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Metallurgical failure analysis is the process by which a metallurgist determines the mechanism that has caused a metal component to fail. Typical failure modes involve various types of corrosion and mechanical damage. It has been estimated that the direct annual cost of corrosion alone in the United States was $276 billion, approximately 3.1% of GDP, in 1998.〔‘Corrosion Costs and Preventive Strategies in the United States,’ Report FHWA-RD-01-156, contact the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161; phone: 703/605-6000.〕 Since then, corrosion costs have continued to skyrocket and total corrosion costs now are greater than $1 trillion annually in the United States as of 2012.〔(G2MT Labs Cost of Corrosion Updated Estimate )〕 Metal components fail as a result of the environmental conditions to which they are exposed to as well as the mechanical stresses that they experience. Often a combination of both environmental conditions and stress will cause failure. Metal components are designed to withstand the environment and stresses that they will be subjected to. The design of a metal component involves not only a specific elemental composition but also specific manufacturing processes such as heat treatments, machining processes, etc.… The huge arrays of different metals that result all have unique physical properties.〔(M&M Engineering Conduit Fall 2007 “Ferrous Metallurgy 101,” ) 〕 Specific properties are designed into metal components to make them more robust to various environmental conditions. These differences in physical properties will exhibit unique failure modes. A metallurgical failure analysis takes into account as much of this information as possible during analysis. The end goal of failure analysis is to provide a determination of the root cause and a solution to any underlying problems to prevent future failures.〔http://www.g2mtlabs.com/failure-analysis/what-is-failure-analysis/ G2MT Labs - "What is Failure Analysis?"〕 Analysis of a failed part can be done using destructive testing or non-destructive testing. Destructive testing involves removing a metal component from service and sectioning the component for analysis. Destructive testing gives the failure analyst the ability to conduct the analysis in a laboratory setting and perform tests on the material that will ultimately destroy the component. Non destructive testing is a test method that allows certain physical properties of metal to be examined without taking the samples completely out of service. NDT is generally used to detect failures in components before the component fails catastrophically. There is no standardized list of metallurgical failure modes and different metallurgists might use a different name for the same failure mode. The Failure Mode Terms listed below are those accepted by ASTM,〔“Standard Terms Relating to Corrosion and Corrosion Testing” (G 15), Annual Book of ASTM Standards, ASTM, Philadelphia, PA. 〕 ASM,〔ASM-International Metals Handbook, Ninth Edition, Corrosion, ASM-International, Metals Park, OH 〕 and/or NACE〔NACE-International NACE Basic Corrosion Course, NACE-International, Houston, TX〕 as distinct metallurgical failure mechanisms. == Metallurgical Failure Modes Caused By Corrosion and Stress == *Stress Corrosion Cracking〔M&M Engineering Conduit Fall 2007 “Chloride Pitting and Stress Corrosion Cracking of Stainless Steel Alloys,” () 〕 *Corrosion Fatigue *Caustic Cracking (ASTM term) *Caustic Embrittlement (ASM term) *Stress Corrosion (NACE term) *Sulfide Stress Cracking (ASM, NACE term) *Stress Accelerated Corrosion (NACE term) *Hydrogen Stress Cracking (ASM term) *Hydrogen Assisted Stress Corrosion Cracking (ASM term) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Metallurgical failure analysis」の詳細全文を読む スポンサード リンク
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