Study on Chip Morphology and Adiabatic Shear in High Speed Cutting of Alloy Steels with Different Hardness

2010 ◽  
Vol 26-28 ◽  
pp. 875-879
Author(s):  
Chun Zheng Duan ◽  
Hong Hua Li ◽  
Min Jie Wang ◽  
Yu Jun Cai
Keyword(s):  
Shear Band ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Shear Bands ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Optical Microscope ◽  
Adiabatic Shear ◽  
Serrated Chip ◽  
High Speed Cutting

The chip morphology and the formation and development of the adiabatic shear band within the serrated chips formed in high speed cutting of 30CrNi3MoV steel with two tempering hardness were observed and analyzed using optical microscope and SEM. The investigation shows that as the adiabatic shear phenomenon occurs and develops, the chip morphology changes as follows: ribbon chip→serrated chip with deformed band→serrated chip with transformed band→fractured chip. The cutting speed and tempering hardness is the two main factors affecting adiabatic shear, in the case of lower cutting speed the formation and development of adiabatic shear band are more sensitive to tempered hardness increase. The deformed shear bands are constituted by large deformed microstructure, while the formation of the transformed shear bands has experienced the large plastic deformation and grain refinement.

Component Analysis of Adiabatic Shear Band Formed in High Speed Cutting of High Strength Alloy Steel

2011 ◽  
Vol 52-54 ◽  
pp. 1482-1485
Author(s):  
Chun Zheng Duan ◽  
Zhao Xi Wang ◽  
Min Jie Wang ◽  
Wei Sen Kong
Keyword(s):  
Shear Band ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Diffusion Mechanism ◽  
Shear Bands ◽  
Cutting Speed ◽  
High Strength ◽  
Adiabatic Shear ◽  
Serrated Chip ◽  
High Speed Cutting

The component distribution of adiabatic shear banding during high speed cutting(HSC) is important to understand the phase transformation during formation of adiabatic shear band and mechanism of serrated chip formation. This paper analyzed element distribution inside and near the adiabatic shear bands formed during HSC of 30CrNi3MoV high strength steel using electronic probe. It was found that there is no obvious element segregation, but carbon element tends to gather towards adiabatic shear band’s boundaries. The density of carbon inside the shear bands tends to increase with the increase of cutting speed. The results indicated that the diffusion and gather of carbon may occur during formation of adiabatic shear band. The diffusion mechanism may be short-range diffusion driven by high-speed deformation and high temperature rise.

Adiabatic Shear Localization in High Speed Cutting of Hardened Steel

2011 ◽  
Vol 55-57 ◽  
pp. 983-987 ◽  
Author(s):  
Chun Zheng Duan ◽  
Wei Sen Kong ◽  
Zhao Xi Wang ◽  
Min Jie Wang
Keyword(s):  
Shear Band ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Shear Bands ◽  
Cutting Speed ◽  
Shear Localization ◽  
Adiabatic Shear ◽  
Adiabatic Shear Bands ◽  
High Speed Cutting ◽  
Serrated Chips

The formation and development of adiabatic shear localization in serrated chips have great significance to study of mechanism of high speed cutting. This paper investigates the theory prediction and experimental verification of the critical cutting speed of adiabatic shear localization, distribution of adiabatic shear band in serrated chip and the geometry of adiabatic shear band during high speed cutting of hardened steel. The results indicated that the theoretical prediction of critical cutting speed is consistent with the experimental results.With the increase of cutting speed, the width and spacing of adiabatic shear bands in the serrated chips decrease linearly. There are two types of adiabatic shear bands during the formation and development of adiabatic shear localization, i.e. the deformation shear band and the transformed shear band.

Experimental Study of Serrated Chip in High Speed Cutting

2012 ◽  
Vol 723 ◽  
pp. 99-104
Author(s):  
Guo He Li ◽  
Hou Jun Qi ◽  
Bing Yan
Keyword(s):  
Shear Band ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Rake Angle ◽  
Adiabatic Shear ◽  
Cutting Depth ◽  
Serrated Chip ◽  
High Speed Cutting

In this paper, some high speed cutting experiments of hardened 45 steel are carried out. The effects of cutting parameters on the width and space of adiabatic shear band, the frequency and degree of sawtooth are investigated by metallographic observation and theoretical calculation. The results show that the space of adiabatic shear band decreases with the increase of cutting speed and rake angle, but increases with the increase of cutting depth. The width of adiabatic shear band decreases with the increase of cutting speed and cutting depth, however, increases with the increase of rake angle. The frequency of sawtooth increases with the increases of cutting speed, decreases with the increase of rake angle, and has no obvious relationship with cutting depth. The degree of sawtooth increases with the increase of cutting speed and cutting depth, but decreases with the increase of rake angle.

Chip Formation Characteristics in High-Speed Machining of Hardened AISI1045 Steel

2012 ◽  
Vol 565 ◽  
pp. 484-489
Author(s):  
Bing Wang ◽  
Zhan Qiang Liu ◽  
Qi Biao Yang
Keyword(s):  
Shear Band ◽  
Chip Formation ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Cutting Speed ◽  
Adiabatic Shear ◽  
High Speed Machining ◽  
Micro Hardness ◽  
Serrated Chip ◽  
Aisi1045 Steel

Analyzing mechanism of the chip formation is a significant way to understand the metal cutting process better. The characterization of serrated chip formation in high speed machining of hardened AISI1045 steel is investigated with the aid of optical microscopy and micro-hardness measurement in this paper. The chip morphology evolving from continuous one to serrated one with the cutting speed increasing from 100-1500m/min is observed. Compared with the continuous chip pattern, serrated chip has its particular characterization parameters. The characteristics of serration degree and the segmentation frequency of the serrated chip are presented. The micro-hardness at the adiabatic shear band of serrated chip is then measured. The results show that the serration degree and segmentation frequency of serrated chip have a tendency of enhancement with the cutting speed increasing. The micro-hardness along the adiabatic shear band increases with the cutting speed increasing due to severe strain hardening. With a critical speed at about 100-200m/min, micro-hardness decreases from the tool-chip interface to the free surface of the chip.

Research on Adiabatic Shear during Serrated Chip Formation of High Speed Turning of Hardened Steel

2010 ◽  
Vol 139-141 ◽  
pp. 743-747
Author(s):  
Chun Zheng Duan ◽  
Hai Yang Yu ◽  
Min Jie Wang ◽  
Bing Yan ◽  
Yu Jun Cai
Keyword(s):  
Chip Formation ◽  
Cutting Forces ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Rake Angle ◽  
Adiabatic Shear ◽  
Cutting Condition ◽  
Serrated Chip ◽  
Serrated Chip Formation

The development of chip morphology, critical cutting condition of adiabatic shear during serrated chip formation and cutting forces were observed and measured by high speed turning experiment for 30CrNi3MoV hardened steel. Results show that the cutting speed and rake angle are leading factors to influence chip morphology and cutting forces. With the increase of cutting speed, the continuous band chip transforms into serrated chip at a certain critical value. As the rake angle is changed from positive to negative, the critical cutting speed of adiabatic shear significantly decreases, the cutting forces abruptly reduces when the serrated chip forms. The results from predicting critical cutting speed using the critical cutting condition criterion of adiabatic shear in metal cutting process show that the leading reason of serrated chip formation is that the adiabatic shear fracture repeatedly occurs in the primary shear zone.

Experiment Study of Serrated Chip and Surface Roughness of High Speed Cutting of Ti6Al4V

2014 ◽  
Vol 800-801 ◽  
pp. 571-575
Author(s):  
Guo He Li ◽  
Yu Jun Cai ◽  
Hou Jun Qi
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Cutting Speed ◽  
Rake Angle ◽  
Adiabatic Shear ◽  
Cutting Condition ◽  
Experiment Study ◽  
Cutting Depth ◽  
Serrated Chip ◽  
High Speed Cutting

Under the condition of cutting speed 10-300m/min, rake angle -10°、0°、10°and cutting depths 0.05mm、0.1mm and 0.2mm, the experiment study of adiabatic shear serrated chip and surface roughness are carried out. The influence of cutting condition on serrated chip is analyzed through the metallographic observation of obtained chip. By the measurement of finished surface, the influenc of cutting condition and adiabatic shear on surface roughness is also investigated. The rusults show that the reason lead to serrated chip in high speed cutting of Ti6Al4V is adiabatic shear, not the periodic fracture.The adiabatic shear serrated chip is easier appear and the degree of segment is more large under the condition of higher cutting speed, larger cutting depth and smaller rake angle. The surface roughness is smaller when the cutting speed is higher, cutting depth is larger, and rake angle is smaller.

Investigation of Chip Morphology in High-Speed Milling of Nickel-Based Superalloy GH706

2014 ◽  
Vol 800-801 ◽  
pp. 113-118
Author(s):  
Sheng Lei Xiao ◽  
Xian Li Liu ◽  
Yu Wang ◽  
Kai Li
Keyword(s):  
Chip Formation ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Adiabatic Shear ◽  
Shear Instability ◽  
Serrated Chip ◽  
High Speed Milling ◽  
Nickel Based Superalloy ◽  
Serrated Chip Formation

This paper analyzed the serrated chip formation process and mechanism in high-speed milling of nickel-based superalloy GH706. Firstly, analyzed two theories of serrated chip formation: cyclical fracture theory and adiabatic shear theory. Secondly, used the simulation of chip formation in high-speed milling of GH706 process, and concluded that the two major theories have achieved dialectical unity when machining for such difficult machining materials. Finally experiments for serrated chip, when cutting speed exceeded 200/min, serrated chips became more obvious. Research has shown that for nickel-based superalloy, adiabatic shear instability of the unstable thermoplastic in the first deformation zoon become the leader of formation of serrated chip, followed as the speed increases, fracture aggravate the degree of serrated chip.

Research on Dynamic Constitutive Relation of Materials Taking Account of Damage Evolution and Fracture Law for High Speed Cutting

2011 ◽  
Vol 188 ◽  
pp. 224-229
Author(s):  
J.Q. Li ◽  
Tao Tao Dong ◽  
Min Jie Wang
Keyword(s):  
Shear Band ◽  
Strain Rate ◽  
Constitutive Relation ◽  
Damage Evolution ◽  
High Speed ◽  
Adiabatic Shear Band ◽  
Adiabatic Shear ◽  
Damage Effect ◽  
Serrated Chip ◽  
Softening Effect

The adiabatic shear, which may produce serrated chip, usually occurs for a large number of materials in high speed machining. Adiabatic shear band is an important damage model for metals under high-velocity deformation process. The damage evolution of micro-voids in adiabatic shear bands resulted in material fracture finally. Now the thermal softening effect, the strain rate harding effect and the strain harding effect have been discussed extensively in literature, but there is very little research on its damage effect. Based on the experiments of predecessors, this paper presents a new damage evolution equation that is dependent on strain, strain rate and is suitable for the description of voids damage evolution in adiabatic shear band. The corresponding rate-dependent constitutive relation taking account of damage evolution and temperature are proposed. The predicted results are in good agreement with the experiment datum.

Microscopic Examination of Primary Shear Zone in High Speed Machining of Hardened High Strength Steel

2010 ◽  
Vol 97-101 ◽  
pp. 1887-1890 ◽  
Author(s):  
Chun Zheng Duan ◽  
Min Jie Wang ◽  
Tao Dou
Keyword(s):  
Shear Zone ◽  
High Strength Steel ◽  
High Speed ◽  
Shear Bands ◽  
Cutting Speed ◽  
High Strength ◽  
Optical Microscope ◽  
Adiabatic Shear ◽  
High Speed Machining ◽  
Adiabatic Shear Bands

The microstructure observation and microhardness measurement were performed on the adiabatic shear bands in primary shear zone in the serrated chips formed during high speed machining of two tempering hardness of hardened high strength steel under different cutting speeds by optical microscope, SEM, TEM and microhardness tester. The investigation results show that two types of adiabatic shear bands are formed as cutting speed increases. One is deformed band with heavy elongated microstructures generated under lower cutting speed, another is transformed band with fine grains under higher cutting speed. The increase of the cutting speed little influences on the microhardness in the transformed bands, and the microhardness in deformed band results from strain hardening, whereas transformation hardening leads to very high microhardness in transformed band.

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