High Carbon Tool Steel Research Articles

The Influence of Stress Ratio on Changes in Magnetic Flux Density around Fatigue Crack Tips of Carbon Tool Steel

Fatigue failure of steel occurs when cracks form in a component and continue to grow to a size large enough to cause fracture. In order to understand the strength of a steel component, it is important to locate these cracks. We developed a scanning Hall probe microscope (SHPM), equipped with GaAs film sensors to observe fatigue cracks at room temperature in air while they were growing. In our previous works [1,2], the correlation between crack growth and magnetic field in high carbon tool steels (JIS SKS93 and JIS SUJ2) were determined. We also reported the sensitivity of the SHPM equipped with a three-dimensional line-probe that was developed to decrease the sensor gaps. By using the line-probe sensor we succeeded to measure the magnetic flux density distributions in very close proximity to the specimen’s surface. However, in order to further understand the relation between magnetic flux density and crack growth, other materials, microstructures and fatigue test conditions should be evaluated. In the present work, we focus on the effect of stress ratios on the changes of the magnetic flux density in annealed carbon tool steel.

The Observation of Changes in the Magnetic Field due to the Crack Initiation under Different Stress Ratio Conditions

Fatigue failure of steel occurs when cracks form in a component and continue to grow to a size large enough to cause fracture. In order to understand the strength of a steel component, it is important to locate these cracks. We developed a scanning Hall probe microscope (SHPM) equipped with GaAs films sensors and observed fatigue cracks at room temperature in air while they were growing. In our previous works, we determined the correlation between crack growth and magnetic field in high carbon tool steels (JIS SKS93 and JIS SUJ2). We also reported the sensitivity of the SHPM equipped with a three-dimensional line-probe that was developed to decrease the sensor gaps. By using the line-probe sensor we succeeded to measure the magnetic flux density distributions in very close proximity to the specimen’s surface. However, in order to further understand the relation between magnetic flux density and crack growth, other materials, microstructures and fatigue test conditions should be evaluated. In the present work, we focus on the effect of stress ratios on the changes of the magnetic flux density in annealed carbon tool steel.

The Mössbauer Spectroscopy and X-Ray Diffraction Studies of Phase Transformation during Tempering in High-Carbon Tool Steel

This work presents the results of investigations using Mössbauer spectroscopy technique and XRD, and their interpretation concerning precipitations and transformation of iron carbides and retained austenite stabilization. It also discusses changes in hardened matrix during tempering in relation to previously conducted dilatometric, microscopic and mechanical examinations. This research was carried out using a new high-carbon alloy 120MnCrMoV8-6-4-2 steel, which was designed in 1998, in Phase Transformations Research Group at the AGH UST. The influence of the tempering time on the mechanical and chemical stability of retained austenite and on the products of its transformation, nucleation and solubility of iron carbides and cementite nucleation and growth, was determined.

Structural transformations of amorphous iron-based alloys upon abrasive and thermal treatments

Wear resistance and structural changes have been investigated in amorphous alloys Fe64Co30Si3B3 and Fe73.5Nb3Cu1Si13.5B9 upon wear using a fixed abrasive. The structural studies have been performed by the methods of metallography, electron microscopy, and Mossbauer spectroscopy. It has been shown that the abrasive resistance of amorphous alloys is 1.6–3.1 times lower than that of high-carbon tool steels, which have a close level of hardness. The low abrasive wear resistance of amorphous alloys is caused by the deformation softening of the alloy surface in the process of wear. The major volume of the deformed surface layer of the alloys preserves the amorphous state. Its structural changes upon wear are characterized by the formation of inhomogeneities (fragments with a size of 10–50 nm) and by a decrease in the width of the strongest “halo” in the selected-area electron-diffractions patterns. In the amorphous matrix of the Fe64Co30Si3B3 alloy, a strong magnetic texture is formed and a redistribution of atoms occurs, which leads to an increase in the local shortrange order corresponding to FeB, Fe2B, Fe3B and α-Fe phases. In microvolumes of a thin (several μm) surface layer, the formation of a nanocrystalline structure (on the order of several volume %) was revealed. A tempering of the Fe73.5Cu1Nb3S13.5B9 alloy at temperatures below 500°C does not affect the hardness and wear resistance of the alloy. At 500°C, there occurs an increase in microhardness and wear resistance of the Fe73.5Cu1Nb3S13.5B9 alloy as a result of the formation in it of a nanocrystalline structure with the retention of a certain amount of the amorphous phase. The complete crystallization of the alloy at 540°C increases the brittleness of the alloy, which leads to a sharp reduction in its wear resistance.

Structural transformations in wear resistance of iron- and cobalt-based amorphous alloys during abrasive wear

The wear resistance and structural changes in a number of amorphous alloys based on iron and cobalt and in high-carbon tool steels are studied during wear by a fixed abrasive (crondum, Carborundum) at room temperature and −196°C. The abrasive wear resistance of the amorphous alloys is shown to be 1.6–3.1 lower than that of the high-carbon tool steels having a similar hardness. The relatively low level of the abrasive wear resistance of the amorphous alloys is assumed to be caused by strain softening of their surface during wear. A nanocrystalline structure is found to form in local microvolumes in a thin deformed surface layer of the alloys.

Studies on laser surface melting of tool steel — Part II: Mechanical properties of the surface

In the present study, the effect of laser surface melting using different proportions of argon and nitrogen as shrouding atmosphere on microhardness and wear resistance properties of a low alloy high carbon tool steel (SAE 52100 steel) has been undertaken. Laser surface melting in argon (Ar) atmosphere significantly refined the microstructure (grain size) with the presence of carbides (both iron and chromium) and martensites and improved microhardness (350–500 VHN) as compared to as-received SAE 52100 steel (280 VHN). Laser surface melting in 100% N 2 atmosphere led to formation of thin nitride (consisting of Fe 4N and Fe 2N and Cr 2N) layer with improved microhardness to as high as 1050 VHN. Wear studies showed a significant enhancement in wear resistance against hardened steel ball, a maximum improvement was achieved when lased using 100% N 2. The mechanism of wear was studied in details.

The Mössbauer spectroscopy studies of matrix changes during continuous heating from as-quenched state of high carbon tool steel

This work presents the results of investigations carried out using Mossbauer spectroscopy technique, and their interpretation concerning ferrite or martensite matrix and its changes during tempering. The changes in the matrix are brought about by the stress relaxation, retained austenite transformation, nucleation and solubility of e carbides as well as cementite nucleation and growth. This research was conducted on a new high-carbon alloy 120MnCrMoV8–6–4–2 steel, which was designed by the Phase Transformations Research Group, AGH UST, in 1998. Mossbauer spectroscopy was applied not only for magnetic hyperfine field studies, but also for analysis of the values of quadrupole splitting and isomeric shift, what resulted in significant conclusions concerning the changes in matrix chemical composition, microstructure, and the level of stresses being present in it.

Mössbauer spectroscopic investigation of retained-austenite content of high-carbon tool steel during isothermal tempering of as-quenched samples

This work presents the results of investigations using Mossbauer spectroscopy technique and their interpretation concerning retained austenite (RA) and its transformation during tempering in relation to previously conducted dilatometric, microscopic and mechanical investigations. This research was conducted on a new high-carbon alloy steel 120 MnCrMoV8-6-4-2, which was designed in 1998, in Phase Transformations Research Group at the AGH UST. The influence of the tempering time on the mechanical and chemical stability of retained austenite and on the products of its transformation, nucleation and solubility of e carbides and cementite nucleation and growth, was determined.

Influence of the carbon content on dislocation relaxation in martensitic steels

Mechanical-loss measurements were performed in three grades of martensitic high-carbon tool steels. These steels were treated under carburizing gas before quenching, in order to vary the concentration of interstitial carbon in the martensite, as assessed by thermoelectric-power measurements. The mechanical-loss spectra present a relaxation peak due to interaction between dislocations and carbon interstitials, similar to the Snoek–Köster peak found in ferrite. The amplitude of the Snoek–Köster peak is expected to be independent of the concentration of interstitials. However, the amplitude of the corresponding peak in martensite is found to increase with the concentration of interstitial carbon. This effect is attributed to an increase of the dislocation density with the carbon content.

Role of nickel undercoat and reduction-flame heating on the mechanical properties of Cr–C deposit electroplated from a trivalent chromium based bath

In this study, a surface hardening method for Cr–C deposits using flame heating for a short period is proposed. The hardness and wear resistance behavior of as-plated and flame-heated Cr–C deposits were investigated. The Cr–C deposits were electroplated on high carbon tool steel in a bath with trivalent chromium ions. Experimental results show that Cr–C deposits with an extremely high hardness of ca. 1700 Hv can be achieved after reduction-flame heating for 1 s. Meanwhile, the wear resistance of Cr–C deposited steel was improved after flame heating. To increase the wear resistance and bonding strength of the Cr–C deposited specimen, pre-electrodeposition of a thin Ni deposit between the Cr–C deposit and the steel substrate is recommended. A Ni undercoat with a thickness of few micrometers could reduce the crack density in the Cr–C deposit and increase the bonding strength between the Cr–C deposit and the steel substrate. As determined by a microstructure study, the as-plated Cr–C deposit has an amorphous structure, but transforms to a crystalline structure after flame heating. The main hardening mechanism is a result of the precipitation of nanograined diamond membranes, which can be extracted by immersing the flame-hardened Cr–C deposit in an etching solution comprised of 33 vol.% HNO 3 and 67 vol.% HCl.

Effect of partial heat treatment on the mechanical properties of high carbon tool steel used in manufacturing active parts in cold work tool steel dies

Effect of partial heat treatment on the mechanical properties of high carbon tool steel used in manufacturing active parts in cold work tool steel dies

The Mössbauer Spectroscopy Studies of ϵ to Cementite Carbides Transformation during Isothermal Heating from As-Quenched State οf High Carbon Tool Steel

This work presents results of investigations using the Mossbauer spectroscopy technique and their interpretation concerning transformation of 2 to cementite carbides during tempering in relation to the previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The influence of the tempering time on nucleation and solubility of 2 carbides, and on cementite nucleation and growth, was determined. The analysis of phase transformations during various periods of tempering using the Mossbauer spectroscopy technique made possible to reveal fine details connected with the processes.

Preparation of a needle probe with a sharp tip and high aspect ratio geometry by an electrochemical etching method

In this study, an electrochemical etching method was used to fabricate a fine needle probe with high aspect ratio. The needle probe was made of quenched and tempered high-carbon tool steel, SK 4. The needle electrode was preformed with turning machine, and then etched in the NH 4HF 2-based etchant. Owing to deactivation at the needle tip through surface adsorption of chemical species, the tip shape and contour of preformed needle can be maintained during anodic dissolution in the etchant. The anodic dissolution behavior of the needle probe can be realized with cyclic voltammetry test and Auger electron spectrometer analysis.

Wear resistant metal matrix composites with improved corrosion resistance and toughness: H.Berns. (Ruhr University, Bochum, Germany.)

Metal matrix composites (MMCs) have been prepared by melting in an argon arc two high carbon tool steels in the presence of particles of fused tungsten carbide. The microstructures were examined using scanning electron microscopy (SEM) and energy dispersive analysis (EDA). The corrosion characteristics were ascertained in both acidic and alkaline environments by potentiodynamic polarisation. SEM showed that the tungsten carbide collects mainly along the grain boundaries where it appears as dendritic-like deposits. The tungsten is present as iron tungsten carbide, Fe3W3C. The polarisation studies, in conjunction with SEM, showed that in acid environments the MMC is susceptible to general corrosion along the grain boundaries. However, in aerated alkaline corrodents containing aggressive chloride ions, spontaneous passivation will occur followed by pitting corrosion of the iron-rich grains.

A study of the effect of cobalt additions on thecorrosion of tungsten carbide⧸carbon steel metal matrixcomposites

Metal matrix composites (MMCs), similar to those generated in an industrialhard-facing process, have been prepared in the laboratory by melting high carbon tool steel in anargon arc with particles of fused tungsten carbide. Cobalt will improve shock resistance but itseffect on the corrosion of the MMC is unknown. MMCs with different cobalt concentrationswere therefore prepared and their microstructures examined before and after corrosion usingscanning electron microscopy (SEM). Energy dispersive X-ray spectrometry (EDX) was alsoemployed for chemical analysis and X-ray diffraction (XRD) for phase identification. Specimenswere examined after exposure to both aerated sulphuric acid and to aerated, alkaline sodiumchloride. The nature of the anodic and cathodic corrosion reactions was studied bypotentiodynamic polarisation. SEM showed that Co dissolves into the grains of the base steel andFe3W3C grain boundary deposits are formed as for the base MMC. Cobalt additions act to reducethe corrosion rate of the base MMC in acid. However, in alkaline chloride, and in contrast to thebehaviour of the base MMC, cobalt markedly diminishes the ability of the iron to form aprotective passive film.

The effect of chromium additions on the corrosion behaviour of tungsten carbide⧹carbon steel metal matrix composites

Metal matrix composites (MMCs) have been prepared by melting in an argon arc a high carbon tool steel with particles of fused tungsten carbide and metallic chromium. The microstructures were examined using scanning electron microscopy (SEM) and energy dispersive analysis (EDA) . The corrosion behaviour was established in both acidic and chloride containing alkaline environments by potentiodynamic polarisation. SEM showed that Cr migrates to the grain boundary region of the parent steel where it is present in discrete deposits, probably as an Fe⧹W⧹Cr carbide. The polarisation studies, in conjunction with SEM, show that, in an acidic corrodent, Cr additions will decrease the uniform corrosion of the base MMC. In aerated, alkaline environments, spontaneous passivation will occur to produce a very stable film. As with a Cr–steel, pitting corrosion will occur and the susceptibility to this appears to increase above a certain Cr level. This is possibly due to increased chromium carbide formation.

The matrix corrosion of tungsten carbide/carbon steel metal matrix composites

Metal matrix composites (MMCs) have been prepared by melting in an argon arc two high carbon tool steels in the presence of particles of fused tungsten carbide. The microstructures were examined using scanning electron microscopy (SEM) and energy dispersive analysis (EDA). The corrosion characteristics were ascertained in both acidic and alkaline environments by potentiodynamic polarisation. SEM showed that the tungsten carbide collects mainly along the grain boundaries where it appears as dendritic-like deposits. The tungsten is present as iron tungsten carbide, Fe 3W 3C. The polarisation studies, in conjunction with SEM, showed that in acid environments the MMC is susceptible to general corrosion along the grain boundaries. However, in aerated alkaline corrodents containing aggressive chloride ions, spontaneous passivation will occur followed by pitting corrosion of the iron-rich grains.

Nonmetallic inclusions in steel U10A wire

1. In wire of high-carbon tool steel U10A intended for manufacturing sewing machine needles nonmetallic inclusions of two types are observed: globular and drawn-out in shape. 2. The inclusions have a complex composition and they are not pure graphite. They contain a high amount of carbon.

SAE 1070

Abstract SAE 1070 is a high-carbon water or oil-hardening tool and spring steel of low hardenability. It is used for railroad and street railway rails, heavy machinery parts, shafts, springs and a wide variety of hand and machine tools requiring strength and wear resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: CS-121. Producer or source: Carbon steel mills.

UNS T30106

Abstract UNS No. T30106 is an air-hardening high-carbon tool steel designed for a combination of high strength, good wear resistance, and good toughness. It is easy to heat treat with a minimum of distortion and is used extensively for plastic molds. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength as well as fracture toughness and fatigue. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-489. Producer or source: Tool steel mills.