Strain rate sensitivity of flow stress at low temperatures in 304n stainless steel

Finite element analysis is used to simulate indentation creep experiments with a cone-shaped indenter. The purpose of the work is to help identify the relationship between the strain-rate sensitivity of the hardness, νH, and that of the flow stress, νσ in materials for which elastic deformations are significant. In general, νH differs from νσ, but the ratio νH/νσ is found to be a unique function of H/E* where H is the hardness and E* is the modulus relevant to Hertzian contact. νH/νσ approaches 1 for small H/E*, 0 for large H/E*, and is insensitive to work hardening. The trend in νH/νσ as a function of H/E* can be explained based on a generalized analysis of Tabor’s relation in which hardness is proportional to the flow stress H = k × σeff and in which the proportionality factor k is a function of σeff/E*.

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Strain Rate Sensitivity of Alloys 800H and 617

Volume 1A: Codes and Standards ◽

10.1115/pvp2013-98045 ◽

2013 ◽

Cited By ~ 2

Author(s):

J. K. Wright ◽

J. A. Simpson ◽

R. N. Wright ◽

L. J. Carroll ◽

T. L. Sham

Keyword(s):

High Temperature ◽

Flow Stress ◽

Strain Rate ◽

Strain Rate Sensitivity ◽

Rate Sensitivity ◽

Temperature Limit ◽

Applied Strain ◽

Alloy 800H ◽

Alloy 617 ◽

Temperature Heat

The flow stress of many materials is a function of the applied strain rate at elevated temperature. The magnitude of this effect is captured by the strain rate sensitivity parameter “m”. The strain rate sensitivity of two face–center cubic solid solution alloys that are proposed for use in high temperature heat exchanger or steam generator applications, Alloys 800H and 617, has been determined as a function of temperature over that range of temperatures relevant for these applications. In addition to determining the strain rate sensitivity, it is important for nuclear design within Section III of the ASME Boiler and Pressure Vessel Code to determine temperature below which the flow stress is not affected by the strain rate. This temperature has been determined for both Alloy 800H and Alloy 617. At high temperature the strain rate sensitivity of the two alloys is significant and they have similar m values. For Alloy 617 the temperature limit below which little or no strain rate sensitivity is observed is approximately 700°C. For Alloy 800H this temperature is approximately 650°C.

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Strain Rate Dependence of the Flow Stress and Work-Hardening of Single Crystals of NI3(Al,Hf)B

MRS Proceedings ◽

10.1557/proc-364-695 ◽

1994 ◽

Vol 364 ◽

Author(s):

S. S. Ezz ◽

Y. Q. Sun ◽

P. B. Hirsch

Keyword(s):

Flow Stress ◽

Strain Rate ◽

Temperature Dependence ◽

Single Crystals ◽

Yield Stress ◽

Strain Rate Sensitivity ◽

Work Hardening ◽

Room Temperature ◽

Rate Sensitivity ◽

Controlling Mechanism

AbstractThe strain rate sensitivity ß of the flow stress τ is associated with workhardening and β=(δτ/δln ε) is proportional to the workhardening increment τh = τ - τy, where τy is the strain rate independent yield stress. The temperature dependence of β/τh reflects changes in the rate controlling mechanism. At intermediate and high temperatures, the hardening correlates with the density of [101] dislocations on (010). The nature of the local obstacles at room temperature is not established.

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On the strain rate sensitivity of the flow stress of ultrafine-grained Cu processed by equal channel angular extrusion (ECAE)

Scripta Materialia ◽

10.1016/j.scriptamat.2005.04.030 ◽

2005 ◽

Vol 53 (5) ◽

pp. 581-584 ◽

Cited By ~ 50

Author(s):

H. Conrad ◽

K. Jung

Keyword(s):

Flow Stress ◽

Strain Rate ◽

Strain Rate Sensitivity ◽

Equal Channel Angular Extrusion ◽

Rate Sensitivity ◽

Ultrafine Grained ◽

Angular Extrusion

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Microstructure and Plasticity of Hot Deformed 5083 Aluminum Alloy Produced by Rapid Solidification and Hot Extrusion / Badania Mikrostruktury I Plastyczności Odkształcanego Na Gorąco Szybko-Krystalizowanego I Wyciskanego Stopu Aluminium 5083

Archives of Metallurgy and Materials ◽

10.2478/v10172-012-0140-2 ◽

2012 ◽

Vol 57 (4) ◽

pp. 1253-1259 ◽

Cited By ~ 8

Author(s):

T. Tokarski ◽

Ł. Wzorek ◽

H. Dybiec

Keyword(s):

Aluminum Alloy ◽

High Temperature ◽

Flow Stress ◽

Strain Rate ◽

Strain Rate Sensitivity ◽

Rate Sensitivity ◽

Temperature Range ◽

Rapidly Solidified ◽

5083 Aluminum Alloy ◽

Conventionally Cast

The objective of the present study is to analyze the mechanical properties and thermal stability for rapidly solidified and extruded 5083 aluminum alloy (RS). Compression tests were performed in order to estimate flow stress and strain rate sensitivity relation for 5083 alloy in the temperature range of 20°C to 450°C. For the comparison purposes, conventionally cast and extruded industrial material (IM) was studied as well. Deformation tests performed at room temperature conditions show that rapidly solidified material exhibits about 40% higher yield stress (YS=320 MPa) than conventionally cast material (YS=180 MPa), while the deformation at 450°C results in significant decrease of flow stress parameters for RS material (YS=20 MPa) in comparison to IM material (YS=40 MPa). Strain rate sensitivity parameter determined for high temperature conditions indicates superplasticity behavior of RS material. Structural observations show that under conditions of high-temperature deformation there are no operating recrystallization mechanisms. In general, grain size below 1µm and size of reinforcing phases below 50 nm is preserved within the used deformation temperature range.

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Dynamic Mechanical Response of Biomedical 316L Stainless Steel as Function of Strain Rate and Temperature

Bioinorganic Chemistry and Applications ◽

10.1155/2011/173782 ◽

2011 ◽

Vol 2011 ◽

pp. 1-13 ◽

Cited By ~ 21

Author(s):

Woei-Shyan Lee ◽

Tao-Hsing Chen ◽

Chi-Feng Lin ◽

Wen-Zhen Luo

Keyword(s):

Activation Energy ◽

Stainless Steel ◽

Flow Stress ◽

Strain Rate ◽

Thermal Activation ◽

316L Stainless Steel ◽

Rate Sensitivity ◽

Thermal Activation Energy ◽

Work Hardening Rate ◽

Stress Work

A split Hopkinson pressure bar is used to investigate the dynamic mechanical properties of biomedical 316L stainless steel under strain rates ranging from 1 × 103 s-1to 5 × 103 s-1and temperatures between25∘Cand800∘C. The results indicate that the flow stress, work-hardening rate, strain rate sensitivity, and thermal activation energy are all significantly dependent on the strain, strain rate, and temperature. For a constant temperature, the flow stress, work-hardening rate, and strain rate sensitivity increase with increasing strain rate, while the thermal activation energy decreases. Catastrophic failure occurs only for the specimens deformed at a strain rate of 5 × 103 s-1and temperatures of25∘Cor200∘C. Scanning electron microscopy observations show that the specimens fracture in a ductile shear mode. Optical microscopy analyses reveal that the number of slip bands within the grains increases with an increasing strain rate. Moreover, a dynamic recrystallisation of the deformed microstructure is observed in the specimens tested at the highest temperature of800∘C.

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