Steels magnetic properties

EXAMINATION OF THE KINETICS OF MAGNETIC PROPERTIES IN TEMPERING STRUCTURAL STEELS WITH SPECIAL REFERENCE TO ACTIVE INSPECTION OF THEIR QUALITY by E.S. Gorkunov and I.n. Batuklitina, Vol. 23, No.3, pp. 177-183... 

Iron—Aluminum and Iron—Aluminum—Silicon Alloys. The influence of aluminum on the physical and magnetic properties of iron is similar to that of silicon, ie, stabilization of the bcc phase, increased resistivity, decreased ductility, and decreased saturation magnetization, magnetocrystalline anisotropy, and magnetostriction. Whereas Si—Ee alloys are well estabHshed for electrical appHcations, the aluminum—iron alloys have not been studied commercially. However, small (up to ca 0.3%) amounts of A1 have been added to the nonoriented grades of siHcon steel, because the decrease in ductiHty is less with A1 than with Si. 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

We have already mentioned some of the important roles that the d-block metals play in virtually every aspect of our lives. Steel, an alloy based on iron, is important in construction and transportation and the nonferrous alloys, those based on other metals—most notably, copper—are also important in industry, for their corrosion resistance and strength. Some of these alloys are also desired for their magnetic properties. 

Many other atom-probe analyses of different phases in different types of steels exist as steels are one of the most important materials. It is possible to investigate how the magnetic properties of alloys are correlated to the microstructures of different phases in the alloys.57,58,59 The chemical contents, growth process and structures of metallic carbides in different alloy steels have been studied with the field ion microscope and the atom-probe field ion microscope.60 61 62 63 We refer the reader to some of the original papers published on these subjects. 

Grade S Density Surface area Surface finish Surface protection Magnetic properties Corrosion resistance Hardness 7.7-8.1 g/cm3 (for 50 mg and larger) Not to exceed that of a cylinder of equal height and diameter Highly polished None permitted No more magnetic than 300 series stainless steels Same as 303 stainless steel At least as hard as brass... 

Silicon in the form of ferrosilicon is used in large quantities as a deoxidizing agent in steel manufacture. Silicon steel alloys are utilized as dynamo and transformer plates due to their soft magnetic properties, as machine tool steels, as spring steels and as corrosion resistant casting steels for chemical plant. 

Properties Steel-gray, shining, hard, ductile, somewhat malleable metal ferromagnetic, with permeability two-thirds that of iron has exceptional magnetic properties in alloys. D 8.9, mp 1493C, bp 3100C. Attacked by dilute hydrochloric and sulfuric acids, soluble in nitric acid. Corrodes readily in air. Hardness cast 124 Brinell, electrodeposited 300 Brinell. An important trace element in soils and necessary for animal nutrition. Cobalt has unusual coordinating properties, especially the trivalent ion. Noncombustible except as powder. 

Typical concentration range generally >40 wt% calcium carbonate, calcinated kaolin, talc - 20-40 wt% carbon fiber 5-30% (depending on aspect ratio) " titanium dioxide - 1 wt% (occasionally concentrations of 10 wt% are found in thin sections) " ferromagnetic powder - up to 90 wt% " stainless steel fiber - 2-3 wt% " nickel fibers for magnetic properties -10-30% starch in biodegradable products - 4-8 wt% ... 

In alloy steels, iron is mixed with carbon and varying amounts of other elements, mainly metals. Added metals produce desired properties such as hardness and corrosion resistance (Cr), resistance to wear (Mn), toughness (Ni), heat resistance (W and Mo), and springiness (V). Stainless steel is a well-known, corrosion-resistant alloy steel. It contains ten to 30 percent chromium and sometimes nickel and/or silicon. Because of its outstanding magnetic properties, Alnico steel is used to make permanent magnets. Alnico magnets are used in voltmeters and ammeters to rotate the cod of wire connected to the pointer. 

Steel can be further improved by the addition of other elements to make alloys. Nickel and chromium are used to make stainless steel. Molybdenum, vanadium, tungsten, cobalt, titanium and other elements may be added to improve hardness, strength, or magnetic properties. 

Alloy steels (low alloy steels) contain up to 5% of elemental additions, in addition to carbon and manganese. Alloying enhances mechanical properties, machinability, abrasion resistance, hardenability, corrosion resistance, magnetic properties, etc. Alloy steels are favored over carbon steels for demanding applications in components where significantly higher strength and hardness are required. Examples of common alloy steels include ... 

Magnetic properties of some metals may change with their mechanical history. For example, 302 and 304 stainless steels are nonmagnetic in the annealed (soft) condition, but become increasingly magnetic as they are cold worked. 

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