Pct Manganese Research Articles

Hot Ductility Behavior of Boron Containing Microalloyed Steels with Varying Manganese Contents

The hot ductility is measured for six different steel grades with different microalloying elements and with varying manganese contents using the hot tensile test machine with melting/solidification unit at the Department of Ferrous Metallurgy RWTH Aachen University. To identify the influence of manganese on hot ductility, tests are performed with varying the manganese content from 0.7 to 18.2 wt pct, a high manganese steel. Additionally, the effect of different cooling and strain rates is analyzed by changing the particular rate for selected samples in the minima. To investigate and detect the cause of cracking during testing, the fracture surfaces in the ductility minima are considered with scanning electron microscope–energy dispersive X-ray spectroscopy. Thermodynamic modeling is conducted on basis of the commercial software ThermoCalc©. A sharp decrease of the hot ductility is recognizable at 1398 K (1125 °C), at only 0.7 wt pct manganese because of the low manganese to sulfur ratio. The grades with a Mn content up to 1.9 wt pct show a good ductility with minimal ductility loss. In comparison, the steel grade with 18.2 wt pct has a poor hot ductility. Because of the formation of complex precipitates, where several alloying elements are involved, the influence of boron on hot ductility is not fully clarified. By increasing the cooling rate, the reduction of area values are shifted to smaller values. For high test temperatures, these measured values are decreased for lower strain rates. Thereby, an early drop of the ductility is noticeable for the high temperatures around 1373 K (1100 °C).

The Effect of Nd on the Tension and Compression Deformation Behavior of Extruded Mg-1Mn (wt pct) at Temperatures Between 298 K and 523 K (25 °C and 250 °C)

The tension and compression deformation behavior of extruded magnesium-1 wt pct manganese alloys with nominally 0.3 wt pct (MN10) and 1 wt pct neodymium (MN11) was studied over the temperature range of 298 K to 523 K (25 °C to 250 °C). Nd additions to Mg alloys tend to reduce the strong basal texture exhibited by conventional wrought Mg alloys and this work was intended to study the effect of Nd on the deformation behavior of Mg alloys. Insitu tensile and compressive experiments were performed using a scanning electron microscopy, and electron backscatter diffraction was performed both before and after the deformation. A slip trace analysis technique was used to identify the distribution of the deformation systems as a function of strain, and based on this analysis and the texture of the undeformed samples, the critical resolved shear stress ratios between the deformation systems were estimated. In the case of MN11, the deformation behavior under tension at all temperatures was dominated by slip, while in compression, extension twinning was the major deformation mode. In tension at 323 K (50 °C), extension twinning, basal, prismatic 〈a〉, and pyramidal 〈c + a〉 slip were active in MN11. Much less extension twinning was observed at 423 K (150 °C), while basal slip and prismatic 〈a〉 slip were dominant and presented similar relative activities. At 523 K (250 °C), twinning was not observed, and basal slip controlled the deformation. With the reduction of Nd content, less slip deformation and more twinning were observed during the tensile deformation. However, like for MN11, the extent of twinning in MN10 decreased with increasing temperature and basal slip was the primary deformation mode at elevated temperatures. Extension twinning was the major deformation mode under compression for all test temperatures in MN10 and MN11. The tensile strength decreased with increasing temperature for both alloys, where MN10 was slightly stronger than MN11 at 323 K (50 °C), which was expected to be a result of the stronger basal texture exhibited by MN10 due to its lower Nd content. However, MN11 maintained its strength more at elevated temperatures compared with MN10, and this was explained to be a result of the greater Nd content.

Corrosion Behavior of Low Alloy Steels Containing Manganese in Mixed Chloride Sulfate Solution

The corrosion resistance of the low alloy steels was improved by the addition of Mn up to 2.0 wt pct due to grain refinement and the formation of a protective rust layer. On the other hand, the addition of 5.0 wt pct manganese decreased the corrosion resistance of low alloy steel due to the microstructural changes that hinder the formation of the protective rust layer.

Reason for the Beneficial Effect of Sulfur Additions on the Hypoperitectic Reaction in a 0.1 Pct Carbon and the Sulfur Content Needed to Establish the Effect

It has been shown that the addition of 0.3 pct sulfur to the 0.1 pct carbon, 0.9 pct manganese, and 0.3 pct silicon peritectic steel does not exhibit a rippled shell because of the accommodation of the buckling strains by the presence of a significant amount of low-melting point liquid when solid austenite and ferrite are formed. A similar solidification path will exist for sulfur contents down to approximately 0.1 pct for this alloy. A significant amount of low melting liquid will be present down to that sulfur concentration. The exact point for the disappearance of the peritectic effect still must be determined experimentally, but it certainly is in the range of 0.1 to 0.15 pct sulfur. For other peritectic alloys, the approximate sulfur content at which the effect of the peritectic reaction will disappear can be determined similarly to the method used in this study.

Effects of Residual Elements Arsenic, Antimony, and Tin on Surface Hot Shortness

Scrap-based electric arc furnace (EAF) steelmaking is limited by a surface cracking problem in the recycled steel products, which is known as surface hot shortness. This problem originates from the excessive amount of copper (Cu) in the steel scrap, which enriches during the oxidation of iron (Fe) and consequently melts and penetrates into the austenite grain boundaries. In this article, the effects of arsenic (As), antimony (Sb), and tin (Sn) on surface hot shortness were investigated. A series of Fe-0.3 wt pct Cu-x wt pct (As, Sb, or Sn) alloys with x content ranging from 0.06 to 0.10 wt pct was oxidized in air at 1423 K (1150 °C) for 60, 300, and 600 seconds inside the chamber of a thermogravimety analyzer (TGA) where heat is supplied through infrared radiation. Scanning electron microscopy (SEM) investigations show that (1) the presence of Sb and Sn results in severe grain boundary cracking, whereas the presence of As does not, (2) open cracks with Fe oxides were found beneath the oxide/metal interface in the Sb and Sn alloys, and (3) the oxide/metal interfaces for all As, Sb, and Sn alloys are planar. Penetration experiments of pure Cu and Cu-30 wt pct Sn liquid were also conducted in the chamber of a hot-stage confocal laser scanning microscopy (CLSM) in nonoxidizing atmosphere: (1) on the Fe-35 wt pct manganese (Mn) alloys to study the correlation between cracking and grain boundary characters, and (2) on the pure Fe substrates to exclude the bulk segregation effects of Sn on grain boundary cracking. It was found that grain boundary cracking rarely took place on low-energy grain boundaries. The results also suggest that the bulk segregation of Sn in the substrate is not necessary to promote significant grain boundary cracking, and as long as the liquid phase contains Sn, it will be highly embrittling.

Deoxidation equilibria of molten nickel by Mg-Al and Mn-Al

The deoxidation equilibria of aluminum-magnesium and aluminum-manganese in liquid nickel equilibrated with Al2O3-saturated MgAl2O4 and MnAl2O4, respectively, were investigated in the temperature range of 1773 to 1873 K. At 1773 K, the oxygen levels could be reduced to 5.8 to 6.6 ppm with 2.5 to 10 ppm magnesium and 0.05 to 0.9 mass pct aluminum in the Ni-Mg-Al-O system, and to less than 20 ppm with more than 1.5 mass pct manganese and 30 ppm aluminum in the Ni-Mn-Al-O system. With the experimental results mainly obtained in the present work, the interaction parameters, e Mg Al , e Mn Al , e O Mg , e O Mn , and e O Al , and the equilibrium constants, log \(K_{MgAl_2 O_4 (Ni)} \), log \(K_{MnAl_2 O_4 (Ni)} \), log K Mg(Ni), log K Mn(Ni), and log K Al(Ni), were estimated using a multiple regression analysis.

Kinetics of oxidation of carbon in liquid iron-carbon-silicon-manganese-sulfur alloys by carbon dioxide in nitrogen

The oxidation of carbon with the simultaneous oxidation of silicon, manganese, and iron of liquid alloys by carbon dioxide in nitrogen and the absorption of oxygen by the alloys from the gas were studied using 1-g liquid iron droplets levitated in a stream of the gas at 1575 °C to 1715 °C. Oxidation of carbon was favored over oxidation of silicon and manganese when cast iron (3.35 pct C, 2.0 pct Si, 0.36 pct Mn, and 0.05 pct S) reacted with CO2/N2 gas at 1635 °C. An increase in the flow rate of CO2/N2 gas increased the decarburization rate of cast iron. The rate of carbon oxidation by this gas mixture was found to be independent of temperature and alloying element concentrations (in the range of silicon = 0 to 2.0 pct manganese = 0 to 0.36 pct and sulfur = 0 to 0.5 pct) within the temperature range of the present study. Based on the results of a kinetic analysis, diffusion of CO2 in the boundary layer of the gas phase was found to be the rate-limiting step for the reactions during the earlier period of the reaction when the contents of carbon, silicon, and manganese are higher. However, the limiting step changed to diffusion of the elements in the metal phase during the middle period of the reaction and then to the diffusion of CO in the gas phase during the later period of the reaction when the content of the elements in the metal were relatively low. For the simultaneous oxidation reactions of several elements in the metal, however, the diffusion of CO2 in the gas phase is the primary limiting step of the reaction rate for the oxidation of carbon during the later period of reaction.

Effect of alloying elements on the solidification characteristics and microstructure of Al- Si- Cu- Mg- Fe 380 alloy

The effect of varying the major alloying elements within the limits of specification on the solidification behavior, fluidity, and microstructure of a 380 alloy has been studied at two cooling rates. The thermal analysis technique has been used to study the solidification behavior. The alloying elements investigated ranged from 3.22 to 4.09 pct copper, 1.01 to 1.70 pct iron, 0.06 to 0.50 pct magnesium, 1.69 to 3.00 pct zinc, and 0.16 to 0.46 pct manganese. The results show that the solidification behavior of the 380 alloys is complicated, and the cooling curve at 0.4 ‡C/s indicates six reactions taking place during the process of solidification. Cooling curves obtained for each of the alloying element additions, their analysis, and the resultant microstructures are discussed.

Effect of shape of sulfide inclusions on anisotropy of inclusion spacings and on directionality of ductility in hot-rolled C-Mn steels

The effects of sulfur content (0.004 or 0.013 pct) and sulfide morphology (stringered or globular) on anisotropy of tensile ductility and Charpy shelf energy were investigated in a series of 0.1 and 0.2 pct carbon, 1.0 pct manganese steels. The effect of sulfide inclusions on fracture strain or Charpy shelf energy correlated with the projected area of inclusions per unit volume,Av, on a plane perpendicular to the tensile direction and the mean free distance between inclusions, λ, in a direction parallel to the tensile direction regardless of the amount or the shape of the inclusions or the test direction: longitudinal, transverse, or through-thickness. The magnitude ofAv is directly proportional to the volume fraction of inclusions and inversely proportional to the inclusion dimension parallel to the tensile direction. The mean free distance, λ, is inversely proportional toAv. Approximate relations were obtained for the nearest-neighbor distances between inclusions on the longitudinal, transverse, and through-thickness planes. These distances were incorporated into a model for ductile fracture based on an adaptation of a previously proposed criterion for the linkage of voids nucleated at second-phase particles. The agreement between the observed and predicted fracture strains for longitudinal, transverse, and through-thickness specimens of the steels studied is encouraging.

Effect of sulfide inclusion morphology and pearlite banding on anisotropy of mechanical properties in normalized C-Mn steels

The influence of sulfur content, sulfide shape, and pearlite banding on the anisotropy of mechanical properties was evaluated in a series of 0.2 pct carbon, 1.0 pct manganese steels containing either 0.004 or about 0.013 pct sulfur with and without rare-earth additions. Both globular and stringered sulfide inclusions had a detrimental effect on reduction of area and Charpy shelf energy; this effect was particularly evident in the deterioration of through-thickness properties and was much more severe for stringered inclusions than for globular inclusions. The effect of the sulfide inclusions in the different steels on the through-thickness reduction of area and Charpy shelf energy correlated with differences in their mean free distances or nearest-neighbor distances, both of which depended upon the inclusion characteristics of volume fraction, size, and aspect ratio. The projected length of sulfide inclusions per unit area on a plane perpendicular to the transverse direction seemed to reflect the overall effect of the inclusion characteristics on through-thickness reduction of area and Charpy shelf energy and appeared to be a useful parameter for assessment of steel’s susceptibility to fracture. Pearlite banding had no obvious effect on reduction of area or Charpy shelf energy in any of the steels studied. The improvement observed for the steel with stringered sulfide inclusions as a result of the removal of pearlite banding was a consequence of the inclusions coarsening during the short-time high-temperature treatment used to remove banding.

Effect of Sulfides and Sulfide Morphology on Anisotropy of Tensile Ductility and Toughness of Hot-Rolled C-Mn Steels

The effects of sulfur content (0.004 or about 0.013 pct) and sulfide morphology (stringered or globular) on anisotropy of tensile ductility and Charpy V-notch (CVN) shelf energy were investigated in a series of 0.1 and 0.2 pct carbon, 1.0 pct manganese steels. The effect of sulfide inclusions on fracture strain or CVN shelf energy correlated with a single parameter,P, regardless of inclusion shape, stringered or globular, or test direction, longitudinal, transverse, or through-thickness. The parameterP was defined as the total projected length of inclusions per unit area on a plane parallel to the fracture plane. The fracture strain and CVN shelf energy decreased with an increase inP. The magnitude ofP was directly proportional to the volume fraction of inclusions and inversely proportional to the inclusion dimension perpendicular to the fracture plane. The lower tensile ductility and CVN shelf energy in the 0.2 as compared with the 0.1 pct carbon steels was a consequence of the greater pearlite content in the former steels. This greater pearlite content had no apparent effect on the work-hardening rate,H, but decreased the strain-rate sensitivity of the flow stress,M, and the strain-rate sensitivity of the work-hardening rate,B. The decrease inM andB with increasing pearlite content is in accord with a decrease in tensile ductility according to recent models of neck development in tension tests. It appears that the decrease in tensile ductility with increasing pearlite content is a result of enhanced localized shearing, which promotes the coalescence of voids nucleated at second phases.

Formation of Austenite During Intercritical Annealing of Dual-Phase Steels

The formation of austenite during intercritical annealing at temperatures between 740 and 900 °C was studied in a series of 1.5 pct manganese steels containing 0.06 to 0.20 pct carbon and with a ferrite-pearlite starting microstructure, typical of most dual-phase steels.

Influence of sulfide inclusions and pearlite content on the mechanical properties of hot-rolled carbon steels

Sulfur content and sulfide shape are known to have a marked influence on the tensile ductility and notch toughness of plate steels. To investigate the initiation and growth of fractures at inclusions during plastic straining, a detailed study was conducted with a series of 0.1 and 0.2 pct carbon, 1.0 pct manganese steels containing either 0.004 or 0.013 pct sulfur with and without rare-earth additions. This paper describes the results of this study and evaluates the influence of sulfur content and sulfide shape on the anisotropy in tensile ductility and notch toughness in the steels and assesses the influence of other factors, such as pearlite content, affecting the ductility and toughness. Both globular and stringered sulfide inclusions had a detrimental effect on reduction of area, shelf energy, and transition temperature, which was particularly evident in deterioration of through-thickness properties and which was much more severe for stringered inclusions than for globular inclusions. Increased pearlite content was more detrimental to reduction of area and transition temperature when stringered inclusions were also present, whereas its effect on shelf energy appeared to be about the same regardless of the presence of inclusions or their morphology.

Thermodynamics of iron-manganese aluminate spinel inclusions in steel

The effect of manganese on the residual oxygen concentrations of liquid iron in equilibrium with alumina saturated iron-manganese aluminate spinel solid solutions was investigated at temperatures of 1550, 1600, and 1650°C. The relationship between the equilibrium concentrations of manganese and oxygen in iron melts containing up to 6 wt pct manganese has been established. The compositions of the spinel deoxidation products, (Fe x Mn j-x ) O · Al2O3, which were formed during equilibration with the iron melts were determined with electron microprobe and neutron activation analysis. From these results, new thermodynamic data pertaining to galaxite formation reactions have been derived and their implications with respect to the deoxidation of aluminum semikilled, silicon free, steels have been discussed.

Hardness of tempered martensite in carbon and low-alloy steels

This paper presents the results of a systematic study of the effect of carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, and vanadium on the hardness of martensite in low to medium carbon steels tempered for one hour at 100°F (56°C) intervals in the range 400 to 1300°F (204 to 704°C). Results show that the as-quenched hardness depends solely on carbon content. On tempering, the effect of carbon on hardness decreases markedly with increasing tempering temperature. Studies of carbon-0.5 manganese steels showed that the incremental increase in hardness from 0.5 pct manganese after a given tempering treatment was independent of carbon content. Based on this result, studies of the effects of the other alloying elements were made using a 0.2 or 0.3 pct carbon, 0.3 to 0.5 pct manganese steel base composition. The hardness of the resulting tempered martensite was assumed to be due to a given alloy addition, and when two or more alloying elements were added, their effects were assumed to be additive. Each of the seven alloying elements increased the hardness of tempered martensite by varying amounts, the increase being greater as more of each element was present. Nickel and phosphorus have substantially the same effect at all tempering temperatures. Manganese has essentially the same hardening effect at any temperature in the range 700 (371°C) to 1300°F; silicon is most effective at 600°F (316°C), chromium at 800°F (427°C), molybdenum at 1000 to 1100°F (538 to 592°C), and vanadium at 1200°F (649°C). Using the data obtained, a procedure is established for calculating the hardness of tempered martensite for carbon and alloy steel compositions in the range studied and for any combination of tempering time and temperature.

Metallurgical aspects in cold rolled high strength steel sheets

Cold rolled high strength steel sheets with yield strength from 300 to 500 N/mm2 have been developed by using conventional equipment for producing commercial cold rolled steel sheet, that is, cold rolling, box annealing, and temper rolling. Effective alloying elements for strengthening are carbon, silicon, manganese, phosphorus, niobium, etc. The sheets up to 400 N/mm2 yield strength grade are easily produced by selecting appropriate chemical compositions. The sheets with higher yield strength grade than 450 N/mm2 are obtained by introducing the new idea that the steel with more than 2 pct manganese is annealed between A1 and A3 transformation temperatures, and moderately temper rolled. Increase of tensile strength does not affect deep drawability while it deteriorates stretch-forming and stretch-flanging properties. As for electric resistance spot welding, shear tension strength increases in proportion to tensile strength, but cross tension strength hardly increases or tends to decrease. These sheets have been applied to door beams and bumper reinforcements.

Phenomenology of precipitation in copper-20 pct nickel-20 pct manganese

The precipitation phenomena in the alloy copper-20 pct nickel-20 pct manganese have been investigated. Utilizing transmission electron microscopy as the principal tool; the effects of aging temperature and time as well as prior cold work were studied. For all aging temperatures the reaction products are the solute depleted fcc solid solution and an ordered structure with fct symmetry. Three aging temperatures characterized by different precipitate morphologies were studied. At 350°C discontinuous precipitation is the predominant mode of decomposition. Precipitate colonies nucleate at grain and twin boundaries and eventually grow through the entire structure. Microtwinning of the colony matrix accompanies the precipitation reaction. At 450°C both grain boundary nucleated discontinuous precipitates and fine periodic homogeneous arrays are observed in the absence of cold work. The fine periodic arrays coarsen and eventually form nuclei for the ordered fct phase. The coarsening of the periodic arrays prohibits the growth of the discontinuous precipitate early in the process, so only a small volume fraction of discontinuous precipitate is formed at the grain boundaries. Aging subsequent to cold work results in ordered, fct precipitates heterogeneously nucleated on dislocations. At 500°C no precipitate is observed in the absence of cold work. When aging is preceded by cold work, the ordered fct phase appears as heterogeneously nucleated Widmanstatten laths. No grain boundary nucleated colonies are observed at this temperature.