Construction and manufacturing equipment, which often endure harsh conditions, require materials that are durable enough to withstand such conditions without wearing out or causing equipment failure.

In applications where wear-resistance is crucial, project engineers may opt to use quenched and tempered (Q&T) steel materials. Q&T steel is heat-treated, a process that intensely heats and cools a material to alter its physical properties, to enable the material to withstand severe impact and abrasion.

This article will explore what Q&T steel is, typical applications of Q&T steel and the common steel plate grades stocked by steel plate suppliers like Leeco® Steel.

What is Quenched and Tempered Steel?

Quenched and tempered steel gets its name from the heat treatment it receives: quenching and tempering. 

Quenching and tempering is a two-part heat treatment process that follows the steps below and alters a material’s internal grain structure to give it greater strength, toughness and hardness, properties which are important for materials used in high-wear applications.

  1. Quenching: A steel material is heated to a high temperature that falls between 1,500- and 1,650-degrees Fahrenheit. The material is then rapidly cooled with water.
  2. Tempering: After being cooled with water, a steel material is re-heated to a below-critical temperature – which falls between 300- and 700-degrees Fahrenheit. The material is then air-cooled.

Related: Steel Heat Treatment Processes

Properties and Applications of Common Q&T Steel Plate Grades

While there are various grades of Q&T steel plate, the grades that Leeco sees most commonly requested – and keeps readily stocked – are ASTM A514, AR400 and AR500.

A514

A514 has a chemical composition that is governed by ASTM code, shown in the chart below. Quenching and tempering this grade enhances the presence of chemicals, such as silicon and chromium, that strengthen and increase hardness.

 

Chemical Compositions of Common Q&T Steel Plate Grades

Grade

Carbon

Manganese

Phosphorus

Sulfur

Silicon

Chromium

Molybdenum

A514 Grade B

0.12-0.21%

0.70-1.00%

0.030%

0.030%

0.20-0.35%

0.40-0.65%

0.15-0.25%

A514 Grade H

0.12-0.21%

0.95-1.30%

0.030%

0.030%

0.20-0.35%

0.40-0.65%

0.20-0.30%

A514 Grade Q

0.14-0.21%

0.95-1.30%

0.030%

0.030%

0.15-0.35%

1.00-1.50%

0.40-0.60%

A514 Grade S

0.11-0.21%

1.10-1.50%

0.030%

0.020%

0.15-0.45%

N/A

0.10-0.60%

 

As a result of its chemical composition and being heat-treated, A514 has greater strength and toughness compared to non-heat-treated, mild carbon steel grades.

For example, A514 has a much higher yield point and tensile strength than ASTM A572, a structural carbon steel plate grade, as shown in the chart below. Yield point and tensile strength measure the point at which a steel material will deform and the point at which a steel material will break, respectively, and are core indicators of material strength.

 

Mechanical Properties of A514 Plate vs. A572 Grade 50

Q&T Plate Grade

Yield Point

Tensile Strength

A514 ¾” or less thick

100 ksi

110-130 ksi

A514 >3/4” to 2.5” thick

100 ksi

110-130 ksi

A514 >2.5” to 6” thick

90 ksi

100-130 ksi

A572 Grade 50

50 ksi

65 ksi

 

Due to its high strength and wear-resistance abilities, A514 is typically used in applications such as construction equipment – like cranes – and large, heavy-load machines.

AR400 & AR500

While A514 is regulated by ASTM code, AR400 and AR500 are certified to meet a specific Brinell Hardness Number (BHN) range, which indicates material hardness. The specific chemical composition is not regulated or standardized between mills.

Related: Understanding Abrasion Resistant Steel Plate

Quenching and tempering these grades gives them a stronger, harder quality than standard mild carbon steel grades, making them suitable for high-wear applications such as construction buckets and mining equipment.

Less Common Q&T Steel Plate Grades

While A514, AR400 and AR500 are the most widely used Q&T steel plate grades, other Q&T plate grades are used for more specific applications, including the following.

 

Grade

Common Uses

130 ksi

An ultra-high strength structural-quality steel plate grade commonly used in semi-truck trailers and forestry and mining equipment. This grade is not governed by ASTM code and is instead certified to have a minimum yield strength of 130 ksi.

140 ksi

An ultra-high strength structural-quality steel plate grade commonly used in the manufacture of construction and logging equipment and semi-truck trailers. This grade is not governed by ASTM code and is instead certified to have a minimum yield strength of 140 ksi.

ASTM A710

A low-carbon, high-yield steel plate grade commonly used in the manufacturing of construction equipment, rail cars and barges.

AR450

An abrasion resistant steel plate grade commonly used in moderate-to-heavy wear applications, including bucket components, dump truck bodies and construction equipment.

AR600

An abrasion resistant steel plate grade commonly used in high-wear applications, including aggregate removal and mining.

Sourcing Q&T Steel Plate

When determining which steel plate supplier to use for your Q&T steel plate order, it is important to look for suppliers who have the following:

  • A quality management system, such as one that is ISO 9001 certified, to ensure steel plate products have been inspected and verified to meet proper specifications.
  • Various distribution centers across a wide geographic footprint to help reduce freight costs.
  • A large inventory of the grade your order requires to ensure you can source the material you need in a timely manner.

With 11 distribution centers located across North America and an ample stock of quenched and tempered steel plate grades, Leeco Steel can get you the grade you need, when you need. Leeco is also ISO 9001 certified in quality management to ensure we provide our customers with high-quality products and service.

Contact Leeco Steel to request a quote for Q&T steel plate grades today.