HIGH STRENGTH STEELS FOR LOW TEMPERATURE STRUCTURAL APPLICATIONS
Stefan Herion 1*and Stephan Scherf 2
1 KoRoH GmbH – CCTH Center of Competence for Tubes and Hollow Sections, Karlsruhe, Germany
2 Vallourec Deutschland GmbH, Düsseldorf, Germany
During the last years the demand of new steels has constantly increased. The development goes to operational temperatures ranging from about -70°C to +30°C. At the same time there is also a need of special steels with yield strengths up to fy = 690 MPa and high ductility at -40°C. Steel manufacturers are developing better production lines and steel qualities resulting in high strength heavy plates and seamless hollow sections. These new steels are aiming for structural solutions with high demands for fatigue and toughness. Besides understanding the production methods and selecting the best steels for projects one of the important aspects using high strength steels is their weldability. Exemplarily on basis of the new Vallourec steel grade for seamless quenched and tempered hollow sections with a strength level 690 MPa up to wall thickness of 40 mm, which is based on a micro-alloyed low carbon concept, the welding concept will be presented. It will be shown that the welding procedures and the welding consumables together with the new high strength steels match the high requirements even for arctic structural applications under extreme conditions.
High strength steels, arctic conditions, seamless hollow sections, welding, high toughness