Medium-carbon alloy steels

SAE J429 Grade 7 See Note 4 Bolts, screws Medium carbon alloy steel, quenched and tempered... 

The dies themselves are generally constructed of medium carbon alloy steels, with flame-hardened lips and chrome or nickel plating on the flow surfaces. Insulation of the die body Is common to prevent temperature variations that could result from air drafts. Dies can be electrically heated, or steam or oil heat can be used. Cooling is usually provided by natural convection, though forced air can also be used. 

Usually flat film and sheet dies are constructed of medium carbon alloy steels. Die flow surfaces are chrome-plated to provide corrosion resistance. The exterior of the die is usually flash chrome-plated to prevent rusting. Where chemical attack can be a severe problem (with PVC, etc.), various grades of stainless steel are used (Tables 2-4 and 2-8). 

Medium-carbon alloy steels lCr-0.35Mo-0.25V steel 7.86... 

The mechanical properties of low- or medium-carbon structural steels can be improved considerably by small alloy additions. For example, 1% of chromium will raise the yield point of 0.2% carbon steel from about 280MN/m to 390MN/m. This has led to the development of a range of so-called low-alloy steels with high tensile properties. A typical example is grade 817M40 (En 24), which contains 0.4% C, 0.2% Si, 0.6%, Mn, 1.2%, Cr, 0.3% Mo and 1.5% Ni. 

No grade mark SAE J429 Grade 8.1 Studs Medium carbon alloy or SAE 1041 modified elevated temperature drawn steel... 

Substitution of medium-carbon manganese steels by alloy steels, and the use of stainless steel, monel, sateUite, and copper-based alloys for valves and other wellhead parts for corrosion control are subject to the technical and economic evaluation of the subject. 

Therefore, the critical crack length is proportional to the square of KjJay, which is the basis for the ranking of the metal alloys in Table B.5. The ranking is provided in Table 8.3, where it may be seen that the medium carbon (1040) steel with the largest ratio has the longest critical crack length and, therefore, is the most desirable material on the basis of this criterion. 

Refined Ferromanganese. Refined ferromanganese refers to alloys that are not carbon saturated and range from less than 0.10 to 1.50% maximum carbon. Medium carbon grades are used in special grades of steels where in final additions carbon control is important. The low carbon grades are used mainly in the production of certain grades of stainless steels. 

The physical and mechanical properties of steel depend on its microstmcture, that is, the nature, distribution, and amounts of its metaHographic constituents as distinct from its chemical composition. The amount and distribution of iron and iron carbide determine most of the properties, although most plain carbon steels also contain manganese, siUcon, phosphoms, sulfur, oxygen, and traces of nitrogen, hydrogen, and other chemical elements such as aluminum and copper. These elements may modify, to a certain extent, the main effects of iron and iron carbide, but the influence of iron carbide always predominates. This is tme even of medium alloy steels, which may contain considerable amounts of nickel, chromium, and molybdenum. 

Carbon Steels and Low—Medium Alloy Steels. Plain carbon steels, the most common cutting tool materials of the nineteenth century, were replaced by low—medium alloy steels at the turn of that century because of the need for increased machining productivity in many appHcations. Low—medium carbon steels have since then been largely superseded by other tool materials, except for some low speed appHcations. 

Table 4. Compositions of Carbon and Low-Medium Alloy Steels, Wt...

CLOSED DIE FORGING PROCESS CAPABILITY MAP FOR LOW TO MEDIUM CARBON AND LOW ALLOY STEELS... 

Grinding Abrasion. The suitable alloys range from austenitic manganese steel (which once dominated the field) through hardenable carbon and medium alloy steels to the abrasion-resistant cast irons. 

Shafts are made of material ranging from medium carbon to low alloy steel and are usually heat treated. Shafts were originally made of forgings for the compressors in process service. But because of the availability ot high quality material, hot rolled bar stock has been used for shafts up to S inches in diameter. Bar stock shafts are given the same heat treatment and quality control as forgings. Many of the process users prefer a low alloy, chrome-moly-nickel material for shafting, particularly for compressors in critical service. 

For most general-service noncorrosive applications, the wheels use medium- to heavy-gauge carbon or alloy steel. For the centrifugal types, a die-formed entrance shroud provides smooth entrance flow of the air into the wheel. A solid steel plate serves as a back plate of the single entrance wheel, but of course, cannot be used on a double-entry wheel. Flere, both sides of the wheel have entrance shrouds. Figure 12-120C. 

The scope of the term stainless steel has not been precisely defined, but for general purposes it may be considered to include alloys whose main constituent is iron but which also contain not less than 10% Cr. As with low-alloy steels, a distinction between low or medium carbon grades and high carbon grades must also be drawn, the latter being more in the nature of alloy cast irons. These are used mainly for oxidation resistance at high temperatures and for applications where abrasion resistance allied to a certain amount of corrosion resistance is required, and will not be considered in this section. 

The most common types of steels used in castings are carbon steels, which contain only carbon as the major alloying element. Carbon steels are classified by their carbon content into three groups low-carbon steel (C < 0.20%), medium-carbon steel (C = 0.20 to 0.50%), and high-carbon steel (C > 0.50%). Steel s hardness also depends upon the carbon content. 

FERROTITANIUM. An alloy composed principally of iron and titanium. used to add titanium to steel. It is often made from titanium scrap. Three classifications are available low, high, and medium carbon content. Furnished in various lump, crushed, and ground sizes. 

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