SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 25 - DECEMBER 16, 2005

26 METALS AND METALLIC MATERIALS
Includes physical, chemical, and mechanical properties of metals and metallic materials; and metallurgy.

20050240939 Environmental Protection Agency, Washington, DC, USA

Profile of the Fabricated Metal Products Industry

EPA Office of Compliance Sector Notebook Project. Sep. 1995; 142 pp.; In Spanish Report No.(s): PB2006-101410; EPA/310/R-95/007-SP; No Copyright; Avail.: CASI: A07, Hardcopy

The key elements chosen for inclusion are: general industry information (economic and geographic); a description of industrial processes; pollution ouputs; pollution prevention opportunities; Federal statutory and regulatory framework; compliance history; and a description of partnerships that have been formed between regulatory agencies, the regulated community, and the public. NTIS

Fabrication; Industries; Regulations; Waste Management

20050242043 Savannah River National Lab., Aiken, SC, USA

Microstructural Study of Fusion Welds on 304L and 21Cr-6Ni-9Mn Stainless Steels

Tosten, M. H.; Morgan, M. J.; Mar. 2005; 34 pp.; In English Report No.(s): DE2005-840795; WSRC-TR-2004-00456; No Copyright; Avail.: National Technical Information Service (NTIS)

Light-optical and transmission electron microscopy (TEM) have been employed to characterize the microstructures of a series of fusion welds made on 304L and 21-6-9 stainless steels. The materials investigated in this study included high-energy-rate-forged 304L, conventionally forged 21-6-9, and 304L weld critical plate (higher ferrite potential).

The weld critical plate contained an electron beam weld (no filler wire) while other specimens were welded with various combinations of 308L, 309L modified (MOD) and 312 MOD stainless steel filler wires to produce samples with a range of delta ferrite contents (4 to 33 percent) in the resulting welds. TEM specimens were prepared from broken arc-shaped, mechanical property test specimens that had been used to measure fracture toughness of the fusion welds. Specimens were prepared from regions of the weld heat-affected zones as well as from areas within the weld metal, including areas close to the fracture surface (plastically deformed regions).

The observed microstructures varied according to the amount of ferrite in each weld. At the lowest ferrite levels the microstructure consisted of austenite and skeletal ferrite with austenite being the majority (matrix) phase. At intermediate levels of ferrite, lathy austenite/ferrite was observed and the ferrite became continuous throughout the specimens examined. In the weld with the most ferrite, many austenite morphologies were observed and ferrite was the matrix phase. Closest to the fracture surface an increase in dislocation density in both the ferrite and austenite were observed in all welds. Deformation twinning was also observed in the austenite. Many of the welds contained a large number of non-metallic inclusions (oxide particles) which most likely originated from impurities in the weld wires. NTIS

Microstructure; Stainless Steels; Welded Joints

20050242967 Electric Power Research Inst., Palo Alto, CA, USA

BWRVIP-140NP: BWR Vessels and Internals Project Fracture Toughness and Crack Growth Program on Irradiated Austenitic Stainless Steel

January 2005; 50 pp.; In English Report No.(s): DE2005-839513; No Copyright; Avail.: Department of Energy Information Bridge

To prepare for this project, EPRI and BWRVIP conducted a workshop at Ponte Vedra Beach, Florida during February 19-21, 2003 (EPRI report 1007822). Attendees were invited to exchange relevant information on the effects of irradiation on austenitic materials in light water reactors and to produce recommendations for further work. EPRI reviewed the data, recommendations, and conclusions derived from the workshop and developed prioritized test matrices defining new data needs. Proposals were solicited, and selected proposals are the basis for the program described in this report. Results The planned test matrix for fracture toughness testing includes 21 tests on 5 materials. NTIS

Austenitic Stainless Steels; Fracture Strength; Stress Corrosion Cracking; Austenite

20050243012 North Carolina State Univ., Raleigh, NC USA

A Homogenized Energy Framework for Ferromagnetic Hysteresis

Smith, Ralph C.; Dapino, Marcelo J.; Braun, Thomas R.; Mortensen, Anthony P.; Jan. 1, 2005; 41 pp.; In English Contract(s)/Grant(s): F49620-01-1-0107; FA9550-04-1-0203 Report No.(s): AD-A439433; No Copyright; Avail.: Defense Technical Information Center (DTIC)

In this paper, we develop a macroscopic framework quantifying the hysteresis and constitutive nonlinearities inherent to ferromagnetic materials.

In the first step of the development, we construct Helmholtz and Gibbs energy relations at the mesoscopic or lattice level based on the assumption that magnetic moments or spins are restricted to two orientations. Direct minimization of the Gibbs energy yields local average magnetization relations appropriate for operating regimes in which relaxation mechanisms are negligible, whereas the balance of the Gibbs and relative thermal energies through Boltzmann principles provides local models which incorporate mechanisms such as thermal after-effects. To construct macroscopic relations that incorporate material nonhomogeneities, poly-crystallinity, and variable effective fields, we employ stochastic homogenization techniques based on the assumption that parameters such as local coercive and interaction fields are manifestations of underlying distributions.

The resulting framework quantifies in a natural manner the anhysteretic magnetization provided by decaying AC fields and guarantees the closure of biased minor loops once transient accommodation and after-effects are complete. Furthermore, noncongruency is achieved with certain choices for the energy functionals. Hence the framework provides an energy basis for certain extended Preisach models and the relation of the framework to several macroscopic hysteresis models is detailed. The behavior of both the nonlinear anhysteretic relations and full hysteresis model are validated through comparison with experimental steel and nickel data. DTIC

Ferromagnetic Materials; Homogeneity; Hysteresis

20050243025 Naval Postgraduate School, Monterey, CA USA

Thermo-Mechanical Response of Monolithic and NiTi Shape Memory Alloy Fiber Reinforced Sn-3.8Ag-0.7Cu Solder

Fountoukidis, Evangelos; Sep. 1, 2005; 89 pp.; In English; Original contains color illustrations Report No.(s): AD-A439457; No Copyright; Avail.: CASI: A05, Hardcopy

In electronic packaging, the reliability of solders is a critical issue, since serve as both electrical and mechanical connections. The most common failures arise from the thermo-mechanical fatigue (TMF) of solders, due to mismatches in the coefficient of thermal expansion between the Si-chip and the printed circuit board. In order to meet the demands of miniaturization and enhanced performance in severe environments, a novel adaptive Tin-Silver-Copper (SnAgCu) solder reinforced with NiTi shape-memory alloy (particles or fiber) developed. An experimental apparatus has been designed to investigate the thermo-mechanical straincontrolled fatigue life of the solder during both single and multiple thermal cycling under double-shear loading. For comparison, thermo-mechanical single shear tests were also performed in monolithic Tin-Silver-Copper solder and in solder reinforced with Cu fiber. Also, micro-structural evaluation of the solders during the 5th cycle was possible using Scanning and Optical microcopy together with EDS analysis. DTIC

Binary Alloys; Fiber Composites; Nickel Alloys; Shape Memory Alloys; Soldering; Solders; Thermodynamics; Titanium Alloys

20050243410 Jefferson (Thomas) National Accelerator Facility, Newport News, VA, USA, Reference Metals Co., Inc., Bridgeville, PA, USA

Preliminary Results from Single Crystal Niobium Cavities

Kneisel, P.; Myneni, G. R.; Ciovati, G.; Sekutowicz, J.; January 2005; 8 pp.; In English Report No.(s): DE2005-840252; No Copyright; Avail.: National Technical Information Service (NTIS)

We have fabricated and tested several single cell cavities using material from very large grain niobium ingots. In one case the central grain exceeded 7 inches in diameter and this was used to fabricate two 2.2 GHz cavities. This activity had a dual purpose: to investigate the influence of grain boundaries on the often observed Q-drop at gradients E(sub acc) \g 20 MV/m in the absence of field emission, and to study the possibility of using ingot material for cavity fabrication without going through the expensive rolling process.

The sheets for these cavities were cut from the ingot by wire electro-discharge machining (EDM) and subsequently formed into half-cells by deep drawing. The following fabrication steps were standard: machining of weld recesses, electron beam welding of beam pipes onto the half cells and final equator weld to join both half cell/beam pipe subunits. The cavities showed heavy Q-disease caused by the EDM. After hydrogen degassing at 800 C for 3 hrs in UHV and about 200 (micro)m total removals from the inner surface by BCP 1:1:1, the cavities showed promising results, however, the Q-drop was still present. In the two cavities made from large grain material accelerating gradients of 30 MV/m have been reached. After ‘in-situ’ baking the Q-drop disappeared. The smaller cavities made from single crystal material showed very low residual resistances and accelerating gradients up to E(sub acc) = 45 MV/m were reached (one of the highest ever achieved), corresponding to a peak surface magnetic fields (B(sub p)) of 160 mT. In one rf test at 2 K, a B(sub p) = 185 mT was reached for few hundred milliseconds, close to the theoretical critical field of this material. NTIS

Crystals; Niobium; Single Crystals

Source: NASA.