Increase in Strength and Fretting Resistance of Alloy 718 Using the Surface Modification Process

This work comparatively investigated the strength (hardness, yield strength, dynamic elastic modulus, and surface residual stress), fretting failure, and corrosion resistance of the as-received and treated Ni-based superalloy Alloy 718. The goal of the current research is to improve the hardness, fretting wear, and corrosion resistances of Alloy 718 through the ultrasonic nanocrystal surface modification (UNSM) process with the aim of extending the lifespan of aircraft and nuclear components made of Alloy 718. The experimental results revealed that the surface hardness increased by about 32%, the fretting wear resistance increased by about 14%, and the corrosion resistance increased by about 18% after UNSM process. In addition, the UNSM process induced a tremendous high compressive surface residual stress of about −1324 MPa that led to an increase in yield strength and dynamic Young’s modulus by about 14 and 9%, respectively. Grain size refinement up to ~50 nm after the UNSM process is found to be responsible for the increase in surface hardness as well. The depth of the effective layer generated by the UNSM process was about 20 µm. It was concluded that the UNSM process played a vital role in increasing the strength and enhancing the corrosion and fretting resistances of Alloy 718

Experimental Investigation on Friction and Wear Behavior of the Vertical Spindle and V-belt of a Cotton Picker

This study deals with the friction and wear behavior of the vertical spindle and V-belt to improve the reliability, operation and to extend the service life of a cotton picker. The vertical spindle made of low-carbon steel (ST3) was treated by the ultrasonic nanocrystal surface modification (UNSM) technique to control the friction and wear behavior. It was found that the UNSM technique reduced surface roughness and increased surface hardness of the vertical spindle. The friction and wear behavior of the vertical spindle and V-belt was assessed by carrying out tribological tests and the results showed that the UNSM-treated vertical spindle generated a higher friction coefficient compared to the untreated one due to having less slip. In case of wear resistance, unmeasurable wear occurred on the surface of the vertical spindle due to its significant high hardness compared to the hardness of the V-belt that came into contact with the vertical spindle in relative motion. Hence, the wear behavior and mechanisms of the V-belts were systematically investigated and also discussed based on the wear track profiles and micrographs. It can be concluded that the application of the UNSM technique to the vertical spindle may contribute to improve the performance of cotton pickers by reducing the slip and prolonging the service life

Determination of Strain Properties of the Leather Semi-Finished Product and Moisture-Removing Materials of Compression Rolls

The paper presents the results of experimental studies to determine the strain properties and characteristics of a chrome leather semi-finished product of middle-weight bovine hide by its topographic sections and the coatings of the processing compression rolls. The strain pressure equations of depend on the topographic sections of a leather semi-finished product are obtained, and the results of experiments on the effect of a number of layers on the amount of pressed moisture are presented. A mathematical dependence of the pressed moisture from the leather semi-finished product is obtained under various pressure values, rates, and the number of skin layers with monchons. The influence of the number of layers of leather semi-finished products with moisture-removing materials (monchons) on the process of moisture extraction at their vertical feed on the base plate is determined. In this paper, the influence of the number of skin layers and moisture-removing materials (monchons) on the technological process of moisture extraction from wet leather semi-finished products at their vertical feed on a base plate is studied as well