A ribbed steel bar is a type of deformed, high strength steel that is manufactured by processes called cold rolling or hot rolling. Ribbed Steel Bar vary in sizes, ranging from 8 mm to 40 mm wide. These bars have characteristics that make them most suitable in reinforcement of concrete. These characteristics range from their flexibility to their cost saving nature.
Cold rolling is a process which guide coiled wire through UKO tungsten carbide rollers held by UKO cold roller holder below its recrystallization temperatures. Such process enhances the TRS and hardness of the metal. Cold rolling is actually processed by introducing defects into the crystal structure of the metal creating a hardened microstructure. As the metal is at room temperature, it is less malleable than metal above its recrystallization temperature. Therefore it makes cold rolling a more labor intensive and expensive process than hot rolling. Cold rolling can also reduce the grain size of the metal resulting in Hall-Petch Hardening. Cold rolling has decisive cost advantage through use of the highest in process reliability and roll working life and increased wire quality through improved surface finishing and rib geometry.
Standard UKO tungsten carbide roll dimension
|
WIRE RANGE Ø |
OUTSIDE Ø mm |
INSIDE Ø mm |
THICKNESS mm(T) |
|
4-8.5 |
123 |
82 |
15 |
|
9-12 |
123 |
82 |
20 |
|
4-8.5 |
125 |
82 |
15 |
|
9-12 |
125 |
82 |
20 |
|
4-8.5 |
140 |
90 |
15 |
|
9-12 |
140 |
90 |
20 |
|
4-8.5 |
150 |
90 |
15 |
|
9-12 |
150 |
90 |
20 |
Hot rolling heats Large metal pieces above their recrystallization temperature. The metal pieces will be deformed between UKO tungsten carbide mill rolls resulting thin cross sections. These cross sections are thinner than those formed by cold rolling processes with the same number of stages. Hot rolling also reduces the average grain size of metal but maintains an equiaxed microstructure.
The lifetime of UKO tungsten carbide mill roll rings is 60-70 times that of conventional cast iron roll rings when they are used for hot rolling of rebars, and the surface quality and dimensional precision is substantially improved. Based on the conditions of rebar rolling machines (rolling force, speed, rebar diameter) what is recommended is the use of either integrated roll rings or composite roll rings, achieving better economical goals.
Standard Grade of UKO Tungsten Carbide Mill Rolls
| Grade | Co+Ni | WC | Hardness | T.R.S |
Compressive Strenth |
Young's Elastic Modulus |
Density |
Thermal Conductivity |
| (%) | (%) | ≥HRA | ≥Nmm2 | Mpa | KN/mm2 | g/cm3 | W/cm.k | |
| A104 | 10 | 90 | ≥86 | ≥2500 | 3500 | 560 | 14.2~14.5 | 0.2 |
| A154 | 15 | 85 | ≥83.5 | ≥2520 | 3300 | 540 | 13.8~14.2 | 0.2 |
| A204 | 20 | 80 | ≥82 | ≥2570 | 3100 | 480 | 12.6~13.2 | 0.18 |
| A253 | 26 | 74 | ≥81 | ≥2570 | 3000 | 50 | 14.2~14.8 | 0.17 |
| B104 | 10 | 90 | ≥85 | ≥2400 | 3400 | 550 | 14.0~14.3 | 0.2 |
| B154 | 15 | 85 | ≥83 | ≥2360 | 3200 | 530 | 13.8~14.3 | 0.2 |
| B184 | 18 | 82 | ≥82 | ≥2400 | 3200 | 430 | 13.5~13.9 | 0.2 |
| B253 | 25 | 75 | ≥79 | ≥2400 | 2800 | 420 | 12.9~13.4 | 0.17 |
| B305 | 30 | 70 | ≥78.5 | ≥2200 | 2600 | 300 | 12.6~13.1 |
0.16 |