P91 steel is also known as modified 9Cr-1Mo (P91) steel is widely used as a structural material in the construction of power plant components. In high-Cr ferritic steels, toughness degradation in welds was caused by the presence of δ-ferrite phase in the martensite matrix. The δ-ferrite phase formation is influenced by factors such as chemical composition of welds, Creq and Nieq , heat input used during welding. As the δ-ferrite phase content increases there was reduction in toughness of welds below the specified requirement of 47 Joules as per the standard EN1557: 1997. The poor toughness of welds having δ-ferrite phase can be improved by prolonging the PWHT duration at 760°C. Flux system of consumables also influences the toughness of welds. Basic flux system produces welds having higher toughness than acidic flux system. This is due to microinclusion content of welds. The flux basicity, V and Nb content, and ferrite factor are interrelated and presented as a line diagram. The present study discusses about the role of chemical composition, and welding processes (SMAW and FCAW) on the formation of δ-ferrite phase in welds and its influence on toughness of welds.

Rare earths (RE) have been used to improve the high temperature oxidation resistance of low alloy steel containing elements like Cr, Al, V and Mo. Further, the RE can be added either to the alloy or by applying as an oxide coating to the alloy surface. In this study the high temperature oxidation resistance of rare earth (RE) oxide coated 1Cr-0.3Mo-0.25V alloy was determined. This paper presents the influence of surface additions of nano-crystalline oxides CeO2 on the isothermal oxidation behavior of 1Cr-0.3Mo-0.25V alloys at temperatures ranging from 600 °C to 900 °C. The oxidation rate of RE oxide coated1Cr-0.3Mo-0.25V was significantly lower than that of the uncoated alloy. The improvements in oxidation resistance are the reduced oxidation rates and the increased oxide scale adhesion. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and electron probe micro analyzer (EPMA) were employed for these analyses. The scale formed in the presence of RE oxides was very thin, fine grained and adherent.

Incremental forging processes like radial forging become more and more crucial in industry due to their outstanding economic performance, their high flexibility and their advantageous compressive stress states. However, nowadays a basic method to analyze forging processes, FEM simulation is still a very time consuming procedure and needs complex models to implement incremental processes. Especially long term studies with focus on tool temperature development during several hours of production cannot be performed with classical FEM models for radial forging. The main problem in modelling is the high operating frequency of the forging devices, which leads to small necessary time steps and, therefore, to inacceptable calculation time due to numerous simulations that have to be run to complete a cogging process sequence. Steady state in die temperature is often only reached after processing several workpieces. Hence, it is necessary to use a simplified FE-model of the forging process to predict the steady state temperature of the forging dies. In the present work a simplified FE-model is established to investigate the steady state temperature of the dies. This approach is verified by metallographic studies proving its accuracy.

High-manganese steels are characterized by high ductility, strength and work hardening resulting from the formation of strain induced martensite (TRIP-effect) or twins (TWIP-effect). A third type is shear band induced plasticity (SIP) in Triplex steels. The Mn-content ranges from 15 to 30 %. Mn and additions of C, Si and Al exert a strong influence on the microstructure and the deformation mechanism and can accordingly affect both strength and ductility. The max. carbon content can be around 1.2 %. The main interest is currently concentrating on TWIP steels. Production of these grades via the conventional steelmaking routes can raise problems and, therefore, modifications and/or alternative production methods have to be applied. With respect to their extreme strength levels, high-Mn steels exhibit an extraordinary forming potential. Welding involves some specific challenges. The possible occurrence of delayed fracture is discussed. High-Mn steels have to compete with other lower alloy steels and special stainless grades with the same objective targets. Referring to this, the laboratory and industrial trials are to be continued in order to fully exploit the considerable market potential of the new steels.

A process for electroless deposition of NiP films on a transparent non-conductive soda lime glass is investigated. The process requires at least two repetitive cycles of etching and activation. The annealing process of the NiP films at 400 and 600˚C has been studied and the optimal heat treatment condition has been established. Different Ni bath with different pH has been employed to assess the NiP deposition. Characterization of the deposits by optical and scanning electron microscopy has provided information on the nature of crystallites and on the surface topography.

news in steel

NLMK Group, Russia, commissions SMS group to supply a thick slab caster

NLMK Group has contracted SMS group (www.sms-group.com) to supply a new thick slab caster for its steel mill no. 2 in Lipetsk in Central Russia.

JAK-Metalli named Swedish Steel Prize 2018 finalist

For developing a new cutting solution for vegetation management that is safer, less energy intensive and more durable, JAK-Metalli has been nominated for the Swedish Steel Prize 2018.

Another successful partnership between industry and the university

Already a model for success: In addition to the recently extended partnership with the Materials Science Department at the University of Saarland, AG der Dillinger Hüttenwerke (Dillinger) is supporting another ambitious research project: The Department of Numerical Mathematics at Saarland University is studying the modelling of the cooling process of premium heavy plate at Dillinger.

thyssenkrupp Schulte rolls out Cargoclix TimeSlot System

Successful test phase in Nuremberg / Materials distributor to introduce Cargoclix "TimeSlot" system at 30 sites