Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science 

About: Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Slag & Alloy. It has an ISSN identifier of 1073-5615. Over the lifetime, 7665 publications have been published receiving 182995 citations. The journal is also known as: Process metallurgy and materials processing science.

A new finite element model for welding heat sources

Abstract: A mathematical model for weld heat sources based on a Gaussian distribution of power density in space is presented. In particular a double ellipsoidal geometry is proposed so that the size and shape of the heat source can be easily changed to model both the shallow penetration arc welding processes and the deeper penetration laser and electron beam processes. In addition, it has the versatility and flexibility to handle non-axisymmetric cases such as strip electrodes or dissimilar metal joining. Previous models assumed circular or spherical symmetry. The computations are performed with ASGARD, a nonlinear transient finite element (FEM) heat flow program developed for the thermal stress analysis of welds.* Computed temperature distributions for submerged arc welds in thick workpieces are compared to the measured values reported by Christensen1 and the FEM calculated values (surface heat source model) of Krutz and Segerlind.2 In addition the computed thermal history of deep penetration electron beam welds are compared to measured values reported by Chong.3 The agreement between the computed and measured values is shown to be excellent.

Behavior of metal alloys in the semisolid state

Abstract: During dendritic solidification of castings and ingots, a number of processes take place simultaneously within the semisolid region. These include crystallization, solute redistribution, ripening, interdendritic fluid flow, and solid movement. The dendritic structure which forms is greatly affected by convection during the early stages of solidification. In the limit of vigorous convection and slow cooling, grains become spheroidal. Alloys with this microstructure possess rheological properties in the semisolid state which are quite different from those of dendritic alloys. They behave thixotropically, and viscosity can be varied over a wide range, depending on processing conditions. The metal structure and its rheological properties are retained after solidification and partial remelting. The semisolid alloys can be formed in new ways, broadly termed «semisolid metal (SSM) forming processes». Some of these are now employed commercially to produce metal components and are also used to produce metal-matrix composites

A new model for hydrogen-assisted cracking (hydrogen “embrittlement”)

Abstract: A new model is presented for hydrogen-assisted cracking (HAC) which explains the observations of decreasing microscopic plasticity and changes of fracture modes with decreasing stress intensities at crack tips during stress-corrosion cracking and HAC of quenched-and- tempered steels The model suggests that the presence of sufficiently concentrated hydrogen dissolved in the lattice just ahead of the crack tip aids whatever deformation processes the microstructure will allow Intergranular, quasicleavage, or microvoid coalescence fracture modes operate depending upon the microstructure, the crack-tip stress intensity, and the concentration of hydrogen The model unifies several theories but shows how the stress-sorption and lattice embrittlement models are unnecessary The model shows that planar pressure effects are necessary at low stress intensities and are necessary only to augment the driving force from the applied loads The basic hydrogen-steel interaction appears to be an easing of dislocation motion or generation, or both

The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid iron

Abstract: A systematic study of carbide and nitride additions on the heterogeneous nucleation behavior of supercooled liquid iron was undertaken. It was found that titanium nitride and titanium carbide were very effective in promoting heterogeneous nucleation. These compounds were followed by silicon carbide, zirconium nitride, zirconium carbide, and tungsten carbide in decreasing order of effectiveness. The degree of potency of the nucleation catalysts is explained on the basis of the disregistry between the lattice parameters of the substrate and the nucleating phase. Through the inclusion of planar terms the Turnbull-Vonnegut “linear” disregistry equation was modified to more accurately describe the crystallographic relationship at the interface during heterogeneous nucleation.

The relation between polycrystal deformation and single-crystal deformation

Abstract: A phenomenological description of crystallographic slip and pencil glide in single crystals is outlined, with emphasis on the behavior under prescribed strains Theoretical relations are established between these single-crystal properties and the behavior of quasi-homogeneous, quasi-isotropic polycrystals deforming uniformly on a macroscopic scale, at subdiffusive temperatures Experimental comparisons between single crystals and polycrystals are reviewed, considering flow stress, work hardening, temperature and strain rate effects, and various effects of grain size