High Speed Steel Research Articles

Evaluation of the effect of cryogenic treatment of HSS drills at different holding time in drilling AISI 316-SS

Cryogenic treatment has been acknowledged as an effective means of extending tool life of many cutting tool materials, thus improving productivity significantly. However, the real mechanisms which guarantee better tool performance have not been very clearly understood. This work aims to study the effect the effect of different holding time during cryogenic treatment on M2 high speed steel (HSS) drills. The performance of these cryo-treated tools were compared on the basis of thrust force, surface roughness, tool wear and chip formation by drilling on AISI 316 SS. The thrust force was least at 600 rpm and the rapid deep cryogenic treated (DCT) drills had much less thrust force (45%–55% lower) compared to untreated drills. From the various parameters involved it was observed that the cryo-treated tool bit at holding time of 24 h and at a cutting speed of 600 rpm and feed rate of 0.06 mm rev−1 showed better performance. The relative wear resistance of the cryo-treated drill at 24 h was at least two times better than the untreated drill while the surface roughness of the holes drilled with this drill was half that of those drilled with untreated drills. This investigation was further extended by gradual shallow cryogenic treatment (GSCT) and gradual deep cryogenic treatment (GDCT) of drills at the optimum holding time of 24 h. Both GSCT and GDCT treated drills showed 35% and 15% less thrust force respectively when compared to DCT. The better performance can be attributed to the lack of internal residual stresses. Microstructure SEM images and Rockwell hardness testing was done to support the findings.

Effect of deep and shallow cryogenic treatment on high speed steel grade M2 drilling tool

Every element in existence will have to undergo a manufacturing process. One of the more challenging processes would be material removal especially with respect to metal. Single point cutting tools and drill bits are observed to have a shorter lifespan due to early wear or breakage. Advancements in the field of tool manufacturing have shown drastic improvements with respect to tool life; these advancements have been done in the form of surface treatments but are known to be superficial, not showing any major improvements in tool life. Experimentation was done by means of treating the tool at shallow cooling temperature and deep cooling temperatures at varying timeframes. Deep treatment of the tool to −196 °C has shown to have a 92% increase in life when cryogenically treated with liquid nitrogen. The corroboration of the aforementioned statements can be verified by tests conducted showing a reduction of 11.2% in surface roughness in comparison with an untreated drill bit.

Characteristics of Diamond-Like Carbon Coating Using Plasma Assisted Chemical Vapor Deposition on Steel Tool

High Speed Steel (HSS) tool is commonly used in engineering applications, especially as cutters. The shortfall of this materials are wear and corrosion. However, these can be reduced by coating the surface of the material. Therefore, the purpose of this research is to investigate the effects of Diamond Like Carbon (DLC) coating, quenching heating treatment, and tempering on the physical and mechanical properties of HSS surface. The physical characteristics which will be investigated is the micro structure, while the mechanical characteristics are hardness, wear and corrosion rate. HSS has variations in their chemical composition (% mass): 0.75–1.5 C, Co >12, V > 5, 4–4.5 Cr,10–20 W and Mo. Furthermore, DLC coating uses Plasma Assisted Chemical Vapor Deposition (PACVD) technique with variation in the duration of coating (1,2,3,4,5 and 6 hours) at temperature of 300℃, with pressure variations of 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 millibar. DLC coating material be treated from methane or ethane gas, which is streamed into the fire with Argon (Ar). The result shows variations in DLC coating and the hardness grade depends on the coating time and pressure variation. DLC coating for a duration of 4 hours under 1.8 mbar pressure can reduce the surface hardness of HSS tool by 62% accompanied by increased ductility.

Numerical simulation of mold rotation and its effect on carbides in HSS ESR ingot

High-speed steel contains a large amount of carbides, the shape and distribution of which have an important influence on its quality. To improve the distribution of carbides in M high-speed steel, the temperature field and the shape of the metal pool during the mold-rotation process were investigated in detail using a numerical simulation. Moreover, the effect of the mold-rotation speed on the electroslag remelting process was investigated using a rotating bifilar electroslag remelting furnace under laboratory conditions. The morphology and distribution of carbides in an ESR ingot were observed using an SEM, and the composition of carbides was analyzed through an electrolytic extraction experiment. Results show that with increase in mold rotation speed, the high-temperature zone of the slag pool moves from the core to the edge. Moreover, the temperature distribution becomes uniform. The depth of the metal pool becomes shallow, and the thickness of the two-phase region decreases, which results in a short local solidification time and small secondary dendrite spacing. Correspondingly, with the increase in the mold rotation speed, the slag skin of ESR ingot becomes thin and more uniform than earlier. The cooling intensity of the mold on the ESR ingot is high, and the carbide network begins to break and become thin. The morphology of carbides changes from flake to fine rod. XRD analysis determines whether the mold rotates or not, carbides always comprise M2C, MC, and M6C. However, the content of M2C increases and the contents of MC and M6C decrease with the increase in mold-rotation speed.The main reason for the improvement in the carbide structure is that the mold rotation decreases the metal pool depth and two-phase zone thickness,which improves the solidification conditions and reduces the element segregation.

Development of a System to Control Flow of Coolant in Turning Operation

Automation of cooling system in machine tools is an effective method for achieving higher productivity and increased tool life. A cooling system is designed to control the operating temperature on the cutting tool tip by circulating coolant through a reservoir built on the top of the machine tool. This arrangement maintains the coolant flow rate as per variation of cutting tool tip temperature sensed by LM-35 temperature sensor which is located 1 cm away (calibrated distance) from the cutting tool tip and whose output voltage is linearly proportional to the temperature. Coolant flow rate is varied in such a manner that the temperature of the cutting tool tip remains within fixed value of temperature. The aim of present work is to develop a cooling control panel system to provide coolant on cutting tool tip in turning operation of mild steel. The coolant flow rate can be increased or decreased as per the variation of sensor temperature during turning of mild steel with high speed steel (HSS) cutting tool at different depth of cut, and spindle speed ,keeping feed rate constant which results in effective cooling of the cutting tool tip. The experiments were carried out with and without use of coolant. It supplies the coolant as per instructions of cooling control panel system which results in saving of coolant as well as power. The mechatronics application of designed cooling control panel system enabled the reduction in cutting tool tip temperature in more robust way as compare to conventional cooling system.

Effect of the inert/reactive gases ratio and bias voltage on the tribological properties of VN coatings

Vanadium nitride (VN) thin films were deposited on 304L high-speed stainless steel (HSS) specimens using a DC reactive magnetron sputtering system. The experiments were carried out with a varying ratio of reactive/inert gases of 1.7, 2.3 and 3 and a negative substrate bias of –30 V, –40 V and –50 V. Grazing incidence X-ray diffraction was used to characterize the structure of the layers produced. The coatings’ roughness and tribological behavior was evaluated.

Microstructure and Mechanical Properties of 3-Wire Electroslag Welded (ESW) High-Speed Pearlitic Rail Steel Joint

The present paper aims at utilizing the 3-wire electroslag welding (ESW) to join high-speed pearlitic rail steels where microstructure and mechanical properties were investigated. The welded joint has produced an improved fracture force of 1396KN. WM was consisted of ferrite and pearlite having hardness of 27HRC, tensile strength of 748MPa and toughness of 12J, successively. HAZ was composed of pro-eutectoid ferrite and pearlite, where austenite grain size and pearlite colony size were reduced by moving away from the fusion line. In HAZ, near to the fusion line, the austenite grain size was 143±19μm, pearlite colony size was 52±9μm and pearlite interlamellar spacing was 90±27nm, which has produced hardness of 43.5HRC, tensile strength of 1228MPa, and toughness of 8J, successively. The entire investigation concludes that 3-wire ESW is an optimum and viable method, which has provided fine pearlite microstructure along with improved hardness and tensile strength.

Mechanical properties dependence on the modulation period in multilayered TiN/ZrN coatings

This article presents results from a study on the properties of nanostructured multilayered TiN/ZrN coatings with different modulation periods deposited by cathodic-arc evaporation from Ti and Zr targets in nitrogen atmosphere on high-speed steel substrates. The thickness of the TiN-ZrN bilayers varied from 12 nm to 52 nm depending on the rotation speed of the holder. In order to investigate the effect of heat treatment on the mechanical and structural properties, the multilayer ZrN/TiN coatings were annealed in Ar atmosphere at different temperatures for two hours. The surface morphology, elemental composition, nano-hardness and adhesion strength of the as-deposited and annealed coatings were analyzed by scanning electron microscopy complemented with energy dispersive X-ray spectroscopy analysis, and nanoindentation and micro-scratch tests. The results obtained show that the mechanical properties of multilayer TiN/ZrN coatings are considerably improved in comparison to those of the monolayer ZrN and TiN coatings.

Hardfacing of metal-cutting tools by arc welding in vacuum

Purpose: To present a technology for hardfacing of metal-cutting tools by arc welding in vacuum. Design/methodology/approach: The experiments were carried out using an installation for arc welding in vacuum. Objects of research were metal cutting tools (lathe knives), made of high-speed steel HS6-5-2 on a base metal of structural steel C45. The structure, hardness and wear resistance after hardfacing and after a triple tempering at 560°C have been determined. The heat resistance of the obtained instruments has been examined. Findings: The microstructural analysis showed that the structure of the built-up layer consisted of martensite, retained austenite and carbides. This was confirmed by the values of measured hardness after welding which were about 63-64 HRC. The triple tempering led to an increase in hardness by 3-4 HRC. It was found that the built-up layers (cutting edges of tools) retain their hardness (HRC=63-65) up to a temperature of 615-620°C, which shows that the heat resistance of the build-up layers was similar to that of the hardened and tempered tools of the same steel. The built-up work-pieces (excluding heat treated) and the reference knife showed the same cutting qualities at cutting speeds in the range of 55 to 120 m/min. It has been found that triple tempering after hardfacing led to increased wear resistance and consequently the durability of the tool also increased due to the higher hardness. Practical implications: The practical application is related to the production of metalcutting tools. Originality/value: The proposed technological method allows to produce defects free built-up layers. The cutting properties of the built-up in vacuum layers are comparable to or better than those of new tools made of steel HS 6-5-2.

Lowering the Temperature in Grinding High-Speed Steel

The temperature variation in grinding high-speed steel by means of Elbor (cubic boron nitride) wheels is considered, in conditions with and without solid lubricant. Experimental and practical values of the grinding temperature are compared. The effectiveness of the proposed solid lubricant is demonstrated.

EFFECTS OF DIFFERENT CRYOGENIC TREATMENTS ON DRILLING PERFORMANCE OF HSS DRILLS

Cryogenic processing is a heat treatment which has been widely used in recent years to improve the properties of tool materials. This process has been reported in the literature as it provides significant contributions to wear resistance and tool life of tool steels. This study presents the differences in tool performance between untreated and cryogenically treated M2 high speed steel (HSS) drill bits in terms of their tool wear, tool life, hardness and chip formation properties. Also, the effects of two different tempering temperatures (200 oC and 250 oC) in cryogenic treatment on tool performance are discussed. Drilling performances were studied on different workpieces of SAE 1050, lamellar cast iron and sphero cast iron, and the type of wear is characterized by a high resolution camera. Moreover, fracture tests were performed on a steel workpiece using a constant drilling speed of 1100 m/min and a feed rate of 0.5mm/rev. The microstructures of the samples were characterized using optical microscopy and SEM. The Vickers micro-hardness tests of the samples were performed using 100 g load. Microstructural studies showed that cryogenically treated samples exhibit better microstructure with finer and more homogeneous carbides which yields better tool wear and hardness properties. In paralel, cryogenically treated drills showed improved tool life than untreated drills during fracture tests. When tempering temperatures are compared, tempering at 250 °C resulted in better performance than 200 °C of tempering temperature. Also, the reduction in diameter values during drilling tests were consistent with the tool life tests.

Development of the Chromium-Rich High-Speed Steel: As-Cast Microstructure

The present study has been undertaken to replace W by Cr in as-cast HSSs using B as alloying element. For this reason, a special alloying system was suggested. The basic steel containing approximately 12 wt. % of Cr was alloyed with B, V, V and Mo in different proportions. The microstructure of the steels was studied using electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. It was shown that the matrix structure, as well as the origin and morphology of the carbides or carboborides formed during solidification greatly depended on the alloy chemical composition.

EFFECTS OF NEEM, STRAIGHT AND SOLUBLE OILS AS CUTTING FLUIDS ON TOOL WEARING DURING METALWORK PRACTICALS IN TECHNICAL COLLEGES IN KANO STATE, NIGERIA

The study investigated the effects cutting fluids on tool wearing on high speed steel (HSS) using mild steel workpiece for teaching machining operation. Two specific objectives guided the study, two corresponding research questions were poised and two null hypotheses were formulated. The theoretical frame work for the study was hinged on experiential learning theory as propounded by Rogers (1969). The growing demand for biodegradable materials has opened an avenue for using vegetable oils such as neem seed oil, castor oil and water melon seed oil as an alternative to conventional cutting fluids. In this study, some aspects of the turning process on mild steel using HSS cutting tool at variety of spindle speed, feed rate and constant depth of cut were observed using neem seed oil, soluble oil and straight oil in comparison. The data collected from the study was analyzed using mean and analysis of variance (ANOVA). The decision rule was that, the smaller the mean value obtained the more effective the cutting fluid and the higher the mean value, the less effective the cutting fluid. The hypotheses were tested at α=0.05 significance level using analysis of variance (ANOVA). The findings of the study revealed that soluble oil is more effective in reducing tool wearing than neem oil and straight oil at variety of feed rates and spindle speeds during machining operation. Also there is no significant difference in the mean readings of tool wearing when using neem oil, soluble oil, and straight oil as cutting fluid. It was therefore recommended that machinists should be encouraged to use soluble oil which has greater advantage over neem and straight oils in machining operations

Recent Advances on Coated Milling Tool Technology—A Comprehensive Review

The milling process is one of the most used processes in the manufacturing industry. Milling, as a process, as evolved, with new machines and methods being employed, in order to obtain the best results consistently. Milling tools have also seen quite an evolution, from the uncoated high-speed steel tool, to the now vastly used, coated tools. Information on the use of these coated tools in recent scientific researches was collected. The coatings that are currently being researched are going to be presented, highlighting some novel advances in the nanocomposite and diamond coatings area, as these coatings are seeing a growing use in the industry, with very satisfactory results, with performance and tool-life increase. Wear mechanism of various types of coatings are also a popular topic on recent research, as the cutting behavior of these coated tools provides valuable information on the tool’s-life. Furthermore, analysis of these mechanisms enables for the selection of the best coating type for the correct application. Recently, the employment of coated tools paired with sustainable lubrication methods as seen some use. As this presents the opportunity to enhance the coated tool’s and the process’s performance, obtaining better results, in terms of better tool-life and better surface finish quality, in a more sustainable fashion.

Modelling Surface Roughness in the Function of Torque When Drilling

Given the application of a multiple regression and artificial neural networks (ANNs), this paper describes development of models for predicting surface roughness, linking an arithmetic mean deviation of a surface roughness to a torque as an input variable, in the process of drilling enhancement steel EN 42CrMo4, thermally treated to the hardness level of 28 HRC, using cruciform blade twist drills made of high speed steel with hardness level of 64–68 HRC. The model was developed using process parameters (nominal diameters of twist drills, speed, feed, and angle of installation of work pieces) as input variables varied at three levels by Taguchi design of experiment and measured experimental data for a torque and arithmetic mean deviation of a surface roughness for different values of flank wear of twist drills. The comparative analysis of the models results and the experimental data, acquired for the inputs at the moment when a wear span reaches a limit value corresponding to a moment of the drills blunting, demonstrates that the neural network model gives better results than the results obtained in the application of multiple linear and nonlinear regression models.

Investigation of the Effect of the Plasma Thin-Film Coating System Si−O−C−N on the Surface Hardening of High-Speed Steel

The results of studying changes in the strength properties of the surface of a tool product from high-speed steel (HSS) of the W6Mo5Cr4V2 type after its hardening by the application of the Si−O−C−N micron plasma coating system are presented. The study is conducted by comparing the properties of the surface, evaluated by the same methods before and after coating. In this case, the sample goes through a complete cycle of mechanical and heat treatment designed for the product before coating. The results of evaluation of the adhesive strength of the coating using the proposed method of recalculation are given, and the correspondence between the index of destruction of the coating of the VDI 3198: 1992-08 technique and the delamination coefficient is obtained. The study itself is carried out by indenting and scratching the surface with HV, HRC and HRB-type indenters in the load variation range of 0.1–200 N, which makes it possible to simulate different levels of contact pressure in the surface layer of the substrate and at the base–coating interface. It is shown that the application of a thin-film coating of the Si−O−C−N system by the plasma method makes it possible, in addition to standard heat treatment of HSS steel, to increase the surface resistance to penetration and scratching with harder bodies. The causes of the obtained positive effect are analyzed and the limits of the expediency of applying plasma hardening depending on the contact task are described. These results make it possible to consider the method of the additional plasma hardening of HSS steel as promising for implementation.

The Wear Features of a Plasma Thin-Film Coating on High-Speed Steel

The Wear Features of a Plasma Thin-Film Coating on High-Speed Steel

Improvement of Magnetic-Abrasive Finishing of Nonuniform Products Made of High-Speed Steel in Digital Conditions

The paper considers the implementation of magnetic-abrasive finishing in the conditions of digital technologies, in particular within CNC systems. The process was implemented through the development of a special device for MAF based on vertical processing center with CNC – Emco Concept Mill 250 and the definition of the combination of working motions of a billet in the interpole space of a magnetic system and their speeds. The result of the study are optimal combinations of working motions and their speeds taking into account formed surface roughness and processing efficiency.

Secondary Hardness and Heat Resistance of High-Speed Steels

Secondary Hardness and Heat Resistance of High-Speed Steels

Fatigue behavior of two notched cutting tool materials – High speed steel and cemented carbide

Abstract Fatigue testing experiments and computer-simulations have been conducted for notched specimens of two cutting-tool materials: high speed steel (M42 HSS) and cemented carbide composite (WC-10Co). The effects of varying loads and notches on the fatigue lives of M42 HSS and WC-10Co, including a comparative study of the fatigue behavior of the two cutting-tool materials, have been reported. The fatigue behavior of the two cutting-tool materials has been investigated by developing their S-N curves as well as through an examination of the fracture surfaces of the materials. A fatigue life of 107 cycles corresponding to a fatigue limit of 430 × 106 N × m−2 was determined for M42 HSS. It has been found that a reduction of stress amplitude by 60 × 106 N × m−2 results in an increase of fatigue life by around 175 percent for the notched specimens of cemented carbide. The computer simulation studies involved the use of ANSYS finite element analysis (FEA) as well as SolidWorks software packages. Both experimental and simulation results were found to be in agreement. These research findings might enable engineers to select a suitable cutting tool material with a notch for application under cyclic stressed machining.