Amount Of Cold Reduction Research Articles

Influence of production methods on creep deformation of cold rolled 329LA lean duplex stainless steel in continuous annealing condition

The effects of processing methods, line tension, cold reduction and temperature on creep deformation of 329LA lean duplex stainless steel under continuous annealing condition are investigated. Two different processes, conventional continuous casting followed by hot rolling process and strip casting process, were used to make steel plates. Creep tests were carried out at 1010°C up to 1100°C using cold rolled specimens with various cold reductions for both kinds of specimen. It was found that continuous cast specimens show higher strain rate than strip cast specimens when tested with the same cold reduction and stress condition at all temperatures. Creep strain rate increases with the increase of line tension, temperature and the amount of cold reduction. The measured strain rate sensitivity values (m), around 0.5, show the superplastic behavior of both continuous and strip cast specimens at all test conditions, while the stress exponents (n), around 2, are consistent with the model of grain/phase boundary sliding as the rate controlling mechanism. The strip cast specimen has a very inhomogeneous microstructure which leads to larger average grain size, while the continuous cast specimen shows a uniform distribution of ferrite (δ) and austenite (γ). Electron back scattered diffraction (EBSD) results show that cold rolled texture is destroyed during heating to deformation temperature and δ/γ interface becomes high angle boundary which slides easily. Lastly, phase boundary sliding during creep deformation was confirmed by scanning transmission electron microscopy (STEM) in both specimens.

Effect of Thermomechanical Parameters on Texture of 90-10 Brass Sheets

Optimized conditions of hot and cold rolling followed by annealing can result in a balance between recrystallization and rolling textures in order to reduce the planar anisotropy of brass sheets. In this work, the effect of finish rolling temperature, cold reduction and annealing temperature on texture development has been investigated. It is shown that uniform deformation at higher finishing temperature is responsible of formation of a severe Cube and G texture components. In contrast, mechanical twinnings are widely formed at low finishing temperatures. There is also a direct relation between the intensity of Cube component and the amount of cold reduction.

Effect of cold reduction on the magnetic properties of a nonoriented, low silicon electrical steel

The effect of cold reduction on the magnetic properties of a nonoriented, low silicon electrical steel was investigated in the laboratory and in the mill. Both the hot band gauge as well as the cold band gauge were varied to obtain various cold reductions ranging from 57 to 80%. Magnetic test results from coil centers show that, at a given cold band gauge, core loss is independent of percentage of cold reduction for both mill and laboratory processed samples. Relative permeability, on the other hand, shows a functional relationship with the amount of cold reduction and the relationship varies with cold band gauge. For all cold band gauge, permeability initially improves with increasing cold reduction and this improvement is partially attributed to an increased coiling temperature due to hot band gauge increase. It is also observed that permeability measured from coil ends is substantially lower than that from coil center due to coil end effects. Possible cause and remedy of coil end effects are discussed.

A Material for Tubing and Casing Applications in Deep, Sour Gas Wells

Introduction Multiphase MP35N is a nickel-cobalt-base alloy containing 35-percent nickel, 35-percent cobalt, 20-percent chromium, and 10-percent molybdenum that is produced by double vacuum melting. MP35N exhibits a produced by double vacuum melting. MP35N exhibits a unique combination of ultrahigh strengths, good ductility, and excellent corrosion resistance. Multiphase MP35N develops yield strengths of 150 to 250 ksi with 10- to 25-percent elongation by cold working and aging. Mechanical property data for large bars and tubing are presented. Corrosion test results show excellent resistance to cracking in H2S environments. Testing by a number of oil companies has resulted in very high interest in this alloy for such applications as down-hole tubing and casing in deep, sour well environments and for valve cores exposed to H2S. Presently, this alloy is being used successfully for Presently, this alloy is being used successfully for cables to suspend instrument packages in sour wells. Metallurgy At high temperatures MP35N has an austenitic face-centered cubic (FCC) structure. Although a hexagonal close-packed (HCP) structure is stable below about 800 deg. F, this transformation is so sluggish that the FCC structure remains after cooling to room temperature. Subsequent cold working results in the formation of thin, coherent HCP platelets in the metastable FCC matrix. The coherency of the platelets strains the lattice and results in strengthening. The amount of strengthening (transformation) depends on the amount and, to a lesser degree, the temperature of deformation. Further strengthening can be achieved by aging, which results in precipitation of a Co3Mo compound at the interfaces between the FCC matrix and the HCP platelets. In the annealed condition (Table 1) MP35N exhibits moderate strengths and very high ductilities. The effect of cold reduction (by drawing) and aging on the room-temperature tensile properties of MP35N is shown in Fig. 1. For fastener applications (bar sizes of 0.2 to 1.3 in.), cold reduction is designed to provide an ultimate minimum tensile strength of 260 ksi, a 0.2-percent minimum yield strength of 240 ksi, and ductility minimums of 8-percent elongation and 35-percent reduction of area after aging at 1,100 deg. F. Note also that the properties of MP35N can be controlled over a wide range by adjusting the amount of cold reduction. Properties obtained from large-diameter bars are shown in Table 2. The two larger bars were produced by cold Pilgering rather than by cold drawing. Note that, after equivalent amounts of cold work, the material reduced by drawing exhibits higher strengths than the Pilgered material. TABLE 1 -- TYPICAL ANNEALED PROPERTIES OF MP35N Tensile strength, ksi 135 0.2-percent yield strength, ksi 60 Elongation in four dimensions, percent 70 Reduction of area, percent 70 Hardness 90 to 100 Rb Charpy V-notch impact, ft lb 2,001 JPT P. 705

Effect of two-stage cold rolling and annealing on texture development and plastic strain ratio

AbstractRecrystallization textures developed during two-stage cold rolling and annealing have been studied in an aluminium-stabilized steel by means of an inverse pole figures technique. An intensity parameter involving a combination of reflections, has been related to the average plastic strain ratio, R. The results show that the amount of cold reduction in the first stage has a greater effect on texture than the rolling in the second stage. Nevertheless, the second stage may have some important effects. Suppression of the {100} and intensification of the {111} and {211} components are of particular interest, but these are significant only if a strong {111} texture has already been produced in the first stage. The most important factor which controls the texture development is the distribution of reductions between the two stages. Combination of rolling and annealing in two stages with high reduction in the first and low in the second stage may produce not only as strong a texture and as high an R value ...

Deformation structure and the tensile fracture characteristics of a cold worked 1080 pearlitic steel

The tensile mechanical properties, deformation structure, and tensile fracture characteristics of a 1080 perlitic steel were examined at various reduction ratios of cold work. The final tensile fracture ductility exhibited an unusual behavior in that this parameter first decreased and then increased with increasing reduction ratio. At a reduction ratio of 1.92, the cold worked material exhibited greater tensile ductility than the as-heat treated material even though the yield strength was greater by more than 400 pct. Microscopic regions of structural damage in the form of shear bands were observed at all reduction ratios, but appeared to become less detrimental to the subsequent tensile ductility as the reduction ratio increased. The fracture mode observed on the broken tensile specimens changed from predominantly cleavage to completely fibrous as the amount of cold reduction was increased. These observations are thought to result from a complex interaction between the interfacial strength of the shear bands, interlamellar spacing and texture effects and the stress state during deformation.

Microstructural stability of thermal-mechanically pretreated type 316 austenitic stainless steel

Studies of the microstructural stability of Type 316 austenitic stainless steel were performed for a wide range of thermal-mechanical pretreatments in the limited aging temperature range of 550° to 760°C. The pretreatments were selected in order to investigate the effects of varying solution treatment temperature, amount of cold reduction by rolling, initial grain size, and initial precipitate distribution. Large variations in both phase stability and recrystallization behavior can be effected by appropriate pretreatments. Cold work accelerates precipitation of M23C6 carbide and the intermetallic compounds (Laves, χ, and σ phases). Both the amount and kinetics of σ phase formation are especially enhanced by recrystallization occurring in the aging temperature range. It is suggested that this occurs due to ready σ nucleation at slowly moving (recrystallizing) grain boundaries together with enhanced growth rates due to diffusion along the boundary. Fine grain size enhances phase instability by providing additional nucleating sites and decreased diffusion paths for precipitate forming elements, but in the grain size range studied (ASTM No. 3.5 to No. 13) the effect is not as significant as the effect of cold work, particularly when recrystallization occurs during the aging treatment. Fine grain size and pretreatments which precipitate the carbides prior to the final cold working step enhance recrystallization kinetics relative to solution treated and cold-worked materials. This is apparently due to stabilization of the cold-worked substructure in the solution treated samples by precipitation of carbide and Laves phases on the dislocations and stacking faults.

Influence of Cold-Reduction and Heat-Treatment Combinations On Hydrogen Solubility and Permeability in Steel

Abstract Tests were made to determine the effect of cold reduction on hydrogen solubility in steel. It was found that this direct relationship persisted through subsequent heat-treatment and later cold reduction. This was not true, though, of hydrogen permeability. Increasing the amount of cold reduction increased the hydrogen solubility. Increasing the amount of cold reduction also increased the hydrogen permeability until a maximum was reached (below 30 percent reduction for initially hot-rolled steel), after which the permeability decreased as the amount of cold work increased. 3.7.3