Christopher W. San Marchi

Effect of reaction on the tensile behavior of infiltrated boron carbide/ aluminum composites

Keywords: Aluminum ; Boron carbide ; Damage in composites ; Metal matrix composite ; Tensile ductility ; Ductility ; Fabrication ; Infiltration ; Liquid metals ; Plastic flow ; Stiffness ; Tensile stress ; Metal infiltration ; Boron carbide ; aluminum ; boron carbide ; chemical reaction ; composite ; infiltration ; tensile structure ; Boron carbide ; aluminum ; boron carbide ; infiltration Note: Laboratory for Mechanical Metallurgy, Ecole Polytechnique Fed. de Lausanne, Lausanne CH-1015, Switzerland Dept. of Materials Sci./Engineering, Northwestern University, Evanston, IL 60208-3108, United States09215093 (ISSN)DOI: 10.1016/S0921-5093(02)00039-4 Reference LMM-ARTICLE-2002-004doi:10.1016/S0921-5093(02)00039-4View record in Web of ScienceView record in Scopus Record created on 2006-10-09, modified on 2017-05-10

Fracture and Fatigue of Commercial Grade API Pipeline Steels in Gaseous Hydrogen

Gaseous hydrogen is an alternative to petroleum-based fuels, but it is known to significantly reduce the fatigue and fracture resistance of steels. Steels are commonly used for containment and distribution of gaseous hydrogen, albeit under conservative operating conditions (i.e., large safety factors) to mitigate so-called gaseous hydrogen embrittlement. Economical methods of distributing gaseous hydrogen (such as using existing pipeline infrastructure) are necessary to make hydrogen fuel competitive with alternatives. The effects of gaseous hydrogen on fracture resistance and fatigue resistance of pipeline steels, however, has not been comprehensively evaluated and this data is necessary for structural integrity assessment in gaseous hydrogen environments. In addition, existing standardized test methods for environment assisted cracking under sustained load appear to be inadequate to characterize low-strength steels (such as pipeline steels) exposed to relevant gaseous hydrogen environments. In this study, the principles of fracture mechanics are used to compare the fracture and fatigue performance of two pipeline steels in high-purity gaseous hydrogen at two pressures: 5.5 MPa and 21 MPa. In particular, elastic-plastic fracture toughness and fatigue crack growth rates were measured using the compact tension geometry and a pressure vessel designed for testing materials while exposed to gaseous hydrogen.Copyright

Microstructural tailoring of open-pore microcellular aluminium by replication processing

The replication process is presented and discussed with emphasis on methods for microstructural tailoring of open-pore microcellular aluminium-based foams, highlighting methods it offers for control of principal foam mesostructural and microstructural parameters: pore volume fraction, pore shape, pore size(s), as well as the composition and microstructure of the metal making the foam.

“Assessment of Metal Matrix Composites for Innovations” — intermediate report of a European Thematic Network

Abstract The Thematic Network “Assessment of Metal Matrix Composites for Innovations” (acronym MMC-ASSESS) is a consortium of 21 partners from industry, research organisations and universities involved in research, development and application of metal matrix composites (MMC). The general goal of the project is to increase market acceptance of MMC by collecting and evaluating information related to the engineering potential of these materials. The working groups of the network are referring to production, characterisation and properties as well as modelling and applications of MMC. These topics are considered as well specifically for the four categories of MMC: particulate, short fibre and whisker, continuous fibre, and monofilament reinforced metals. A web page has been established ( http://mmc-assess.tuwien.ac.at/ ) as an ongoing dissemination activity. An intermediate report on the networks activities is presented, which started in October 1998 by funding of the European Commission for a 36 months period.

Fracture and fatigue tolerant steel pressure vessels for gaseous hydrogen.

Fatigue crack growth rates and rising displacement fracture thresholds have been measured for a 4130X steel in 45 MPa hydrogen gas. The ratio of minimum to maximum load (R-ratio) and cyclic frequency was varied to assess the effects of these variables on fatigue crack growth rates. Decreasing frequency and increasing R were both found to increase crack growth rate, however, these variables are not independent of each other. Changing frequency from 0.1 Hz to 1 Hz reduced crack growth rates at R = 0.5, but had no effect at R = 0.1. When applied to a design life calculation for a steel pressure vessel consistent with a typical hydrogen trailer tube, the measured fatigue and fracture data predicted a re-inspection interval of nearly 29 years, consistent with the excellent service history of such vessels which have been in use for many years.Copyright

Investigation of the hydrogen release incident at the AC Transit Emeryville Facility.

This report summarizes the investigation of the release of approximately 300kg of hydrogen at the AC Transit Facility in Emeryville, CA. The hydrogen release was avoidable in both the root cause and contributing factors. The report highlights the need for communication in all phases of project planning and implementation. Apart from the failed valve, the hydrogen system functioned as designed, venting the hydrogen gas a safe distance above surrounding structures and keeping the subsequent fire away from personnel and equipment. The Emeryville Fire Department responded appropriately given the information provided to the Incident Commander. No injuries or fatalities resulted from the incident.

Scaling of conductivity and Young’s modulus in replicated microcellular materials

Scaling exponents for the conductivity and stiffness of replicated microcellular materials exceed commonly predicted values of 1 and 2. We show here that this is caused by the fact that, in replicated microcellular materials, the solid architecture varies with the relative density: a simple derivation based on the physics of powder consolidation returns and explains the observed scaling behaviour. The same derivation also gives an explanation for Archie’s law, known to describe the conductivity of wet soils.

Measurement of Fatigue Crack Growth Rates for SA-372 Gr. J Steel in 100 MPa Hydrogen Gas Following Article KD-10

The objective of this work is to enable the safe design of hydrogen pressure vessels by measuring the fatigue crack growth rates of ASME code-qualified steels in high-pressure hydrogen gas. While a design-life calculation framework has recently been established for high-pressure hydrogen vessels, a material property database does not exist to support the analysis. This study addresses such voids in the database by measuring the fatigue crack growth rates for three heats of ASME SA-372 Grade J steel in 100 MPa hydrogen gas at two different load ratios (R). Results show that fatigue crack growth rates are similar for all three steel heats and are only a mild function of R. Hydrogen accelerates the fatigue crack growth rates of the steels by at least an order of magnitude relative to crack growth rates in inert environments. Despite such dramatic effects of hydrogen on the fatigue crack growth rates, measurement of these properties enables reliable definition of the design life of steel hydrogen containment vessels.Copyright

Processing Metal Matrix Composites

By the definition adopted here (Section 1.1), all metal matrix composites are produced by artificially combining reinforcements with a metallic phase, “artificially” meaning that the two phases preexist the material before being combined. “Making a composite” is therefore the act of combining these two preexisting phases, matrix and reinforcement, into a new material, the composite (as illustrated in Figure 1.1). This we call “primary processing” of the composite. It is distinct from “secondary processing” where the composite is deformed, shaped, hardened, machined, coated, or joined (with itself or with another material) after it is created. Preliminary processing steps may also exist upstream of primary processing; these we call “pre-processing”. This of course includes making the reinforcement and the matrix, but may also comprise steps such as arranging these in various configurations. Examples include packing short fibres held together with a silica binder into a preform for subsequent infiltration, or creating powdered matrix cloth using an organic binder before solid-state consolidation with monofilaments.

Safety, codes and standards for hydrogen installations. Metrics development and benchmarking

Automakers and fuel providers have made public commitments to commercialize light duty fuel cell electric vehicles and fueling infrastructure in select US regions beginning in 2014. The development, implementation, and advancement of meaningful codes and standards is critical to enable the effective deployment of clean and efficient fuel cell and hydrogen solutions in the energy technology marketplace. Metrics pertaining to the development and implementation of safety knowledge, codes, and standards are important to communicate progress and inform future R&D investments. This document describes the development and benchmarking of metrics specific to the development of hydrogen specific codes relevant for hydrogen refueling stations. These metrics will be most useful as the hydrogen fuel market transitions from pre-commercial to early-commercial phases. The target regions in California will serve as benchmarking case studies to quantify the success of past investments in research and development supporting safety codes and standards R&D.