Product Introduction

Hot-rolled steel products of this company include deformed rebar in grades AII and AIII, as well as other grades (based on customer requirements), manufactured according to INSO 3132 standard in sizes ranging from 8 to 32 mm. These products are also suitable for export to international markets.

The annual production capacity of this line is 250,000 tons, and the products are widely used in various construction and industrial projects including bridge construction, dam construction, power plants, industrial facilities, as well as commercial and residential buildings.

The trademark of this production unit is the letter D, which is stamped on rebars as follows:

- Sizes 8 to 10: JUD
- Sizes 12 to 32: CTD

Rebar Production Process

The rebar production process at Darpad Industrial Group includes several stages such as billet preparation, heating, hot rolling, cooling, cutting, and packaging. This process is carried out using advanced technology and strict quality control to ensure the final product has the required mechanical properties and high quality. Hot rolling is one of the most common and effective methods for producing steel rebar as described below:

1. Billet Preparation

Rebar production starts with steel billets. Billets can be produced through continuous casting or traditional methods. They must have a suitable chemical composition including elements such as carbon, manganese, silicon, phosphorus, and sulfur.

2. Billet Heating

Steel billets are heated in reheating furnaces to a temperature of approximately 1100 to 1250°C. This stage is necessary to prepare the billets for rolling.

3. Hot Rolling (Hot Rolling Process)

After heating, steel billets are transferred to rolling mills. The hot rolling process for deformed rebar consists of heating, roughing, finishing stands, rib formation, cutting, and cooling. First, the billet is fed through roller systems into the furnace and heated to the required temperature (usually above 900°C). In the roughing stage, the steel is passed through rollers to reduce its diameter. After roughing, rib formation is performed. In the finishing stands (8–10 stands), ribs are formed on the bars according to the required standard. Finally, rebars are cut into 12-meter lengths and bundled.

4. Cooling

Rolled rebars are transferred to cooling beds where they are gradually cooled. This process helps control the mechanical properties and microstructure of the rebar.

5. Cutting and Measurement

After cooling, rebars are cut into standard lengths. The produced rebars are inspected for diameter, length, and rib quality to ensure compliance with relevant standards.

6. Packaging and Transportation

The rebars are packaged in 2-ton bundles to facilitate handling and storage. They are then shipped to domestic and international customers.

Rebar Classification by Strength Grade

Rebars are classified based on their resistance to tensile force, known as characteristic strength. Rebars produced in Iran (based on Russian standards) are generally divided into three main groups: A1, A2, and A3.

In construction practice, based on mechanical properties and appearance, they are generally classified into four categories: A1, A2, A3, and A4.

A1 Rebar (Plain - No Ribs)

The first group (A1) corresponds to a yield strength of 240 MPa (240F grade). These rebars are smooth, without any ribs, and are known as plain rebars.

A2 Rebar (Semi-Hard with Simple Ribs)

A2 rebars are ribbed bars classified as 340S grade. They have a spiral rib pattern along the longitudinal axis. They have higher strength than A1 rebars. Their yield strength is approximately 340 MPa and tensile strength is around 500 MPa.

A3 Rebar (Hard with Deformed Rib Pattern)

A3 rebars feature a herringbone rib pattern along the longitudinal axis. They provide higher strength compared to A1 and A2 rebars.

A4 Rebar (High Strength with Complex Rib Pattern)

A4 rebars are high-strength steel bars with a complex rib structure and are classified as 500S grade. They are widely used in modern structural designs. In some cases, using this type of rebar can reduce the total steel weight by approximately 1 to 2 kg per square meter. Their price is generally higher and depends on the bar size.

It is worth noting that the rebars produced by this company are mainly in A2 and A3 grades.