Carpenter Technology Corporation

About: Carpenter Technology Corporation is a based out in . It is known for research contribution in the topics: Alloy & Corrosion. The organization has 214 authors who have published 215 publications receiving 2561 citations.

A defect-resistant Co-Ni superalloy for 3D printing.

Abstract: Additive manufacturing promises a major transformation of the production of high economic value metallic materials, enabling innovative, geometrically complex designs with minimal material waste. The overarching challenge is to design alloys that are compatible with the unique additive processing conditions while maintaining material properties sufficient for the challenging environments encountered in energy, space, and nuclear applications. Here we describe a class of high strength, defect-resistant 3D printable superalloys containing approximately equal parts of Co and Ni along with Al, Cr, Ta and W that possess strengths in excess of 1.1 GPa in as-printed and post-processed forms and tensile ductilities of greater than 13% at room temperature. These alloys are amenable to crack-free 3D printing via electron beam melting (EBM) with preheat as well as selective laser melting (SLM) with limited preheat. Alloy design principles are described along with the structure and properties of EBM and SLM CoNi-base materials. Additive manufacturing promises a major transformation of the production of high economic value metallic materials. Here, the authors describe a new class of 3D printable superalloys that are amenable to crack-free 3D printing via electron beam melting as well as selective laser melting.

Co-optimization of wrought alumina-forming austenitic stainless steel composition ranges for high-temperature creep and oxidation/corrosion resistance

Abstract: A series of candidate alumina-forming austenitic (AFA) stainless steels designed to evaluate the effects of variation in Al, C, Cr, Mn, Nb, and Ni content on high-temperature tensile properties, creep, and oxidation/corrosion resistance were studied. The compositions assessed were based on medium Ni (20–25 wt%) and low Ni (12 wt%) AFA variations strengthened primarily by MC and/or M23C6 carbide precipitates, and a high Ni (32 wt%) AFA superalloy variation strengthened primarily by γ′-Ni3Al intermetallic precipitates. Tensile and creep properties were measured at 650 and 750/760 °C, oxidation resistance from 650 to 900 °C in air with water vapor and steam environments, and sulfidation–oxidation resistance in Ar–20%H2–20%H2O–5% H2S at 550 and 650 °C. Optimized composition ranges for different use temperatures ranges based on these evaluations are presented.

Temperature-dependent ideal strength and stacking fault energy of fcc Ni: a first-principles study of shear deformation.

Abstract: Variations of energy, stress, and magnetic moment of fcc Ni as a response to shear deformation and the associated ideal shear strength (τ(IS)), intrinsic (γ(SF)) and unstable (γ(US)) stacking fault energies have been studied in terms of first-principles calculations under both the alias and affine shear regimes within the {111} slip plane along the and directions. It is found that (i) the intrinsic stacking fault energy γ(SF) is nearly independent of the shear deformation regimes used, albeit a slightly smaller value is predicted by pure shear (with relaxation) compared to the one from simple shear (without relaxation); (ii) the minimum ideal shear strength τ(IS) is obtained by pure alias shear of {111} ; and (iii) the dissociation of the 1/2[110] dislocation into two partial Shockley dislocations (1/6[211] + 1/6[121]) is observed under pure alias shear of {111} . Based on the quasiharmonic approach from first-principles phonon calculations, the predicted γ(SF) has been extended to finite temperatures. In particular, using a proposed quasistatic approach on the basis of the predicted volume versus temperature relation, the temperature dependence of τ(IS) is also obtained. Both the γ(SF) and the τ(IS) of fcc Ni decrease with increasing temperature. The computed ideal shear strengths as well as the intrinsic and unstable stacking fault energies are in favorable accord with experiments and other predictions in the literature.

Carbides in M-50 high speed steel

Abstract: The carbides in M-50 high speed tool steel were studied in detail. The dissolution of carbides as a function of austenitizing temperature, and their precipitation as a function of tempering temperature were characterized by X-ray diffraction and microchemical analysis. The carbides in the annealed steel are M23C6, M6C, M2C, and MC. Upon austenitizing, with increasing temperatures, the carbides dissolve in the order: M23C6, metastable M2C, M6C, and MC. The residual carbides in the heat treated steel are MC and stable M2C. The solvus temperatures of M23C6 and M6C were determined. Upon tempering the hardened steel, with increasing tempering temperatures, carbides precipitate in the order: M23C6, metastable M2C, MC, and M6C. It is shown that the composition of the precipitated metastable M2C is different from that of the residual stable M2C and it varies with the tempering temperature.

Effect of bulk microstructure of commercially pure titanium on surface characteristics and fatigue properties after surface modification by sand blasting and acid-etching.

Abstract: Surface modification techniques are widely used to enhance the biological response to the implant materials. These techniques generally create a roughened surface, effectively increasing the surface area thus promoting cell adhesion. However, a negative side effect is a higher susceptibility of a roughened surface to failure due to the presence of multiple stress concentrators. The purpose of the study reported here was to examine the effects of surface modification by sand blasting and acid-etching (SLA) on the microstructure and fatigue performance of coarse-grained and ultrafine-grained (UFG) commercially pure titanium. Finer grain sizes, produced by equal channel angular pressing, resulted in lower values of surface roughness in SLA-processed material. This effect was associated with greater resistance of the UFG structure to plastic deformation. The fatigue properties of UFG Ti were found to be superior to those of coarse-grained Ti and conventional Ti-6Al-4V, both before and after SLA-treatment.