scholarly journals Occurrence of Dynamic Shear Bands in AISI 4340 Steel under Impact Loads

2013 ◽  
Vol 03 (02) ◽  
pp. 139-145 ◽  
Author(s):  
Gbadebo Owolabi ◽  
Daniel Odoh ◽  
Akindele Odeshi ◽  
Horace Whitworth
Keyword(s):  
Shear Bands ◽  
Impact Loads ◽  
Dynamic Shear ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

On the Catastrophic Shear Instability in High-Speed Machining of an AISI 4340 Steel

1982 ◽  
Vol 104 (2) ◽  
pp. 121-131 ◽  
Author(s):  
R. Komanduri ◽  
T. Schroeder ◽  
J. Hazra ◽  
B. F. von Turkovich ◽  
D. G. Flom
Keyword(s):  
Titanium Alloys ◽  
Shear Zone ◽  
Chip Formation ◽  
High Speed ◽  
Shear Bands ◽  
Shear Instability ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Cutting Speeds ◽  
Aisi 4340

An AISI 4340 Steel (325 BHN) was machined at various speeds up to 2500 m/min (8000 SFPM). Longitudinal midsections of the chips were examined metallurgically to delineate the differences in the chip formation characteristics at various speeds. Chips were found to be continuous at 30 to 60 m/min (100 to 200 SFPM) but discontinuous below this speed. Instabilities in the cutting process, leading to different types of cyclic chip formations, were observed at cutting speeds above 60 m/min (200 SFPM). Fully developed catastrophic shear bands separated by large areas (segments) of relatively less deformed material, similar to that when machining titanium alloys, were observed in the chips at cutting speeds above 275 m/min (800 SFPM). The intense shear bands between the segments appeared to have formed subsequent to the localized intense deformation of the segment in the primary shear zone. As the cutting speed increases, the extent of contact between the segments is found to decrease rapidly. At speeds of 1000 m/min (3200 SFPM) and above, due to rapid intense, localized shear between the segments, these segments were found to separate completely as isolated segments instead of being held intact as a long chip. The speed at which this decohesion occurs was found to depend upon the metallurgical state of the steel machined and its hardness. As in the case of machining titanium alloys, the deformation of the chip as it slides on the tool face, i.e., “secondary shear zone,” appeared to be negligible when machining this AISI 4340 steel at high speed. Based on the metallurgical study of the chip and the similarities of machining this material at high speed and that of titanium alloys at normal speed, a cyclic phenomenon in the primary shear zone is identified as the source of instability responsible for the large-scale heterogeneity and a mechanism of chip formation when machining AISI 4340 steel at high speed is proposed.

scholarly journals Shear band formation in AISI 4340 steel under dynamic impact loads: Modeling and experiment

2013 ◽  
Vol 26 (4) ◽  
pp. 378-384 ◽  
Author(s):  
Daniel Odoh ◽  
Gbadebo Owolabi ◽  
Akindele Odeshi ◽  
Horace Whitworth
Keyword(s):  
Shear Band ◽  
Impact Loads ◽  
Shear Band Formation ◽  
Dynamic Impact ◽  
Band Formation ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

Modeling and Simulation of Adiabatic Shear Bands in AISI 4340 Steel Under Impact Loads

2012 ◽  
Author(s):  
Gbadebo Owolabi ◽  
Daniel Odoh ◽  
Akindele Odeshi ◽  
Horace Whitworth
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Experimental Results ◽  
Strain Rates ◽  
Adiabatic Shear Bands ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

In this study, the effects of microstructure and strain rate on the occurrence and failure of adiabatic shear bands in AISI 4340 steel under high velocity impact loads are investigated using finite element analysis and experimental tests. The shear band generated due to impact load was divided into some set of elements separated by nodes using finite element method in ABAQUS environment with initial and boundary conditions specified. The material properties were assumed to be lower at the second element set in order to initialize the adiabatic shear bands. The strain energy density for each successive node was calculated successively starting from the first element where initial boundary condition, initial strain hardening constant, and stress resistance had been specified. As the load time is increased, its corresponding effect on the localized shear deformation and width of the adiabatic shear band was also determined. The finite element model was used to determine the maximum stress, the strain hardening, the thermal softening, and the time to reach critical strain for formation of adiabatic shear bands. Experimental results show that deformed bands were formed at low strain rates and there was a minimum strain rate required for formation of transformed band in the alloy. The experimental results also show that cracks were initiated and propagated along transformed bands leading to fragmentation under the impact loading. The susceptibility of the adiabatic shear bands to cracking was markedly influenced by strain-rates and the initial material microstructures. The numerical results obtained were compared with the experimental results obtained for the AISI 4340 steel under high strain-rate loading in compression using split impact Hopkinson bars. A good agreement between the experimental and simulation results are also obtained.

Dynamic shear band propagation and failure in AISI 4340 steel

2005 ◽  
Vol 169 (2) ◽  
pp. 150-155 ◽  
Author(s):  
A.G. Odeshi ◽  
M.N. Bassim ◽  
S. Al-Ameeri ◽  
Q. Li
Keyword(s):  
Shear Band ◽  
Dynamic Shear ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Aisi 4340

Influence of Minimum Quantity Lubrication on Grinding Performance of Annealed AISI 4340 Steel

2017 ◽  
Vol 31 (2) ◽  
pp. 17 ◽  
Author(s):  
Sirsendu Mahata ◽  
Ankesh Samanta ◽  
Joydip Roy ◽  
Bijoy Mandal ◽  
Santanu Das
Keyword(s):  
Minimum Quantity Lubrication ◽  
Aisi 4340 Steel ◽  
Minimum Quantity ◽  
Grinding Performance ◽  
4340 Steel ◽  
Aisi 4340
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