Effects of Magnetic Field Direction on γ‐fiber Texture Evolution in Cold‐rolled Interstitial‐free Steel Sheet during Annealing

The effects of magnetic field direction on γ‐fiber texture evolution in as‐annealed interstitial‐free (IF) steel sheet were investigated by means of X‐ray diffraction ODF analysis. Specimens cut from cold‐rolled IF steel sheets were placed at the center of a 12‐T magnetic field, tilted by different angles to the magnetic field direction respectively, and annealed at 750 °C for 30 min. The results show that altering the specimen orientation to the magnetic field direction during annealing does not change the final annealing textures. The average intensity of the γ‐fiber texture of specimens annealed under the magnetic field is higher compared to conventionally annealed specimens. The intensity of the main γ‐fiber texture components presents a similar periodic variation with respect to the specimen orientation to the magnetic field, i.e., it is weakened as the tilt angle increases from 0°, and subsequently strengthened to a maximum value at 45°, and then weakened again as the tilt angle continues to increase. When the magnetic field is applied in the direction perpendicular to the specimen's rolling plane, the intensity of the main γ‐fiber texture components of specimens annealed in the magnetic field is close to that of the specimen annealed without field. This phenomenon might be attributed to the demagnetic effect.     

Formation of magnetic anisotropy in amorphous Fe–Ni–B–Si alloys

The influence of annealing at 520°C on the saturation magnetic field and coercive force of amorphous 2NSR Fe–Ni–B–Si alloys is investigated. As a result of annealing, the saturation magnetic field reaches 1000–1800 Oe. Regions of short-range order (clusters) with a direction in which the atomic pairs are ordered are thought to be formed in the alloys. The formation of the coercive force in amorphous 2NSR alloys is described.     

X-ray study of the decomposition of metastable Al-rich Al-Fe solid solutions

The extension of the solid-solubility limit obtained in Al-Fe alloys up to 4.4 at. pct Fe by rapid quenching from the melt and the appearance of metastable Al₆Fe phase for 4 to 20 wt pct Fe have been reported in the past. Present experiments with isochronal and isothermal annealing of Al-Fe solid solutions containing 3.6 at. pct Fe have shown that the solutions are very stable at room temperature, and less stable at 200°C, while at 300°C they decompose very rapidly and a metastable Al₆Fe phase appears. This phase is replaced by Al₃Fe after annealing for 10 min at 550°C or for 16 hr at 400°C. The Al₆Fe phase remains stable for 76 hr at 300°C, while taking more than 670 hr to be replaced by Al₃Fe. The author discusses the operation of the “two-piston” quenching apparatus and concludes that the sample thickness cannot serve as a sufficient criterion for quenching effectiveness.     

Effects of magnetic annealing on crystallization and magnetic properties of Nd2Fe14B/α-Fe nanocomposite magnets

Crystallization and magnetic properties of Nd₂Fe₁₄B/α-Fe nanocomposite magnets have been investigated by annealing the as-spun ribbons with magnetic field. The crystallization process was accelerated by field annealing. The hysteresis loop became to be fat by magnetic annealing at 645 °C for 4 min, which was 690 °C for ribbons annealing without magnetic field. The relative content of α-Fe phase was increased from the results of XRD. The strength of the magnetic field had no obvious influence on the remanence and coercivity, but modified the squareness of hysteresis loop.     

Investigation on Recrystallization Behavior of Cold-Rolled Silicon Steel in Continuous Heating with Three-Point Bending Testing

Understanding the recrystallization behavior of cold-rolled silicon steel during continuous heating is essential for optimizing continuous annealing parameters and accurately controlling material performance. To address the limitations of isothermal annealing studies in interpreting actual continuous annealing processes, this study investigates the recrystallization kinetics of Fe–2.3 wt%Si steel using a continuous heating three-point bending method. The method effectively determines the characteristic recrystallization temperatures. Interestingly, these recrystallization characteristic temperatures remain unaffected by the initial load but shift toward higher temperatures with increasing heating rates in the range of 5–15 °C min⁻¹. The average activation energy of recrystallization is estimated to be 144.5 kJ mol⁻¹, comparable to the value of 147.0 kJ mol⁻¹ obtained from the isothermal process through microhardness measurement. The recrystallization kinetics, described by an extended version of the Ozawa–Flynn–Wall model, exhibits excellent agreement with experimental evaluations. By combining the present processing technologies with continuous heating recrystallization kinetics, different recrystallization temperatures and times can be determined, offering valuable insights for optimizing annealing processes.     

Textural changes during recovery annealing of a heavily cold-rolled Fe–Mn–Al–Si–C alloy

A heavily cold-rolled (80%) high manganese austenitic steel was subjected to isochronal and isothermal heat treatments, in order to study the texture development during the recovery stage. Progress of recovery was negligible after annealing at 500°C for 60?min, but annealing for 60?min at 800°C led to complete recrystallisation, and appearance of the final texture was very similar to that of a copper type deformation texture. Isothermal heat treatments at 600°C revealed that at the very early stage of recovery, there was a weakening of brass type deformation texture, but it was followed by a sharpening of Bs component. At the same time, there was a shift of peak intensity towards Bs/Goss location. After this stage of intermediate sharpening, the texture sharpness experienced a continuous weakening with further progress of recovery.     

Breakdown of primary grain boundary inhibition in 3 pct si-fe sheet

Grain boundary inhibition in 11-mil cold rolled decarburized 3 pct Si-Fe sheet was observed to break down by isothermal annealing at temperatures in excess of 1075°C. Small MnS particles (-r < ~260Å) responsible for inhibiting primary grain growth in this material were observed to undergo complete dissolution within 3 min at temperatures of 1100°C and higher. Calculated dissolution rates were in good agreement with this observation. The dissolution of these particles produced appreciable primary grain growth during the early stages of (110)[00l] secondary recrystallization which was responsible for an overall reduction in the volume percent of (H0)[00l] grains produced on prolonged isothermal annealing at temperatures above 1075°C.     

Effects of boron doping on the grain-growth kinetics and mechanical properties of γ/γ′ nickel-aluminum alloys

The effects of 0.5 at. pct of boron doping on the microstructures and mechanical properties of γ/γ′ nickel-aluminum alloys have been investigated in the present study. A nickel-rich grain-boundary zone was observed in the boron-doped alloy after homogenization at 1100 °C and prolonged annealing at 1200 °C. Boron doping also caused remarkable improvements in toughness and tensile elongation and caused the fracture mode to change from completely intergranular to completely transgranular. The grain growth following recrystallization at 1200 °C was found to be retarded upon boron doping. A sudden increase in tensile elongation and a sudden drop in hardness were also observed upon prolonged heating during isothermal annealing at 1200 °C. The results are interpreted with reference to boron-nickel cosegregation at the grain boundaries.     

Effect of Magnetic Field Intensity on Microstructure and Orientation of Proeutectoid Ferrite in Fe‐0.76%C Alloy

Effect of high magnetic field annealing on microstructure and orientation of proeutectoid ferrite in Fe–0.76%C alloy was investigated. It was found that the high magnetic field increases the number of proeutectoid ferrite grains considerably, and the elongation tendency of proeutectoid ferrite grains along the magnetic field direction is increased by the applied magnetic field, too. These effects increased with the enhancement of magnetic filed intensity. Crystallographic orientation analysis by EBSD showed that no preferential orientations exist in the proeutectoid ferrite when applied a magnetic field with different intensity. Possible reasons of the above phenomena were discussed in the paper.     

Relation between the structure and the pitting corrosion resistance of hypereutectoid U10 steel

Polarization pitting corrosion tests are used to investigate the effect of a structure on the corrosion resistance of hypereutectoid U10 steel. In the steel structure, coarse-lamellar and fine-lamellar pearlite forms as a result of isothermal decomposition at temperatures of 500 and 650°C and fine-lamellar pearlite forms during additional annealing at 650°C for 10 or 300 min. The nonequilibrium structure of fine-lamellar pearlite obtained in the process of isothermal decomposition at a temperature of 500°C is found to have the maximum pitting corrosion resistance among the structural states under study.     

Effect of Heating Rate on the Austenite Formation in Low-Carbon High-Strength Steels Annealed in the Intercritical Region

Austenite formation during intercritical annealing was studied in a cold-rolled dual-phase (DP) steel based on a low-carbon DP780 composition processed in the mill. Two heating rates, 10 and 50 K/s, and a range of annealing temperatures from 1053 K to 1133 K (780 °C to 860 °C) were applied to study their effects on the progress of austenitization. The effect of these process parameters on the final microstructures and mechanical properties was also investigated using a fixed cooling rate of 10 K/s after corresponding annealing treatments. It was found that the heating rate affects the austenite formation not only during continuous heating, but also during isothermal holding, and the effect is more pronounced at lower annealing temperatures. Faster heating delays the recrystallization kinetics of the investigated steel. The rate of austenite formation and its distribution are strongly influenced by the extent of overlapping of the processes of recrystallization and austenitization. It appeared that the heating rate and temperature of intercritical annealing have a stronger effect on the final tensile strength (TS) of the DP steel than holding time. Both higher annealing temperatures and long holding times minimize the strength difference caused by a difference in heating rate.     

Coercive force and microstructure in a Zr-permalloy

An alloy containing 80.0 pct Ni, 12.65 pct Fe, 6.74 pct Mo, 0.36 pct Zr, and 0.25 pct Mn by weight was cast, homogenized, and successively cold rolled into thin strips with area reductions of 0, 50, 75, and 90 pct. Annealed samples were studied by optical and electron microscopy, electron diffraction, and magnetic testing to determine the effects of cold work and annealing upon the microstructure and magnetic properties of the alloy. Cold work produced a high initial hardness together with high coercive force. Recrystallization of the cold worked structures occurred upon annealing at 600°C (873 K) and above and caused significant and parallel decreases in hardness and coercive force. The activation energy for recrystallization was found to be 80.5 kcal/g mole (337.0 kJ/g mole) for the 50, 75, and 90 pct cold worked specimens. After annealing at 600°C (873 K), a small number of spherical Ni₄Mo particles were observed, but the particles produced little change in magnetic properties apparently because of their relatively coarse size and large spacing. Beginning at 700°C (973 K) ribbon-shaped particles of a Ni₅Zr intermetallic compound also precipitated out of solid solution. Both the Ni₄Mo and Ni₅Zr precipitates were the result of a homogeneous continuous precipitation reaction within the grains. A peak in coercive force at 800°C (1073 K) is attributed to domain wall pinning associated with the fine distribution of rodlike Ni₅Zr particles. Cold working 90 pct and aging at 800°C (1073 K) was found to increase coercive force by almost 60 pct from the minimum produced by complete recrystallization. Annealing, however, decreased hysteresis and improved squareness.     

Crystallization of an Fe-Ni base amorphous alloy

The crystallization of an amorphous Fe-Ni base alloy was studied in a dynamic heating mode from room temperature to 700°C and during isothermal annealing at 400°C. Differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, and hardness measurement were used to characterize the crystallization process under two heating conditions. In the dynamic heating condition, structural relaxation or atomic regrouping was thought to occur belowT _c. AboveT _c, crystallization occurred spontaneously and four crystalline phases were formed. The number of phases and the relative amount of these phases varied with the heating temperature. At a higher temperature, recrystallization occurred which resulted in grain growth. The final matrix phase was observed to coexist with other phases after crystallization. In the isothermal heating condition, it was found that the transformation of the alloy from amorphous state to crystalline state was through the nucleation and growth process. The first crystallization steps were via the formation of metastable phases. The final matrix phase than nucleated from the existing metastable phases. Hardness measurements in both heating conditions indicated that the alloy attained its peak hardness immediately after complete crystallization.     

Kinetics of texture development and sulfur removal in oriented silicon iron

The kinetics of (110)[001] secondary grain growth, the temperature dependence of selectivity to a (110)[001] texture, and the kinetics of desulfurization in cold rolled-decarburized, thin sheet (semiprocessed 3 pct Si?Fe) were measured as were the parameters requited to produce (110)[001] grain-oriented sheet by high temperature strip annealing. Kinetic studies revealed that (110)[001] grain growth in several semiprocessed sheets exhibited the following characteristics: 1) sigmoidal growth kinetics; 2) an activation energy of ～64 Kcal; and 3) essentially complete (110)[001] secondary grain growth within 8 min at temperatures of 1000°C and higher. Measurements of magnetic torque properties and pole figures of isothermally annealed semiprocessed sheet showed a degradation in selectivity to a (110)[001] texture above 1050°C. Desulfurization kinetics were in good agreement with a theoretical diffusion model which takes into account sulfur removal in the presence of a dispersed second phase of MnS particles. A two-stage high temperature strip annealing cycle in dry hydrogen produced (110)[001] grain-oriented sheet having magnetic properties comparable to those obtained by conventional box annealing.     

Microstructural Changes by Annealing in Ultrafine-Grained Electrodeposited Pure Iron

In situ neutron diffraction during annealing was performed for ultrafine-grained as-deposited and cold-rolled pure iron. Changes in the integrated intensity and full-width at half-maximum in the diffraction profiles during annealing were measured. EBSD measurements were performed before and after annealing to obtain microstructural change. Abnormal grain growth was clearly found at 673 K (400 °C) upon annealing; this observation corresponds to the hydrogen desorption behavior of the as-deposited specimen. The texture changes from {111}〈hkl〉 to {211}〈hkl〉 between 673 K and 873 K (400 °C and 600 °C) upon continuous heating. Such a texture change is postulated to decrease the Lankford value from 7.6 to 2.2. The 40 pct cold-rolled specimen exhibited a complicated textural evolution upon annealing, which was caused by the intrusion of recrystallization at deformation bands.     

Recrystallization of W-1 wt pct ThO2 wire

The recrystallization behavior of W-l wt pct ThO₂ wires of two sizes, 0.457 and 0.178 mm (18 and 7 mil), was studied using optical microscopy, transmission electron microscopy, hardness, and resistivity ratio techniques. For the 0.178 mm wire the effects of heating rate were also analyzed. Recrystallization of the 18 mil wire is characterized by rather gradual changes in hardness, resistivity ratio, and microstructure leading to a small recrystallized grain size. The 0.178 mm wire, on the other hand, exhibits more abrupt changes in resistivity ratio and hardness which coincide with the development of a recrystallized structure having a large grain-size range. Variation of heating rates between about 150,000°C/min and 500°C/min did not significantly affect the grain structure or hardness achieved for annealing temperatures of 2000°, 2500°, and 2700°C. However, very slow heating rates, less than 10°C/min, were shown to prevent the formation of large grains in the 0.178 mm wire. These results are explained on the basis of differences in the effectiveness of ThO₂ particles in hindering grain boundary motion.     

The system Ag−Fe−S: Phase relations between 1200° and 700°C

Phase relations in the system Ag?Fe?S between 1200° and 700°C were studied at the vapor pressures of the system by quenching and D.T.A. experiments with the use of sealed, evacuated, silica tubes as reaction vessels. Only liquids and binary solids were encountered in this temperature interval. Two extensive liquid-immiscibility fields are present above 906°C; microtextures developed from the metal-rich immiscible-liquid field are illustrated. Condensed isothermal diagrams at 1200° and 700°C are presented, and reactions occurring between these temperatures are discussed.     

Effect of Isothermal Bainite Treatment on Microstructure and Mechanical Properties of Low‐Carbon TRIP Seamless Steel Tube

In this work, a low‐carbon transformation‐induced‐plasticity (TRIP) seamless steel tube (Fe–0.15C–1.34Si–1.45Mn–0.029Nb–0.024Ti, in wt%), having potential in application of hydroforming process, has been successfully manufactured by using piercing, cold‐drawing, and two‐stage heat‐treatment process. The optimal heat‐treatment conditions, inter‐critical annealing (IA), and isothermal bainite treatment (IBT) were firstly obtained to maximize the volume fraction and stability of the retained austenite (RA). The effects of temperature and holding time IBT on the microstructures of the TRIP steel tube were studied via optical microscopy (OM), scanning microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffractometer (XRD). The mechanical properties in the axial direction and hydroformability were also evaluated by conventional tensile test and flaring test, respectively. Two‐stage heat‐treatment was finally performed to achieve the required mechanical properties for the hydroformed tube. The results shows that the RA volume fraction increased at first and then decreased with the increase of IBT holding time and IBT temperature for a particular set of IA temperature and IA holding time. It was also demonstrated that high tensile strength of 618 MPa, total elongation of 35.5%, n‐value of 0.23, and better hydroformability could be successfully produced in this TRIP steel tube at IA temperature of 800°C, holding for 10 min, and IBT of 410°C for 4 min holding time.     

Sintering High Tungsten Content W-Ni-Fe Heavy Alloys by Microwave Radiation

This paper presents a detailed study of microwave (MW) sintering of W-Ni-Fe heavy alloys (WHAs) with tungsten (W) content 90 to 98 mass pct (Ni and Fe mass ratio of 7 to 3) in comparison with conventional (CV) hydrogen sintering. Experimental results show that WHAs were MW sintered to fully dense (≥99 pct of theoretical) when heated to sintering temperatures at a heating rate of 50 K/min to 80 K/min (50 °C/min to 80 °C/min) and isothermally held for 2 to 10 minutes, with sintering cycle times of only 25 to 35 minutes (excluding the cooling time). The desired microstructures of finer W grains, more matrix phases, and lower W contiguity (in 95W and 98W) were produced compared to the counterparts by CV sintering. Such microstructural features offered the alloys excellent tensile properties: ultimate tensile strengths (UTS) 1080 to 1110 MPa and tensile elongation 22.1 to 26.8 pct in 90 to 95W, and UTS 920 MPa and elongation 11.2 pct in 98W. MW sintering appeared to be more effective in fabricating WHAs with W content ≥95 pct. It was observed that the superior UTS with MW-sintered alloys was mainly due to the fast heating and shortened isothermal holding times. Prolonged sintering led to substantial grain coarsening as a result of faster tungsten grain growth in MW sintering, and consequently deteriorated the tensile properties. The grain growth rate constant K achieved was calculated to be 5.1 μm³/s for MW sintering compared to 2.9 μm³/s for CV sintering. Fast heating and short isothermal holding times are thus suggested for the fabrication of WHAs by MW sintering.