Predictive modeling of surface roughness in high speed machining of AISI 4340 steel using yttria stabilized zirconia toughened alumina turning insert

Author(s):  
Nilrudra Mandal ◽  
B. Doloi ◽  
B. Mondal
2009 ◽  
Vol 407-408 ◽  
pp. 335-338 ◽  
Author(s):  
Jin Sheng Wang ◽  
Da Jian Zhao ◽  
Ya Dong Gong

A micromilling experimental study on AISI 4340 steel is conducted to understand the micromilling principle deeply. The experimental results, especially on the surface roughness and cutting force, are discussed in detail. It has been found the minimum chip thickness influences the surface roughness and cutting force greatly. Meanwhile, the material elastic recover induces the increase of the axial micromilling force. The average cutting force and its spectrum analysis validate the minimum chip thickness approximation of AISI 4340 is about 0.35μm.


1982 ◽  
Vol 104 (2) ◽  
pp. 121-131 ◽  
Author(s):  
R. Komanduri ◽  
T. Schroeder ◽  
J. Hazra ◽  
B. F. von Turkovich ◽  
D. G. Flom

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.


The intent of this study is to produce optimum quality grinding spindle using hardened AISI 4340 steel through the cylindrical grinding process. Primarily the AISI 4340 steel specimens are cut according to the product specification and subjected to rough machining. Then the steel specimens are subjected to a heat-treatment process to enhance the mechanical property hardness so that the specimen becomes wear-resistant. The experimental runs are planned depending on Taguchi’s L27(37) array and conducted in a cylindrical grinding machine (Toyoda G32 cylindrical grinding machine). The surface roughness of the machined specimens is measured using a calibrated surface roughness tester. A prediction model is created through regression analysis for the outcome. The significance of the selected grinding factors and their levels on surface roughness is found by analysis of variance (ANOVA) and F-test and finally. An affirmation test is directed to produce the ideal components.


2020 ◽  
Vol 62 (12) ◽  
pp. 1235-1242
Author(s):  
Hatice Varol Ozkavak ◽  
Serife Sahin ◽  
Mehmet Fahri Sarac ◽  
Zehra Alkan

Abstract Low alloy and stainless steel are the most used types of iron-based materials world wide. Their use against in machine element work, reclamation, corrosion and wear resistance are still challenging. To overcome this problem, many steel alloys are coated with cermet coatings to protect the parts from wear and corrosion. In the present study, WC-Co and WC-CoCr coatings were applied by means of a high velocity oxy-fuel (HVOF) technique on AISI 304, AISI 1040, and AISI 4340 steel alloys used as substrates. The aim was to investigate surface properties and wear resistance of the coatings and to determine their relationship with the type of coating and substrate. In accordance with this purpose, hardness and thickness of the coatings were measured, sliding wear tests were performed, scanning electron microscope (SEM) images and X-ray diffractions (XRD) were taken, surface roughness and friction coefficients were determined. The results showed that the WC-CoCr coatings had higher hardness and lower thickness than the WC-Co coatings. Maximum hardness was obtained in the WC-CoCr coating applied to AISI 4340 steel, which was also the hardest alloy among those studied. After wear resistance tests, it was revealed that the wear resistance of the WC-CoCr coatings was better than that of the WC-Co coatings for each steel substrate. During the coating, the new phases resulting from the decomposition of the WC phase in the WC-CoCr coatings contributed more to wear resistance than those of the WC-Co coatings. A lower friction coefficient and lower surface roughness of the WC-CoCr coatings during wear were obtained, resulting in higher wear resistance. A WC-CoCr coating on AISI 4340 alloy which has the highest hardness, lowest surface roughness and lowest friction coefficient resulted in the highest wear resistance among all types studied.


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