BDCS Notes - Steel Alloys

Steel Alloys

Alloys: used to alter the characteristics of steel. Around 250,000 different alloys of steel produced. As many as 200 used for civil engineering applications.

Alloys are added to improve:

1. Hardenability
2. Corrosion Resistance
3. Machineability
4. Ductility
5. Strength

By altering the carbon and alloy content and by using different heat treatments, steel can have many different characteristics.

Sectional Shapes:

Wide Flange: (W, HP and M shapes) (W used for beams/columns) (HP for bearing piles)

I-Beam: (S shape) (S used for beams/girders)

Channel: (C and MC shapes)

Equal Legs Angle: (L shape)

Unequal-legs Angle: (L shape)

Tee: (T shape)

Sheet Piling

Rail

W, M, S, HP, C, and MC shapes are designated by a letter, followed by two numbers separated by an “X.”

And example is W 44 X 335. The W indicates the W-shape, the 44 indicates nominal depth, and the 335 indicates the weight per lineal unit length.

Materials identified as “preferred” are available in the market place. Those identified as “other applicable materials” may or may not be readily available.

Specialty Steels in Structural Application

HPS: High Performance Steels (come as either 50W or 70W) (weathering steels)

(70W has higher tensile properties, and is used for bridge construction.)

Stainless Steels

Whereas structural steels have 0.3 to 0.4% chromium, stainless steel has in excess of 10%

Types of AISI Stainless Steels

304: The most readily available stainless steel, containing 18% chromium and 8% nickel.

316: Similar to 304, but with the addition of 3-4% molybdenum for greater corrosion resistance.

409: A straight chrome alloy, 11-12% chromium. Used for interiors.

410-3: A dual phase alloy with micro alloy element control that permits welding in up to 1.25 inches.

2205: A duplex structure with about equal parts of austenite and ferrite. Excellent corrosion resistance and about twice the yield strength of conventional grades.

Fastening Products

Conventional Bolts (snug-tightened, pre-tensioned, or slip critical)

Twist-off-type Tension Control Bolt Assemblies

Nuts

Washers

Compressible-Washer-Type Direction Tension Indicators

Anchor Rods

Threaded Rods

Forged Steel Structural Hardware