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Date：2025-04-30 14:23:51
Author: DTI
Classification of Quality Appraisal for Metal Materials and Mechanical Components
Quality appraisal involves two major categories: metal materials and mechanical components. Detection should be classified based on material properties, processing techniques, and service environments. Below is a systematic classification method:
I. Classification of Quality Appraisal for Metal Materials
1. Classification by Material Type
| Material Category | Key Tests | Typical Standards |
|---|---|---|
| Carbon Steel/Low Alloy Steel | Composition (C, Mn, P, S), Mechanical Properties (Tensile, Impact), Metallography (Pearlite/Ferrite) | GB/T 699, ASTM A36 |
| Stainless Steel | Corrosion Resistance (Intergranular Corrosion, Salt Spray), Cr/Ni Content, δ-Ferrite Content (Austenitic Stainless Steel) | GB/T 1220, ASTM A240 |
| Aluminum Alloy | Composition (Si, Cu, Mg), Hardness (HBW), Anodizing Film Thickness (e.g., 6061-T6) | GB/T 3190, ASTM B209 |
| Titanium Alloy | Oxygen Content (O), Microstructure (α/β Phases), High-Temperature Creep Resistance (e.g., TC4) | GB/T 3620, ASTM B348 |
| Superalloys | Creep Strength (Above 650℃), γ' Phase Content (e.g., Inconel 718) | GB/T 14992, ASTM B637 |
2. Classification by Processing State
| Processing State | Key Tests |
|---|---|
| Casting | Shrinkage/Porosity (X-ray), Grain Size (Metallography), Composition Segregation (EDS) |
| Forging | Flow Line Orientation (Macroetching), Non-Metallic Inclusion Rating (GB/T 10561) |
| Welding | Weld Mechanical Properties (Tensile, Bend), Non-Destructive Testing (RT/UT), Hardness Gradient (Heat-Affected Zone) |
| Heat Treatment | Surface Hardness (HRC), Hardenability (End-Quench Test), Residual Stress (X-ray Diffraction) |
II. Classification of Quality Appraisal for Mechanical Components
1. Classification by Function
| Component Type | Key Tests | Applicable Standards |
|---|---|---|
| Shaft Components | Fatigue Life (Rotating Bending Test), Surface Hardness (HRC), Radial Runout (CMM Inspection) | GB/T 3075, ISO 1143 |
| Gears | Tooth Surface Hardness (HV), Case Hardening Depth (Microhardness Method), Contact Fatigue Testing (GB/T 14230) | GB/T 10095, AGMA 2001 |
| Bearings | Clearance Measurement, Material Purity (Non-Metallic Inclusions), Wear Resistance (Bench Testing) | GB/T 307, ISO 281 |
| Fasteners | Tensile Strength (Bolts), Torque Coefficient (Friction Testing), Hydrogen Embrittlement (Delayed Fracture Testing) | GB/T 3098, ISO 898 |
| Pressure Vessels | Hydrostatic Testing, Non-Destructive Testing (RT/UT), Impact Toughness (Low-Temperature Service) | NB/T 47013, ASME VIII |
2. Classification by Failure Mode
| Failure Type | Targeted Tests |
|---|---|
| Fracture Failure | Fracture Surface Analysis (SEM), Chemical Composition (Spectroscopy), Residual Stress Detection |
| Wear Failure | Surface Topography (3D Profilometry), Hardness Gradient, Lubricant Composition Analysis |
| Corrosion Failure | Corrosion Product Analysis (EDS), Electrochemical Testing (Polarization Curves) |
| Deformation Failure | Dimensional Re-measurement (CMM), Material Yield Strength Verification |
III. General Classification of Quality Appraisal Process
1. Raw Material Incoming Inspection
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Tests: Composition Analysis, Mechanical Properties, Dimensional Tolerance, Surface Defects (Visual/Magnetic Particle).
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Standards: Procurement Technical Agreement (e.g., GB/T 702), ASTM A6 (Structural Steel).
2. In-Process Quality Control
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Casting/Forging: X-ray Inspection (Shrinkage), Ultrasonic Testing (Internal Cracks).
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Machining: Dimensional Accuracy (CMM), Surface Roughness (Ra).
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Heat Treatment: Hardness Spot Checks, Metallography (Martensite/Bainite Ratio).
3. Final Inspection of Finished Products
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Functional Testing: Sealing (Pressure Testing), Dynamic Balancing (Rotating Components).
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Full-Size Inspection: 100% Inspection of Critical Dimensions (e.g., Gear Module, Thread Accuracy).
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Documentation Review: Material Reports, Heat Treatment Records, NDT Reports.
IV. Industry - Specific Requirements Classification
1. Automotive Industry (IATF 16949)
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Key Tests: Dimensional CPK (Process Capability Index), Cleanliness (Particle Contamination), VDA6.3 Process Audit.
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Example: Engine Crankshaft requires Roundness (≤0.005mm) and Fatigue Life (≥10⁷ cycles).
2. Aerospace Industry (NADCAP Certification)
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Special Requirements: Microstructure of Superalloys (γ' Phase), Non-Destructive Testing (Penetrant/Eddy Current), Stress Corrosion Sensitivity.
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Standards: AMS 2750 (Heat Treatment), AMS 2644 (Penetrant Testing).
3. Energy (Nuclear/Wind Power)
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Nuclear Power: Irradiation Embrittlement Testing (Charpy V-notch Impact), Intergranular Corrosion (ASTM A262).
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Wind Power: Lubricant Wear Analysis of Gearbox Bearings (FE8 Test Rig).
V. Summary
Quality appraisal of metal materials and mechanical components should be implemented based on material type, processing state, functional requirements, and industry standards:
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Material Category: Composition → Mechanical Properties → Metallography → Corrosion Resistance.
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Component Category: Dimensions → Non-Destructive Testing → Functional Testing → Failure Analysis.
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Industry Category: Automotive (CPK), Aerospace (NADCAP), Energy (SCC).
Key Points:
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Material is the foundation (composition and microstructure determine properties).
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Processing affects quality (heat treatment/welding requires strict monitoring).
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Failure analysis is the core of improvement (fracture surface analysis + root cause investigation).
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