Controlled Atmospheres for Heat Treatment describes the reaction complexities in heat treatment of metals under controlled atmosphere. Organized into 13 chapters, this book begins with the methods and classifications of heat treatment in controlled atmospheres. This topic is followed by the most popular atmospheres of heat treatment, namely, nitrogen and vacuum. The subsequent chapters deal with the components of heat treatment atmospheres, such as exogas, nitrogen base of monogas, endogas, and ammonia. The discussion then shifts to special gas atmospheres, including steam and those produced by cracking organic liquids. This book also covers several heat treatment processes, such as annealing, hardening, tempering, and heat treatment of powder metallurgical products in controlled atmospheres. A chapter describes the common methods used in protective gas techniques. The concluding chapter presents some dangers associated with controlled atmospheres and their corresponding technical safety precautions.

1 Heat Treatment in Controlled Atmospheres 1.1 Interaction Between Metals and Gas Atmospheres 1.2 Gaseous Constituents of Controlled Atmospheres 1.2.1 Oxygen 1.2.2 Nitrogen 1.2.3 Carbon Monoxide and Carbon Dioxide 1.2.4 Hydrogen 1.2.5 Water Vapor 1.2.6 Hydrocarbons 1.3 Chemical Effects of the Individual Atmosphere Constituents on Metals and Alloys 1.3.1 Equilibrium Conditions between Controlled Atmospheres and Metals 1.3.2 Interpretation of the Equilibrium Constant and Its Application in Controlled-Atmosphere Technology 1.3.3 Oxidation 1.3.4 Calculation of Principal Oxidizing Reactions 1.3.5 Decarburizing Reactions 1.3.6 Calculations for Reactions Involving Decarburization 1.3.7 Reactions Resulting in Sulphide Formation 1.3.8 Controlled Oxidation Effects 1.4 Interchange of Elements Between Atmosphere and Metals and Alloys2 Methods of Heat Treatment in Controlled Atmospheres and the Principal Atmospheres Employed 2.1 Principal Controlled Atmospheres 2.1.1 Endogas Atmospheres 2.1.2 Exogas Atmospheres 2.1.3 Prepared Nitrogen Base or Monogas Atmospheres 2.1.4 Resume of the Chemistry of Atmosphere Preparation 2.1.5 Dissociated Ammonia 2.2 Controlled Atmosphere Generating Plant 2.3 Main Characteristics of Controlled Atmospheres 2.3.1 Composition, Dew Point and Fields of Application 2.3.2 Relative Usage of Protective Atmospheres 2.3.3 Relative Costs of Producing Protective Atmospheres 2.4 Classification of Annealing Treatments Carried out in Controlled Atmospheres 2.4.1 Bright Annealing 2.4.2 Reducing Annealing 2.4.3 Scale-Free Annealing 2.4.4 Low-scale Annealing 2.5 Classification of Atmospheres According to Their Effects 2.5.1 Inert Atmospheres 2.5.2 Neutral Atmospheres 2.5.3 Active Gas Atmospheres3 Inert-Gas Atmospheres and Vacuum 3.1 Argon and Helium 3.2 Nitrogen 3.3 Hydrogen 3.4 Vacuum as an Atmosphere4 Exogas Atmospheres 4.1 Properties of Exogas Atmospheres 4.2 Construction and Operation of Exothermic Gas Generators 4.2.1 Oxygen Removal 4.2.2 Sulphur Removal 4.3 Advantages, Disadvantages and Typical Applications of Exothermic-Base Atmospheres 4.4 Production of Exothermic-Base Atmospheres from Hydrocarbons5 Prepared Nitrogen-Base or Monogas Atmospheres 5.1 Properties 5.2 Prepared Nitrogen-Base or Monogas Generators 5.2.1 Modern Methods of Monogas Production 5.3 Advantages and Disadvantages of Prepared Nitrogenbase or Monogas Atmospheres and Typical Applications 5.3.1 Applicability as a Function of Temperature 5.3.2 Advantages and Disadvantages of Monogas 5.4 Limitations on the Application of Monogas 5.5 Evaluation of Monogas6 Endogas Atmospheres 6.1 Theoretical Considerations 6.2 Fuel Gas Bases for Endogas Production 6.2.1 Natural Gas 6.2.2 Propane 6.2.3 Town Gas 6.2.4 Hydrocarbon-Steam Reaction 6.3 Design and Operation of Endogas Generators 6.3.1 Catalysts 6.4 Advantages and Disadvantages of Endogas Atmospheres and Fields of Application 6.5 Production of Endogas from Liquid Hydrocarbons 6.6 Exo-endogas Atmospheres7 Ammonia-Base Atmospheres 7.1 Types of Ammonia-Base Atmospheres 7.2 Properties of Atmospheres Obtained by the Dissociation of Ammonia 7.3 Design and Operation of Ammonia Crackers 7.3.1 Cylinder Battery 7.3.2 Preparation of Controlled, Protective Atmospheres from Liquid Ammonia 7.3.3 Auxiliary Equipment 7.3.4 Safety Precautions 7.3.5 Handling of Protective Atmospheres Consisting of H2 + N2 7.4 Advantages and Disadvantages of Dissociated/Cracked Ammonia and Typical Applications 7.