Mn Sheet Research Articles

The Effects of Super-Fast Heating Rate and Holding Time on the Microstructure and Properties of DP Fe-0.16C-1.4Mn Sheet Steel.

This study investigates the influence of super-fast heating rate and holding time on the microstructure and mechanical properties of dual-phase (DP) Fe-0.16C-1.4Mn sheet steel. Super-fast heating and cooling rates were achieved via induction heating and gas quenching. The results were also compared with those for a conventional low-speed heat treatment. The microstructures were characterized in detail using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and electron probe microanalysis. The results showed that the layered structure of the DP Fe-0.16C-1.4Mn steel after super-fast heating was mainly composed of recrystallized ferrite, martensite clusters, and a small amount of residual austenite. Compared with the conventional method, super-fast heating significantly refined the grains and improved yield and tensile strength, but it slightly reduced the elongation. The fraction of martensite, which depends on the nucleation and growth behavior of austenite, was significantly affected by the heating rate and holding time. The DP structure of Fe-0.16C-1.4Mn steel had an atypical layered heterogeneous structure, with an uneven plastic strain between the two phases occurring during the deformation process, which is something that can improve fracture elongation.

Effect of Ca addition on structure, phase composition and hardness of Al–6 %Cu–2 %Mn sheet alloy

The Al–Cu–Mn–Ca system was proposed as a bases for the design of new group of heat-resistant alloys which can be used for high-temperature applications instead of the 2219 types industrial alloys. Unlike the latter ones, the new alloys also do not require a full cycle of strengthening heat treatment including solid solution treatment, quenching and aging. The effect of calcium addition in the 1–4 wt% range on the structure, phase composition and hardness after high temperature annealing of the Al–6 %Cu–2 %Mn base sheet alloy has been studied. It has been shown that calcium addition leads to the formation of high-temperature eutectics (614–617 °С) with the participation of the Al27Ca3Cu7 and (Al,Cu)4Ca phases that are capable of spheroidization at high temperature annealing. The ingots of Ca-containing alloys do not require homogenization but have sufficient deformation plasticity at both hot and cold rolling. The structure of the previously unstudied quaternary Al–Cu–Mn–Ca phase diagram in the region of the aluminum corner has been also proposed, according to which it can contain 5 four-phase fields in the solid state with the participation of (Al), binary (Al2Cu, Al4Ca, Al6Mn) and ternary (Al8CaCu4, Al27Ca3Cu7, Al10CaMn2 and Al20Cu2Mn3) phases. Based on the obtained data, the composition Al–6 %Cu–2 %Mn–1 %Ca has been proposed as a basis for the development of a new heat-resistant alloy. It is shown that this alloy superior to industrial 2219 alloy in terms of heat resistance, especially after annealing at 400 °C, when the difference in hardness reaches 32 HV. The high heat resistance of the new wrought alloy originates from the formation of a specific microstructure consisting of fine Ca-containing eutectic inclusions and Al20Cu2Mn3 phase dispersoids with a size of about 100 nm which prevent recrystallization and allow maintaining the fine sub-grained structure.

Comparative analysis of the effect of magnesium and zinc on the structure and mechanical properties of hot-rolled and cold-rolled alloy Al–2%Cu–1.5%Mn sheets

Comparative analysis of the effect of magnesium and zinc on the structure and mechanical properties of hot-rolled and cold-rolled alloy Al–2%Cu–1.5%Mn sheets

Effect of quenching temperature on the austenite stability and mechanical properties of high-strength air-cooled TRIP steel prepared with hot-rolled C–Si–Mn sheets

This paper systematically studies the effect of quenching temperature on the microstructure evolution and the relationship between the microstructure and mechanical properties of air-cooled TRIP steel prepared with C–Si–Mn hot-rolled sheet. The results indicate that when the quenching temperature is lower than (200 °C) or close to (250 °C) the Ms temperature, the martensite transformation mainly occurs during quenching or at early stage of air cooling. When the quenching temperature reaches 300 °C, lathy bainite begins to form. As the quenching temperature increases, the morphology of bainite is transformed from lathy to granular. Bainite transformation during air cooling can promote the C enrichment in austenite, thus improving the thermal stability of the austenite. However, martensite transformation also occurs during subsequent air cooling, and the start temperature of martensite transformation first decreases and then increases with the increase of quenching temperature from 300 °C to 450 °C. The yield and tensile strength of TRIP specimens first decrease and then increase, while the retained austenite content, elongation and product of strength and elongation (PSE) first increase and then decrease. When the quenching temperature is 400 °C, the best elongation and PSE are obtained. The best elongation of 400TRIP specimen is mainly attributed to its highest content and suitable mechanical stability of retained austenite, which is favorable for the expansion of the TRIP effect range. The TRIP specimens prepared with hot-rolled sheet all exhibit ultra-high tensile strength (over 1050 MPa), which is related to the ultrafine ferrite grains, martensite transformation during air cooling and TRIP effect of retained austenite.

Effect of Solution Temperature and Natural Aging Period on Microstructure and Properties of Al-4Cu-2Mg-0.7Mn Sheets

Effect of Solution Temperature and Natural Aging Period on Microstructure and Properties of Al-4Cu-2Mg-0.7Mn Sheets

Superior combined strength and elongation by conducting elevated temperature constrained groove pressing on Al–Mg–Mn sheets

Al 5083 alloy has widely been employed in marine and offshore engineering as well as production of various types of superplastically formed parts in aerospace and automotive industries. The constrained groove pressing (CGP) is also one of important sheet severe plastic deformation (SPD) technique. In this study, The CGP process has been performed on Al 5083 sheets at an elevated temperature and up to three cycles. Complementary experiments, namely metallography, precipitation evolution, hardness and tensile tests as well as fractography were conducted for various deformed and undeformed sheets. The 1-passed workpiece represented the minimum average grain size (AGS) 8 μm due to huge strain induction. By computing the inhomogeneity factor (IF), it was also found that the 2-passed sample was the most inhomogeneous worksheet with an IF of 6.3. By performing three CGP cycles, superior elongation of 56.2% combined with UTS of 309 MPa were achieved for the 3-passed sample, making this workpiece very suitable for conducting any subsequent metal forming process. This was mainly due to the precipitation evolutions of Al6(Fe,Mn) and Al3Mg2 particles. Moreover, fractography of various specimens showed that by performing greater number of CGP cycles, the fracture mechanisms changed to a ductile mode due to creation of tiny and deep dimples.

High strength-ductility synergy and low anisotropy of Mg-4.5Al-2.6Zn-0.3Mn alloy sheet achieved by annealing after rolling

• The integration of extrusion, rolling and annealing was designed and applied. • Shear bands and twins dominate after rolling with cold rolls. • Shear bands provide nucleation sites for recrystallization during annealing. • The final sheet exhibits high strength-ductility synergy and low anisotropy. • The Mg-4.5Al-2.6Zn-0.3Mn sheet owns potential to replace commercial AZ31 sheets. Mg-4.5Al-2.6Zn-0.3Mn sheets with high strength-ductility synergy and low anisotropy were fabricated by the integration of extrusion, rolling, and annealing, which act as excellent replacements for commercial AZ31 alloys. Finer grains, lower dislocation density, and weaker basal texture endow the as-annealed sheets, instead of the as-rolled ones, with the higher performance.

DFT calculations of 2D graphene like ZnS:Mn sheet for RESOLFT microscopic applications

DFT calculations of 2D graphene like ZnS:Mn sheet for RESOLFT microscopic applications

Comparative study on microstructures and mechanical properties of Q&P steels prepared with hot-rolled and cold-rolled C–Si–Mn sheets

In this study, we investigate the microstructures and mechanical properties of quenching and partitioning (Q&P) steels prepared with hot-rolled (HR) and cold-rolled (CR) sheets at different annealing temperatures (partial austenitisation). The ferrite and retained austenite are present in laths and blocks in HR-Q&P samples but are mainly blocky in CR-Q&P samples. Compared with CR-Q&P, the HR-Q&P samples have higher content of retained austenite, better elongation and higher product of strength and elongation (PSE). The lath-shaped retained austenite in HR-Q&P samples with a higher ratio of surface to volume is conducive to homogenization of carbon in austenite grains, thus improving the thermal stability and content of retained austenite. The lath-shaped retained austenite transforms into martensite obviously until the strain exceeds 5% and exhibits higher mechanical stability than coarse blocky retained austenite. When annealed at 810 °C, HR-Q&P and CR-Q&P samples present best PSEs. Indeed, the PSE of HR-810°C-Q&P sample is 62.8% higher than that of CR%-810°C-Q&P. The better elongation and higher PSE possessed by HR-810°C-Q&P sample are linked with the higher content of retained austenite and the presence of two kinds of retained austenite with different mechanical stability. The retained austenite with different mechanical stability in HR-810°C-Q&P sample, contributes to continuous transformation during tensile deformation, thereby improving the elongation. Meanwhile, the lath-shaped structures can delay the formation of voids and microcracks, thereby improving the elongation.

Microstructure‐dependent corrosion of herringbone‐grooved embossed Al–1.1 wt% Mn strips for heat exchanger tubes

AbstractThis paper studied the effect of embossing on the microstructure and corrosion behaviour of an Al−1.1 wt% Mn sheet. The microstructure of the embossed Al−1.1 wt% Mn sheets was studied by differential interference contrast microscopy, scanning electron microscopy, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, focused ion beam microscopy and X‐ray computational tomography. Finite element modelling was used to assess the stress and strain distribution developed during embossing, and to support the experimental analyses. The corrosion behaviour of the embossed sheets was assessed using potentiodynamic anodic polarisation tests, followed by corrosion surface morphology analysis. Results showed a microstructural evolution of the alloy during embossing, which is dependent on both the embossed pattern geometry and the roll forming direction. Nonsymmetrical displacement of material, in respect to the pattern geometry, was caused by the anisotropic forming pressure applied on the strip during roll forming, which yielded the formation of more susceptible sites for pitting and intergranular corrosion on the embossed aluminium surfaces.

Microstructure and Texture Evolutions During Deep Drawing of Mg-Al-Mn Sheets at Elevated Temperatures.

Texture and microstructure evolution of ingot and twin-roll casted Mg–Al–Mn magnesium sheets were examined during deep drawing at elevated temperatures. The twin-roll casted sheets possessed smaller grain sizes and weaker basal intensity levels than the ingot-casted sheets. The strength and elongation at room temperature for the twin-roll casted sheets were greater than those of the ingot-casted sheets. At elevated temperatures, the ingot-casted sheets showed better elongation than the twin-roll casted sheets. Different size and density of precipitates were examined using transmission electron microscopy (TEM) for both ingot-casted and twin-roll-casted sheets. The deep drawing process was also carried out at various working temperatures and deformation rates, and 30 mm/min to 50 mm/min, respectively. The middle wall part of cups were mainly tensile deformation, and the lower bent regions of drawn cups were most thinned region. Overall, the ingot-casted sheets revealed better deep drawability than the twin-roll casted sheets. Microstructure and texture evolution of the top, middle and lower parts of drawn cups were investigated using electron backscatter diffraction. Increased deformation rate is important to activate tensile twins both near the bent and flange areas. Ingot casted sheets revealed more tensile twins than twin-roll casted sheets. Increased working temperature is important to activate non-basal slips and produce the DRXed grain structure in the flange. Dynamic recrystallization were frequently found in the top flanges of the cups. Both tensile twins and non-basal slips contributed to occurrence of the dynamic recrystallization in the flange.

Role of Zn on the room temperature formability and strength in Mg–Al–Ca–Mn sheet alloys

We clarified the role of Zn on the mechanical properties and texture evolution in Mg-1.2Al-0.5Ca-0.4Mn-xZn (wt.%, x = 0, 0.8 and 1.6) alloy sheets fabricated by twin-roll casting and hot rolling. The room temperature stretch formability of the solution-treated sheet is improved with increasing Zn content, x. The Mg-1.2Al-0.5Ca-0.4Mn-1.6Zn alloy shows excellent stretch formability with the largest Index Erichsen value of 8.2 mm due to a weak transverse direction split texture. The development of the transverse direction split texture is attributed to the preferential nucleation of recrystallized grains at double twin boundaries promoted by the moderate segregation of Zn and Al. Subsequent artificial aging at 170 °C for 2 h (T6) leads to a substantial increase in strength without loss of ductility. The peak-aged Mg-1.2Al-0.5Ca-0.4Mn-1.6Zn alloy exhibits a high tensile yield stress of 210 MPa with an excellent elongation of 30.1% because of the dense dispersion of Guinier Preston zones within the Mg matrix. The insights gained in this work would establish a base for rational design and fabrication of bake-hardenable magnesium alloy sheet with excellent room temperature formability and high strength.

Microstructures and Mechanical Properties of Mg–xAl–1Sn–0.3Mn (x = 1, 3, 5) Alloy Sheets

The influence of Al alloying on the microstructures and the mechanical properties of Mg–xAl–1Sn–0.3Mn alloy sheets was investigated. The microstructure of Mg–xAl–1Sn–0.3Mn consisted of α-Mg and Mg17Al12 precipitates. Alloying with Al increased the amount of Mg17Al12 and the average grain size. Uniaxial tensile tests were carried out along the extrusion direction (ED), the transverse direction (TD) and 45° toward the ED. Mg–5Al–1Sn–0.3Mn alloy sheet exhibited the best combination of mechanical properties along the ED: a yield strength of 142 MPa, an ultimate tensile strength of 282 MPa and an elongation of 23%. The good performance of Mg–5Al–1Sn–0.3Mn sheet was mainly attributed to the large quantity of Mg17Al12 precipitates and a weak basal texture. Annealing caused static dynamic recrystallization, refined the grain size and enhanced the mechanical properties: yield strength of 186 MPa, ultimate tensile strength of 304 MPa, elongation of 21% along ED. Both strength and ductility were enhanced by Al alloying.

Twin nucleation, twin growth and their effects on annealing strengths of Mg–Al–Zn–Mn sheets experienced different pre-compressive strains

We combine pre-compressive test, annealing, re-compressive test, quasi-in-situ optical microscopy (OM), electron backscattered diffraction (EBSD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to systematically investigate the macroscopic yield strength differences (ΔASs) of Mg-1.5Al-1.0Zn-0.3Mn (AZM110, wt.%) sheets with different pre-compressive strains 2%, 4% and 6% after re-compression with annealing, respectively. We observe that with increasing the annealing time, ΔAS firstly increased and then decreased. Moreover, with the increase of pre-compressive strains, ΔAS peak value gradually decreased. Quasi-in-situ OM images reveal that the contribution of new twin nucleation increased and initial twin growth decreased for pre-compressed AZM110 sheets after re-compression with annealing. With the pre-compressive strains, the contribution of new twin nucleation gradually is weakened and initial twin growth is enhanced, which leads to the alteration of ΔAS. By the observation of HAADF-STEM, twin boundaries are stabilized by the segregation of Al and Zn solutes and nano-Al8Mn5 phases pinning, creating pre-compressive annealing strengthening (PCAS). With the annealing time, the disappearance of back stress and dislocation tangle decreases the PCAS effect. Pre-compressive strain also strongly influences the PCAS effect. The increasing volume fraction and width of twins observed from EBSD accelerate twin boundary motion (TBM) with pre-compressive strains from 2% to 4%, decreasing the PCAS effect after re-compression with annealing. Although increasing pre-compressive strain to 6% can put off TBM, low new twin nucleation rate still gives rise to the decreasing PCAS effect.

Effects of Hot Band Annealing on the Mechanical Properties of Cold-Rolled and Intercritically Annealed Medium Manganese Steels

The effects of intercritical annealing, before and after cold rolling, on retained austenite volume fractions, austenite stability, and tensile properties of a 7.39Mn-0.14C-1.55Al-0.2Si (wt pct) medium Mn sheet steel were evaluated. The extent of hot band annealing at 650 °C prior to cold rolling is shown to be an important parameter to consider in the development of processing histories leading to high strength–ductility combinations required for third-generation advanced high-strength steels.

Biogas detection on carbon nitride sheet with embedded Mn atom: dispersion-corrected density functional theory

This article investigates the structural, electronic and magnetic properties of three configurations of Mn embedded gCN1–Mn (s-triazine), gCN2–Mn (heptazine) and gCN3–Mn (C2N) sheets with adsorbed atoms () and molecules () via DFT + U calculations with the inclusion of van der Waals (vdW) corrections. Our results show that all the atoms and molecules chemisorb on the gCN1–Mn, gCN2–Mn and gCN3–Mn systems. The total magnetic moment of both sheets after adsorption could reduce or increase, depending on the spin state coupling of the unpaired electrons in the 3d orbitals of the Mn atom and the adsorbed atom/molecules and surrounding atoms. It is found that the semiconducting property of gCN1–Mn, gCN2–Mn, and gCN3–Mn are modulated into a wide band gap, metallic or half-metallic through the adsorption of atoms and biogas molecules. Based on our estimates, biogas molecules can be detected with high degree of sensitivity for the gCN1–Mn case where the electronic property predominantly changes into either metal or half-metallic. Moreover, the calculated values of adsorption energy numerically infer that gCN2–Mn, which has a less positive adsorption energy would have a shorter recovery time as compared to gCN1–Mn and gCN3–Mn.

The magnetic order of a manganese vanadate system with two-dimensional striped triangular lattice

Results of magnetization and neutron diffraction measurements of the manganese vanadate system Mn5(VO4)2(OH)4 are reported. The crystal structure of this compound contains triangular [Mn3O13] building blocks that produce two-dimensional Mn2+ magnetic networks with striped triangular topologies. The Mn sheets are connected through the nonmagnetic vanadate tetrahedra extending along the a-axis. Magnetization measurements performed on single crystals reveal the onset of a long-range antiferromagnetic order below approximately 45 K. The magnetic structure is Néel-type with nearest-neighbor Mn atoms coupled via three or four antiferromagnetic bonds. The magnetic moments are confined within the layers and are oriented parallel to the b direction. The magnitudes of ordered moments are reduced, presumably by geometrical frustration and the low-dimensionality of the lattice structure.

Influence of cold rolling on the precipitation in an Al–Mn–Zr alloy

Abstract The aim of the experiments was to study the influence of the rolling reduction (39, 87, and 96%) on the size and distribution of secondary particles and recrystallization behaviour of Al–Mn sheets with Zr addition prepared by twin-roll casting (TRC) in the industrial conditions. Samples, cold rolled on a laboratory mill, were subjected to a two-step precipitation annealing. Their microstructure (grain structure, substructure, particle analysis) as well as mechanical and physical properties (microhardness, electrical conductivity, resisitivity) were then characterized. The material cold worked with 39% reduction shows a moderate decrease of microhardness due to recovery, while sheets cold worked with 87 and 96% reduction soften more due to recrystallization. Regardless of the cold rolling reduction, the highest density of precipitates of α-Al(Mn,Fe)Si phase form during heating to 450 °C in the temperature range from 350 °C to 450 °C. Quantitative particle analysis of the sheets after the whole annealing cycle indicate that the alloy deformed 96% shows the highest density of particles in the size range from 50 to 140 nm. In addition, many spherical particles up to 15 nm were observed by transmission electron microscopy, some of them were identified by electron diffraction as Al 3 Zr phase with L1 2 crystal structure.

Stability of Retained Austenite Through a Combined Intercritical Annealing and Quenching and Partitioning (IAQP) Treatment

Intercritical annealing (IA) at various temperatures followed by quenching and partitioning (IAQP) treatments was conducted on a cold-rolled Fe–0.2C–1.42Si–1.87Mn (wt%) sheet steel. Optimized microstructure and enhanced mechanical properties were achieved through appropriate adjustment of IA temperatures. The steel which was annealed at 1,033 K for 600 s, then quenched to 573 K and partitioned at 693 K for 20 min, designated as 1033QP steel, exhibits maximum 16.3 vol% retained austenite (RA) with good mechanical properties (ultimate tensile strength 886 MPa and total elongation 27%). It was found that the thermal and mechanical stabilities of RA are mainly influenced by the combined effect of its average carbon content and amount of adjacent martensite. Furthermore, the transformation-induced plasticity effect increased the peak n-values observed at the second stage of the work hardening of IAQP steels.

Microstructure and Mechanical Properties of As-Rolled Mg-Zn-Gd-Ca-Mn Sheets

The Mg-(4,6)Zn-1Ca-1RE-0.5Mn magnesium alloy sheets were processed by hot rolling, and the effect of Zn concentration on the microstructure and mechanical properties was investigated using OM,SEM and XRD technique. The Mg-4Zn-1Ca-1RE-0.5Mn sheet exhibits excellent tensile properties at ambient temperature with ultimate tensile strength of 332MPa and elongation to failure of 4.5%. The notable mechanical properties were attributed to fine DRX grains and large deformed grains with intense basal texture.