Search Results for stress-induced cracking

This chapter presents the primary considerations and mechanisms for corrosion and how they are involved in the selection of materials for process equipment in petroleum refineries and petrochemical plants. In addition, specific information on mechanical properties, corrosion, sulfide stress cracking, hydrogen-induced cracking, stress-oriented hydrogen-induced cracking, hydrogen embrittlement cracking, stress-corrosion cracking, velocity-accelerated corrosion, erosion-corrosion, and corrosion control is provided.

This chapter discusses the conditions and sequence of events that lead to stress-corrosion cracking (SCC) and the mechanisms by which it progresses. It explains that the stresses involved in SCC are relatively small and, in most cases, work in combination with the development of a surface film. It describes bulk and surface reactions that contribute to SCC, including dissolution, mass transport, absorption, diffusion, and embrittlement, and their role in crack nucleation and growth. It also discusses crack tip chemistry, grain-boundary interactions, and the effect of stress-intensity on crack propagation rates, and describes several mechanical fracture models, including corrosion tunnel, film-induced cleavage, and tarnish rupture models.

Aluminum is protected by a barrier oxide film that, if damaged, reforms immediately in most environments. Despite this inherent corrosion resistance, there are conditions where aluminum alloys, like many materials, are subject to the effects of stress-corrosion cracking (SCC). This chapter describes those conditions, focusing initially on the effects of alloying elements and temper on solution potential and how it compares to other metals. It then addresses the issue of intergranular corrosion and its role in SCC. It explains how factors such as stress loads, grain structure, and environment determine whether or not stress-corrosion cracking develops in a susceptible alloy. It also provides stress-corrosion ratings for many alloys, tempers, and product forms and includes information on hydrogen-induced cracking.

Although zirconium resists stress-corrosion cracking (SCC) where many alloys fail, it is susceptible in Fe3+- and Cu2+-containing solutions, concentrated HNO3, halogen vapors, mercury, cesium, and CH3OH + halides. This chapter explains how composition, texture, stress levels, and strain rate affect the SCC behavior of zirconium and its alloys. It describes environments known to induce SCC, including aqueous solutions, organic liquids, hot and fused salts, and liquid metals. It also discusses cracking mechanisms and SCC prevention and control techniques.

Irradiation-assisted stress-corrosion cracking (IASCC) has been a topic of engineering interest since it was first reported in the 1960s, having been observed in stainless steel cladding on light water reactor fuel elements. This chapter summarizes the results of decades of investigation, showing that IASCC can essentially be defined as the intergranular cracking of austenitic alloys in high-temperature water, where both the material and its environment have been altered by radiation. Of the many interactions that can occur when metals and water are exposed to radiation, the international consensus is that the three with the greatest impact on crack growth rates are the formation of material defects, radiation-induced segregation, and chemical reactions that increase the corrosion potential of water. The chapter discusses each of these in great detail, and includes information on predictive modeling as well.

Corrosion problems can be divided into eight categories based on the appearance of the corrosion damage or the mechanism of attack: uniform or general corrosion; pitting corrosion; crevice corrosion, including corrosion under tubercles or deposits, filiform corrosion, and poultice corrosion; galvanic corrosion; erosion-corrosion, including cavitation erosion and fretting corrosion; intergranular corrosion, including sensitization and exfoliation; dealloying; environmentally assisted cracking, including stress-corrosion cracking, corrosion fatigue, and hydrogen damage (including hydrogen embrittlement, hydrogen-induced blistering, high-temperature hydrogen attack, and hydride formation). All these forms are addressed in this chapter in the context of aqueous corrosion. For each form, a general description is provided along with information on the causes and the list of metals that can be affected, with particular emphasis on the recognition and prevention measures.

This chapter discusses the effects of corrosion on boiler tube surfaces exposed to water and steam. It describes the process of corrosion, the formation of scale, and the oxides of iron from which it forms. It addresses the primary types of corrosion found in boiler environments, including general corrosion, under-deposit corrosion, microbially induced corrosion, flow-accelerated corrosion, stress-assisted corrosion, erosion-corrosion, cavitation, oxygen pitting, stress-corrosion cracking, and caustic embrittlement. The discussion is supported by several illustrations and relevant case studies.

Martensitic stainless steels are essentially iron-chromium-carbon alloys that possess a body-centered tetragonal crystal structure (martensitic) in the hardened condition. Martensitic stainless steels are similar to plain carbon or low-alloy steels that are austenitized, hardened by quenching, and then tempered for increased ductility and toughness. This chapter provides a basic understanding of grade designations, properties, corrosion resistance, and general welding considerations of martensitic stainless steels. It also discusses the causes for hydrogen-induced cracking in martensitic stainless steels and describes sulfide stress corrosion resistance of type 410 weldments.

This chapter explores the behavior of stainless steel in media that promote corrosion. The forms of corrosion covered are uniform corrosion, atmospheric corrosion, localized corrosion, pitting corrosion, crevice corrosion, and grain boundary corrosion. The chapter discusses the influence of material and environmental variables on stress-corrosion cracking (SCC) and the mechanisms proposed for SCC in stainless steel, comparing the mechanism of SCC with hydrogen embrittlement. In addition, it provides information on biocorrosion and microbiologically induced corrosion in ambient aqueous environments.

This chapter provides an introduction to various forms of corrosion, namely uniform corrosion, localized corrosion, mechanically assisted degradation, environmentally induced cracking, microbiologically influenced corrosion, and metallurgically influenced corrosion.

The susceptibility of plastics to environmental failure, when exposed to organic chemicals, limits their use in many applications. Environmental factors can be classified into two categories: chemical and physical effects. This article discusses the effects of these environmental factors on the mechanical properties of plastics.

This chapter focuses on stress-corrosion cracking (SCC) of metals and their alloys. It is intended to familiarize the reader with the phenomenological and mechanistic aspects of stress corrosion. The phenomenological description of crack initiation and propagation describes well-established experimental evidence and observations of stress corrosion, while the discussions on mechanisms describe the physical process involved in crack initiation and propagation. Several parameters that are known to influence the rate of crack growth in aqueous solutions are presented, along with important fracture features.

The formation of defects in materials that have been fusion welded is a major concern in the design of welded assemblies. This article describes four types of defects that, in particular, have been the focus of much attention because of the magnitude of their impact on product quality. Colloquially, these four defect types are known as hot cracks, heat-affected zone microfissures, cold cracks, and lamellar tearing.

This chapter focuses on common failure characteristics exhibited by mechanical and electrical components. The topic is considered from two perspectives: one possibility is that the system failed because parts were nonconforming to drawing requirements and another possibility is that the system failed even though all parts in the system met their drawing requirements. The common failures discussed in this chapter include those associated with metallic components, composite materials, plastic components, ceramic components, and electrical and electronic components.

The performance attributes of advanced high-strength steels are summarized in this chapter. These attributes include stiffness, strength, strain hardening, fatigue, crashworthiness, formability, toughness, and bake hardening.

This chapter explains how the authors assessed the potential risks of creep-fatigue in several aerospace applications using the tools and techniques presented in earlier chapters. It begins by identifying the fatigue regimes encountered in the main engines of the Space Shuttle. It then describes the types of damage observed in engine components and the methods used to mitigate problems. It also discusses the results of analyses that led to changes in design or approach and examines fatigue-related issues in turbine engines used in commercial aircraft.