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Glossary » Materials » Alloys » Steel » Alloy Steel » AISI 4340H
AISI 4340H is an H-Steel grade Alloy Steel. It is commonly called AISI 4340H Nickel-chromium-molybdenum steel. It is composed of (in weight percentage) 0.37-0.44% Carbon (C), 0.55-0.90% Manganese (Mn), 0.65-0.95% Chromium (Cr), 1.55-2.00% Nickel (Ni), 0.20-0.30% Molybdenum (Mo), 0.035% Phosphorus (P), 0.040% Sulfur (S), 0.15-0.30% Silicon (Si), and the base metal Iron (Fe). Other designations of AISI 4340H alloy steel include UNS H43400 and AISI 4340H.
Steel is the common name for a large family of iron alloys. Steels can either be cast directly to shape, or into ingots which are reheated and hot worked into a wrought shape by forging, extrusion, rolling, or other processes. Wrought steels are the most common engineering material used, and come in a variety of forms with different finishes and properties. Alloy steels are steels that exceed the element limits for Carbon steels. However, steels containing more than 3.99% chromium are classified differently as stainless and tool steels. Alloy steels also includes steels that contain elements not found in carbon steels such as nickel, chromium (up to 3.99%), cobalt, etc.

The typical elastic modulus of alloy steels at room temperature (25°C) ranges from 190 to 210 GPa. The typical density of alloy steels is about 7.85 g/cm3. The typical tensile strength varies between 758 and 1882 MPa. The wide range of ultimate tensile strength is largely due to different heat treatment conditions.

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