Super Abrasive Machining of Integral Rotary Components Using Grinding Flank Tools

Nickel-based superalloys are widely used in the aeronautical industry, especially in components requiring excellent corrosion resistance, enhanced thermal fatigue properties, and thermal stability. Haynes 282 is a nickel-based superalloy that was developed to improve the low weldability, formability, and creep strength of other γ’-strengthened Ni superalloys. Despite the industrial interest in Haynes 282, there is a lack of research that is focused on this alloy. Moreover, it is difficult to find studies dealing with the machinability of Haynes 282. Although Haynes 282 is considered an alloy with improved formability when compared with other nickel alloys, its machining performance should be analyzed. High pressure and temperature localized in the cutting zone, the abrasion generated by the hard carbides included in the material, and the tendency toward adhesion during machining are phenomena that generate extreme thermomechanical loading on the tool during the cutting process. Excessive wear results in reduced tool life, leading to frequent tool change, low productivity, and a high consumption of energy; consequentially, there are increased costs. With regard to tool materials, cemented carbide tools are widely used in different applications, and carbide is a recommended cutting material for turning Haynes 282, for both finishing and roughing operations. This work focuses on the finishing turning of Haynes 282 using coated carbide tools with conventional coolant. Machining forces, surface roughness, tool wear, and tool life were quantified for different cutting speeds and feeds.

Section: Introductionmentioning

confidence: 99%

Finishing Turning of Ni Superalloy Haynes 282

Díaz-Álvarez

Miguélez

et al. 2018

“…Surface integrity and tool wear are challenges when machining these difficult to cut materials due to strong work hardening, presence of hard carbides, and low thermal conductivity leading to high temperatures during machining [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

PCBN Performance in High Speed Finishing Turning of Inconel 718

Díaz-Álvarez

Criado

Miguélez

et al. 2018

Inconel 718 is a Ni superalloy widely used in high responsibility components requiring excellent mechanical properties at high temperature and elevated corrosion resistance. Inconel 718 is a difficult to cut material due to the elevated temperature generated during cutting, its low thermal conductivity, and the strong abrasive tool wear during cutting process. Finishing operations should ensure surface integrity of the component commonly requiring the use of hard metal tools with sharp tool edges and moderate cutting speeds. Polycrystalline cubic boron nitride (PCBN) tools recently developed an enhanced toughness suitable for these final operations. This paper focuses on the study of PCBN tools performance in finishing turning of Inconel 718. Several inserts representative of different manufacturers were tested and compared to a reference carbide tool. The evolution of tool wear, surface roughness, and cutting forces was analyzed and discussed. PCBN tools demonstrated their suitability for finishing operations, presenting reasonable removal rates and surface quality.

“…Regarding the complete refurbishment of turbine blades, the machining of weld-repaired components is also a very important issue. Super Abrasive Machining is reported to be a good solution to increase machining efficiency during the production of blades and turbine disks [44]. Moreover, in case of machining IN718 superalloy, high performance cutting can be obtained in those tools with proper chemical vapor deposition (CVD) coating [45].…”

Section: Discussionmentioning

confidence: 99%

Liquation Cracking in the Heat-Affected Zone of IN738 Superalloy Weld

Chen

Shiue

et al. 2018

Abstract:The main scope of this study investigated the occurrence of liquation cracking in the heat-affected zone (HAZ) of IN738 superalloy weld, IN738 is widely used in gas turbine blades in land-based power plants. Microstructural examinations showed considerable amounts of γ' uniformly precipitated in the γ matrix. Electron probe microanalysis (EPMA) maps showed the γ-γ' colonies were rich in Al and Ti, but lean in other alloy elements. Moreover, the metal carbides (MC), fine borides (M 3 B 2 and M 5 B 3 ), η-Ni 3 Ti, σ (Cr-Co) and lamellar Ni 7 Zr 2 intermetallic compounds could be found at the interdendritic boundaries. The fracture morphologies and the corresponding EPMA maps confirmed that the liquation cracking in the HAZ of the IN738 superalloy weld resulted from the presence of complex microconstituents at the interdendritic boundaries.