Shipbuilding steels differ from structural steels in terms of stricter tolerances. Most of the shipbuilding steels we stock are approved by the Det Norske Veritas (DNV). There are also steels approved by other agencies such as American Bureau of Shipping (ABS) and Russian Maritime Register (RMRS).
Normal high-strength ship building steels are manufactured by either hot rolling and normalization or normalization rolling. The quality standards of the steels are indicated by the letters A, B, D, E or F. Plate products are according to the standard EN10029 and the thickness tolerance class B. The shipbuilding steels are delivered with the certificate 3.2 which issued in accordance with the requirements of the classification agencies.
The formability and machinability of the shipbuilding steel correspond the similar properties of structural steel.
- Dimensions
- Welding
The most common ship building steel plate thicknesses and sizes available in our stock:
| Grade | Thickness (mm) | Width x length (mm) |
|---|---|---|
| D36 / DH36 | 10–120 | 2750 x 9000 |
Moreover, we supply ship building steels directly from the mill according to your needs (e.g. special thickness/width/length or classification).
During welding attention should be paid to prevention of the cold cracking behavior of the steel and the mechanical properties of the weld joint. The optimal working temperature and the cleanliness of the surfaces are both crucial. An effective mean to avoiding cold cracking is preheating. It delays the cooling of the weld region and thereby slows the hydrogen effusion.
Steel’s susceptibility to cold cracking and the need for preheating can be estimated by the carbon equivalent. The most often used formula for this is:
CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
Experience has showed that the weldability of the steel is at its best at the room temperature when the CEV is below 0,4 %.
| CEV (%) | |
|---|---|
| < 0,41 | steel is good for welding |
| 0,41–0,45 | austenitic welding filler metals |
| 0,45–0,59 | preheating and heat treatment |
| 0,6–0,8 | difficult to weld |
| > 0,8 | not suitable for welding |
Welding conditions have a crucial effect on mechanical properties of welding joints. Thermal effects of welding are not allowed to weaken the steel properties in the way the construction would not meet the requirements set. Mechanical properties should be achieved both welding metal and heat-affected-zone (HAZ).
