scholarly journals Investigations on Strain Hardening During Cutting of Heat-Resistant Austenitic Stainless Steel

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Rabiae Arif ◽  
Guillaume Fromentin ◽  
Frédéric Rossi ◽  
Bertrand Marcon
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Plastic Strain ◽  
Strain Hardening ◽  
Subsurface Layer ◽  
Hardened Layer ◽  
Cutting Edge ◽  
Cutting Process ◽  
Image Correlation ◽  
Correlation Technique

Abstract This study presents a novel analysis of the machined subsurface layer formation dealing with strain hardening phenomenon which results from complex mechanisms due to cutting edge multiple passes in drilling. On the one hand, the hardened layer during drilling is characterized in relation with the local cutting geometry and thanks to a quick-stop device (QSD) to suddenly interrupt the operation. Micro hardness is used to determine the hardened thickness of the machined subsurface layers along the local cutting edge geometry. On the other hand, orthogonal cutting performed with a complex self-designed planing experiment is used to investigate in details the hardening accumulation aspects. Then, dedicated methodologies are proposed to quantify the strain hardening as well as the incremental plastic strain generated by consecutive tool passes. In addition to the subsurface hardness evolution, the work material strain is observed during the steady-state cutting process thanks to the high-speed camera. The digital image correlation technique is exploited to analyze not only the plastic strain remaining on the workpiece after the cut but also the effect of the incremental plastic strain generated by the consecutive planing passes as the cutting edges in drilling do. One of the outcomes is that the hardened layer thickness can reach from two to three times the cut thickness in drilling or in planing. As a consequence, this work demonstrates that the cutting process affects itself by hardening. Thus, the studied austenitic stainless steel in such a way that this last is never cut in its initial state.

scholarly journals Strain rate jump tests on an austenitic stainless steel with a modified tensile Hopkinson split bar

2018 ◽  
Vol 183 ◽  
pp. 02026
Author(s):  
Naiara I. Vazquez Fernandez ◽  
Matti Isakov ◽  
Mikko Hokka ◽  
Veli-Tapani Kuokkala
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Localization ◽  
Image Correlation ◽  
High Rate ◽  
Correlation Technique ◽  
Gauge Section ◽  
Strain Hardening Rate

This paper presents an improved experimental setup for high strain rate testing based on the modified Tensile Hopkinson Split Bar device developed previously at TUT. The test setup can be used to study the effects of a sudden large change in the strain rate on the stress flow of the material. The setup allows deforming the sample at a low rate and at isothermal conditions before the high rate loading. During the strain rate jump, the deformation rate is rapidly increased by approximately six orders of magnitude. In this work, the low and high rate deformation of the specimen was recorded with a combination of low and high-speed digital cameras and analyzed using the Digital Image Correlation technique. The measurement provides information about the effects of the strain rate jump on the macroscopic response of the material and allows accurate observation of the deformation of the sample just before, during, and immediately after the strain rate jump, when the conditions change from isothermal to adiabatic. In this paper, we present the results for a metastable austenitic stainless steel and discuss the effects of the strain rate jump on the strain-hardening rate, compare the experimental results with numerical results from a thermomechanical model, and evaluate the effects of the preceding deformation at a low strain rate on the strain localization. We conclude that the strain rate jump results in a clear decrease in the strain-hardening rate, the deformation following the jump is uniform along the gauge section, and that the strain localization is not significantly affected by the strain rate or the amount of pre-strain in the studied conditions.

Estimation of Strain-Hardness Correlation in Cold-Forged Austenitic Stainless Steel

2014 ◽  
Vol 622-623 ◽  
pp. 179-185 ◽  
Author(s):  
Piotr Skubisz ◽  
Maciej Rumiński ◽  
Łukasz Lisiecki
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Hardening ◽  
Effective Strain ◽  
Cold Deformation ◽  
Metal Flow ◽  
Fem Simulation ◽  
Large Head ◽  
The Relationship

The paper presents selected aspects of analysis cold micro-forging process of a screw made of austenitic stainless steel, concerning relation between strain and hardness. Strain hardening character of a material in consecutive forming operations was analyzed experimentally by the measurement of hardness distribution made on longitudinal axial sections of screws. The relationship between hardness and effective strain (hardness curve) was determined, which made it possible to obtain strain distributions in different regions of a material subjected to cold deformation on the basis of strain distribution numerically estimated with FEM simulation performed using QForm2D/3D commercial software. Conclusions were formulated concerning strain inhomogeneity and strain-hardening intensity with respect to the correlation between strain and hardness. It was also concluded, that nonuniformity of hardening rate in a bulk can lead to local variations in flow stress and eventually, to occurrence of the metal flow related defects, which was illustrated with a case study of cold heading of self-tapping screw of AISI 304Cu stainless steel, with large head diameter to shank diameter ratio. In order to validate the obtained results, the same method was used for analysis of hardness development in steel 19MnB4.

scholarly journals Cutting Properties of Austenitic Stainless Steel by Using Laser Cutting Process without Assist Gas

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Hitoshi Ozaki ◽  
Yosuke Koike ◽  
Hiroshi Kawakami ◽  
Jippei Suzuki
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Molten Metal ◽  
Laser Power ◽  
Laser Cutting ◽  
Cutting Speed ◽  
Cutting Process ◽  
Metallic Materials ◽  
Bottom Side ◽  
Gas Nozzle

Recently, laser cutting is used in many industries. Generally, in laser cutting of metallic materials, suitable assist gas and its nozzle are needed to remove the molten metal. However, because of the gas nozzle should be set closer to the surface of a workpiece, existence of the nozzle seems to prevent laser cutting from being used flexible. Therefore, the new cutting process, Assist Gas Free laser cutting or AGF laser cutting, has been developed. In this process, the pressure at the bottom side of a workpiece is reduced by a vacuum pump, and the molten metal can be removed by the air flow caused by the pressure difference between both sides of the specimen. In this study, cutting properties of austenitic stainless steel by using AGF laser cutting with 2 kW CO2 laser were investigated. Laser power and cutting speed were varied in order to study the effect of these parameters on cutting properties. As a result, austenitic stainless steel could be cut with dross-free by AGF laser cutting. When laser power was 2.0 kW, cutting speed could be increased up to 100 mm/s, and kerf width at specimen surface was 0.28 mm.

Characterisation of Microstructure and Properties of a Transition Weld

2016 ◽  
Author(s):  
W. J. Brayshaw ◽  
A. H. Sherry ◽  
M. G. Burke ◽  
P. James
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Heat Affected Zone ◽  
Ferritic Steel ◽  
Image Correlation ◽  
Micro Hardness ◽  
Flow Properties ◽  
Material Interfaces ◽  
Local Composition ◽  
Microstructure And Properties

Transition welds represent a challenge for the assessment of structural integrity of nuclear plant due to the complexity of the microstructure, properties and local stress state. This paper presents the initial findings of a study aimed at characterising the local microstructure and properties of a transition weld between SA508-4N ferritic steel and SS316LN austenitic stainless steel using a nickel-base filler of Alloy 82. The local microstructures and local composition of the material interfaces are characterised using backscattered electron imaging and Energy-dispersive X-ray spectroscopy. The ferritic steel shows significant grain refinement in the heat affected zone compared to the base metal. This refinement is also observed in the heat affected zone of the austenitic stainless steel although not as significant. Micro-hardness testing has also been incorporated to provide an indication of the influence of local microstructure on flow properties across the weld region. The results indicate a hardness range of between 180–340HV across the weld with the highest value in the heat affected zone of the ferritic steel and the lowest in the austenitic stainless steel. Yield and flow properties derived from flat transweld tensile tests incorporating digital image correlation are related to the micro-hardness results and microstructural characterisation, and an initial assessment of the fracture mechanism performed using fractography.

Effects of Nanometric Control in Tool Cutting Edge Sharpness on Micropunching of Austenitic Stainless Steel SUS304

2020 ◽  
Vol 61 (714) ◽  
pp. 147-153
Author(s):  
Tomomi SHIRATORI ◽  
Tomoaki YOSHINO ◽  
Takuya AIHARA ◽  
Yohei SUZUKI ◽  
Shizuka NAKANO ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cutting Edge ◽  
Edge Sharpness ◽  
Tool Cutting
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