Exploring Q&T Steel Plate
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.
- 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.
- 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 Max |
Sulfur Max |
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 |
| 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. |
|
| 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. |
|
| A low-carbon, high-yield steel plate grade commonly used in the manufacturing of construction equipment, rail cars and barges. |
|
| An abrasion resistant steel plate grade commonly used in moderate-to-heavy wear applications, including bucket components, dump truck bodies and construction equipment. |
|
| 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.
