Product Specification

SAE 4145 Steel Round Bar Diameter 10 - 350mm Hot Rolled Cold Rolled Steel Bars ASTM A29

Products Specification

Regular Standard Size of our Round Bar in Stock

About 4145 Steel Round Bar

4145 is a low alloy chromium molybdenum steel similar to 4140 but with amended analysis which contributes towards its increased hardenability at larger diameters. 4145 steel bars are popular in larger diameters due to this increased strength and hardenability.

4145 alloy steel can be easily forged, machined and welded. It can also be heat treated to a wide range of strength and ductility levels. This forged bar stock is used in many oil and gas application including as forged down-hole drilling tools.

AISI 4145 Composition 

AISI 4145 is a low-alloy steel grade containing 0.45% carbon, 0.75% manganese, 1.00% chromium, 0.20% molybdenum, and 0.15% vanadium. The alloying elements enhance their mechanical and physical properties, such as strength and toughness. Additionally, the alloy’s controlled composition enables it to be quenched and tempered to improve its hardness and wear resistance.

AISI 4145 Mechanical Properties

AISI 4145 exhibits excellent strength, toughness, and wear resistance as a low-alloy steel grade. The minimum yield strength of AISI 4145 is 89 KSI, while the ultimate tensile strength is between 125-140 KSI, depending on the heat treatment conditions. The alloy’s high toughness and fatigue resistance make it an ideal choice for manufacturing critical components, including drill collars and heavy-duty shafts.

AISI 4145 Physical Properties

AISI 4145 has a density of 7.85 g/cm3 and a melting point of 1424°C (2580°F). Its coefficient of thermal expansion is 11.2 µm/mK and has a thermal conductivity of 42.6 W/mK. The alloy’s physical properties remain stable within a broad temperature range, making it an ideal choice for high-temperature applications.

AISI 4145 Equivalents

AISI 4145 Uses

AISI 4145 finds application in various heavy-duty and high-stress applications. In the energy sector, it is used for manufacturing drilling tools, pump shafts, and other components used in exploration and production activities. It also finds extensive use in the aerospace and defence sectors for manufacturing gears, shafts, and other critical components. Its excellent corrosion resistance and strength make it an ideal choice for seawater-drenched components, including marine motor shafts and other offshore applications.

AISI 4145 Heat Treatment

AISI 4145 can be subjected to various heat treatment processes to modify its mechanical and physical properties. The most common form of heat treatment for AISI 4145 is quenching and tempering, which involves heating the steel to a temperature of 927°C (1700°F) and cooling it rapidly in a quenching medium such as water, oil or air. The steel is then tempered to refine its mechanical properties.

AISI 4145 Machining

AISI 4145 is a moderately difficult steel machine that can be machined successfully using the right equipment and techniques. The alloy’s moderate hardness and toughness require high cutting forces, and sharp cutting tools and minimum chip loads are necessary to avoid tool wear and premature failure. Cutting fluids is highly recommended to prevent overheating and prolong tool life.

AISI 4145 Welding

AISI 4145 is an alloy steel that is commonly used for welding components. Its hardenability and wear resistance suit various applications, including heavy machinery, construction and automotive parts. Additionally, its high-strength properties allow for higher performance in challenging conditions when compared to other steels.