What is cold rolled steel coil, what is the production process of cold rolled steel coil?
1/ Types of products
+ Cold rolled steel:
– Quality: SPCC (commercial quality), SPCD (Stamping quality), SPCE (Deep stamping quality)
– Width (mm): 500÷650
– Thickness (mm): 0.7÷1.8mm
– Steel grade: SPHC; SAE1006; Q195…..
2/ Production process:
Cold rolled steel is manufactured according to the following steps:
+ Preparation of Ingredients:
Raw materials for hot-rolled corrugated iron are imported according to standards or cut according to production requirements. Specifications are wide from 500- 650; thickness from 1.0 to 4.0. according to standard SPCC, SAE1006….
+ Cleaning process of corrugated iron surface:
The Rust Removal Line performs the Cleaning of hot rolled steel coils. Steel coils are treated by special cleaning tanks, using hydrochloric acid (HCL at a temperature of 60-700c) to ensure the removal of oxide layers on the surface of corrugated iron before being sent to the cold rolling stage. The manufacturer’s special detergent tank, which contains a relatively small amount of detergent, ensures fast cleaning, cleaning efficiency and high productivity. In addition, the line also has a washing system designed by pressure spray in a cascade style to ensure cleaning of chloride remaining on the steel surface after pickling. And protected clean surface with specialized surface protectant NaNO2.
+ Cold rolling process
– Cold rolling equipment of Bac Viet Metal Joint Stock Company is the most advanced technology today. Equipped with 3 and 4 rack continuous rolling lines, the thickness and flatness of corrugated iron are controlled by a modern thickness gauge when passing each roll, ensuring accurate thickness and flat surface. Automatic control system (including peripheral equipment and processing software) ensures synchronous tension between racks, smooth technology.
– The required number of rolls on the rolling mill depends on the thickness of the hot rolled coil material and the thickness of the cold rolled coil product. Usually the amount of distortion is from 50% – 60%, up to 80%. In order to achieve good quality in terms of microorganism and physical and mechanical properties.
+ Soft annealing stage
– After cold rolling, the corrugated iron surface after rolling is hardened, in order to recreate the grain structure and achieve the complete mechanical properties and surface, the steel coil will be annealed in an electric annealing furnace with a protective gas environment. The annealing line has the very important feature of operating in an environment of 100% hydrogen gas protecting the steel coil. Therefore, the steel coil after annealing will have a uniform quality and a higher annealing rate due to the higher heat conversion. Reduce hardening after rolling, increase toughness, reduce product hardness.
+ Inspection and control of the production process
The quality of each steel coil of Bac Viet Metallurgy Joint Stock Company is checked and controlled at each stage, throughout the production process until the finished product. The geometrical dimensions and surface state of the coils are strictly controlled.
3/ Technical characteristics of cold rolled corrugated iron.
Table 1: Product quality and symbols
Quality symbol Note
SPCC Commercial Quality
SPCD Stamping Quality
SPCE Deep stamping quality
Table 2: Chemical composition
Quality class symbol C Mn P S
SPCC 0.12 Max 0.50 Max. 0.040 Max 0.045 Max
SPCD 0.10 Max 0.45 Max 0.035 Max 0.035 Max
SPCE 0.08 Max 0.40 Max 0.030 Max 0.030 Max
Table 3: Thickness tolerances (class A, Unit:mm.)
Nominal Thickness Less than 500 From 500 to less than 650
From 0.80 to less than ± 0.06 ± 0.06
From 0.80 to less than 1.0 ± 0.06 ± 0.06
From 1.0 to less than 1.25 ± 0.07 ± 0.07
From 1.25 to less than 1.6 ± 0.08 ± 0.09
From 1.6 to less than 2.00 ± 0.10 ± 0.11
Thus, we have a clear understanding of the production process, types as well as technical characteristics of cold rolled steel. Vietnam Steel Pipe Company is a leading unit in the field of cold-rolled steel coil production, with modern machinery lines, the output products are up to quality standards.