scholarly journals Effect of Microstructure on Chip Formation during Machining of Super Austenitic Stainless Steel

2017 ◽  
Vol 4 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Mohanad Alabdullah ◽  
Ashwin Polishetty ◽  
Junior Nomani ◽  
Guy Littlefair
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Electron Backscatter Diffraction ◽  
Shear Bands ◽  
Chip Morphology ◽  
Machining Process ◽  
On Chip ◽  
Corrosive Environments ◽  
Backscatter Diffraction ◽  
Super Austenitic Stainless Steel

The AL6XN Super Austenitic Stainless Steel alloy is a commonly used steel in corrosive environments and tough applications. This paper aims to investigate the execution of a machining process on the AL6XN alloy. A wet machining process has been executed to machine the alloy under a combination of various cutting conditions using an up milling approach. Two cutting speeds, two cutting depths and two feeds were used. The outputs obtained and listed in this paper are the microstructure analysis, surface microhardness and the chip morphology. The microstructure of the AL6XN alloy was revealed using Electron Microscope and Electron Backscatter Diffraction (EBSD). Work hardening layer was located in the subsurface of the machined alloy. EBSD data assured that no phase transformation was occurred within the deformed microstructure due to machining. The chip cross-section was revealed to identify the presence of the shear bands and to calculate the alloy serration degree.

scholarly journals Experimental study on chip shape in ultrasonic vibration–assisted turning of 304 austenitic stainless steel

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401987089 ◽  
Author(s):  
Yingshuai Xu ◽  
Zhihui Wan ◽  
Ping Zou ◽  
Qinjian Zhang
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ultrasonic Vibration ◽  
Process Parameters ◽  
Chip Morphology ◽  
Cutting Parameters ◽  
Chip Shape ◽  
304 Austenitic Stainless Steel ◽  
On Chip ◽  
The Impact

There are many problems and physical phenomena in turning process, like machined surface quality, cutting force, tool wear, and so on. These factors and the chip shape of workpiece materials, which is an important aspect to study the mechanism of ultrasonic vibration–assisted turning, go hand in hand. This article first introduces the types and changes of chip, meanwhile the chip formation mechanism of ultrasonic vibration–assisted turning is studied and analyzed, and the turning experiments of 304 austenitic stainless steel with and without ultrasonic vibration are carried out. The difference of chip morphology between ultrasonic vibration–assisted turning and conventional turning is contrasted and analyzed from the macroscopic and microscopic point of view. The influence of process parameters on chip shape and the impact of chip shape on machining effect are also analyzed. Results indicate that when process parameters (vibration frequency, ultrasonic amplitude, and cutting parameters) are suitably selected, ultrasonic vibration–assisted turning can gain access to better chip shape and chip breaking effect than conventional turning. By contrast with conventional turning, phenomenon of serrated burr on the chip edge and the surface defects of chip in ultrasonic vibration–assisted turning have improved significantly. Moreover, it is found that superior chip morphology in ultrasonic vibration–assisted turning can be acquired under the circumstance of comparatively small cutting parameters (cutting speed, depth of cut, and feed rate); at the same time, preferable chips can also obtain ranking machining effect.

scholarly journals Microstructural and Surface Texture Analysis due to Machining in Super Austenitic Stainless Steel

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Mohanad Alabdullah ◽  
A. Polishetty ◽  
G. Littlefair
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Texture Analysis ◽  
Surface Texture ◽  
Cutting Parameters ◽  
Machining Process ◽  
Super Austenitic Stainless Steel ◽  
Surface Texture Analysis ◽  
Machined Surfaces

Inferior surface quality is a significant problem faced by machinist. The purpose of this study is to present a surface texture analysis undertaken as part of machinability assessment of Super Austenitic Stainless Steel alloy-AL6XN. The surface texture analysis includes measuring the surface roughness and investigating the microstructural behaviour of the machined surfaces. Eight milling trials were conducted using combination of cutting parameters under wet machining. An optical profilometer (noncontact) was used to evaluate the surface texture at three positions. The surface texture was represented using the parameter, average surface roughness. Scanning Electron Microscope was utilised to inspect the machined surface microstructure and correlate the microstructure with the surface roughness. Results showed that maximum roughness values recorded at the three positions in the longitudinal direction (perpendicular to the machining grooves) were 1.21 μm (trial 1), 1.63 μm (trial 6), and 1.68 μm (trial 7), respectively, whereas the roughness values were greatly reduced in the lateral direction. Also, results showed that the feed rate parameter significantly influences the roughness values compared to the other cutting parameters. The microstructure of the machined surfaces was distorted by the existence of cracks, deformed edges, and bands and wear deposition due to machining process.

scholarly journals Microstructure Evolution During Hot Deformation of REX734 Austenitic Stainless Steel

2019 ◽  
Vol 51 (2) ◽  
pp. 845-854 ◽  
Author(s):  
Mykola Kulakov ◽  
Jianglin Huang ◽  
Michail Ntovas ◽  
Shanmukha Moturu
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Electron Backscatter Diffraction ◽  
Compression Testing ◽  
Recrystallization Process ◽  
Twin Boundaries ◽  
Wide Range ◽  
Evolution Of Microstructure ◽  
Backscatter Diffraction

AbstractMechanical properties of a REX734 austenitic stainless steel were examined through compression testing over a wide range of temperatures (1173 K to 1373 K (900 °C to 1100 °C)) and strain rates (0.1 to 40 s−1) that cover deformation conditions encountered in different metalworking processes. The evolution of microstructure was studied using electron microscopy combined with electron backscatter diffraction and energy-dispersive spectroscopy. Partially recrystallized microstructures were obtained after compression testing at 1173 K (900 °C), while after deformation at 1273 K and 1373 K (1000 °C and 1100 °C), the material was fully recrystallized almost in all examined cases. The role of dynamic and metadynamic restoration processes in the formation of final microstructure was investigated. Σ3 twin boundaries lost their twin character and transformed into general high-angle grain boundaries as a result of deformation, while during recrystallization new Σ3 twin boundaries formed. The evolution of precipitates during compression testing and their role in the recrystallization process was also discussed.

Effect of Hot Deformation Temperature on the Restoration Mechanisms and Texture in a High-Cr Ferritic Stainless Steel

2013 ◽  
Vol 762 ◽  
pp. 705-710 ◽  
Author(s):  
Saara Mehtonen ◽  
L. Pentti Karjalainen ◽  
David A. Porter
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Electron Backscatter Diffraction ◽  
Shear Bands ◽  
Compression Tests ◽  
Recrystallized Grain Size ◽  
Evolution Of Microstructure ◽  
Backscatter Diffraction

The effect of hot deformation temperature on the deformed microstructures and evolution of microstructure and texture of a 21Cr Ti-Nb dual-stabilized ferritic stainless steel was studied using plane strain hot compression tests on a Gleeble 1500 thermomechanical simulator. The deformation was carried out at 550 - 950 °C with a strain of 0.5 at 1 s-1. The compression was followed by fast cooling to room temperature in order to study the deformed microstructures. Some specimens were heated from the deformation stage to either 750 or 950 °C and held for 0 or 30 s in order to study the nucleation process of recrystallization. The electron backscatter diffraction technique was used to analyze the resultant microstructures and textures. Lowering of the deformation temperature increased the rate of static recrystallization (SRX) and decreased the recrystallized grain size. After deformation at 550 and 600 °C and complete SRX, beneficial γ-fibre texture formed presumably as a result of nucleation at in-grain shear bands. SRX after deformation at 750 °C or above led to the formation of harmful α-fibre textures with weak γ-fibre.

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