Effect of Phase and Elemental Composition, Structure and Texture of Multilayer Coatings Based on Ticn and Tinbcn on Electrochemical Behavior of High-Speed Steel in 3% Nacl Solution

Wear resistance of cutting tools in combination of ion mixing and duplex coating

The paper presents the results of a study of one of the ways to improve the wear resistance of “duplex” coatings applied to cutting tools, which are due to preliminary ion nitriding, involving nitrogen saturation of the tool surface by diffusion method with the possibility of physical deposition of the main wear-resistant coating — (Ti,Cr)N. In addition to the above, the investigated tool surface assumes the presence of a layer of impurity ions, which was deposited on the nitrided substrate prior to the application of the main coating. In this work, the following commonly used metals were applied as an intermediate, transitional layer as Ti, Zr, W and Al and the combination (combination) with non-metals N, C and O was provided. The “triplex” coating deposition was performed by implantation of the above ions, which allowed the creation of an additional hardened layer. To confirm and evaluate the increase in the wear resistance of the cutting tool made of high-speed steel with “triplex” coating a series of in-situ durability experiments during turning and tribotechnical tests were carried out. It was found that the greatest effect can be achieved using titanium implantation in the nitrided sublayer. This surface sublayer (with an ionic mixture) of the tool before and after cutting was examined by electron Auger Spectroscopy (EOS) and Secondary Ion Mass Spectrometry (SIMS). In tribotechnical tests, the adhesion component of the friction coefficient in a wide range of contact temperature changes was determined. In nano-indentation tests, an improved ability of the ion-mix layer to accumulate elastic strain energy was shown. Some researchers suggest that ion mixing leads to a surface film on the tool with an amorphous-like structure and a lubricating effect depending on the temperature-rate mode of cutting machining. The above-mentioned assumes the possibility of prolongation of the normal wear stage on the classical wear curve and, as a consequence, the wear resistance (durability period) of the cutting tool, which is connected with the phenomenon of adaptation of its near-surface layer during cutting.

An appraisal of the cradle-to-gate energy demand and carbon footprint of high-speed steel cutting tools

The awareness of the environmental impact of the manufacturing sector has increased over the last few decades. This paper presents the results of an LCA-based approach used to evaluate the production of a threading tool (i.e., an M10 × 1.25 spiral point tap) made of high-speed steel. The cumulative energy demand and CO2-equivalent emissions have been quantified throughout the entire tool manufacturing process. Both the pre-manufacturing steps and the upstream/downstream flows of the used material have been accounted for, considering cradle-to-gate (plus end-of-life) system boundaries. The results show that the share of primary energy employed to produce the tool is mainly imputable to the manufacturing processes. Therefore, this analysis could contribute to fostering the development of structured assessment frameworks that would allow cutting tool manufacturers to identify the weak points of their production routes to be optimized.

Exploratory investigation of chip formation and surface integrity in ultra-high-speed gear hobbing

Gear hobbing is widely employed to manufacture automotive gears, where the productivity depends on the cutting speed. Currently, gear hobbing is performed at ∼300 m/min using high-speed steel hob cutters. In this study, ultra-high-speed gear hobbing was attempted using a large-diameter cemented carbide hob cutter on a gear grinder. This enabled a cutting speed up to 2450 m/min. Many interesting phenomena were acquired in this speed range. Chips were severely oxidized, whereas the gear surface was not affected. Compressive residual stress was generated at the gear surfaces with low surface roughness and high hardness, while the wear of hob cutter was insignificant.

Анализ влияния режима резания и СОЖ на образование заусенцев при сверлении алюминиевого сплава

Aluminum alloy Ak5m is widely used in the aerospace and automotive industries to replace heavier alloys. This is due to its excellent properties of high specific strength, high corrosion resistance, good formability and low manufacturing cost. Ductility and heat generation during drilling AK5MCH often leads to the formation of burrs at the inlet and outlet from the surface of the workpiece. This study shows the effect of cutting speed and drilling conditions on the formation of burrs in the AK5MCH alloy. Drilling is carried out using coolant and without coolant using drills made of high-speed steel with a diameter of 6,0 mm with cutting speeds of 20, 42 and 60 m/min at a constant feed of 0,15 mm/rev. This study showes that drilling AK5MCH with a cutting speed of 42 m/min using a coolant is advantageous, as it leads to the least tool wear and minimal burr formation.

Thermal Investigation on Coated and Uncoated HSS Twist Drill using ANSYS Software

Abstract: In drilling, a cylindrical hole is produced in workpiece, removing the material inside the workpiece. The cutting tool used in drilling operation is called ‘Twist Drill’; it rotates and allows the material to be removed from the workpiece in the form of chips and thus drill the hole. Cutting fluids or coolants are used to perform this operation smoothly. The coating on the drill bits helps to reduce friction in the cut and the heat buildup in the drill bit. Coating also helps in protecting against corrosion. The present work focuses on the features of uncoated High Speed Steel (HSS) Twist Drill bit and Titanium Nitride (TiN) and Titanium Aluminium Nitride (TiAlN) coated on HSS Drills. The workpiece material was Mild Steel and the drilling operation was done using normal machining condition i.e. in presence of coolant. The cutting parameters used are cutting speed (35.5 m / min), spindle speed (1500 rpm), feed rate (0.2 mm / rev.), depth of cut (10 mm). These parameters were kept constant. Temperatures were measured with the help of thermal imaging camera and with the help of ANSYS software thermal analysis were done. Experimental results showed that the average rise in temperature of uncoated HSS tool was higher as compared to TiN coated and TiAlN coated HSS tools. TiAlN coated drills showed the least average rise in temperature. Keywords: High Speed Steel (HSS) Drill, TiN and TiAlN Coated HSS Twist Drill, Mild Steel (MS), Thermal Analysis, ANSYS Software.

Crevice corrosion of U75V high-speed rail steel with varying crevice gap size by in-situ monitoring

Crevice corrosion of high-speed rail steel U75V was studied with varying gap size by using self-designed device. Increasing gap size inhibited exterior cathodic reduction reaction of oxygen, inducing decrease of potential difference between interior and exterior. Gap size decrease after increase induced increase of potential difference after decrease, not completely reversible because rust kept expanding, acting as weaker depolarizer than oxygen. Anodic dissolution of interior was under ohmic-control, fastest near crevice mouth and slowest near but not at deepest site. Corrosion initiation was observed, closely related to pearlite nodules with larger interlamellar spacing and different lamellar directions, inducing deep attack.

Effect of niobium and austenitizing temperature on the microstructures and properties of spray-deposited AISI M3:2 high speed steel

The microstructure and properties of niobium-containing AISI M3:2 high speed steels (HSSs) fabricated by spray forming and traditional casting have been investigated. The results show that fine and uniformly-distributed grains without macrosegregation appeared in the as-deposited HSSs that differ from those of as-cast HSSs. Nb mostly appears in primary MC carbides, whereas it contributes less to the formation of M6C carbides. The high stabilization of Nb-rich MC carbides can pin the grain boundaries during high-temperature austenitizing process, thus conferring a fine grains and raising the content of dissolved alloying elements. Enhanced precipitation strengthening and fine dispersion of NbC carbides throughout the matrix contribute to the high hardness and red hardness of Nb-containing HSS.

Morphology tailoring of metal pool and eutectic carbides in magnetic-controlled electroslag remelted M2 high-speed steel

A transverse static magnetic field (TSMF) was superimposed during electroslag remelting (ESR) process to regulate the shape of metal pool, the eutectic carbides morphology as well as the mechanical properties of electroslag remelted M2 high-speed steel (HSS) in current study. The metal pool became shallower and flatter after applying a 65 mT TSMF. Moreover, refined eutectic carbides and solidification structure (tended to grow axial) of the ESR ingot were obtained, together with uniform/improved mechanical properties (hardness, wear). Modifications of the morphology of metal pool and grain growth angle under the TSMF were attributed to a periodic electromagnetic excitation effect on droplets transition characteristics, which changed the drop path of the droplets (single to multiple drop) and homogenized the temperature distribution in metal pool. In addition, local solidification time (LST) became shorter and the number of inclusions ((Ti, V)N–Al2O3 and (Ti, V)N) which acted as heterogeneous nuclei for eutectic carbides formation increased (the inclusions also became finer) due to TSMF, resulting in the refinement of the eutectic carbides in ESR ingots.

Sulfonitrocarburizing of High-Speed Steel Cutting Tools: Kinetics and Performances.

The scholarly literature records information related to the performance increase of the cutting tools covered by the superficial layers formed “in situ” when applying thermochemical processing. In this context, information is frequently reported on the carbamide role in processes aiming carbon and nitrogen surface saturation. Sulfur, together with these elements adsorbed and diffused in the cutting tools superficial layers, undoubtedly ensures an increase of their operating sustainability. The present paper discusses the process of sulfonitrocarburizing in pulverulent solid media of high-speed tools steel (AISI T1, HS18-0-1) and its consequences. The peculiarity of the considered process is that the source of nitrogen and carbon is mainly carbamide (CON2H4), which is found in solid powdery mixtures together with components that do not lead to cyan complex formation (non-toxic media), and the sulfur source is native sulfur. The kinetics of the sulfonitrocarburizing process, depending on the carbamide proportion in the powdered solid mixture and the processing temperature, was studied. The consequences of the achieved sulfonitrocarburized layers on the cutting tools’ performance are expressed by the maximum permissible cutting speed and the maximum cut length. An interesting aspect is highlighted, namely the possibility of using chemically active mixtures. Their components, by initiation of the metallothermic reduction reaction, become able to provide both elements of interest and the amount of heat needed for the ultrafast saturation of the targeted metal surfaces.

Investigation of microstructure and mechanical characteristic of underwater friction stir welding for Aluminum 6061 alloy – Silicon carbide (SiC) metal matrix composite

Demand for metal matrix composites (MMCs) is expected to increase in these applications, such as ‎in the aerospace and automotive sectors. Adequate joining techniques, which are important for ‎structural materials, have not yet been developed for Metal Matrix Composite (MMCs), however. ‎This work aimed to demonstrate the feasibility of ‎friction stir welding (FSW) and ‎underwater friction stir welding (UFSW) for joining Al 6061/5, Al 6061/10, and Al ‎‎6061/18 wt. %SiC composites have been produced by utilizing reinforce stir casting technique. Two ‎rotational ‎speeds,1000and 1800 rpm, and traverse speed 10mm \ min were examined. Specimen ‎composite plates 10 mm thick have been successfully welded by FSW. For FSW and UFSW, a tool ‎made of high-speed steel (HSS) with a conical pin shape was used. The result revealed that the ‎ultimate tensile strength of the welded joint by FSW and UFSW at rotation speed 1800 rpm for (Al ‎‎6061/18 wt. ‎‎% SiC composites) was 195 MPa and 230 MPa respectively. The ultimate ‎tensile ‎strength of the welded joint by FSW and UFSW (Al 6061/18 wt.% SiCe composites) was 165 MPa ‎and 180 MPa at rotation speed ‎‎1000 rpm respectively. The microstructural assessment showed that due ‎to larger grain sizes at FSW and UFSW, most of the fractures are located in the thermal ‎mechanically affected zone (TMAZ) adjacent to the weld nugget zone (WNZ). It is observed that in ‎failure, most of the joints show ductile features. As the volume fraction of SiC (18 wt.%) increases, ‎the friction stir welded and underwater friction stir welded efficiency decreases.

Effect of Deep Cryogenic Treatment on Wear and Galling Properties of High-Speed Steels.

New approaches to improving wear resistance with an affordable and noncomplex technology, such as deep cryogenic treatment, (DCT0), are receiving attention. The aim of this study is to investigate the effect of DCT on the friction and wear performance of high-speed steels. AISI M2, AISI M3:2 and AISI M35 were heat-treated under different conditions, and then investigated under dry sliding conditions. Tribological testing involved different contact conditions, prevailing wear mechanisms and loading conditions. The DCT effect on sliding wear resistance depends on HSS steel grade, as well as contact conditions and wear mode, whereas it improves the dynamic impact of the wear and galling resistance.

Effects of sintering temperature on interface microstructure and element diffusion of WC-Co-Ni-Fe/high-speed steel composites

In this study, the layered composites of the micro bit with WC-Co-Ni-Fe as outer material and high-speed steel (HSS) as inner material were prepared by self-designed mold in the laboratory. The effects of sintering temperature on microstructure, interfacial element diffusion and microhardness of WC-Co-Ni-Fe/HSS composites were studied. The results show that with the increase of sintering temperature, the number of micropores in WC-Co-Ni-Fe/HSS composites decreases, the mutual diffusion trend of Co, Ni, Cr and Mo at band area increases, and W element has no obvious diffusion in band area. When the sintering temperature is 1250 °C, a reaction layer with a certain width begins to form at the interface between the WC-Co-Ni-Fe and high-speed steel, and the two materials are metallurgical bonded. When the sintering temperature was 1310℃, micropores were observed at the interface.

Fatigue strength assessment of high-speed railway axle EA4T steel with foreign object damage

Axle is easy to be hit by ballast and other foreign object rolled up due to aerodynamic effect to form the typical foreign object damage (FOD) on the surface, leading to deteriorate the axle structural integrity and reduction of fatigue performance. In order to evaluate the effects of surface damage and strengthening treatment on the fatigue performance, the EA4T axle steel specimens with or without shot peening (SP) were induced FOD by a compressed-gas gun. Meanwhile, the strengthening mechanism of shot peening were investigated by both nanoindentation technique and X-ray diffraction. Then the probabilistic fatigue S-N curves (P-S-N) were acquired for unSPed and SPed specimens subjected to FOD or not. In addition, the fatigue limit of FODed axle estimated by Murakami equation was corrected by size effect, surface quality, loading mode factors. Finally, the fatigue limits with 97.5% reliability were adopted to construct the modified Kitagawa-Takahashi (K-T) diagrams for FODed axle with or without shot peening treatment, which can be used in the service performance evaluation of foreign object damaged axle.

The effect of temperature on the tribological characteristics of high speed steels under conditions of friction without lubricant on the structural steel 30HGSA

This article focuses on the study of the effect of temperature in the contact zone on the process of dissipative structures formation on the surfaces of specimens made of high speed steels (HSS) grades with different levels of thermal entropy and absolute thermo-EMF under conditions of friction without lubricant on the structural steel 30HGSA. Tribological tests were performed on the tribometer which implemented a scheme of friction “pin on disk” at constant sliding speed and normal load values. The temperature in the friction zone has changed artificially from 100 to 300°C with a special intelligent heating device. It has been established experimentally that in the process of friction of HSS specimens characterized by low values of absolute thermo-EMF the dissipative structures thickness growth rate over time at temperatures of 200-250oC decreases or remains virtually unchanged; friction coefficient decreases with the increase in temperature. For specimens made of steels with high absolute thermo-EMF the rates of dissipative structures thickness growth and their utmost thicknesses increase when the contact zone temperature increases, which is accompanied by an increase in friction coefficients.