Duplex stainless steels are often used today in the oil and gas industry because of theirhigh strength and good corrosion resistance. New developments in arctic conditions and athigh pressure require the qualification of these materials at very low temperatures. Thispaper will present the results of an extensive test program dedicated to assessing thelow-temperature behavior of various heavy-wall duplex stainless steel forgings, hotisostatically-pressed (HIP) connectors and hot extruded pipes at temperatures down to –60°C. Several welding processes were also evaluated. The implications for thedesign of duplex stainless steel production facilities will be discussed.

A laser-welded blank (LWB) offers several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness and improved dimensional consistency. However, in order to take advantage of these benefits, designers need to overcome the formability of LWBs and be able to accurately predict the LWB forming characteristics early in the design process. We present a new approach to predict the maximum elongation of the laser seam; for example, for Advanced High-Strength Steel (AHSS)-based LWBs. This approach is based on a coupling model taking into account the thermal, metallurgical and mechanical phenomena. A comparison of numerical and experimental results shows very good agreement. These approaches offer a considerable advantage in obtaining the formability limits for all configurations.

Online detection and monitoring of phase transformation using non-destructiveelectromagnetic system in industrial hot strip mill processing of steels are reported. Thesystem renders wide range of possibilities for advanced control and fine tuning of the hotrolling and run-out table cooling parameters. These in turn allow for processmodifications to better control the microstructure of hot rolled bands. In particular,such modifications can attenuate the adverse effects of uncontrollable cooling of hot bandcoils that leads to severely non-homogeneous hot band microstructure. An example ofapplication is given demonstrating how reducing the non-homogeneity of hot bandmicrostructure with the aid of online hot strip mill electromagnetic system can helpeliminating the off-thickness defects in advanced high strength steel full hard stripsthus contributing to lowering the production costs and increasing the yield.

les différentes méthodes qui utilisent l’essai d’indentation pour estimer la ténacité sont revues et commentées. Pour les matériaux fragiles, les formules sont principalement basées sur la mesure des fissures formées par l’indenteur ou, si l’essai est instrumenté, sur les décrochements (pop-in) observés sur la courbe charge-déplacement. D’autres méthodes moins connues peuvent utiliser la mesure de l’ouverture en fond de fissure, une équivalence entre la longueur de fissure formée et l’accroissement de pénétration de l’indenteur ou le clivage provoqué par une indentation proche du bord du matériau étudié. Pour les matériaux ductiles aucune fissure n’est visible à la surface, même pour les fortes charges appliquées. Dans ce cas la ténacité est reliée par la mécanique continue du dommage à un dommage critique mis en évidence par la diminution du module d’élasticité avec l’augmentation de la profondeur d’indentation. Toutes ces méthodes permettent de calculer la ténacité avec une incertitude pouvant aller au maximum à 50 %.

Amorphous alloys have high tensile strength and easy soft magnetization, and are corrosion-resistant. As conventional amorphous alloy strips are mainly produced by the single rolling method, their thickness is less than 100 µm and their width is less than 200 mm. By combining ultra-rapid cooling, large-scale thermal spraying and warm rolling, the world’s first ever amorphous alloy strips were produced with thickness exceeding 300 µm and width exceeding 300 mm.