Steel Dimensions

Steel Dimension and Type

Steel Dimensions, weights, and properties of these sections are given by American Institute of Steel Construction, Steel Construction Manual (AISC Manual)1 Part 1. The W-shape is an I-section with wide flanges having parallel surfaces. This is the most commonly used shape for beams and columns and is designated by nominal depth and weight per foot. Thus a W24 × 84 has a depth of 24.1 in and a weight of 84 lb/ft. Columns are loaded primarily in compression and it is preferable to have as large a radius of gyration about the minor axis as possible to prevent buckling. W12 and W14 sections are fabricated with the flange width approximately equal to the depth so as to achieve this. For example, a W12 × 132 has a depth of 14.7 in and a flange width of 14.7 in. The radii of gyration about the major and minor axes are 6.28 in and 3.76 in, respectively. Both S-shapes and M-shapes are I-sections with tapered flanges that are narrower than comparable W-shapes and provide less resistance to lateral torsional buckling. M-shapes are available in small sizes up to a depth of 12.5 in. S-shapes are available up to a depth of 24 in and have thicker webs than comparable W-shapes making them less economical.

Steel dimension can be formed in many type as on the picture below:

Steel Model

The HP-shape is also an I-section and is used for bearing piles.

Shape                                                      Designation
Wide flanged beams                                     W
Miscellaneous beams                                    M
Standard beams                                             S
Bearing piles                                                 HP
Standard channels                                         C
Miscellaneous channels                                MC
Angles                                                           L
Tees cut from W-shapes                              WT
Tees cut from M-shapes                               MT
Tees cut from S-shapes                                ST
Rectangular hollow structural sections        HSS
Square hollow structural sections                HSS
Round hollow structural sections                 HSS
Pipe                                                              Pipe

Other articles:

• Prefabricated Building Steel
• UFC Steel

Prefabricated Building Steel

Applied Steel Construction For Prefabricated Building

Prefabricated building steel mean the construction of building steel frame can be arranged in outside the building. The building is constructed by steel frame and after combine on the field, then lift up and install on the building. Contraction material can be from galvanized steel or from aluminum steel material.

The example of steel construction of prefabricated building as on the picture below. Prefabricated construction steel can be used for several purposes.

Site Cabin Office

Office

Garage

Other articles:

• Galvanized Carbon Steel material
• Steel Dimension

Low Temperature Metals

The low-temperature properties of metals have created some unusual problems in fabricating cryogenic equipment. Most metals lose their ductility and impact strength at low temperatures, although in many cases yield and tensile strengths increase as the temperature goes down.

Materials selection for low-temperature service is a specialized area. In general, it is necessary to select materials and fabrication methods which will provide adequate toughness at all operating conditions. It is frequently necessary to specify Charpy V-notch (or other appropriate) qualification tests to demonstrate adequate toughness of carbon and low-alloy steels at minimum operating temperatures.

Stainless Steels
Chromium-nickel steels are suitable for service at temperatures as low as -250°C (-425°F). Type 304 is the most popular. The original cost of stainless steel may be higher than that of another metal, but ease of fabrication (no heat treatment) and welding, combined with high strength, offsets the higher initial cost. Sensitization or formation of chromium carbides can occur in several stainless steels during welding, and this will affect impact strength.

However, tests have shown that impact properties of types 304 and 304L are not greatly affected by sensitization but that the properties of 302 are impaired at -185°C (-300°F).

Nickel Steel
Low-carbon 9 percent nickel steel is a ferritic alloy developed for use in cryogenic equipment operating as low as -195°C (-320°F). ASTM specifications A 300 and A 353 cover low-carbon 9 percent nickel steel (A 300 is the basic specification for low temperature ferritic steels). Refinements in welding and (ASME code-approved) elimination of post-weld thermal treatments make 9 percent steel competitive with many low-cost materials used at low
temperatures.

Aluminum
Aluminum alloys have unusual ability to maintain strength and shock resistance at temperatures as low as -250°C (-425°F). Good corrosion resistance and relatively low cost make these alloys very popular for low-temperature equipment. For most welded construction the 5000-series aluminum alloys are widely used.
These are the aluminum-magnesium and aluminum-magnesium manganese materials.

Copper and Alloys
With few exceptions the tensile strength of copper and its alloys increases quite markedly as the temperature goes down. However, copper’s low structural strength becomes a problem when constructing large-scale equipment. Therefore, alloy must be used. One of the most successful for low temperatures is silicon bronze, which can be used to -195°C (-320°F) with safety.

See more on: Belt carbon steel

Transformation Behavior

The crystalline structure of pure iron is ferrite at room temperature. The room temperature form of ferrite is called alpha (α) ferrite. At higher temperatures, the ferritic structure is unstable and transforms into a facecentered cubic structure called gamma (γ) austenite. At even higher temperatures, the austenitic structure might again transform into a higher temperature form of ferrite; this is called delta (δ) ferrite. This structure change because of the crystalline structure is changed affected by temperature.

Iron-iron carbide phase diagrams (see Figure below) represent the crystalline structures, or phases, of the carbon steels in an equilibrium state that are determined by very slow cooling from molten material. This is not a realistic view of the microstructural phases that exist during normal fabrication processes because the heating and cooling rates significantly affect the temperatures at which the suggested phase transformations occur.

This effect can be seen in the temperature difference between A1, the equilibrium lower transformation temperature, and Ar1, the lower transformation temperature upon cooling. Although not shown, there is also a lower transformation temperature upon heating, Ac1, which is somewhat higher than A1. The Ac1 temperatures depict the start point of the transformation between the α ferrite and the γ austenite upon heating.

The phase diagram in Figure below also shows an equilibrium upper transformation temperature—A3. Similar to the variations noted for A1, there are also upper transformation temperatures upon heating and cooling (Ac3 and Ar3, respectively). The transformation temperatures indicate the points at which the structure becomes an unstable form and begins to undergo a transformation to a different crystalline structure. It can be seen that carbon steels, with a typical maximum carbon content of less than 0.35% for pressure-containing applications, will have a transformation temperature range that will vary with the carbon content and the rate of heating or cooling.




The ferritic structure at room temperature has a relatively low ability (probably less than 0.008%) to contain carbon atoms in the space between the iron atoms (interstitially). The face-centered cubic structure has a much higher affinity for carbon and can contain as much as approximately 2.1%. Carbon that cannot be contained interstitially can exist in other forms, such as iron carbides or carbides of other metal elements. In a carbon steel microstructure, iron carbides can appear as platelets or particles of cementite (Fe3C). A microstructure that has alternating platelets of ferrite and cementite is called pearlite. With certain rates of cooling, the carbon steel microstructure can also be bainite. Bainitic structures represent a variety of ferrite aggregates with a distribution of small iron carbide precipitates.

Upon heating the carbon steel microstructure through the transformation range, the ferrite will transform into an austenitic structure. Because the austenitic structure has a much higher solubility of carbon, the iron carbides dissolve and the carbon enters into solution with the austenitic iron microstructure. This is a time- and temperature-dependent mechanism that takes longer if the cementite particles or platelets are large. An increased rate of heating will also have the effect of requiring a higher temperature to complete the dissolution.

See more on:

• Fluid Corrosion Effect