Zainul Huda

Influence of Particle Mechanisms on Kinetics of Grain Growth in a P/M Superalloy

The current literature reports the quantitative analysis of the kinetics of grain growth influenced by second-phase particle mechanisms for a powder metallurgy nickel-base superalloy: APK-6. Annealing treatments in the superalloy are shown to involve coarsening/dissolution of γ’ particles, and these particles mechanisms are shown to influence the kinetics of grain growth. The grain-growth exponent, n, is computed, and the γ’-solvus temperature of the superalloy is determined to lie between 220 and 270 oC. The kinetic data is interpreted to establish dependence of γ’ particles coarsening/dissolution mechanisms, grain size, γ’-solvus temperature, and annealing time and temperature on the rates of grain growth in the superalloy.

Temperature Effects on Material Behavior of Aerospace Aluminum Alloys for Subsonic and Supersonic Aircraft

This review-cum-research paper reports the effects of temperature and time exposure on the material behavior of the aerospace aluminum alloys currently in use in subsonic and supersonic aircraft. The research reported in this paper involves experimental study of the microstructural characterization and temperature effects on the hardness behavior of the age-hardenable 2024-T3 aluminum alloy; the latter was acquired by one of the authors from Royal Malaysian Air Force (RMAF) aerospace industry. The ALCLAD 2024-T3 alloy is being used in C-130 Hercules aircraft by the RMAF. Recent research on various aluminum alloys being used and being considered for application in Concorde is also reviewed.

Effects of annealing parameters on grain-growth behavior of HAYNES ® -718 superalloy

Annealing heat-treatment experiments at temperatures in the range of 1050 to 1150°C (1323 to 1423K) for durations in the range of 20 min to 22 h were conducted for HAYNES 718 superalloy plate. Grain sizes for the as-received and the annealed samples of the superalloy were measured by application of quantitative metallographic techniques. The grain-growth exponents, n, for the kinetic relationship (dD/dt = kt n ) were then computed, and the n values were found to lie in the range of 0.067 to 0.183. The microstructures of the as-received and annealed samples were critically compared for applications of the superalloy at high temperatures.

New Trends in Designing Markets, Configurations, and Materials for Very Light Jet Aircrafts

AbstractThis paper reviews recent advances and explores new trends in designing configuration and materials for application in very light jet (VLJ) aircrafts. Current technical information of the light jet aircraft in the market have been studied for competitor analysis purpose; the review of market design considers maximum take-off weight (MTOW), empty weight (WE), maximum cruise speed (Vcr·max⁡), direct operating cost (DOC), and aircraft price. Recent trends in aircraft configurations have been reviewed with particular reference to both conventional and unconventional designs. The existing technology of lightweight aerospace materials has been reviewed and the recommendations have been made for applications of composite and appropriate advanced materials in new VLJ aircrafts.

Failure of car’s drive shaft under torsion

Abstract This investigation reports analysis of fracture by splitting a car’s front wheel drive shaft into two parts, which ruptured at a very early stage (<10 cycles) of its endurance/driving test. Besides computations for shear stress and shear strength, a number of experimental techniques, e.g. non-destructive testing (ultrasonic flaw detection), chemical and metallographic analyses, hardness measurements, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques, are used to determine the cause of the drive shaft’s fracture. Non-destructive testing results showed the absence of any internal crack or flaw in the failed component, thereby excluding possibility of fast fracture due to propagation of crack. Scanning electron microscopy fractographs showed cleavage fracture at the outer surface of the shaft, whereas chemical analysis results showed that the steel used in the drive shaft conforms to mild steel. On the basis of the design calculations, it is concluded that failure of the shaft occurs due to shear overstressing. On the basis of hardness profile, it is concluded that the shaft has been casehardened by induction hardening. It is recommended that the steel of 25CrMo4/27CD4 type should be selected in the manufacturing of drive shaft, which should be casehardened by carbonitriding for application in modern cars.

Failure Analysis of Steel Superheater Tube Fractured in a Boiler of a Power Plant

This paper presents a case study of ASME SA213 type-T22 alloy steel superheater tube that failed in a boiler of a power plant. The failed superheater tube was investigated by visual examination, metallography, optical microscopy, electron fractography, and hardness testing. Microscopic examinations revealed inclusion, pre-existing micro-cracks and cementite precipitates at the grain boundaries in the microstructure; which were thought to be one of the major causes of failure of the superheater tube. Another major cause failure of boiler type T-22 was found to be creep failure because the boiler had been under use for a long time (36573 hours) at high steam temperature of around 420 °C with 130 bar pressure. Finally, recommendations have been suggested to improve the material characteristics and properties of the superheater tube for application in boiler of the power plant.

Designing Fail-Safe Biomaterials against Wear for Artificial Total Hip Replacement

This review paper presents a fail-safe approach in designing biomaterials against wear for application in an artificial total hip replacement in view of the recent advances in orthopedic bioengineering materials. It has been established that substantially different alloys should be used for minimizing wear in bearing surfaces. Frictional forces at these rubbing counter-faces must be minimized to prevent loosening of the femoral stem and acetabular socket assembly from their positions secured by the fixation agent. A comparative analysis of various wear-resistant biomaterials resulted in the lowest production of wear particles in a total hip where a ceramic socket articulates against the ceramic ball: it produces only 0.004 cubic millimeters of ceramic wear particles. Surface modification, through the application of coatings, offers the potential to reduce the wear rate without compromising the bulk mechanical behavior of the implant material. These hard coatings were found to include diamond-like carbon, amorphous diamond, and titanium nitride.