No abstract

The safe supply of energy has become a major concern for the coming decades. An essential contribution is the use of reliable material for pipeline and offshore constructions. The oil and gas industry has been looking for steel materials with superior properties. The paper presents the approach for designing and producing modern types of heavy plate suitable for such challenging purpose. To produce steels with superior and balanced profile of mechanical properties and weldability, the potential of modern equipment in steel shops and plate mills is exploited based on systematic research and design work. Especially the progress in secondary metallurgy and in thermomechanical rolling technology allows offering of new steel types to challenging projects in the oil and gas industry worldwide. The world energy consumption is steadily increasing. A forecast says that it will double from the year 2000 to 2050. Mainly the consumption of natural gas will increase in the future. The exploitation and transportation of natural gas in the future will be under more severe conditions for example in arctic regions or in very deep water. This is also a challenge for material design for linepipe steels, offshore structures, vessels, etc. The plate production has to fulfil the new requirements.

Die Simulation moderner Warmumformverfahren erfolgt im Flach-Advanced Simulation Technique of Hot Deformation stauchversuch an einem rechnergesteuerten Warmumformsimulator (WUMSI). Die Vorteile der Methode und die Verbesserungen im For simulation of modern hot working processes plane strain compresVersuchsaufbau und -ablauf, die kurzlich durchgefuhrt wurden, wer-sion tests on a computer-controlled hot deformation simulator den beschrieben.(WUMSI) are applied. The merits of this method and the latest developments of the experimental technique are described. EinleitungDie Entwicklung und Optimierung neuer Umformtechnologien ist nicht nur auf den Zweck der geometrischen Formgebung des Werkstiickes und energiesparender Prozeljfiihrung abgestimmt, sondern verfolgt auch immer mehr eine gleichzeitige Beeinflussung von Gefiige und somit mechanischen Eigenschaften des Werkstoffes. Um dieser umfassenden Aufgabenstellung gerecht zu werden, bedarf es einer Versuchsmethodik, die sowohl geometrie-und kraftbestimmende Parameter eines Warmumformprozesses als auch strukturverandernde Vorgange im Werkstoff sowie deren komplexe Wechselwirkungen beriicksichtigen und erfassen kann. So zu beschreibende Verfahrens-bzw. Versuchsablaufe, die im weitesten Sinne als thermomechanische Behandlung bezeichnet werden konnen, verlangen den Einsatz leistungsfahiger und standig weiterentwickelter Simulationsmethoden im Labor, die gezielte Anwendung physikalischer und metallkundlicher Auswerteverfahren und eine gewahrleistete Ubertragbarkeit der dabei gewonnenen Ergebnisse in die betriebliche Praxis.

To derive a representative assessment of the achieved level of control in the production of heavy plates the increasing relevancy and the various aspects of homogeneity and reproducibility criteria, the role of process control and the investigation methods have to be considered. The aspects of fitness for use and of fabrication are driving forces for a narrow control of plate properties, which includes the homogeneity within all parts of a delivered plate and also the repeatability of properties from plate to plate produced for the same specification or order. With view to the specified range of composition, process parameters and mechanical properties adapted target ranges are defined. The steps of production are controlled and monitored by process computers. So the desired level of the capability of the process can be assured. This is a prerequisite for process control.

The goal of this study was to define rolling and cooling parameters for these bainitic steels to achieve properties The effect of niobium additions up to 0•10% on the suitable for the following possible applications: E460 to mechanical properties of thermomechanical control E550 plates of thickness up to 70 mm, E690 plates of thickprocessed plates of 20 and 70 mm thickness ness up to 20 mm, and X100 plates for pipe of thickness subjected to various accelerated cooling regimes up to 20 mm. A prerequisite in the alloy design of these has been investigated. The study is based on grades is a low carbon equivalent (CEV<0•42%, where synthetic melts, laboratory rolling, and heatCEV is defined according to IIW guidelines as C+(Mn/6)+ treatment designed to simulate industrial praxis.[(Cr + Mo + V)/5] + [(Cu + Ni)/15]) to guarantee good The results show that a combination of high weldability. strength and excellent toughness can be achieved in bainitic plates of low carbon equivalent.I&S/1594 EXPERIMENTAL METHODThe effect of the niobium addition has been studied with