Search Results for IN-713

Aluminide-coated and uncoated IN-713 turbine blades were returned for evaluation after service in a marine environment because of severe corrosion. Based on service time, failure of these blades by corrosive deterioration was considered to be premature. Analysis (visual inspection, 2.7x micrographic examination on sections etched with ferric chloride and hydrochloric acid in methanol) supported the conclusions that the blades failed by hot-corrosion attack. Variation in rate of attack on coated blades was attributed to variation in integrity of the aluminide coating, which had been applied in 1966, when these coatings were relatively new. It is evident that maintaining the integrity of a protective coating could significantly increase the life of a nickel-base alloy blade operating in a hot and corrosive environment.

A pipe in a chip conveyor cracked at the toe of an exterior fillet weld connecting a flange to the pipe. The chip conveyor consisted of several spool sections. Each section was made up of a length of low-alloy steel pipe and two flanges, which were welded to each end. The composition specified for the pipe steel was 0.25C-0.98Mn-3.52Ni-1.34Cr-0.24Mo, which approximates a 9300 steel with high molybdenum. Investigation supported the conclusion that the conveyor pipe failed by brittle fracture, which was attributed to the stresses induced in forcing the circular flange over the elliptical section of the pipe. The toe of the weld and the adjacent undercut were stress raisers that determined the point of major crack origin. Under residual stress, the internal point of incomplete fusion also initiated additional cracks. Recommendations included ensuring a proper fit between an elliptical flange and pipe end to eliminate the cracking.

Rolling-contact fatigue (RCF) is a surface damage process due to the repeated application of stresses when the surfaces of two bodies roll on each other. This article briefly describes the various surface cracks caused by manufacturing processing faults or blunt impact loads on ceramic balls surfaces. It discusses the propagation of fatigue cracks involved in rolling contacts. The characteristics of various types of RCF test machines are summarized. The article concludes with a discussion on the various failure modes of silicon nitride in rolling contact. These include the spalling fatigue failure, the delamination failure, and the rolling-contact wear.

This article reviews the mechanical behavior and fracture characteristics that discriminate structural polymers from metals. It provides information on deformation, fracture, and crack propagation as well as the fractography involving the examination and interpretation of fracture surfaces, to determine the cause of failure. The fracture modes such as ductile fractures and brittle fractures are reviewed. The article also presents a detailed account of various fracture surface features. It concludes with several cases of field failure in various polymers that illustrate the applicability of available analytical tools in conjunction with an understanding of failure mechanisms.

This article reviews the mechanical behavior and fracture characteristics that discriminate structural polymers from metals, including plastic deformation. It provides overviews of crack propagation and fractography. The article presents the distinction between ductile and brittle fracture modes. Several case studies of field failure in various polymers are also presented to illustrate the applicability of available analytical tools in conjunction with an understanding of failure mechanisms.

This article provides an overview of the physics and math associated with moisture-related failures in plastic components. It develops key equations, showing how they are used to analyze the causes and effects of water uptake, diffusion, and moisture concentration in polymeric materials and resins. It explains how absorbed moisture affects a wide range of properties, including glass transition temperature, flexural and shear modulus,creep, stress relaxation, swelling, tensile and yield strength, and fatigue cracking. It provides relevant data on common polymers, resins, and fiber-resin composites.

This introductory article describes the various aspects of chemical structure that are important to an understanding of polymer properties and thus their eventual effect on the end-use performance of engineering plastics. The polymers covered include hydrocarbon polymers, carbon-chain polymers, heterochain polymers, and polymers containing aromatic rings. The article also includes some general information on the classification and naming of polymers and plastics. The most important properties of polymers, namely, thermal, mechanical, chemical, electrical, and optical properties, and the most significant influences of structure on those properties are then discussed. A variety of engineering thermoplastics, including some that are regarded as high-performance thermoplastics, are covered in this article. In addition, a few examples of commodity thermoplastics and biodegradable thermoplastics are presented for comparison. Finally, the properties and applications of six common thermosets are briefly considered.

This article briefly reviews the general causes of weldment failures, which may arise from rejection after inspection or failure to pass mechanical testing as well as loss of function in service. It focuses on the general discontinuities observed in welds, and shows how some imperfections may be tolerable and how the other may be root-cause defects in service failures. The article explains the effects of joint design on weldment integrity. It outlines the origins of failure associated with the inherent discontinuity of welds and the imperfections that might be introduced from arc welding processes. The article also describes failure origins in other welding processes, such as electroslag welds, electrogas welds, flash welds, upset butt welds, flash welds, electron and laser beam weld, and high-frequency induction welds.

This article describes some of the welding discontinuities and flaws characterized by nondestructive examinations. It focuses on nondestructive inspection methods used in the welding industry. The sources of weld discontinuities and defects as they relate to service failures or rejection in new construction inspection are also discussed. The article discusses the types of base metal cracks and metallurgical weld cracking. The article discusses the processes involved in the analysis of in-service weld failures. It briefly reviews the general types of process-related discontinuities of arc welds. Mechanical and environmental failure origins related to other types of welding processes are also described. The article explains the cause and effects of process-related discontinuities including weld porosity, inclusions, incomplete fusion, and incomplete penetration. Different fitness-for-service assessment methodologies for calculating allowable or critical flaw sizes are also discussed.