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Introduction
20CrNi alloy structural steel is a well-known kind of low alloy structural steel, usually used in automobiles and heavy industry because of its good strength, toughness and weldability. It is a kind of low alloy steel with good strength and toughness, which is widely used in agricultural machinery, automotive parts, construction machinery and other structural parts.
Characteristics
20CrNi alloy structural steel has a balanced composition and good mechanical properties after heat treatment, which is used in a variety of applications. The strength and toughness of 20CrNi steel are relatively high, but due to its low alloy element content, its hardenability is slightly lower than that of medium-carbon low-alloy steel. The carbon content of 20CrNi alloy structural steel is 0.17~0.23%, and the alloy elements are chromium, manganese, nickel, molybdenum, titanium, silicon and vanadium, etc. After tempering and quenching, 20CrNi alloy structural steel can obtain good mechanical properties with a tensile strength of 620~780MPa, a yield strength of 360~460MPa, and good elongation.
Applications
20CrNi alloy structural steel has good overall performance and is widely used in all kinds of mechanical parts. Commonly used in the manufacture of auto parts and components such as crankshaft, connecting rod and gear, etc., 20CrNi steel is also used in the manufacture of agricultural machinery, bridges and other structural parts, and tools and tools.
Heat treatment
20CrNi alloy structural steel has good hardenability, and the most commonly used quenching temperature is 850~860℃. After quenching, the hardness is HRC22~30 and the yield strength is 360~500MPa. The quenching media generally uses a water or oil quenching medium. After quenching, it can be tempered immediately and then slowly cooled to obtain the required size, mechanical properties, and toughness.
Welding
20CrNi alloy structural steel has good weldability and can be welded by all welding methods such as arc welding, gas welding and spot welding. For welding parts with thicker plates, the arc welding process should be used. During welding, the less the welding current, the better; when the welding current is too large, the tending of material baying and crack is easy. The filler metal for welding should be chosen according to the thickness of the base material to reduce welding deformation.
Conclusion
20CrNi alloy structural steel has good strength, toughness, weldability and hardenability, and is widely used in auto parts, agricultural machinery, construction machinery, bridges and other industries. The most suitable quenching temperature is 850~860℃, and the filler metal is appropriately selected according to the thickness of the plate to reduce welding deformation. When welding, the less the welding current, the better, and attention should be paid to prevent material baying and cracking.
