Carbon Tool Steel Research Articles

Ballistic performance of flexible structures composed of UHMWPE fibers and airbag: Effects of the stacking order

A series of flexible structures incorporating an airbag and ultra-high molecular weight polyethylene (UHMWPE) fiber panels were designed as temporary architectures to offer both ballistic protective functions and lightweight constructions. Three primary structural configurations, monolithic structures (airbag or UHMWPE panel alone), bi-layer structures (airbag/ UHMWPE panel and UHMWPE panel/airbag), and sandwich structures (UHMWPE panel/airbag/ UHMWPE panel) were tested. A T12A carbon tool steel sphere with the diameter of 12.7 mm was utilized as the ballistic threat within an impact velocity range of 0–500 m/s. Investigations into the effect of stacking order on ballistic performance were carried out experimentally and numerically. The failure characteristics, ballistic limits, energy dissipations, impact processes and interaction effects of these structures are discussed. To facilitate the establishment of numerical models for impact analysis using ABAQUS, a material constitutive model of thermoplastic polyurethanes (TPU) including strain rate effect was developed. The numerical models of the monolithic single-sheet UHMWPE panel and airbag for impact analysis were subsequently verified by experiments in terms of impact processes and ballistic limits. The results reveal that arranging a few layers of UHMWPE panels in front of the airbag can improve the collapse ballistic limit while maintaining the failure ballistic limit. The inclusion of an airbag reduces the energy dissipation efficiency of composite structures. The potential to enhance ballistic protection through the combination of airbags and UHMWPE panels is highlighted. Stress dispersion and deformation restraint are identified as significant factors influencing the ballistic performance of the composite structures.

Tribological Properties of Carbon Tool Steel after Plasma Electrolytic Nitrocarburizing

The effect of plasma electrolytic nitrocarburizing on the wear resistance of carbon tool steel in friction couples with hardened steel and lead-tin bronze is considered in order to study the mechanism and type of wear, as well as the influence of structural and morphological characteristics of the surface on them. The microgeometry of friction tracks and its change with an increasing duration of friction tests are analyzed. The equilibrium roughness is determined, which is optimal for the friction couple and ensures minimal wear. The optimal values of the plasma electrolytic nitrocarburizing parameters, which provide the lowest values of the friction coefficient and wear rate, have been determined. The phase and elemental composition of the surface layer was studied using X-ray diffraction analysis and EDX analysis. The relationship of the microstructure of the nitrocarburized layer of tool steel with the friction coefficient and weight wear is established.

Structural Factors of Hardening of U8A Carbon Tool Steel under Cyclic Heat Exposure

Structural Factors of Hardening of U8A Carbon Tool Steel under Cyclic Heat Exposure

Development of thermocyclic processing modes for carbon steels used on cold forming tools

In this paper, the effect of thermocyclic processing regimes on carbon tool steels used in cold stamping tools is considered. Thermocyclic processing (TCP) is based on the idea of repeated heating-cooling of steels at a temperature different from conventional heating. In this case, the values of temperature at high and low levels, the heating-cooling rate can be constant. Unlike traditional methods, in thermocyclic processing, each successive cycle occurs with a new structure and phase change. This makes it possible to significantly increase the properties of steel that cannot be achieved with conventional heat treatment due to the combination of different properties that are formed after the final cycle of thermocycling.

Analysis of thin film electrochemical deposition process diffused by carbon tool steels

Chromium (Cr) hard coatings are frequently used for cold shaping and metal cutting in industries. This research work has been performed with the intention of investigating the feasibility of using complex chromium testimony used for phosphating and covering framing apparatus made from a carbon device prepared. Besides, it has been tried to determine the conveying limit of covered phosphate and chromium as well as to evaluate the wear mechanism. This work shows the improvement of wear resistance storing chromium hard covering on materials. Eight apparatus were made, engraved, solidified, tempered, chromed, phosphate, and assembled. The apparatus was installed in machines followed by recording the produced stroke numbers and conducting the tests in grease-free condition. The mechanical characteristics of hardware steel were increased solely by heating it. Instruments made of carbon device steel performed better in terms of erosion, wear, hostile-to-stay parts, and execution when hard chrome plating was used. The strong chromium plating with its excellent antiwear capabilities and high wear obstruction speaks to the optimal arrangement from the standpoint of hardware steel, as well as from the perspective of workpiece surface quality.

The macrosegregation behaviour of Fe-C-Cr-Mo type steel in laboratory scale model ingot.

In ingot casting, it is important to predict and control segregation and casting defects that occur during the solidification process, because they have a significant effect on the quality of the steel ingot. In some special steels, in typical Fe-C-Cr-Mo type high carbon tool steels, macro-segregation tends to be more pronounced due to their wide solid-liquid coexistence temperature range and molten steel properties such as relatively higher liquid viscosity than basic carbon steels. In order to investigate segregation and defect formation phenomena during solidification, many experiments have been conducted using specially designed laboratory scale model ingots that can induce partial difference of solidification to cause macrosegregation phenomena. However, these kind of experimental approaches for special steels are less conducted and influence of alloy types on the macrosegregation behaviour is still not well understood. In this study, a model ingot which have a steel chill ring in the middle region of a mullite mold was prepared, then Fe-0.45C(mass%) carbon steel, Fe-1C-1.8Cr(mass%) bearing steel and Fe-1C-8Cr-2Mo(mass%) high carbon tool steel were cast into 30kg ingots and the macrosegregation behaviour was investigated.

Defect Formation in Aluminum-coated Steel by Heat Treatment

A carbon tool steel plate was coated with an aluminum foil with a thickness of 100 μm by explosive welding. This aluminum-coated steel was heat-treated in the temperature range of 973−1273 K for up to 3.6 ks in the atmosphere to form a Fe-Al alloy layer on the steel surface. The alloy layer was basically composed of Fe2Al5, two kinds of FeAl (Al-rich FeAl and Fe-rich FeAl), Fe3Al containing carbon (Fe3Al(C)) and ferrite stabilized by aluminum diffusion (α-Fe(Al)). FeAl2 was also detected together with Fe2Al5 at more than 1223 K. At 1273 K, island-shaped Fe3Al(C) was produced in α-Fe(Al), and the Fe-rich FeAl/α-Fe(Al) interface became indistinct. In addition, defects like a crack and a void were observed in the vicinity of Fe-rich FeAl. The purpose of the present study is to investigate the reason for the defect formation. Various heat treatments were conducted for the aluminum-coated steel, and it was found that a temperature-rising step was responsible for the defect formation. This consideration got support from the results of two-step heat treatment, which was a heating process at 1273 K immediately after holding for 600 s near the eutectoid temperature in the Fe-C binary system.

Study Leaf Spring for Punch in Press Tools

The development of technology in the material sector is currently very fast, it can be seen from the many uses of metal materials, especially in the mass production industry with certain specifications, such as stainless steel, high carbon steel, and tool steel. Home industries such as the manufacture of rings, pans, bottle caps, stove components and others often use these materials as materials to make tools called press tools. In this press tool, high carbon steel or tool steel is mostly used as a punch, but as the cost and difficulty of these materials make home industries suffer big losses for the manufacture of production tools. For this reason, through this study the authors conducted experiments in the laboratory on recycle leaf spring materials. The experiment was carried out in four stages of testing, namely composition test, tensile test, hardness test, and microstructure test. The composition of elements of the recycle leaf spring are 0.6627% Carbon (C), 0.7304% Manganese (Mn), 0.0240% Sulfur (S), 0.0257% Phosphorus (P). The tensile strength of recycle leaf springs is 1332.5 kg/mm2. The hardness is carried out with the Rockwell C hardness test, the result of the test is 52.5 HRC. There are elements of martensitic and austenite in the microstructure test. The results of the laboratory experiments were compared with the data in the literature, so this recycle leaf spring material could be used as a substitute for cutting blades in press tools.

Single-Track Laser Scanning as a Method for Evaluating Printability: The Effect of Substrate Heat Treatment on Melt Pool Geometry and Cracking in Medium Carbon Tool Steel

Nearly all commercially available alloys have been developed for manufacturing processes other than additive manufacturing. Most of those alloys are not suitable for laser powder bed fusion (L-PBF) processing due to the non-weldable nature of the alloys developed for casting, forging, and machining. Even some weldable alloys can be difficult to produce with L-PBF because the characteristics of L-PBF, such as highly concentrated heat input and the extremely high cooling rate, can lead to very high residual stresses and cracking. In order to speed up the development process of new alloys for additive manufacturing, a powder-free evaluation method was used to evaluate the materials processing window and susceptibility to cracking. Single tracks were scanned with an L-PBF machine onto H13 steel substrates. The substrate condition was varied, and its effect on melt pool geometry and cracking behavior was evaluated. The results clearly show that thermal history of the substrate influences its thermal conductivity, affecting melt pool volume. Melting point of the substrate was not found as significant factor as thermal conductivity on melt pool dimensions. Cracking type was noted to differ between substrates. If printability is assessed without powder, the substrate microstructure should be similar to rapidly solidified material. It is recognized that single-track tests are not adequate in terms of residual stress evaluation, but they can give valuable information about materials’ melting, segregation, and micro-scale cracking behavior.

Friction stir processing as a method of hardening cutting tools

One of the most perspective methods of hardening is friction stir processing. The study shows processing methods based on the friction stir principle. The results of hardening of tool steels 1089 (Fe97%, C0.8%), 3343 (Fe80%, C0.9%, Cr4%, Mo5%, W6%, V2%), 440C (Fe78%, Cr18%, C0.95%) are presented. As a result of hardening, it was possible to increase the microhardness of carbon tool steel by more than 3 times, and also to achieve a decrease in the average grain size in the treated area by more than 10 times in relation to the base material. It is proposed to use the FSP in the manufacture of cutting tools from tool steels to increase physical and mechanical properties.

Influence of oblique geometry of cutting inserts of finishing face mills on cutting forces

The feasibility of using face milling for the final formation of the parts surface layer is confirmed by a large number of scientific works. At the same time, there are significant advantages of technological processes using face mills for oblique cutting, equipped with superhard materials, with a spiral-stepped arrangement of cutting inserts. This work is devoted to the study of the influence of the inclination angle of the oblique face mill cutting edge on the cutting forces when processing the workpiece flat surface made of gray cast iron and carbon tool steel using the Deform-3D program. The influence of the cutting edge inclination in the range from 0 to -45º on the smoothness of penetration of the face mill inserts into the workpiece is discussed.

Control of Metal/Polymer Adhesion Strength by Metal Surface Structure for Sustainable Society

The relationship between the shear strength of the metal-resin and the periodic structure of the metal surface was investigated. Femtosecond laser processing was applied to the Cr-plated carbon tool steel surface to form irregularities with a pitch of about 20 μm and a depth of about 10 μm, and a nano-scale fine periodic structure (so-called LIPSS) was formed on the top of the peaks. The epoxy resin was then placed in a mold and pressed by a heat press onto a metal plate. Then, the molded epoxy resin was pressed from the side with an indenter to measure the shear force, and the shear strength define as the maximum shear force. As a result, a positive correlation was observed between the shear strength and the opening valley angle of the micro-periodic structure, and a negative correlation was observed between the shear strength and the aspect ratio, which is the depth of the micro-periodic structure divided by the pitch.

INFLUENCE OF THE OVERLAP COEFFICIENT ON THE CONTRAST IN LASER MARKING OF C110W STEEL

The laser marking process by melting samples of C110W carbon tool steel was studied. The experiments were performed with a fiber laser and a CuBr laser. A field of squares is marked in a raster method for different values of the overlap coefficient and power density. The contrast of the marking is determined on each marked square. From the obtained experimental data, graphs of the dependence of the contrast on the overlap coefficient for three power densities were drawn. The obtained results for the two lasers are compared and the influence of the wavelength is indirectly analysed. The working intervals of the overlap coefficient for the studied power densities for the two lasers at which the optimal contrast in the processing zone is obtained are determined.

Phase Composition and Tribological Characteristics of the Surface Layers of Carbon Tool Steels after Laser Processing in Air

Phase Composition and Tribological Characteristics of the Surface Layers of Carbon Tool Steels after Laser Processing in Air

Influence of pulse duration on the process of laser marking of CT80 carbon tool steel products

Depending on the processing of a particular material, the laser marking process must meet certain requirements. A certain laser peak intensity or fluency must be reached on the treatment surface above which the laser ablation process starts. Some experimental studies have shown that this particular marking threshold is related to many other parameters characterizing the laser source. This requires the realization of an appropriate combination of peak power or pulse energy and the radius of the beam in focus, the frequency of the laser pulses as well as the pulse duration. Achieving high resolution in the marking process requires optimal focusing, and this in turn is associated with the presence of high quality generated and propagated laser radiation. The study concerns the process of laser marking of CT80 carbon tool steel products with wide application in industry. Numerical experiments are performed with specialized software TEMPERATURFELD3D to obtain two-dimensional and three-dimensional temperature fields in the laser impact zone. The influence of the duration of the pulses of fibre laser on the process is investigated. Graphs of the dependence of normalized temperature on time and depth for pulse duration on 10 ns, 100 ns and 1 μs are discussed.

Mechanical Properties of Xviii Century Persian Bulat Steel Compared with Modern Tool Steels

It is shown that the Persian Kurdistan bulat steel blades (end of the XVIII century) correspond with respect to chemical composition to contemporary high-carbon steel (1.48 and 1.67% C), with a high content of phosphorus impurity (0.192 and 0.236% P). However, contemporary industry carbon tool steels are not used with this carbon and phosphorus content. It is revealed that the main distinguishing feature of ancient bulat steels from modern tool steels is layered heterogeneity with respect to composition, structure, and hardness distribution. Layered carbide heterogeneity develops in the form of patterns after polishing and etching in 3% alcoholic nitric acid solution. It is found that the carbide layers located in a troostite matrix consist of oblong shaped cementite with a 1/3 ratio of axes. The microhardness of carbide layers is determined in the range of values from 820 to 1020 HV. In troostite layers the range of microhardness values is from 390 to 560 HV. The layered distribution of microhardness in the edge of a bulat blade is a micro-saw with teeth from 50 to 100 microns. Tests for cutting edge resistance on cutting felt in a unit with a reciprocating mechanism are carried out. It is revealed that with low cutting forces (up to 40 N) bulat steel withstands a greater number of cuts than carbon tool steel with a uniform structure. With an increase cutting edge force from 6 to 12 kg bulat steel type Ds15P demonstrated 30% fewer cuts than by carbon tool steel type Y15А. It has been established that within the layered structure of bulat steel fatigue crack propagation from the instant of its occurrence to complete destruction occurs in a greater number of cycles than in the homogen eous structure of carbon tool steel. Old blades of bulat steel type Ds15P according to fatigue life indices show twice as long life compared to modern carbon tool steel type Y15А. Loss of cutting capacity is compensated by an increase in blade “viability” with repeated fatigue loads. Thermal tests are conducted for the impact strength of genuine bulat steel type Ds17P. It is shown that in the temperature range from 0 to +40°C impact strength increases by a factor of four. It is established that chemical and structural layering of bulat steel minimizes the negative impact of phosphorus impurities, and impact energy at failure increases by 35%.

Study of the phase composition and tribological properties of carbon tool steels after laser surface hardening by quasi - CW fiber laser

The paper contains the investigation results on the structure and phase composition of the laser radiation area (LRA) of the U8 and U10 steels over its entire thickness. In the present study, the laser surface hardening of both U8 (ASTM - W1-7) and U10 (ASTM - W1-9) steels in the air was performed by exploiting a quasi - CW fiber laser with a 130 W power and 3 mm/s processing speed. The phase composition of the oxide layer formed as a result of laser treatment (LT) in air, as well as the structure of the oxide-metal interface on the surface of U8 (ASTM–W1-7) and U10 (ASTM–W1-9) carbon tool steels were studied by X-ray photoelectron spectroscopy (XPS). It was established that the thickness of the completely oxidized surface layers for U8 and U10 steels is 38.7 nm and 99 nm, respectively.The composition of the oxides of the steel surface after LT was determined. The presence of a wüstite-based film on U8 steel evidences the low wear properties of the LRA surface, while the thicker oxide layer of the modified U10 steel which contains Fe2O3 and Fe3O4 oxides with better strength properties, on the contrary, provides U10 steel surface with higher wear resistance. It was found that the wear rate of U10 steel modified surface decreases by more than two times, while the given value for U8 steel reduces no more than 17%. The paper reports the metallographic examination of the LRA structure. It was shown that the wear-resistant structural components that appeared after laser treatment lead to an increase in the deformation properties of steels. The maximum microhardness value of the LRA is 710 HV0.1 for U8 steel and 750 HV0.1for U10 steel.

Surface characteristics investigation of tool steel machined by powder metallurgy tool in EDA

Use of sintered tool electrodes for surface alloying by electrical discharge alloying (EDA) process has emerged as an alternating machining option with a view to improve surface properties. The present study identifies the appropriate process parameter settings to machine high carbon tool steel (En31) for higher surface finish using copper-manganese (Cu–Mn) powder metallurgy (PM) tool electrode. The effect of six different process parameters was evaluated using Taguchi’s experimental design and analysis of variance. The characterization of the surface alloyed with Mn and carbon was done by micro-hardness measurement, scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive x-ray spectrum (EDX) quantitative analysis and x-ray diffraction (XRD) technique. Also, the comparison was done with the surface machined using conventional Cu electrode. The surface machined with Cu-Mn PM tool electrode was found to be significantly alloyed with Mn and carbon having fewer micro-voids and no micro-cracks. Nano-size hillocks and valleys were found on the alloyed surface that is expected to improve the oil retention property of the surface. Presence of phases like Mn5C2 and Fe3C in the alloyed surface resulted in 95% and 33% higher microhardness than the base material and surface machined with conventional Cu electrode, respectively.

Machining of sub-cooled low carbon tool steel by wire-EDM

ABSTRACTAISI P20 tool steel is a low-carbon steel which is widely used in plastic-molds, die holders, bolsters, backers, shaft and rail making industries. It undergoes metallurgical and microstructural changes when conventionally heat treated with sub-cooling. As Wire-Electro Discharge Machine (WEDM) has become an integral part of finishing most products, this paper gives the influence of sub-cooling of workpiece on its machinability. It also presents the effects of discharge current (I), Pulse on time (Ton), flushing pressure (Fp), wire speed (Ws) and wire tension (Wt) on individual machining response. Sub-cooled metal (SCM) is having more cutting speed (CS) and material removal rate (MRR), and less kerf width (KW), surface roughness (SR) and micro-hardness as compared to parent metal (PM), as both the electrical and thermal conductivities increases with full annealing followed by sub-cooling of metal which affects the thermal diffusivity of metal. It is observed that the machined surface of the SCM is having more spherical globules and smaller melted deposits as compared to that of PM. This is due to the difference in thermal and electrical conductivities, and driving energy with respect to the presence of different phases at the surface.

Influence of the Distribution of Excess Carbide on the Properties of Genuine Damascus Steel

The methods of spectral, x-ray phase and microprobe analysis show that genuine Damascus steel is a high-purity unalloyed high-carbon steel with a high phosphorus content. It is shown that phosphorus in an amount of from 0.1% to 0.2%, having a high liquation coefficient, contributes to the process of segregation of carbon in interdendritic zone in the process of crystallization. Interdendritic zone formed carbon clusters, in the process of forging transform into oblong carbides cementite. The main physical and chemical factors affecting the formation of oblong carbides are revealed. The hardness of carbide layers was determined, which was about 920 HV. The hardness of the troostite matrix was amounted about 475 HV. It is established that the cutting edge of the blade knife of Damascus steel is nothing more than a “micro-saw” consisting of parallel carbide and troostite layers. Tests are conducted on the preservation of the cutting edge sharpness of the blades knife of homogeneous structure of steel У15А (Russian) and the layered structure of genuine Damascus steel Ds15P (Indo-Persian). Found that with little effort cut (to 4 kg) ancient Damascus steel (Ds15P) shows a greater number of cuts than the modern instrument steel У15А. With an increase, force on the cutting edge from 6 kg to 12 kg carbon Tool steel is showed a more number of cutting on the 25% than in genuine Damascus steel. The fatigue crack propagation in the true Layered structure of Damascus steel Ds15P occurs for a greater number of cycles than in a homogeneous structure of the steel У15А. The blade knife of genuine Damascus steel, in terms of fatigue reliability (survivability), has almost 2 times longer service life than the blade knife of the modern carbon tool steel type У15А. It is proved that loss in cutting ability of a genuine Damascus steel compensates increased the reliability (“survivability”) of the blade knife with fatigue loads.