Deformation and fracture behavior of an 8090 Al-Li alloy at cryogenic temperature

Kim

et al. 1998

Metall Mater Trans A

The objective of the present study is to investigate the effect of test temperature on the dynamic torsional deformation behavior of two Al-Li alloys, i.e., 2090 and 8090 alloys. Dynamic torsional tests were conducted using a torsional Kolsky bar at room temperature and a low temperature (Ϫ196 ЊC), and the torsionally deformed regions and the fracture surfaces of the tested specimens were examined. The dynamic properties of the two Al-Li alloys at the low temperature were improved, owing to the modification of the deformation behavior. The dynamic deformation behavior at room temperature was dominated by intergranular cracks due to planar slips and by crack propagation along the grain boundaries. At the low temperature, plastic deformation proceeded more homogeneously as planar slip was prevented. These results indicated that the overall deformation mode of both the Al-Li alloys changed from planar slip to homogeneous deformation with decreasing temperature, resulting in the improvement of cryogenic properties under dynamic torsional loading.

Section: Discussionmentioning

confidence: 99%

Effect of test temperature on the dynamic torsional deformation behavior of two aluminum-lithium alloys

Kim

et al. 1998

Metall Mater Trans A

AIP Conference Proceedings

“…Another series of measurements we propose to make is to study in situ twinning that takes place in Zirconium to complement previous work from interrupted tests [4]. Other materials that are likely candidates for study are Al-Li alloys due to their great potential for use in the aerospace industry [11,12]. They show improvement of their strength, ductility and toughness at low temperatures but the origins of their behavior or deformation mechanisms at cryogenic temperatures are not clear.…”

Section: Proposed Measurementsmentioning

confidence: 99%

Design and Rationale for an In Situ Cryogenic Deformation Capability at a Neutron Source

Livescu¹,

Woodruff²,

Clausen³

et al. 2004

When performed in conjunction with neutron diffraction, in situ loading offers unique insights on microstructural deformation mechanisms. This is by virtue of the penetration and phase sensitivity of neutrons. At Los Alamos National Laboratory room and high temperature (up to 1500°C) polycrystalline constitutive response is modeled using finite element and self-consistent models. The models are compared to neutron diffraction measurements. In doing so the implications of slip and creep to microstructural response have been explored. Recently we have been considering low temperature phenomena. This includes changes in deformation mechanisms such as the increased predilection for twinning over slip. Since this is associated with measurable texture changes as well as microstructural strain effects, it is well suited for study using neutron diffraction. This paper outlines the design and rationale for a cryogenic loading capability that will be used on the Spectrometer for MAterials Research at Temperature and Stress (SMARTS) at the Los Alamos Neutron Science Center (LANSCE).

“…The hull structural steel must have the properities of high strength, excellent low-temperature toughness, high resistance to corrosion and good weldability. A great deal of research has been carried out in the past few years to determine the effect of in-situ tensile testing on different materials by metallurgical researchers, the relationship between the local plastic deformation, crack nucleation, crack propagation and microstructures was revealed [1][2][3], whereas only a limited amount of work has been done on in-situ tensile test of polygonal ferrite-pearlite. This paper focus on the in-situ tensile testing of B-class shipbuilding steel to investigate the action of polygonal ferrite-pearlite in the deforming and cracking process, indicate the relationship between the crack nucleation, propagation and microstructures.…”

Section: Introductionmentioning

confidence: 99%

<i>I</i><i>n Situ</i> Study of Fracture Process for B-Class Shipbuilding Steel

Liang

Wen

et al. 2011

MSF

Crack initiation, propagation and microfracture processes of B-class shipbuilding steel have been investigated by using an in-situ tensile stage installed inside a scanning electron microscope chamber, meanwhile the secondary crack propagation at low temperature brittle fracture has also been studied. It is revealed that micro cracks always nucleated at the notch of specimens due to the stress concentration and then propagate along the interface of ferrite-pearlite. The plastic deformation of polygonal ferrite occurred in the loading process, the cracks propagated as “Z” morphology in the matrix. In the low temperature brittle fracture zone, the secondary crack propagated through the ferrite matrix in the manner of transgranular crack. When the secondary crack propagated to pearlite region, the intragranular crack and transgranular crack were observed in the pearlite region .