A Micromilling Experimental Study on AISI 4340 Steel

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.

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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