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This study investigates the performance of deep cryogenically treated brass (CuZn25Al5) electrodes in the die-sink EDM process. Two different cryogenic treatment durations, 6 h and 12 h, were applied to 8 mm diameter electrodes, and their effects were compared to untreated electrodes. The machining tests were conducted under moderate and aggressive conditions. In the machining tests, the 6-h cryo-treated electrode exhibited a 16.8% increase in material removal rate (MRR) under moderate conditions and a 19.7% increase under aggressive conditions compared to the reference electrode. The 12-h cryo-treated electrode showed similar MRR values to the reference electrode but improved tool wear resistance by 9.4% under moderate conditions. The kerf angle was minimized, indicating better hole verticality, in the 6-h cryo-treated electrode group. The improvement in machining performance was attributed to the enhancement in electrical conductivity of the electrodes, which increased by 28% for the 6-h cryo-treated electrode and 20% for the 12-h cryo-treated electrode. X-ray diffraction (XRD) analysis revealed shifts in peak positions and possible phase transformations due to cryogenic treatment. Surface roughness measurements showed improved surface conditions in the cryo-treated electrodes under aggressive conditions. The results indicate that cryogenic treatment enhances MRR, reduces tool wear, and improves surface quality in die-sink EDM. These improvements are attributed to increased electrical conductivity and changes in the internal structure of the brass electrode.

Effects of various heat treatment processes, including "Q/T (quenching and tempering)", "Q/CT/T (Quenching, cryogenic treatment and tempering)", "Q/T (quenching and tempering) + Ti-nitriding" and "Q/CT/T (Cryogenic treatment and tempering) + Ti-nitriding", on S-N fatigue behavior of AISI D2 tool steel were investigated. The optical micrographs and Vicker's hardness values at near surface and core area were examined for each specimen. Uniaxial fatigue tests were performed by using an electro-magnetic resonance fatigue testing machine at a frequency of 80 Hz and an R ratio of -1. The overall resistance to fatigue tends to decrease significantly with Ti-nitriding treatment compared to those for the general Q/T and Q/CT/T specimens. The reduced resistance to fatigue with Ti-nitriding is discussed based on the microstructural and fractographic analyses.

Powder mixed electro discharge machining (PMEDM) is further advancement of conventional electro discharge machining (EDM) where the powder particles are suspended in the dielectric medium to enhance the machining rate as well as surface finish. Cryogenic treatment is introduced in this process for improving the tool life and cutting tool properties. In the present investigation, the characterization of the cryotreated tempered electrode was performed. An attempt has been made to study the effect of cryotreated double tempered electrode on the radial overcut (ROC) when SiC powder is mixed in the kerosene dielectric during electro discharge machining of AISI 304. The process performance has been evaluated by means of ROC when peak current, pulse on time, gap voltage, duty cycle and powder concentration are considered as process parameters and machining is performed by using tungsten carbide electrodes (untreated and double tempered electrodes). A regression analysis was performed to correlate the data between the response and the process parameters. Microstructural analysis was carried out on the machined surfaces. Least radial overcut was observed for conventional EDM as compared to powder mixed EDM. Cryotreated double tempered electrode significantly reduced the radial overcut than untreated electrode.

In this work, an attempt has been made to optimize the process parameters on turning operation of INCOLOY 800H, with the aid of cryogenically treated (24h, 12h and untreated) multi-layer chemical vapor deposition (CVD) coated tools. The influencing factors like cutting speed, feed rate, depth of cut and cryogenic treatment were selected as input parameters. Surface roughness, microhardness and material removal rate (MRR) were considered as output responses. The experimentation was planned and conducted based on Taguchi L₂₇ standard orthogonal array (OA) with three levels and four factors. Multi-criteria decision making (MCDM) methods like grey relational analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) have been used to optimize the turning parameters in this work. Similar results were obtained from these MCDM techniques. Analysis of variance (ANOVA) was employed to identify the significance of the process parameters on the responses. Experimental research proved that machining performance could be improved efficiently at cutting speed is 55m/min, feed rate is 0.06mm/rev, depth of cut is 1mm and 24h cryogenically treated tool. Tool wear was analyzed for the cutting tool machined at the optimum cutting condition with the help of scanning electron microscope (SEM) and energy dispersion spectroscopy (EDS). Dry sliding wear test was also conducted for the optimal condition. The percentage improvement in machining performances is 12.70%.

This paper addresses an approach based on the Taguchi method with gray relational analysis for optimizing the turning parameters of hardened DIN 1.2344 hot work tool steel (54 HRC) with multiple performance characteristics. A gray relational grade obtained from the gray relational analysis was used for the performance characteristic in the Taguchi method L${}_{18}$ (2${}^1\times 3^2)$. The optimal turning parameters for surface roughness and tool wear were determined using the parameter design proposed by the Taguchi method. Dry turning tests were carried out using cryogenically treated and untreated uncoated carbide cutting tools. The cutting tool (Untreated and Deep Cryogenic Treated), cutting speed (200, 250 and 300m/min) and feed rate (0.09, 0.12 and 0.15mm/rev) were selected as experiment parameters. The analysis results revealed that the feed rate (72.84%) was the dominant factor affecting surface roughness and the cutting speed (93.93%) was the dominant factor affecting flank wear. The optimum turning parameters for the lowest Ra values were A₂B₁C₂ and for the lowest Vb values were A₁B₃C₂. According to the results of gray relational analysis, the optimum parameters for minimum average surface roughness and minimum flank wear were A₁B₂C₂.

In this paper, the effect of cutting parameters during micromilling on surface finish and material removal rate is presented. Inconel 718 alloy and high-speed steel micro end mill are used as work material and cutting tool, respectively. High-speed steel end mill of 1 mm diameter is subjected to cryogenic treatment. Machining studies are performed on Inconel alloy using untreated and cryogenic treated cutters. The milling tests are conducted at three different values of feed rate, cutting speed and depth of cut. Also, tool wear, microstructure and microhardness of different treated and untreated end mill are investigated and discussed in detail. The results showed that cryogenic treatment significantly improved the tool wear. The surface finish produced on machining the work-piece is better with the cryogenic treated tools than when compared with the untreated tools. The material removal rate is better with the cryogenic treated tools than when compared with the untreated tools. Improvement in tool life was up to 53.16% for Inconel 718 material when machined with cryogenically treated micro end mill.

This paper deals with the influence of silicon carbide (SiC) nanopowder in R134 a refrigerant used in a vapor compression refrigeration system. The performance study was done by mixing a SiC nanopowder in R134a refrigerant. The energy consumption of the R134a refrigerant with SiC nanoparticles mixture saves 20% energy with 0.25% mass fraction of SiC nanoparticles when compared to the R134a system. The COP of the refrigerant R134a system is 1.24 whereas COP for R134a-SiC nanopowder is 1.81. The SiC nanopowder is cryogenically treated at $-196^{\circ }$C for 24 h and the COP is found out. The results show that the COP of R134a-SiC nanopowder and R134a-cryo SiC (cryogenically treated silicon carbide nanopowder) is increased when compared to the R134a conventional refrigeration system.

This paper studies the performance of vapor compression refrigeration system using hydrocarbon refrigerant (HCR) mixture (R600a and R290), hydrocarbon nanorefrigerant mixture (R600a and R290/TiC) and cryogenically treated hydrocarbon nanorefrigerant mixture (R600a and R290/Cryo TiC). The COP of HCR (R600a and R290) system is 1.2960, whereas, COP of R600a and R290/TiC nanorefrigerant system is 1.5223. The TiC nanopowder is cryogenically treated at $-196^{\circ }$C for 24h. The treated TiC is dispersed in HCR mixture. Hence, the COP of R600a and R290- Cryo TiC system is further increased to 1.5801. The energy consumption of R600a and R290-TiC is reduced by 10.3% when compared with HCR. Further, it is reduced by 12.69% with respect to cryogenically treated refrigerant (R600a and R290/Cryo TiC) system. The COP is enhanced due to deep cryogenic of TiC nanopowder.

Effects of various heat treatment processes, including "Q/T (quenching and tempering)", "Q/CT/T (Quenching, cryogenic treatment and tempering)", "Q/T (quenching and tempering) + Ti-nitriding" and "Q/CT/T (Cryogenic treatment and tempering) + Ti-nitriding", on S-N fatigue behavior of AISI D2 tool steel were investigated. The optical micrographs and Vicker's hardness values at near surface and core area were examined for each specimen. Uniaxial fatigue tests were performed by using an electro-magnetic resonance fatigue testing machine at a frequency of 80 Hz and an R ratio of -1. The overall resistance to fatigue tends to decrease significantly with Ti-nitriding treatment compared to those for the general Q/T and Q/CT/T specimens. The reduced resistance to fatigue with Ti-nitriding is discussed based on the microstructural and fractographic analyses.