Showing papers on "Austempering published in 2001"
30 Sep 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a low-manganese nodular cast iron with a predominantly pearlitic as-cast structure was processed by a novel two-step austempering process, and two batches of samples were prepared.
Abstract: Austempered ductile cast iron (ADI) has emerged as a major engineering material in recent years because of its excellent mechanical properties. These include high strength with good ductility, good wear resistance and fatigue strength. It is therefore considered as an economical substitute for wrought or forged steel in several structural applications especially in the automotive industry. In this investigation, a low-manganese nodular cast iron with a predominantly pearlitic as-cast structure was processed by a novel two-step austempering process. Two batches of samples were prepared. All the specimens were initially austenitized at 927°C (1700°F) for 2 h. The first batch of samples were processed by conventional single step austempering process at several temperatures such as 260°C (500°F), 273°C (525°F), 288°C (550°F), 316°C (600°F), 330°C (625°F), 343°C (650°F), 357°C (675°F), 371°C (700°F), 385°C (725°F) and 400°C (750°F) for 2 h, whereas the second batch of samples were processed by two-step austempering process. These samples were initially quenched to the following austempering temperatures, i.e. 260°C (500°F), 273°C (525°F) 288°C (550°F), 316°C (600°F), 330°C (625°F), 343°C (650°F), 357°C (675°F) and 371°C (700°F), and while being kept at these temperatures in a salt bath, the temperature of the salt bath was raised by 14°C (25°F) per hour for 2 h. The effect of this two-step austempering heat treatment on the microstructure and mechanical properties of the material was examined and compared with the samples processed by conventional single step austempering process. Test results show a significant improvement in mechanical properties and fracture toughness of the material as a result of the two-step austempering process.
198 citations
31 Jul 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a neural network model within a Bayesian framework has been created using published data to model the retained austenite content, which allows the quantity of retained Austenite to be estimated as a function of the chemical composition and heat treatment parameters.
Abstract: Many of the properties of austempered ductile iron depend on the austenite which is retained following the bainite reaction. A neural network model within a Bayesian framework has been created using published data to model the retained austenite content. The model allows the quantity of retained austenite to be estimated as a function of the chemical composition and heat treatment parameters. The computer programs associated with the work have been made freely available ( http //www.msm.cam.ac.uk/map/mapmain.html )
118 citations
TL;DR: In this paper, the effects of Mn, Si and Nb on the transformation behavior in 0.14C-(2.1∼2.4)Mn-(0.5∼1.0)Si(0.00∼0.02)Nb TRIP steels were studied.
Abstract: Tensile and dilatation tests were conducted in order to study the effects of Mn, Si and Nb on the transformation behavior in the 0.14C-(2.1∼2.4)Mn-(0.5∼1.0)Si-(0.00∼0.02)Nb TRIP steels. All the specimens for dilation tests were annealed under the condition to form the same austenite fraction, followed by cooling to the austempering temperature. The volume fraction of bainite transformed during austempering, ΔV B , and the martensite start temperature, M s , were measured. ΔV B was dependent on the austempering temperature and a minimum in ΔV B was obtained at 450°C for all the examined steels. The M s temperature was linearly decreased as ΔV B was increased. The decreasing rate of M s to ΔV B was not dependent on the steel composition, but on the austempering temperature, exhibiting the maximum value when the austempering temperature was 450°C. It was also observed that volume fraction of retained austenite was linearly increased with the decrease of M s for the steels austempered at various conditions. The highest elongation was obtained when the rate of M s to ΔV B was the maximum. M s was increased when the amount of Mn was increased from 2.1 % to 2.4 %. It was because Mn retarded the ferrite transformation rate, so that the soluble C diffused from the ferrite to the austenite was decreased. The addition of Si decreased M s because it activated the diffusion of C to austenite during the cooling to the austempering temperature. The addition of Nb was observed to give little influence on ΔV B and the M s .
54 citations
30 Jun 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the influence of austempering treatment on the microstructure and mechanical properties of silicon alloyed cast steel has been studied, and the experimental results show that an ausferrite structure consisting of bainitic ferrite and retained austenite can be obtained by austemming the high silicon cast steel in a large temperature range.
Abstract: The influence of austempering treatment on the microstructure and mechanical properties of silicon alloyed cast steel has been studied. The experimental results show that an ausferrite structure consisting of bainitic ferrite and retained austenite can be obtained by austempering the high silicon cast steel in a large temperature range (240–400°C). No carbide would precipitate in the structure. The experimental results also indicate that a full ausferrite structure could be obtained by austempering the steel with a silicon content around 2.64%. Lower silicon would result in the formation of martensite, and excessive silicon would cause proeutectoid ferrite in the structure. The full ausferrite structure has high strength, toughness and hardness. With the increasing of silicon content, the strength decreases, the hardness keeps unchanged and the toughness firstly increases to a maximum value and then decreases. The material has also excellent work hardening ability.
51 citations
TL;DR: In this paper, the effect of a two-step austempering process on the fracture toughness of ductile iron and compared it to that of the conventional upper and lower-ausferrite austempered ductile irons (ADIs).
Abstract: This research studied the effect of a two-step austempering process on the fracture toughness of ductile iron and compared it to that of the conventional upper- and lower-ausferrite austempered ductile irons (ADIs). The results showed that such a two-step austempering heat-treatment process yielded a fracture-toughness value equivalent to that of the upper-ausferrite ADI, while the hardness was maintained at the level of lower-ausferrite ADI. This provided a unique combination of high toughness with good hardness (strength) properties for the ADI with a two-step austempering. Optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction analysis were performed to correlate the properties attained to the microstructural features.
47 citations
01 Dec 2001-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: The microprocesses of crack initiation and propagation in an austempered ductile iron have been investigated by using an scanning electron microscope with a microtensile holder as mentioned in this paper.
Abstract: The microprocesses of crack initiation and propagation in an austempered ductile iron have been investigated by using an scanning electron microscope with a microtensile holder It was revealed that microcracks always initiated at, and propagated along, the graphite–matrix interface Microcracks in the matrix initiated after the interface cracking The graphite nodules in this cast iron could not be regarded as voids with no strength because internal fracture of the graphite was observed When the cracks propagated in the matrix, they often grew along the bainitic ferrite–austenite interface Crack deflection, shear ligament formation, and crack branching occurred during the connection of main cracks and microcracks, which contributed to the strength and toughness of the ADI
30 citations
TL;DR: In this paper, the influence of microstructure and fracture toughness of an alloyed cast steel containing high silicon (3.00%) and high manganese (2.00%).
Abstract: The influence of austempering on the microstructure and mechanical properties of an alloyed cast steel containing high silicon (3.00%) and high manganese (2.00%) was studied. The influence of microstructure on the plain strain fracture toughness of this new steel was also examined. The test results show that by using a suitable austempering process, i.e., by austenitizing at 1010°C (1850°F) for 2 hr and then subsequently austempering at 316°C (600°F) for 6 hr, it is possible to produce more than 80% austenite in the matrix of the material. Such a large percentage of austenite in the matrix made the steel almost nonmagnetic. Austempering resulted in a significant improvement in mechanical properties as well as fracture toughness of the material. The potential applications of this steel are in naval structural components, aircraft, and automotive components.
26 citations
TL;DR: In this paper, impact tests at low temperatures were carried out, aimed at comparing the response of five spheroidal graphite (SG) cast iron with different microstructures and to analyze the influence of the solidification structure size.
Abstract: Impact tests at low temperatures were carried out, aimed at comparing the response of five spheroidal graphite (SG) cast iron with different microstructures and to analyze the influence of the solidification structure size. "Y" blocks with two different thicknesses (13 and 75 mm) were cast using the same industrial melt. The following matrix microstructures were obtained by applying different heat treatments: pearlitic–ferritic (as-cast condition), fully ferritic (sub-critical annealing), fully pearlitic (normalizing) and two ausferritic matrices (ADI grades 2 and 4). Charpy impact tests were performed on unnotched specimens at temperatures ranging from -100°C to +200°C. The results showed a little variation of the upper and lower shelf energy values with the solidification structure size for each matrix type. However, there was a strong displacement in the transition temperature towards increasing temperatures as the solidification structure size enlarged. This effect is also related to the matrix microstructure. The highest impact energy values were obtained on ADI grade 2 samples, and the lowest ones on the samples with pearlitic matrix.
20 citations
TL;DR: In this article, the A1 phase boundary of high Mn and Ni-Cu-Mn alloyed iron was calculated as a function of the austenitization temperature, and the results of the calculated results showed that the A 1 temperature is the lowest in the intercellular region of a high Mn alloy.
Abstract: To control austenite transformation of ductile iron, thermodynamics procedures were used to calculate the Ae3, the Gr/γ (Acm), and the A1 phase boundaries of high Mn and Ni-Cu-Mn alloyed iron as a function of austenitization temperature. The results of calculation show that segregation of Mn in the intergraphite regions reduces the carbon content of austenite at the Ae3 phase boundary to the lowest value. If one ignores the effect of substitutional alloying elements on the nucleation of austenite, the austenite should first nucleate in the cell boundaries and then grow to the graphite nodules. In addition, the calculated results show that the A1 temperature is the lowest in the intercellular region of a high Mn alloy. Therefore, if the austenitization temperature is not sufficiently high, only those parts of the matrix that have the A1 phase boundary below the austenitization temperature transform to austenite, and dual formation of the α and γ phases will occur. By using the procedure introduced in this study, the volume fraction of each phase can be evaluated by calculating the A1 phase boundary as a function of intergraphite distance. In the case of Ni-Cu-Mn alloy, Ni stabilizes austenite, which lowers the Ae3 phase boundary. In this alloy, carbon content of austenite at the Ae3 phase boundary is lower near the graphite nodule and higher in the intergraphite regions. However, the variation of carbon content of austenite at the Ae3 phase boundary in the matrix of this alloy is much lower than in the high Mn alloy.
19 citations
TL;DR: In this article, the effect of testing temperature (− 150 °C, 25 °C and + 150°C) on the fracture toughness of austempered ductile iron (ADI) was studied.
Abstract: The effect of testing temperature (− 150 °C, 25 °C, and + 150 °C) on the fracture toughness of austempered ductile iron (ADI) was studied. Specimens were first austenitized at 900 °C for 1.5 hours and then salt-bath quenched to 360 °C or 300 °C, for 1, 2, or 3 hours of isothermal holding before cooling to room temperature. The resulting matrices of the iron were of upper-ausferrite and lower-ausferrite. It was found that raising the testing temperature to 150 °C from ambient improved the fracture toughness by 18, 30, and 7 pct for the as-cast/lower-ausferrite ADI/upper-ausferrite ADI, respectively. Lowering the testing temperature to −150 °C produced a decrease of −15, −35, and −48 pct. Optical microscopy, X-ray diffraction analysis, and scanning electron microscopy (SEM) fractography were applied to correlate the toughness variation with testing temperatures.
18 citations
TL;DR: In this article, the use of wheel loader bucket tips produced in ductile iron and austempered ductile Iron (ADI) has been evaluated in service performance trials, which were correlated with ASTM G65 wear tests data and microstructural characterization.
1 Jan 2001
TL;DR: In this paper, Austempered irons and steels have been used to improve the performance of gears and shafts in many applications in a wide range of industries, such as automotive and aerospace.
Abstract: Austempered irons and steels offer the design engineer alternatives to conventional material/process combinations. Depending on the material and the application, Austempering may provide the following benefits to producers of gears and shafts: ease of manufacturing, increased bending and/or contact fatigue strength, better wear resistance or enhanced dampening characteristics resulting in lower noise. Austempered materials have been used to improve the performance of gears and shafts in many applications in a wide range of industries.
TL;DR: In this article, the effects of austempering treatment on hardness, tensile properties and wear resistance of a ductile iron were examined, and it was shown that the increase of the time from 45 min to 180 min did not cause further improvement in hardness and strength.
Abstract: In this study, the effects of austempering treatment on hardness, tensile properties and wear resistance of a ductile iron were examined. Austempering at 300 °C after austenitising at 900 °C for 100 min improved the mechanical properties of the investigated ductile iron with respect to as-cast condition. Increase of austempering time from 45 min to 180 min did not cause further improvement in hardness and strength, but increased the ductility and wear resistance, progressively.
TL;DR: In this article, the dimensional change (DC) caused by heat treatment, and the dispersion (ΔDC) of the DC values were measured for several industrial parts of different ADI grades, having different chemical compositions, shapes and sizes.
Abstract: To accurately satisfy the size tolerance of metallic parts, it is necessary to take into account the dimensional change (DC) caused by heat treatment, and the dispersion (ΔDC) of the DC values. The information available on this topic for ADI is very scarce. The present work aims to determine DC and ADC on ADI and SAE 4140 steel parts and to analyze its influence on the size tolerances. Ductile iron and SAE 4140 steel specimens were used to compare DC and ΔDC caused by austempering, and quenching and tempering heat treatments. DC and ΔDC were also measured for several industrial parts of different ADI grades, having different chemical compositions, shapes and sizes. The results show that in average ADI suffer greater DC than SAE 4140 steel parts of similar mechanical properties, but, on the other hand, ADC is always lower for ADI than for steel. A more accurate prediction of the DC is then possible on ADI than on steels. This would allow the use of less strict machining tolerances, under better machinability conditions, when final operations can be done before heat treatment, producing series of ADI parts. This represents a technical and economical advantage for ADI in comparison with steel. The influence that the previous microstructure, the austempering temperature and the piece anisotropy, exert on the DC of ADI were also studied. The effects identified in this work are in agreement with previously reported results.
Journal Article•
TL;DR: The combination of strength and toughness can be improved in granular bainite microstructure (B g) by controlling the size, amount and distribution of martensite/austenite islands(M/A islands).
Abstract: The combination of strength and toughness can be improved in granular bainite microstructure (B g) by controlling the size, amount and distribution of martensite/austenite islands(M/A islands). Based on this discovery, a new granular bainite steel has been first developed. The combination of grain boundary allotrimorphic ferrite (F GBA ) with granular bainite lead to a new F GBA /B g duplex steel in the world. By suitable alloy composition design, a new air cooling carbide free bainite/martensite (CFB/M) steel with ultra fine microstructure has been developed. The bainite units of different grade is surround by retained austenite. The CFB/M duplex steel exhibits a good combination of strength and toughness.
TL;DR: In this paper, the authors reported that Co accelerates the stage I reaction in each Mn ductile irons and has little effect on the stage II reaction, which can be useful in the austempering of thicker section components to obtain the higher ductility grades of the ADI standard.
Abstract: Austempering kinetic measurements and mechanical property measurements are reported for two Mn ductile irons with and without Co and three austempering treatments. It is shown that Co accelerates the stage I reaction in each of the irons and for each of the austempering treatments but has little affect on the stage II reaction. Consequently, the processing window is widened and moves to earlier austempering times. This can be useful in the austempering of thicker section components to obtain the higher ductility grades of the ADI standard and to increase process productivity.
TL;DR: In this paper, the authors applied Mossbauer spectroscopy to study the processes occurring during the stage I of the austempering transformation of compacted graphite cast irons at temperatures from 573 to 673 K for two Mn concentrations.
Abstract: Mossbauer spectroscopy has been applied systematically to study the processes occurring during the Stage I of the austempering transformation of compacted graphite cast irons at temperatures from 573 to 673 K for two Mn concentrations. The kinetics of transformation (γ→αFe+γhc) was followed determining the dependence of the high-carbon austenite percentage on austempering time for different austempering temperatures and Mn contents. The evolution of the C concentration and the total amount of C incorporated into high-carbon austenite were also monitored. The results are compared with those of other morphologies and discussed in the frame of Johnson-Mehl's and diffusion models.
TL;DR: In this paper, contact fatigue tests using artificially indented Ductile Iron (ADI) discs were performed in a twin-disc machine, as a quick procedure to characterize and evaluate the fatigue resistance properties of ADI.
Abstract: A complete study of Austempered Ductile Iron (ADI) contact fatigue resistance would require long-cycle fatigue testing for each austempering variety, a process that could take several months or even years until enough data is gathered. Having this problem in mind, short contact fatigue test methods have been proposed by some authors [1,2,3,4] when approaching the same problem concerning steel components analysis. Contact fatigue tests using artificially indented ADI discs were performed in a twin-disc machine, as a quick procedure to characterize and evaluate the fatigue resistance properties of ADI. The tests were followed-up using several auxiliary surface analysis techniques such as electronic scanning microscopy, video imaging and profilometry. The obtained results allowed the characterization of the main contact fatigue mechanisms around indentations, and how the operating conditions affect those mechanisms. The post-test analysis of surfaces and sub-surfaces at zones away from the indentations allowed the characterization of other contact fatigue mechanisms, such as surface and sub-surface cracking, crack propagation and spalling, and how these phenomena are influenced both by the graphite nodules, foundry defects and Hertzian contact pressure.
Patent•
28 Nov 2001
TL;DR: The utility model relates to a multilayer turntable type austempering device, which is used for the technologies of machine work and heat treatment, and comprises a casing, a quenching liquid stirring and heating system, a charging tray bracket and a positioning rotary driving device.
Abstract: The utility model relates to a multilayer turntable type austempering device, which is used for the technologies of machine work and heat treatment, and comprises a casing, a quenching liquid stirring and heating system, a charging tray bracket and a positioning rotary driving device, a charging tray inlet and outlet mechanism and a material inlet and outlet mechanism. The utility model has the advantages of compact structure, small occupation of land, energy saving, high production efficiency, stable product quality and reliable performance, can fit continuous mass production, can better meet the technological requirement of austempering, and can truly ensure the constancy of temperature that is required to form bainite, so that bainite structure is uniform, and the quality of products is improved.
TL;DR: The tensile strength and the fatigue strength of austempered ductile iron (ADI) are equal to those of forg... as mentioned in this paper, and it is well known that ductile cast iron can be strengthened and toughened by austempering.
Abstract: It is well known that ductile cast iron can be strengthened and toughened by austempering. The tensile strength and the fatigue strength of austempered ductile iron (ADI) are equal to those of forg...
TL;DR: In this paper, a thermomechanical treatment was performed on blocks of a 0.4C-1.4Mn steel and the deformed plates were then partially transformed to bainite and the resulting microstructures were subjected to investigation.
Abstract: This paper aims to give further insights on the changes that are brought on bainite formation by prior hot-deformation. To this end, a thermomechanical treatment was performed on blocks of a 0.4C-1.5Si-1.4Mn steel, The chemistry of this alloy allowed hot-rolling in the full austenitic range up to large reductions without any significant recrystallisation, The deformed plates were then partially transformed to bainite and the resulting microstructures were subjected to investigation. The laths of bainitic ferrite appeared to be grouped in packets in which they exhibit the same crystallographic orientation. When no prior hot-deformation is applied, the bainite packets originating from the same austenite parent grain were randomly distributed. However, severely deformed austenite grains were found to give rise to typical orientations of the bainitic ferrite laths. These results were interpreted in terms of dislocation arrays interacting with a displacive transformation.
Patent•
4 Jul 2001
TL;DR: In this article, an austempered ductile cast iron is provided which has superior mechanical properties and forming property by carrying out an ordinary austempering after performing a special heat treatment such as pre-quenching or pre-heating giving prior structure before austemming a material having the bad forming property.
Abstract: PURPOSE: An austempered ductile cast iron is provided which has superior mechanical properties and forming property by carrying out an ordinary austempering after performing a special heat treatment such as pre-quenching or pre-heating giving prior structure before austempering a material having the bad forming property. CONSTITUTION: The austempered ductile cast iron comprises 2.6 to 4.0 wt.% of C, 2.0 to 3.5 wt.% of Si, 0.5 wt.% or less of Mn, 0.1 wt.% or less of P, 0.3 wt.% or less of S, 0.2 to 0.5 wt.% of Mo, 0.5 to 1.5 wt.% of Ni, 0.1 to 0.4 wt.% of Cu, 0.03 to 0.05 wt.% of Mg and a balance of Fe. The method for manufacturing an austempered ductile cast iron comprises the processes of casting a spheroidal graphite cast iron from an alloy comprising 2.6 to 4.0 wt.% of C, 2.0 to 3.5 wt.% of Si, 0.5 wt.% or less of Mn, 0.1 wt.% or less of P, 0.3 wt.% or less of S, 0.2 to 0.5 wt.% of Mo, 0.5 to 1.5 wt.% of Ni, 0.1 to 0.4 wt.% of Cu, 0.03 to 0.05 wt.% of Mg and a balance of Fe; heat treatment of quenching the austenitic spheroidal graphite cast iron in oil after austenizing the casted spheroidal graphite cast iron at a temperature of 900 deg.C for 1 hour; and austempering in which the heat treated cast iron is treated at the constant temperature of 350 deg.C for 2 hours after treating at the constant temperature of 900 deg.C for 2 hours.
TL;DR: In this article, the viability of manufacturing components by casting a preform, austenitizing it, quenching it to the austempering temperature, forging it, ausforming it, and finally quenched it to a net shape is investigated by simulating the forging operation with finite element analysis.
Abstract: The mechanical properties of ductile iron can be improved by ausforming, that is, applying work during austempering. The resulting yield strength and ductility are comparable to those of SAE 4140 steel, while the density is approximately 10 percent less. The viability of manufacturing components by casting a preform, austenitizing it, quenching it to the austempering temperature, forging it, austempering it, and finally, quenching it to the net shape is investigated by simulating the forging operation with finite element analysis. The preform geometry and die set geometry are determined such that the forging operation imparts a reasonably uniform equivalent plastic strain of 20 percent to the workpiece and the prescribed final component geometry is obtained. Forging of two components of varying geometric complexity is simulated using a commercial software package. The results indicate that the geometry of the final part is reasonably close to the goal and that the equivalent plastic strain distribution is reasonably uniform-over 80 percent of the material was plastically deformed 15-25 percent. The design of the preform and die sets appears to be an excellent application for an optimization algorithm.
Journal Article•
TL;DR: In this article, the effect of vanadium carbide on the structure and properties of bainite ductile cast iron has been studied and the results show that vanadium has less effect on the micro hardness of austenite and Bainite.
Abstract: Effect of vanadium on structure and properties of bainite ductile cast iron has been studied in present research The results show that as the content of vanadium is increased, the content of bainite is increased, the size of bainite needles is decreased and the macro hardness of bainite ductile cast iron is increased, but vanadium has less effect on the micro hardness of austenite and bainite The morphology of vanadium carbide in bainite ductile cast iron is determined and the action mechanism of vanadium is discussed in this paper
Patent•
21 Dec 2001
TL;DR: In this paper, a method for producing an austenite by raising the temperature of a high temperature furnace to 805-950 degree C and transferring the Austenite to a low temperature furnace for Austempering at 280-330 degree C, and maintaining at a constant temperature for 1-3 hours.
Abstract: An Austempered ductile iron mainly comprises: 3.5-3.9% of C, 2.4-2.9% of Si, and 0.025-0.04% of Mg. A method for producing such an iron comprises: producing an austenite by raising the temperature of a high temperature furnace to 805-950 degree C; transferring the austenite to a low temperature furnace for Austempering at 280-330 degree C, and maintaining at a constant temperature for 1-3 hours. The Austempered ductile iron according to the present invention can further comprises: 0.001-0.6% of Mn, 0.001-1.0% of Cu, 0.001-1.0% of Ni, or 0.001-0.3% of Mo, in order to improve its hardening energy. The Austempered ductile iron according to the present invention has a better wear resistance, and can be applied on a thick cast article. In a working environment higher than 400 degree C, the matrix texture thereof will not change while maintaining an excellent mechanical property.
TL;DR: In this article, the authors investigated the performance of two different grades of austempered ductile irons (ADI) which were heat treated respectively at two different austempering temperatures, 573 and 633 K. They found that fatigue crack growth rates (FCGRs) at 20 Hz in humid air and aqueous environments were comparable and faster than those in lubrication oil.
Abstract: Corrosion fatigue crack growth (CFCG) behavior has been investigated for two different grades of austempered ductile irons (ADIs) which were heat treated respectively at two different austempering temperatures, 573 and 633 K. Fatigue crack growth (FCG) tests using compact tension (CT) specimens were conducted in humid air, lubrication oil and three aqueous environments: distilled water (pH = 7.6), sodium chloride solution (pH = 7.3) and sulfuric acid solution (pH = 3). The results showed that fatigue crack growth rates (FCGRs) at 20 Hz in humid air and aqueous environments were comparable and faster than those in lubrication oil. The FCGRs in aqueous environments were found to increase with a reduction in loading frequency or with an increase in solution temperature. The crack growth enhancement by different aqueous media appeared to be equivalent, although the ion species and pH in the bulk solutions were different. The degree of sensitivity to environmental effects for CFCG response in ADI was not essentially influenced by the austempering treatment as the relative difference in FCGR between the two grades of ADIs was not considerably changed in any of the studied.
Journal Article•
TL;DR: In this paper, a king of new medium carbon, high wear resistance steel containing silicon and manganese as alloying elements has been developed, which can be used under as cast condition without heat treatment.
Abstract: According to the natural resources in our country, a king of new medium carbon, high wear resistance steel containing silicon and manganese as alloying elements has been developed. One of the characteristics of this steel is a mixed structure of austenite and bainite under as cast condition. It has high hardness, high toughness (40～58HRC? a k≥15～45J/cm 2) excellent resistance to abrasive wear. It can be used under as cast condition without heat treatment. This austenite bainite wear resistanct steel is an ideal new material for replacement of tranditonal austenitic high manganeses steel.