Improved fracture toughness corrosion-resistant bearing material

A development program was performed to establish whether a corrosion-resistant bearing material, such as a 14Cr steel, could be modified to allow carburization, thereby providing the excellent fracture toughness characteristics feasible with this process. The alloy selected for investigation was AMS 5749. Several modifications were made including the addition of a small amount of nickel for austenite stabilization. While some promising results were achieved, the primary objective of an acceptable combination of case hardness and microstructure was not attained. Because the high chromium content presents a serious problem in achieving a viable carburizing cycle, a number of experimental steels having lower chromium contents (8 to 12%) were produced in laboratory quantities and evaluated. The results were basically the same as those initially obtained with the modified AMS 5749. Corrosion tests were performed on AMS 5749, AISI M50, and 52100 bearing steels as well as some of the lower chromium steels. These tests showed that a reduced chromium level (10 to 12%) provided essentially the same corrosion protection as the 14Cr steels

Damage of the Surface Layer Gears in Grinding Process.

The influence of the grinding process on the condition of the surface layer (SL) obtained by the treatment of the gear with grinding wheels Al2O3, CBN, GF, SG, alloy steels with different parameters of the grinding process and the type of cooling liquid – lubricant (CLL). The stress distribution at the surface layer, structural changes, secondary hardening, forgiveness SL and drastic damage–microcracs have been presented in comparative studies

Protective coatings of metal surfaces by cold plasma treatment

The cold plasma techniques for deposition of various types of protective coatings are reviewed. The main advantage of these techniques for deposition of ceramic films is the lower process temperature, which enables heat treating of the metal prior to deposition. In the field of surface hardening of steel, significant reduction of treatment time and energy consumption were obtained. A simple model for the plasma - surface reactions in a cold plasma system is presented, and the plasma deposition techniques are discussed in view of this model

A Method for Optimizing Chemical Composition of Steels to Reduce Radically Their Alloy Elements and Increase Service Life of Machine Components

A method for optimizing chemical composition of steel is proposed and a correlation is established to reduce cardinally alloy elements in existing steel grades that results in high compressive residual stresses at the surface of intensively quenched steel parts and increasing strength and ductility of material due to super- strengthening phenomenon. The algorithm of optimization consists in reducing alloy elements in existing alloy steel in 1.5 – 2 times and then lowering step-by-step content of steel, beginning from the most costly alloy element and ending the most cheaper one, until established correlation is satisfied. The range of reduction is minimal and during computer calculations can be chosen as 0,001wt%. The proposed approach can save alloy elements, energy, increase service life of machine components and improve environmental condition. The method is a basis for development of the new low hardenability (LH) and optimal hardenability (OH) steels

A study of nanoparticles as a drug carrier on the wall of Stenosed Arteries

The influences of nanoparticles as drug carriers on the walls of stenosed arteries are presented. In this study, three nanoparticles namely Fe3O4 , TiO2 and Cu were used. It is observed that the addition of Fe3O4 nanoparticles tends to reduce the resistance impedance of blood temperature in bell shaped stenosed arteries. The blood temperature increases slightly in the streamwise direction before the throat region. Thereafter, the blood temperature increases at a higher rate and reaches its maximum value at the stenosis throat. It is found that the temperature distribution is heavily dependent on parameters such as periodic body acceleration and Prandtl number

Investigations on the Material Efficacy of Failed Helical Gears in a Gear Train

An investigation on the material efficacy of failed helical gears in the gearbox of an automobile has been carried out. Two helical gear samples taken as representatives of the whole of six in the gearbox were denoted as samples A and B. Methods employed in the failure investigation include visual examination with the unaided eye and fractography; compositional analysis; hardness measurements and microstructural analysis. The results obtained showed that Gear sample A failed by oxidative wear essentially caused by insufficient lubrication. On the other hand, Sample B exhibited no outward sign of failure. Processes culminating in the formation of a wear particle were however noticed few micrometers below the surface of Gear Sample B. Furthermore, in the absence of sufficient lubrication, numerous carbide precipitates formed in both samples contributed to wear of the gear material. It was concluded that the premature service failures of the gears was caused by inadequate lubrication and not inadequate material selection

Design of an advanced 500-hp helicopter transmission

High contact ratio spar gears planetary, spiral besel gears, bearings, investment-cast planet carrier, and investment cast stainless-steel housings are discussed

Solid-Carburizing Process of Low Carbon Steel with Carbonized Organics in Nitrogen Atmosphere

To apply carbonized organics to solid-carburizing compounds, a low carbon steel, S15C substrate, was solid-carburized at 1223 K for 18.0 ks in air with various carbonized organics in nitrogen atmosphere. Each organic changed to the black carbonized matter after carbonizing at 723 K, whereas almost organics kept a shape during carbonizing. X-ray diffraction (XRD) results show that Ca5(PO4)3(OH),both KCl and KHCO3, BaCO3 and CaCO3 were identified on the surface of carbonized meat and bone meal which is organic animal products, carbonized potato, pumpkin and eggplant which are organic plant products, commercial solid-carburizing powder and milled egg shell powder, respectively. As a result of cross-sectional morphology, the martensitic structure was clearly observed on the surface region of each solid-carburized S15C sample after quenching. Hardened layer depth of most samples solid-carburized with various carbonized organics were comparable to the sample treated with commercial solid-carburizing powder, or more. These results indicate that the carbonate in solid-carburizing compounds acts as energizer for solid-carburizing process and carbonized organics and milled egg shell powder can also be used as compounds and energizer for solid-carburizing process, respectively

Impact of corrosion on the emissivity of advanced-reactor structural alloys

Under standard operating conditions, the emissivity of structural alloys used for various components of nuclear reactors may evolve, affecting the heat transfer of the systems. In this study, mid-infrared emissivities of several reactor structural alloys were measured before and after exposure to environments relevant to next-generation reactors. We evaluated nickel-based alloys Haynes 230 and Inconel 617 exposed to helium gas at 1000 $^{\circ}$C, nickel-based Hastelloy N and iron-based 316 stainless steel exposed to molten salts at 750-850 $^{\circ}$C, 316 stainless steel exposed to liquid sodium at 650 $^{\circ}$C, and 316 stainless steel and Haynes 230 exposed to supercritical CO2 at 650 $^{\circ}$C. Emissivity was measured via emissive and reflective techniques using a Fourier transform infrared (FTIR) spectrometer. Large increases in emissivity are observed for alloys exposed to oxidizing environments, while only minor differences were observed in other exposure conditions.Comment: Main text and supplementary info (merged in one file