Effect Of Tempering Temperature Research Articles

Effect of austenitizing and tempering on impact resistance of a hot rolled high strength steel

The aim of this study is to investigate the effect of heat treatments on the impact properties of hot rolled high strength steel and describes the effect of tempering temperature and quenching media on the microstructure, hardness, and impact resistance of plates. In the present study a high strength steel was austenitized at 900 °C with different quenching medium and followed by tempering at 300 °C, 500 °C. After thermal treatments, the values of Charpy impact resistance, hardness, and microscopic structure were evaluated from mechanical and metallographic analysis of metals respectively. The change of mechanical properties and microstructure of the metal with the existence of heat treatment with the ballistic performance of high-strength steel. Experimental results showed that tempering at 500 °C for 2 hours after water quenching medium it provides the best mechanical properties in conjunct on with an improved in microstructure.

Effect of tempering temperature on the microstructure and creep resistance of a 10%Cr martensitic steel

The tempered martensite lath structure of a 10% Cr martensitic steel after normalizing and tempering at 750 °C was studied. The effect of reducing the tempering temperature from 770 by 20 °C on the microstructural parameters in steel was shown. Tempering at a lower temperature of 750 °C provides thinner laths and finer M23C6 particles (55 nm) than tempering at 770 °C. Such structural changes do not affect the creep rupture time at 650 °C and applied stresses of 180 and 160 MPa, whereas the positive effect occurs at 140 MPa, the time to rupture increases by more than two times from 1426 to 3909 hours.

Characteristics of hardness and microstructure of extraction forceps for dental and oral care made of stainless-steel

The reliability of medical devices such as extraction forceps is vital for dental and oral care. Apart from having hygienic properties, the extraction forceps must be strong and resistant to corrosion. This study evaluates the effects of tempering temperature on the hardness and microstructure of a medical device’s material made from stainless-steel DIN 4021. In the experiments, a heat treatment process was carried out previously with a temperature of 1,050°C and a holding time of 20 minutes. A quenching process was conducted using a cooling channel that flowed with water at 10-20°C. After the heat treatment, the material was subjected to a tempering process with temperature variations of 200, 400, and 600°C. The research results indicated that the heat treatment process could increase the material’s hardness —the hardness of the raw material changed from 20 to 48.67 HRC with the heat treatment. The tempering parameters resulted in the highest hardness of 46.67 HRC at 200°C and the lowest value of 42.33 HRC at 600°C. Microstructure testing using optical microscopy showed that it produced ferrite, pearlite, and martensite structures. In contrast, the result of a microstructure testing using Scanning Electron Microscopy on the surface of the material is that the higher the tempering temperature, the greater the microstructures’ dimension.

Elemental redistribution and precipitation reactions of 9Cr1.5Mo1CoB(FB2) steel during tempering

The effect of tempering temperature on the precipitation reactions and elemental redistribution in 9Cr1.5Mo1CoB(FB2) steel has been studied using scanning electron microscope(SEM), transmission electron microscope(TEM), secondary ion mass spectrometry(Tof-SIMS) and atom probe technique (APT). The results show that water-cooling from normalization at 1100 °C produced lathy martensite. During tempering at 500 °C, only C and B atoms were segregated, and formed needle-like Fe3(C, B); After tempering at 600 °C, the segregation of Cr, Mo and Mn showed noticeable difference, forming Cr + Mn + Mo + C + B and Mo + Cr + C + B clusters. Consequently, (Cr,Mo)2(C,B), Cr-rich M7(C,B)3 and Cr-rich M23(C,B)6 were observed in sample tempered at 600 °C. And both (Cr,Mo)2(C,B) and M7(C,B)3 particles were entirely replaced by Cr-rich M23(C,B)6 by enhancing the tempering temperature to 700 °C. Therefore, the evolution of carbides in FB2 steel during tempering at 500 °C–700 °C can be summarised as follows: Fe3(C,B) → (Cr,Mo)2(C,B) + Cr-rich M7(C,B)3 → Cr-rich M23(C,B)6. Besides, the Mo element in (V,Nb,Mo)(N,C) particles was gradually replaced by V and Nb with the increase of temperature from 600 °C to 700 °C. While Si and Co were rejected to the interfaces of carbides/matrix during tempering, forming a flux of Si and Co. Then, this flux may suppress carbides coarsening by retarding the diffusion of Cr, Mo and Mn from the matrix into carbides.

Crack Resistance Evaluation for 38KhN3MFA-Sh Structural Steel According to Fracture Characteristics and Elastic Wave Velocities

The results of studies on the effects of tempering temperature on the static strength and crack resistance of 38KhN3MFA-Sh steel are presented. The fractured surface texture has been studied after different heat treatment modes using electron fractography analysis. Relationships between the fracture characteristics and the critical stress intensity factor have been established. The effect of tempering temperature on the velocities of ultrasonic bulk waves has been investigated. A linear relationship between the velocity of elastic waves and the critical stress intensity factor of 38KhN3MFA-Sh steel has been found. The revealed relationship makes it possible to estimate the changes in crack resistance of steel using a nondestructive testing method with variations in the tempering temperature. The method of electron fractography has been used to analyze the fractures in the samples of structural high-quality 38KhN3MFA-Sh steel with a crack. The investigations of the fractured surface texture after different heat-treatment modes have shown that the microrelief is represented by flattened cone-shaped pits. The increase in the tempering temperature is accompanied by an increase in the diameter of flattened pit-cones on the fracture surface. A quadratic relationship between the crack resistance parameter and the diameter of the pits has been revealed. It has been shown that the contribution of the structural condition of the ferrite matrix to crack resistance is much more significant than the contribution of isolated carbides. The elastic wave velocities in steel have been measured; their values exhibit an increase with an increase in the tempering temperature. The strength and crack resistance parameters of the structural steel exposed to high-temperature tempering have been predicted on the basis of the values of transverse wave velocities. The deviations of the predicted values of crack resistance K1c and ultimate strength σu from the experimental values do not exceed 5.4 and 12.6%, respectively.

Effects of direct-quenching and tempering on the microstructure and mechanical properties of an ultra-low carbon Ti containing bainite steel

Ultra-low carbon Ti containing bainite steel was prepared by multipoint dispersion supplying Ti wire in the melt, followed by controlled rolling, relaxation, direct-quenching (DQ), and tempering at temperatures in the range of 450 °C–700 °C. The evolution of microstructures under various heat treatment were characterized using scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Tensile property and impact toughness test were conducted. Results showed the following: (i) nanoparticles form during solidifying, controlled rolling, and tempering; (ii) microstructure consisted of acicular ferrite (AF), retained austenite (RA), and lath bainite (LB) that was associated with a high density of dislocations was obtained by controlled rolling and DQ; (iii) an optimum balance between strength and toughness can be achieved in an ultra-low carbon Ti containing bainite steel via controlled rolling, relaxation, DQ, and tempering. Effects of tempering temperature on mechanical properties are discussed in terms of the recovery of bainite lath (BL), precipitation of nanoparticles, evolution of martensite-austenite (M-A) constituent, and variations in dislocation density.

Effect of tempering temperature on microstructure and properties of aluminium‐bearing high boron high speed steel

AbstractHeat treatment is of great significance to the performance improvement of high speed steel. Via heat treatment, the microstructure of high speed steel can be improved, thus greatly improving the material performance. The effect of tempering temperature on the microstructure of aluminium‐bearing high boron high speed steel (AB‐HSS) was investigated by optical microscope (OM), scanning electron microscope (SEM) and x‐ray diffraction (XRD). The hardness and wear resistance of the alloy at different tempering temperatures were tested by Rockwell hardness tester, micro‐hardness tester and wear tester. The experimental results indicate that the tempering microstructure of aluminium‐bearing high boron high speed steel consists of α‐Fe, M2B and a few of M23(C, B)6. Tempering temperature could greatly affect the wear resistance of materials. With the increase of tempering temperature, the wear resistance of aluminium‐bearing high boron high speed steel firstly increase and then decrease. The alloy tempered at 450 °C has the best wear resistance and minimum wear weight loss. This study provides a reference for the formulation of heat treatment process of aluminium‐bearing high boron high speed steel.

Research on the intermediate phase of 40CrMnSiB steel shell under different heat treatments

In this study, 40CrMnSiB steel cylindrical shells were tempered at 350, 500 and 600 °C to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A mid-explosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40CrMnSiB steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thickness and the number of the circumferential divisions. The results show that as the tempering temperature was increased from 350 to 600 °C, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.

Effect of quenching and tempering temperature on the tensile properties of low alloyed boron steel

Abstract The effect of quenching and tempering temperature on the tensile properties and the yield strength ratio of 30MnB5, 27MnCrB5, and 34MnB5 boron steel have been investigated. Quenching (Q) and tempering (T) temperatures varied in the range of 850 to 950 °C and 150 to 450 °C, respectively. The mechanical properties of quenched and tempered steel were examined with the application of the tensile test and hardness testing. The microstructure was characterized using optical microscopy and X-ray diffraction. The increase in Q & T temperatures resulted in a decrease in the ultimate tensile strength (UTS), yield strength (YS) and break strength (BS) values and an increase in the yield strength ratio. The tempering temperature was found to be more effective on the UTS, YS and BS values than was the austenitizing temperature. It was noted that the effect of tempering temperature is greater on the ultimate tensile than on the yield strength for the investigated low alloyed boron steel. The effect of the tempering temperature on the elongation to fracture is also greater than the effect on the uniform elongation. The yield strength ratio showed a tendency to increase with increasing tempering temperatures. It was raised considerably by increasing the tempering temperatures from 300 to 450 °C, while it remained at a similar level between 150 and 300 °C. The ratio of ultimate tensile strength and mean hardness decreased with increasing tempering temperatures for the tested varieties of steel. Increasing tempering temperature leads to an increase in yield strength ratio and a total elongation and a decrease in the strength of the tempered martensite.

In situ observation of high temperature microstructure and reverted austenite evolution in 13Cr supermartensitic stainless steel

In situ observation of high-temperature microstructure in 13Cr supermartensitic stainless steel was investigated by the high temperature laser scanning confocal microscopy (LSCM), and the effects of tempering temperature and tempering cooling rate on the morphology and contents of reverted austenite were characterized via transmission electron microscopy (TEM), x-ray diffraction (XRD) and electron backscattered diffraction (EBSD). The results indicate that only α phase appeared in the XRD diffraction pattern after quenching at 1050 °C, there was no retained austenite in the quenched microstructure. The martensite transformation starting temperature (Ms) was around 177.6 °C according to the results of LSCM. The amount of reverted austenite increased first and then decreased with the tempering temperature increasing, and it reached a maximum value when the sample tempered at 620 °C. With the cooling rate increasing, the amount of reverted austenite showed a sharp decrease after tempering at 620 °C. The reverted austenite precipitated on martensite laths, blocks and prior austenite grain boundaries, while the misorientation angles ranged from 0° to 60° in the tempered martensite structure.

The Effect of Tempering Temperature on Medium Carbon Steel Plate of Surface Hardening Result Using Induction Heating as Ballistic Resistant Material Study

Steel that has been heat treatment using quenching is hard but brittle. Tempering was done to remove the agility caused by the residual stress. The objective of this paper writing is to know and analyze the effect of tempering temperature on the mechanic property of steel plate of the surface hardening result. Steel plate with thickness of 8 mm of surface hardening result quenched by oil media was tempered at temperature of 100, 200, 300 and 400°C. Simulation based on finite element method was conducted to know the ballistic resistance. Experiment result showed that heating through induction and quenching on oil resulted in surface hardening. Tempering treatment decreased the hardness but at low temperature, the tensile strength increases. The simulation result showed that quenching and tempering material at temperature of 100°C was more able to resist the ballistic rate compared to other various temperatures.

Evaluation of crack resistance of 38KhN3MFA-Sh structural steel by fracture properties and elastic wave velocities

The results of the study on the effects of tempering temperature on 38KhN3MFA-Sh steel static strength and crack resistance are given. The fractured surface texture has been studied after various heat treatment modes using electron-fractography analysis. Relationships between the fracture properties and the critical stress intensity factor have been established. The effect of tempering temperature on the velocities of ultrasonic bulk waves has been investigated. A linear relationship has been found between the velocity of elastic waves and the critical stress intensity factor of 38KhN3MFA-Sh steel. The dependence discovered allows us to estimate the changes in crack resistance of steel using a non-destructive test method with variations in tempering temperature. The method of electron fractography has been used to analyze specimen fractures having a crack in structural high-quality 38KhN3MFA-Sh steel. Investigations of the fractured surface texture subjected to various heat treatment modes have shown that the microrelief is represented by flattened cone-shape pits. An increase in tempering temperature is accompanied by an increase in the diameter of flattened cone pits on the fractured surface. A quadratic dependence has been established between the crack resistance parameter and the diameter of the pits. It is shown that the contribution of ferrite matrix structural condition to crack resistance value is much more significant than the contribution of isolated carbides. The velocities of elastic waves in steel have been measured; their values increase with the growth of tempering temperature. The characteristics of strength and crack resistance of structural steel exposed to hightemperature tempering have been predicted based on the values of transverse wave velocities. Deviation of the predicted values of crack resistance K1С and ultimate strength σb from the experimental values does not exceed 5.4% and 12.6%, respectively.

Vpliv temperature popuščanja na potek izločanja in mehanske lastnosti jekla 34CrNiMo6

Vpliv temperature popuščanja na potek izločanja in mehanske lastnosti jekla 34CrNiMo6

Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends

Impact toughness of the weld metal is one of the important factors affecting the quality of hot bends, which is strongly dependent on the microstructure transformation during hot bending and tempering. In this study, three kinds of weld metals with different Ni contents were selected, and then the effects of tempering temperature on the microstructure impact toughness of weld metals for hot bends were investigated by simulation conducted on a Gleeble-3500 thermal simulator. The results show that the nonmetallic inclusion particles in weld metals can become the nuclear core of acicular ferrite like in as-welded metal. So, the overlapping acicular ferrite microstructure is obtained in the weld metal after direct cooling from the reheating temperature. During tempering, the overlapping acicular ferrite microstructure is degenerated, and martensite/austenite (M/A) constituents in the acicular ferrite microstructure decompose into ferrites and carbides. The resulting carbide particles mainly distribute along the acicular ferrite grain boundaries. With the increase of the tempering temperature, the carbide particles coarsen, which decreases the impact toughness of the weld metal of hot bends. Addition of Ni to weld metals can refine the acicular ferrite and improve the impact toughness.

Screening of heritage data for improving toughness of creep-resistant martensitic steels

Data science techniques were used to quantify the effect of alloying additions on the tensile behavior of martensitic steels. The effort was undertaken to exploit the heritage data to establish the next experimental design space for the class of 9–12 wt% Cr steels for the application of turbine rotors with an operating temperature of 650 ∘C and above. Linear, lasso, and multivariate multiple regression models were utilized to identify which alloying elements contribute towards strength and ductility. Visualization techniques such as t-distributed stochastic neighbor embedding and pair-wire element specific comparisons were utilized to explore information gaps that exist within the data. The study found that tantalum, recently added to improve the creep rupture lifetime, does not show any effect on tensile properties. All combined, the results suggest that the low tempering temperature has compensated for the low alloying additions in the past, therefore, new experiments are needed to isolate the effects of tempering temperature from those of individual elements.

Effect of Tempering Temperature on Impact Wear Behavior of 30Cr3Mo2WNi Hot-Working Die Steel

Effect of tempering temperature on impact wear morphology and properties of 30Cr3Mo2WNi hot working die steel were investigated by means of SEM, TEM, hardness and impact wear tests. In the tempering temperatures from 300℃ to 680℃, the hardness of the steel decreases and the impact toughness increases with increasing tempering temperature, while a secondary hardening with maximum hardness value of 48.6 HRC was achieved at 550℃. Fatigue delamination wear is the main mechanism during the impact wear of the experimental steel, and three damage features can be identified with different tempering temperatures. Brittle fatigue cracks are easy to occur at low tempered temperature of 300℃. Ductile fatigue cracks occurs at medium temperatures. Surfaces of steel tempered are extruded at high temperature of 680℃.

Effect of tempering temperature at high temperature zone on sulfide stress cracking behavior for casing steel

Three tempering temperatures at high temperature zone (690 °C, 700 °C and 710 °C) are selected into the quenching-and-tempering processes and performed on the rolled Cr-Mo steel to develop API-5CT-C110 casing steels. Effect of tempering temperature on sulfide stress cracking (SSC) behavior is quantitatively evaluated and further explored by characterizing the microstructure and crystallography. The results show that the strength of steel decreases with tempering temperature, but the SSC susceptibility is reversely varied. EBSD analysis indicates that the steel tempered at lower temperature (690 °C) generates more grains with high Taylor factors, which are difficult to yield, leading to the increasing of dislocation density and more susceptible to SSC.

Effects of tempering process on microstructure and mechanical properties of G18NiMoCr3-6

In this article the effects of tempering temperature and tempering time on microstructure and mechanical properties of G18NiMoCr3-6 cast steel were studied. The results show that: the microstructure of G18NiMoCr3-6 treated by different tempering processes is tempered sorbite. When tempering temperature is within 510°C ∼630°C, the hardness and strength gradually decrease; the elongation and impact energy gradually increase with the increasing of the tempering temperature. The reason is that the tempering temperature increases the dislocation density decreases gradually, the martensite decomposes and the carbide precipitates, aggregates and grows. When G18NiMoCr3-6 is tempered at 600 °C for 60min∼120min, the microstructure is tempered sorbite. With the prolongation of holding time, the mechanical properties of G18NiMoCr3-6 changed little.

Effects of tempering temperature on morphology of metastable austenite and mechanical properties of Mn-Ni steel

Effects of tempering temperature on morphology of metastable austenite and mechanical properties of Mn-Ni steel

Effects of Tempering Temperature on the Microstructure and Mechanical Properties of T92 Heat-Resistant Steel

T92 heat-resistant steel is among the most promising candidate materials for structural components in the Generation IV (GEN-IV) reactors. The effects of tempering temperature on the microstructure and mechanical properties of the T92 steel were studied. The microstructural evolution of the T92 steel subjected to various temperatures of the tempering process were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and synchrotron radiation X-ray diffraction (SR-XRD). The mechanical properties of Vickers hardness, tensile test, and impact test were also investigated. The results showed that the grain size of the prior austenite does not significantly change during the tempering process, while the width of the martensite lath and the size of the carbide precipitates increased with increasing tempering temperature. The hardness and yield strength of the T92 steel decreased, and the plasticity and impact energy increased with increasing tempering temperature. Coarsening of the carbide precipitates during the tempering process was considered to be the dominant factor that reduced the yield strength in the T92 steel.