Cold-rolling

ELECTROMAGNETIC MONITORING OF MICROSTRUCTURE AND MECHANICAL PROPERTIES FOR COLD-ROLLED 12Kh2MFSR STEEL TUBE by V.A.Burganova, L.V. Kochman, V.A. Kuz mina and L.P. Chukanova, Vol.10, No. 4, 1974, pp. 432 -437... 

The development of a sharp COE texture in the finished strip requires complex control of numerous variables. The conventional commercial process (18) involves hot-rolling a cast ingot at ca 1370°C to a thickness of about 2 mm, annealing at 800—1000°C, and then cold-rolling to a final thickness of 0.27—0.35 mm in two steps of 70 and 50%, respectively, with a recrystallization (800—1000°C) aimeal in between. The cold-roUed strip is decarburized (800°C) to ca 0.003% C in mixtures of wet results in a primary recrystallized stmcture containing grains of the COE... 

Miscellaneous Methods. Powdered metals such as aluminum, chromium, nickel, and copper, along with various aHoys, can be appHed to parts by electrostatic deposition. The metal strip containing the attached powdered metal must be further processed by cold rolling and sintering to compact and bond the metal powder. 

Measurement of Residual Stress and Strain. The displacement of the 2 -value of a particular line in a diffraction pattern from its nominal, nonstressed position gives a measure of the amount of stress retained in the crystaUites during the crystallization process. Thus metals prepared in certain ways (eg, cold rolling) have stress in their polycrystalline form. Strain is a function of peak width, but the peak shape is different than that due to crystaUite size. Usually the two properties, crystaUite size and strain, are deterrnined together by a computer program. 

Mixed with trap rock and asphalt flux to obtain mix for cold rolling as pavement surfacing. 

Cathodes Hot rolled and cold rolled to produce strip and sheet... 

Most wrought alloys are provided in conditions that have been strengthened by various amounts of cold work or heat treatment. Cold worked tempers are the result of cold rolling or drawing by prescribed amounts of plastic deformation from the annealed condition. Alloys that respond to strengthening by heat treatment are referred to as precipitation or age hardenable. Cold worked conditions can also be thermally treated at relatively low temperatures to affect a slight decrease in strength (stress rehef annealed) to benefit other properties, such as corrosion resistance and formabiUty. 

Sheet and Strip. The manufacture of wrought copper materials starts with either semicontinuously cast slabs that are hot roUed, or cast plate that is thin enough, near 13 mm (0.5 in.), to be cold roUed directly. The surfaces of both hot roUed slabs and as-cast plate are milled to remove defects before proceeding to cold rolling and annealing operations. 

Strengthening by cold rolling is accompanied by decreased ductUity. A softening heat treatment is needed when ductUity is lowered to below levels required by subsequent processing. Annealing treatments are done interchangeably as batch or continuous operations. 

The effect of cold working by cold rolling of sheet on the yield, at 0.2% offset strain, and tensile strengths of copper sheet is shown in Figure 1. 

Fig. 1. The effect of cold rolling upon the tensile properties of unalloyed copper (CllO) (—) represents tensile strength (-...

Fig. 2. Comparison of alloy cold rolling behaviors (—) represents unalloyed copper (CllO) having a grain size of 25 p.m ([[2tb2h]]) and ( ),...

To meet this requirement, the use of steel with a still better silicon content and lower losses is imperative. A cold-rolled non-grain oriented (CRNGO) type of sheet steel is generally used for such applications, in the thickness range of 0.35-0.5 mm, with a higher silicon content of the order of 2.0-1.8% and losses as low as 1.0-1.5 W/kg. 

Heavily scaled and heavily rusted surfaces (hohrotled sheets) Heavily scaled, but mildly rusted-surfaces (hot-rolled sheets) Mildly scaled and mildly rusted surfaces (cold-rolled sheets) ... 

This is a process to remove heavy black scale and rust from the surface. Hot-rolled sheets that may have such scale formation need only be acid pickled. Cold-rolled sheets, which may carry no such scales, need not be acid pickled. Depending upon the type of surface, one of the following methods may be adopted. 

Hot-roHed or cold-rolled acid-hased nisi solveni)... 

Cohl type solvent Cold-rolled sheers... 

The torque required to drive the rolls increases with yield strength so hot-rolling (when CTy is low - see Chapter 17) takes less power than cold-rolling. It obviously increases with the reduction in section (t - t2). And it increases with roll diameter 2r this is one of the reasons why small-diameter rolls, often backed by two or more rolls of larger diameter (simply to stop them bending), are used. 

Demonstrations Take a strip — 0.25 mm X 1 cm X 15 cm of cold-rolled (work-hardened) brass and bend it (on edge) on the overhead until permanent deformation takes place. Anneal brass strip at bright red head for — 0.5 min to soften it. After cooling replace on overhead and show that permanent deformation takes place at a much smaller deflection than before. This illustrates the importance of large Uy in springs. 

Work hardening is achieved by cold rolling. The yield strength increases with strain (reduction in thickness) according to... 

Cold rolling - Copper and eopper alloys Cold rolling - Aluminium alloys... 

COLD ROLLING PROCESS CAPABILITY MAP FOR ALUMINIUM ALLOYS... 

Because of the low glass transition temperature it is not possible to make clear film, stable at room temperature, by quenching. Some improvement in clarity may be obtained by cold rolling as this tends to dispose the crystal structure into layers (see Chapter 6). 

Provided due care is taken with respect to predrying and to crazing tendencies, polycarbonates may also be thermoformed, used for fluidised bed coating and machined and cemented. Like metals, but unlike most thermoplastics, polycarbonates may be cold formed by punching and cold rolling. Cold rolling can in fact improve the impact resistance of the resin. 

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