HSLA is a common material in erecting outdoor structures. Learning the different types of HSLA is vital to know which is a better option for your construction needs.
What Is HSLA Steel?
HSLA is an abbreviation for high-strength low-alloy steel. It is a type of alloy steel with stronger resistance against rusting than carbon steel. HSLA steel works for specific mechanical properties instead of chemical composition.
The forms and cross-sections of HSLA are 20 to 30 percent lighter than carbon steels with identical strength. The martensite microstructure of HSLA steels is ideal for making an aircraft’s landing gear, bolts, fittings, and gearbox components.
HSLA Steel Properties
HSLA steels have mechanical properties, consisting of micro-alloyed and rare earth elements.
Niobium (Nb) helps increase steel’s recrystallization temperature by 100 degrees C. This process slows down grains’ growth and extends the steel’s non-recrystallization region.
Vanadium (V) increases the transition temperature and strength of the steel.
Titanium (Ti) in HSLA steels results in a slight increase in the strength of precipitation and grain refinement.
Vanadium (V) significantly increases the strength and transition temperature of HSLA steel.
HSLA Steel Composition
HSLA contains a carbon content of 0.05 to 0.25 percent. It also includes 2.0 percent manganese.
The remaining percentage could be small quantities of other alloying elements, such as titanium, nickel, vanadium, copper, chromium, niobium, molybdenum, zirconium, and nitrogen.
These alloying elements help increase steel’s hardiness, machinability, toughness, flexibility, and strength. It also provides resistance against heat treatment and resistance to corrosion.
HSLA Steel Grades
HSLA steel comes in various grades. Here are the common HSLA steel grades that adhere to American standards.
ASTM A36 is general-purpose steel. It is popular in steel structures because of its mechanical properties and versatility.
ASTM A572 is inexpensive and commonly used in infrastructures like transmission towers, bridges, construction equipment, and buildings. It has higher tensile strength and yield point.
ASTM A573 is a steel grade common in the gas and oil industry.
API 5L Grade X70 is an HSLA grade for gas and oil transmission pipeline applications. This HSLA grade has a psi minimum yield strength of 70,000, a requirement by the American Petroleum Institute.
ASTM A656 is the first grade of A572. It is ideal for making truck frames, general fabrications, crane booms, and construction equipment.
CSA G40.21 is an HSLA grade that adheres to Canadian standards.
Types of HSLA Steel
Microalloyed Ferrite-Pearlite Steel
This HSLA steel has strong carbide content, usually less than 0.10 percent. The elements present in MFP steel could be vanadium, niobium, and titanium. They provide grain refinement, temperature control transformation, and precipitation strengthening.
This type of steel contains martensite that provides ductility, low yield strength, and flexibility to HSLA steel. Martensite also offers good formability and a high rate of toughness to the steel.
Inclusion-shape-controlled steel contains calcium, titanium, zirconium, and other rare alloying earth elements, which changes the sulfide inclusion shapes from elongated stringers to dispersed and small globules.
ISCS has improved through-thickness flexibility and toughness.
Acicular Ferrite Steel
This type of steel has a very fine and higher strength of acicular ferrite structure. Acicular ferrite steel is a low-carbon steel that is easy to weld and form into different shapes.
As-Rolled Pearlitic Steel
This steel type contains carbon and manganese but may also have some alloying elements. These elements enhance the strength, weldability, toughness, and formability of HSLA steel.
Weathering steel is called by its trade name Corten. It has a high level of tensile strength and atmospheric corrosion resistance. It is ideal for bridge and outdoor structures.
What are the uses of HSLA steel?
Applications of HSLA steels include the following:
- oil and gas pipelines
- heavy-duty highway
- off-road vehicles
- construction and farm machinery
- industrial equipment
- storage tanks
- railroad & mine cars
- barges and dredges
- lawn mowers
- passenger car & aircraft components
- bridges & outdoor structures
- offshore structures
- power transmission towers
- light poles
- building panels & beams
Did you find HSLA a good material for your construction needs? Understanding the quality of steel help determine the type of material you will use in your project.