成人av地址I天天干天天搞天天射I久久丁香网I久久免费视频7I又粗又长又大又爽又黄少妇毛片I日韩啪啪小视频I亚洲 综合 精品I免费欧美精品

Types of Corrosion

腐蝕類型

1. General (Uniform) Corrosion

1. 全面（均勻）腐蝕

- Metal loss occurs uniformly over the exposed surface

- 金屬在整個暴露表面均勻地發生損失

- Governed by overall electrochemical kinetics rather than local chemistry

- 由整體電化學動力學而非局部化學環境所控制

- 常見于暴露在大氣或水環境中的碳鋼

- Typically managed by corrosion allowance, coatings, or inhibitors

- 通常通過腐蝕余量、涂層或緩蝕劑來控制

2. Pitting Corrosion

2. 點蝕

- Highly localized anodic dissolution at discrete points

- 在離散點發生高度局部化的陽極溶解

- Initiated by breakdown of passive films (often due to chlorides or deposits)

- 由鈍化膜的破裂引發（通常由氯化物或沉積物引起）

- Cathodic area is large relative to anodic pit → high local corrosion rate

- 陰極區域相對于陽極點蝕坑較大 → 局部腐蝕速率很高

- Major failure mechanism for stainless steels and duplex alloys

- 是不銹鋼和雙相合金的主要失效機制

- Small pits can penetrate full wall thickness rapidly

- 小的點蝕坑能快速穿透整個壁厚

3. Microbiologically Influenced Corrosion (MIC)

3. 微生物影響腐蝕

- Corrosion accelerated by microbial metabolic activity

- 由微生物代謝活動加速的腐蝕

- Sulphate Reducing Bacteria (SRB) produce sulphides → H₂S generation

- 硫酸鹽還原菌產生硫化物 → 生成硫化氫

- Creates localized acidic and reducing environments

- 造成局部酸性和還原性環境

- Often manifests as deep pitting under biofilms or deposits

- 通常表現為生物膜或沉積物下方的深點蝕

4. Galvanic Corrosion

4. 電偶腐蝕

- Occurs when dissimilar metals are electrically connected in an electrolyte

- 當不同金屬在電解液中電氣連接時發生

- Less noble metal becomes anodic and corrodes preferentially

- 較不活潑的金屬成為陽極并優先腐蝕

- Severity depends on Galvanic series separation, Area ratio (small anode / large cathode = severe attack)

- 嚴重程度取決于電偶序差異、面積比（小陽極 / 大陰極 = 嚴重腐蝕）

- Common failure in bolting, fasteners, mixed-material piping

- 常見于螺栓連接、緊固件、混合材料管道中

5. Erosion–Corrosion

5. 沖刷腐蝕

- Combined effect of mechanical wear and electrochemical corrosion

- 機械磨損和電化學腐蝕的綜合作用

- High-velocity fluids or solids remove protective films

- 高速流體或固體去除保護性膜層

- Accelerated metal loss at elbows, tees, valves, chokes

- 在彎頭、三通、閥門、節流處金屬損失加速

- Damage pattern is directional and often horseshoe-shaped

- 損壞形態呈定向性，常為馬蹄形

6. Crevice Corrosion

6. 縫隙腐蝕

- Localized corrosion in shielded regions with restricted mass transfer

- 發生在傳質受限的屏蔽區域的局部腐蝕

- Differential oxygen concentration creates anodic crevice interior

- 氧濃度差導致縫隙內部成為陽極

- Common under gaskets, flanges, deposits, and lap joints

- 常見于墊片、法蘭、沉積物及搭接接頭下方

- Often more severe than pitting due to stable acidic micro-environment

- 由于穩定的酸性微環境，通常比點蝕更嚴重

7. Stress Corrosion Cracking (SCC)

7. 應力腐蝕開裂

- Synergistic interaction of Tensile stress (applied or residual), Specific corrosive environment and Susceptible material

- 拉應力（施加的或殘余的）、特定腐蝕環境和敏感材料三者協同作用

- Leads to brittle cracking with little plastic deformation

- 導致幾乎沒有塑性變形的脆性開裂

- Cracks may grow sub-surface and remain undetected

- 裂紋可能在表面下擴展且難以探測

8. Hydrogen Induced Cracking (HIC) / Sulphide Stress Cracking (SSC)

8. 氫致開裂 / 硫化物應力開裂

- Associated with hydrogen ingress into steel

- 與氫滲入鋼中有關

- Common in H₂S-containing environments

- 常見于含硫化氫的環境

- Hydrogen accumulates at inclusions → internal cracking

- 氫在夾雜物處聚集 → 導致內部開裂

- SSC requires tensile stress; HIC can occur without applied stress

- 硫化物應力開裂需要拉應力；氫致開裂可在無外加應力時發生

- Major concern for carbon steel in sour service

- 是碳鋼在酸性服役環境中的主要關注點

9. Fatigue Corrosion

9. 腐蝕疲勞

- Corrosion-assisted crack initiation and propagation under cyclic loading

- 在循環載荷下，腐蝕促進裂紋萌生和擴展

- Common in vibrating piping, rotating equipment, offshore structures

- 常見于振動的管道、旋轉設備、海上結構

- Surface corrosion pits often act as crack initiation sites

- 表面腐蝕點蝕坑常作為裂紋萌生點

10. Corrosion Under Insulation (CUI)

10. 保溫層下腐蝕

- External corrosion caused by trapped moisture beneath insulation

- 由保溫層下積聚的濕氣引起的外部腐蝕

- Affects both carbon steel and corrosion-resistant alloys

- 影響碳鋼和耐腐蝕合金

- Most severe in temperature ranges enabling wet/dry cycling

- 在能使干濕交替發生的溫度范圍內最為嚴重