Welding defect 焊接瑕疵.docx

Welding defectFrom Wikipedia, the free encyclopediaJump to: /wiki/Welding_defectnavigation, /wiki/Welding_defectsearchA welding defect is any flaw that compromises the usefulness of a /wiki/weldmentweldment.According to the /wiki/American_Society_of_Mechanical_EngineersAmerican Society of Mechanical Engineers (ASME), welding defect causes are broken down as follows: 45 percent poor process conditions, 32 percent operator error, 12 percent wrong technique, 10 percent incorrect consumables, and 5 percent bad weld grooves./wiki/Welding_defect[1]Contents/wiki/Welding_defect1 Major causes/wiki/Welding_defect1.1 Hydrogen embrittlement/wiki/Welding_defect1.2 Residual stresses/wiki/Welding_defect2 Types/wiki/Welding_defect2.1 Cracks/wiki/Welding_defect2.1.1 Arc strike cracking/wiki/Welding_defect2.1.2 Cold cracking/wiki/Welding_defect2.1.3 Crater crack/wiki/Welding_defect2.1.4 Fusion-line crack/wiki/Welding_defect2.1.5 Hat crack/wiki/Welding_defect2.1.6 Hot cracking/wiki/Welding_defect2.1.7 Underbead crack/wiki/Welding_defect2.1.8 Longitudinal crack/wiki/Welding_defect2.1.9 Reheat cracking/wiki/Welding_defect2.1.10 Root and toe cracks/wiki/Welding_defect2.1.11 Transverse crack/wiki/Welding_defect2.2 Distortion/wiki/Welding_defect2.3 Gas inclusion/wiki/Welding_defect2.4 Inclusions/wiki/Welding_defect2.5 Lack of fusion and incomplete penetration/wiki/Welding_defect2.6 Lamellar tearing/wiki/Welding_defect2.7 Undercut/wiki/Welding_defect3 References/wiki/Welding_defect3.1 Bibliography/wiki/Welding_defect4 External linksMajor causesHydrogen embrittlementMain article: /wiki/Hydrogen_embrittlementHydrogen embrittlementResidual stressesMain article: /wiki/Residual_stressResidual stressThe magnitude of stress that can be formed from welding can be roughly calculated using:[2]Where E is /wiki/Young%27s_modulusYoungs modulus, α is the /wiki/Coefficient_of_thermal_expansioncoefficient of thermal expansion, and ΔT is the temperature change. For steel this calculates out to be approximat