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2022 | Buch

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Alloy 625

Microstructure, Properties and Performance

verfasst von: Dr. Jung Bahadur Singh

Verlag: Springer Nature Singapore

Buchreihe : Materials Horizons: From Nature to Nanomaterials

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

This book gives a brief history of the development of Alloy 625 and a detailed account of its physical, mechanical, and corrosion properties. It also addresses different types of microstructural changes the Alloy 625 undergoes at intermediate temperatures; provides details of properties deterioration due to such microstructural changes; assesses the alloy damage during the in-service inspection of plants; and provides criteria for the damage evaluation for various destructive and non-destructive testing. It combines the industrial data and literature together in one place for damage assessment of service exposed Alloy 625 components. This book serves as a guide to practicing engineers in the industry interested in the use of Alloy 625 and in academia for students pursuing advanced courses in materials science. Alloy 625 is a versatile nickel-chromium-molybdenum alloy known for its unique combination of high strength, excellent fabricability and weldability, and outstanding corrosion resistance.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

The ever-increasing requirement for high-temperature strength and better corrosion-resistant materials for increasingly higher operating temperatures and stresses in the process industry always pushes the envelope for high-performance alloys. This resulted in the development of a variety of compositionally complex alloys, often called “superalloys”, containing various alloying elements, which impart required mechanical and corrosion properties. Alloy 625 is one such alloy with a sizable market size. It is commonly used for many high-temperature applications across various industry sectors for its excellent combinations of mechanical properties, corrosion resistance and fabricability. This chapter gives an overview of the development, manufacturing, applications and market outlook of high-performance alloys.

Jung Bahadur Singh

Chapter 2. Phases in Alloy 625

Abstract

Alloy 625 contains high concentrations of various alloying elements added primarily to impart desired mechanical and corrosion properties. The high concentrations of elements like chromium, molybdenum and niobium induce the precipitation of multiple phases during solidification, processing and thermal exposure. The precipitation of various phases in the austenite nickel matrix makes the microstructure of the alloy very complex and alters its properties significantly. The Chapter briefly introduces crystallographic aspects of various phases in Alloy 625 and lays a foundation for their identification and understanding of phase transformations associated with their evolution.

Jung Bahadur Singh

Chapter 3. Physical Metallurgy of Alloy 625

Abstract

Alloy 625 is designed as a solid-solution alloy. Still, it develops a highly complex microstructure when different intermetallic phases and various carbides precipitate in the austenite matrix during processing and heat treatments. The precipitation of these phases modifies the alloy’s behavior depending upon their nature, morphology and location of formation. This chapter gives an overview of the alloy's chemistry and its phase transformation behavior and describes how the microstructure is modified when these phases evolve.

Jung Bahadur Singh

Chapter 4. Mechanical Behavior of Alloy 625

Abstract

The precipitation of various intermetallic and carbide phases during heat treatment or service exposure of Alloy 625 affects its mechanical properties. The chapter gives details of how the precipitation affects the alloy’s mechanical properties and discusses various factors governing the mechanical behaviour of the age-hardened alloy.

Jung Bahadur Singh

Chapter 5. Alloy 625 PLUS

Abstract

Alloy 625 PLUS alloy is developed as an age-hardenable variant of Alloy 625 to impart strength superior to Alloy 718 but retaining excellent corrosion resistance and welding properties of Alloy 625. This chapter gives a description of the alloy and compares its properties with Alloy 625.

Jung Bahadur Singh

Chapter 6. Fabrication

Abstract

Alloy 625 can be fabricated into various products like sheets, bars, tubes, and pressure vessels. The fabrication process involves hot deformation, heat-treatments, machining and welding. It is also an attractive material for producing complex components by “additive manufacturing”. This chapter gives an overview of essential fabrication techniques used to fabricate Alloy 625 products.

Jung Bahadur Singh

Chapter 7. Corrosion Behavior of Alloy 625

Abstract

Alloy 625 exhibits excellent resistance against the uniform and localized corrosion and stress-corrosion cracking in various environments due to its high chromium and molybdenum contents. At the same time, its niobium content stabilizes the alloy against intergranular attack. Chromium provides resistance to oxidizing chemicals, and molybdenum and high nickel improve the alloy’s resistance to non-oxidizing (or reducing) environments. Under the pressurized water conditions, Alloy 625 exhibits low corrosion rates in acidic and neutral water at supercritical temperatures and in alkaline water at subcritical temperatures. It exhibits good resistance to oxidation, carburization and sulfidation at high temperatures and intermediate resistance to gaseous halides and molten salt environments. This chapter gives a brief account of alloy’s corrosion behaviour in different environments and compares it with other alloys.

Jung Bahadur Singh

Chapter 8. Life Management of Alloy 625 Components

Abstract

Alloy 625 is being used for various applications in the chemical, marine, nuclear, power generation, and aerospace industries. Most of these applications are at temperatures in the intermediate temperature range, at which the alloy undergoes microstructure modifications and, consequently, mechanical properties changes below the codal requirements. Fortunately, in most cases, the degradations can be reversed to rejuvenate the lost properties. This chapter provides details of property deterioration due to such microstructural changes and assesses the alloy damage during in-service inspection of plants. The chapter also provides criteria for the damage evaluation for various destructive and non-destructive testing.

Jung Bahadur Singh

Backmatter

Titel: Alloy 625
verfasst von: Dr. Jung Bahadur Singh
Verlag: Springer Nature Singapore
Electronic ISBN: 978-981-19-1562-8
Print ISBN: 978-981-19-1561-1
DOI: https://doi.org/10.1007/978-981-19-1562-8

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