Search Results for thermal embrittlement

This article discusses the effects of alloying on the properties and behaviors of maraging steels. It describes how maraging steels differ from conventional steels in that they are strengthened, not by carbon, but by the precipitation of intermetallic compounds. It explains how maraging steels typically have high levels of nickel, cobalt, and molybdenum with little carbon content and how that affects their dimensional stability, fracture toughness, weldability, and resistance to stress-corrosion cracking.

The appendix provides a glossary of practical heat treating terms.

This chapter is a compilation of terms and definitions related to corrosion in the petrochemical industry.

The ability to accurately assess the remaining life of components is essential to the operation of plants and equipment, particularly those in service beyond their design life. This, in turn, requires a knowledge of material failure modes and a proficiency for predicting the near and long term effects of mechanical, chemical, and thermal stressors. This chapter presents a broad overview of the types of damage to which materials are exposed at high temperatures and the approaches used to estimate remaining service life. It explains how operating conditions in power plants and oil refineries can cause material-related problems such as embrittlement, creep, thermal fatigue, hot corrosion, and oxidation. It also discusses the factors and considerations involved in determining design life, defining failure criteria, and implementing remaining-life-assessment procedures.

This article discusses the chemical susceptibility of a polymeric material. The discussion covers significant absorption and transportation of an environmental reagent by the polymer; the chemical susceptibility of additives; and thermal degradation, thermal oxidative degradation, photo-oxidative degradation, environmental corrosion, and chemical corrosion of polymers. It also includes some of the techniques used to detect changes in structure during polymer exposure to hostile environments. In addition, the article describes the effects of environment on polymer performance, namely plasticization, solvation, swelling, environmental stress cracking, polymer degradation, surface embrittlement, and temperature effects.

This chapter discusses the compatibility problems that arise from chemical or physical interactions between liquefied gases and the common materials used in their production, storage, transportation, distribution, and use. The discussion covers the compatibility of materials with liquid oxygen and liquid fluorine. Hydrogen-environment embrittlement is unique to low-temperature hydrogen systems and is also discussed.

Liquid metals are frequently used as a heat-transfer medium because of their high thermal conductivities and low vapor pressures. Containment materials used in such heat-transfer systems are subject to molten metal corrosion as well as other problems. This chapter reviews the corrosion behavior of alloys in molten aluminum, zinc, lead, lithium, sodium, magnesium, mercury, cadmium, tin, antimony, and bismuth. It also discusses the problem of liquid metal embrittlement, explaining how it is caused by low-melting-point metals during brazing, welding, and heat treating operations.

This chapter discusses the processes used in manufacturing to thermally alter the properties of metals and alloys. It begins with a review of the iron-carbon system, the factors that affect hardenability, and the use of continuous cooling transformation diagrams. It then explains how various steels respond to heat treatments, such as annealing, normalizing, spheroidizing, tempering, and direct and interrupted quenching, and surface-hardening processes, such as flame and induction hardening, carburizing, nitriding, and carbonitriding. It also addresses the issue of temper embrittlement and discusses the effect of precipitation hardening on aluminum and other alloys.

This chapter takes a practical approach to the problem of stress-corrosion cracking (SCC) in stainless steels, explaining how different application environments affect different grades of stainless steel. It describes the causes of stress-corrosion cracking in chloride, caustic, polythionic acid, and high-temperature environments and the correlating effects on austenitic, ferritic, duplex, martensitic, and precipitation hardening stainless steels and nickel-base alloys. It also discusses the contributing effects of sensitization and hydrogen embrittlement and the role of composition, microstructure, and thermal history. Sensitization is particularly detrimental to austenitic stainless steels, and in many cases, eliminating it will eliminate the susceptibility to SCC. The chapter includes an extensive amount of data and illustrations.

This chapter covers the failure modes and mechanisms of concern in hydroprocessing reactor vessels and the methods used to assess lifetime and performance. It begins with a review of the materials used in the construction of pressure-vessel shells, the challenges they face, and the factors that determine shell integrity. The discussion addresses key properties and design parameters including allowable stress, fracture toughness, the effect of microstructure and composition on embrittlement, high-temperature creep, and subcritical crack growth. The chapter also provides information on the factors that affect cladding integrity and ends with a section on life-assessment techniques.

A systematic procedure for minimizing risks involved in heat treated steel components requires a combination of metallurgical failure analysis and fitness for service with respect to safety and reliability based on risk analysis. This chapter begins with an overview of heat treat processing of steels. This is followed by sections on various aspects of heat treatment design and heat treating practices for minimizing distortion. Influence of design, steel grade, and condition is then illustrated in the examples of failures due to heat treatment. A procedure is analyzed to improve the performance of the design process of a component. A heat-transfer model, coupling with a phase transformation model, a thermomechanical model, and a thermochemical model, is also considered. The chapter further provides information on the failure aspects of and heat treatment procedures applied to welded components. It ends with a section on risk-based approach applicable to heat treated steel components.

This chapter describes the causes of cracking, embrittlement, and low toughness in carbon and low-alloy steels and their differentiating fracture surface characteristics. It discusses the interrelated effects of composition, processing, and microstructure and contributing factors such as hot shortness associated with copper and overheating and burning as occur during forging. It addresses various types of embrittlement, including quench embrittlement, tempered-martensite embrittlement, liquid-metal-induced embrittlement, and hydrogen embrittlement, and concludes with a discussion on high-temperature hydrogen attack and its effect on strength and ductility.

This chapter discusses some of the more advanced methods and procedures used in failure analysis, including in-service material sampling, in situ microstructure analysis, and a form of punch testing that can determine the fracture toughness of any material from a tiny specimen. The chapter also covers quantitative fractography, fracture surface topography analysis, and the use of oxide dating as well as fault tree and failure modes and effects analysis (FMEA) and computational techniques.

This chapter compares and contrasts the high-temperature behaviors of metals and composites. It describes the use of creep curves and stress-rupture testing along with the underlying mechanisms in creep deformation and elevated-temperature fracture. It also discusses creep-life prediction and related design methods and some of the factors involved in high-temperature fatigue, including creep-fatigue interaction and thermomechanical damage.

This chapter provides an overview of the possible mechanisms of failure for heat treated steel components and discusses the techniques for examining fractures, ductile and brittle failures, intergranular failure mechanisms, and fatigue. It begins with a description of the general sources of component failure. This is followed by a section on the stages of a failure analysis, which can proceed one after the other or occur at the same time. These stages of analysis are collection of background data, preliminary visual examination, nondestructive testing, selection and preservation of specimens, mechanical testing, macroexamination, microexamination, metallographic examination, determination of the fracture mechanism, chemical analysis, exemplar testing, and analysis and writing the report. The chapter ends with a discussion on various processes involved in the determination of the fracture mechanism.

Durability is a generic term used to describe the performance of a material or a component made from that material in a given application. In order to be durable, a material must resist failure by wear, corrosion, fracture, fatigue, deformation, and exposure to a range of service temperatures. This chapter covers several types of component and material failure associated with wear, temperature effects, and crack growth. It examines temperature-induced, brittle, ductile, and fatigue failures as well as failures due to abrasive, erosive, adhesive, and fretting wear and cavitation fatigue. It also discusses preventative measures.