HR550LA steel FAQ

What is HR550LA steel?

HR550LA steel is a hot-rolled high-strength low-alloy steel. High-strength low-alloy steel is a steel with yield strength greater than 275MPa. The purpose of adding alloy elements is to provide specific required comprehensive properties, such as strength, toughness, formability, weldability and atmospheric corrosion resistance. High-strength low-alloy steel is a traditional substitute for low-carbon mild steel, which is used for riveted, bolted or welded bridges and building structural materials with shapes, plates and bars.

Steel is one of the most widely used materials in the world. Compared with other metals, it is strong, durable and relatively cheap. But not all steel is born equal. Different grades of steel may have different characteristics. An example of high quality steel is HR550LA low alloy steel. This type of steel has many important characteristics, making it an ideal choice for many applications, including some automobile parts and construction projects.

What is the chemical composition of HR550LA steel?

The chemical composition of HR550LA steel includes carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel and molybdenum as the main alloying elements. The carbon content is between 0.04% and 0.09%. Manganese content ranges from 0.40% to 1.50%. The silicon content is between 0.15% and 0.35%. Phosphorus and sulfur content are lower than 0.045%. The content of chromium and molybdenum is lower than 0.15%. Nickel content is less than 0.25%.

The chemical composition of HR550LA steel is: carbon (C) 0.12-0.21, manganese (Mn) 1.35-1.65, phosphorus (P) 0.04-0.09, sulfur (S) 0.04-0.09, chromium (Cr) 3.50-4.50, molybdenum (Mo) 0.25-1.0, nickel (Ni) 2.50-5.0, copper (Cu) 1.00-2.00, vanadium (V) 0.01-5-0.05, and the remainder is iron (Fe).

What is the Mechanical properties of HR550LA steel

HR550LA steel low alloy steel is the best choice for metal projects requiring excellent strength and toughness. With its high tensile strength, good weldability and excellent fatigue resistance, it is an ideal material for automotive, engineering and construction industries.

His specific mechanical properties are as follows

Yield strength: 550-650 MPa

Tensile strength: 560MPa

Elongation after fracture: 16%

What are the metallographic 3 structures of HR550LA steel?

(1) Ferrite-pearlitic structure, low alloy high strength steel most belong to this category, 300-350MPa.

(2) Low-carbon bainite structure, 450-650MPa.

(3) Low-carbon sorbite structure, which has just been quenched and tempered, is 550-800MPa or higher yield strength ratio o/ O is also a meaningful indicator. The higher the value, the more potential the steel will be. However, in order to use safely, it should not be too large, and the appropriate ratio is between 0.55-0.75.

What are the excellent properties of HR550LA steel?

  1. In terms of plasticity, the elongation of HR550LA steel plate with thickness of 3-20mm is 16%. The impact toughness at room temperature shall not be less than 80 and 60 J/m2 in longitudinal and transverse directions respectively
  2. In addition, HR550LA steel has good process performance and corrosion resistance. One of the important properties of steel for engineering components is that it can be processed and formed by common methods. The steel structure is not easy to undergo heat treatment after welding, so it is required to have good welding performance, that is, the performance of the weld after welding is not lower than or rarely lower than the base metal, and the performance change of the weld heat-affected zone should be small. It will not cause cracks. The steel plate used for cold stamping shall have good stamping performance. It should also have good corrosion resistance because after the use of low-alloy high-strength steel, the loss rate caused by atmospheric corrosion must be correspondingly increased due to the reduction of the thickness of steel in the structure.
  3. Welding performance

At present, the development of low alloy high strength steel is in step with the development of various welding processes. HR550LA steel has appropriate welding properties. If the coal welding operation is proper, most low-alloy high-strength steel can be welded well.

  1. Notch toughness

Notch toughness is impact toughness. HR550LA steel has good toughness weld, and its crack will not expand or expand slowly.

What are the applications of HR550LA steel?

HR550LA steel is a low alloy high strength steel, which can be used for various applications requiring higher strength and toughness. The improved strength and toughness are due to the addition of a small amount of alloy elements, such as manganese, chromium and molybdenum. The microstructure of the resulting HR550LA steel is a fine-grained ferrite-pearlite structure with excellent ductility, toughness and weldability. This microstructure also endows HR550LA steel with good resistance to stress corrosion cracking and intergranular corrosion.

HR550LA steel is mainly used in the manufacture of vehicles, bridges, houses, containers and other structures, which not only meets the requirements of high corrosivity, but also meets the requirements of good formability and weldability.

What is the difference between HR550LA low alloy steel and carbon steel?

Compared with carbon structural steel, the use of low-alloy high-strength steel can reduce the size of structural members and reduce the weight

Sometimes low alloy high strength steel is used to replace carbon structural steel without changing the section size. Its only purpose is to obtain higher strength and more durable structure without increasing weight. Saving weight is the most important to the structure of the transport vehicle, so that it can transport heavier weight and reduce energy consumption.