Aluminum Frame Profiles,Assembly Line Aluminum Profile,Extrusion Aluminium Profile,Solar Pannel Frame Aluminum Profile Guangdong Jihua Aluminium Co., LTD , https://www.jihua-alu.comUseful Tips: Common Terms in Hardware
**A. Yield Strength (Physical Yield Strength):**
Code: σs, Unit: MPa (or N/mm²)
Description: This is the stress at which a metal material begins to deform plastically under tensile load. It represents the maximum stress that the material can withstand before permanent deformation occurs.
**B. Offset Yield Strength (Conditional Yield Strength):**
Code: σr, Unit: MPa (or N/mm²)
Description: The stress at which a metal retains a certain amount of plastic deformation after unloading. Typically, this is defined as the stress corresponding to 0.2% plastic strain, written as σr0.2.
**C. Proportional Limit Stress:**
Code: σp, Unit: MPa (or N/mm²)
Description: The stress at which the material's deformation is still proportional to the applied force. It is defined as the stress at 0.01% elongation, written as σp0.01.
**Hardness Introduction:**
Hardness refers to a material’s resistance to indentation by a harder object. There are several types of hardness measurements:
**Brinell Hardness:**
Code: HBS (for hardened steel ball) or HBW (for tungsten carbide ball), often written as HB
Unit: No unit
Description: A hard ball is pressed into the material with a specific load for a set time. After removing the load, the indentation diameter is measured and used to calculate hardness using a formula.
**Rockwell Hardness:**
Code: HR
Unit: No unit
Description: A diamond cone or hardened steel ball is pressed into the material under a specific load. The depth of penetration determines the hardness value. Common scales include:
- **HRC (Scale C):** Uses a diamond indenter with 150 kgf load, suitable for hardened steels.
- **HRA (Scale A):** Diamond indenter with 60 kgf load, ideal for very hard materials like carburized steel.
- **HRB (Scale B):** Steel ball with 100 kgf load, used for softer materials such as non-ferrous metals.
**Superficial Rockwell Hardness:**
Code: HR
Description: Similar to standard Rockwell but used for thin or surface-treated materials. Scales include HR15N, HR30N, HR45N, HR15T, HR30T, and HR45T.
**Vickers Hardness:**
Code: HV
Unit: No unit
Description: A square-based diamond indenter is pressed into the material under a known load. The diagonal length of the indentation is measured and used to calculate hardness. Suitable for larger parts and deeper layers.
**Tensile Strength:**
Code: σ, Unit: MPa (or N/mm²)
Description: The maximum stress a material can withstand before breaking. Tensile strength includes different types based on loading conditions:
- **Compressive Strength (σbc):** Resistance to crushing forces.
- **Bending Strength (σbb):** Resistance to bending.
- **Shear Strength (σc):** Resistance to sliding forces.
- **Tensile Strength (σb):** Resistance to pulling forces.
**Elastic Limit, Elongation, and Reduction in Area:**
- **Elastic Limit (σe):** The maximum stress a material can endure without permanent deformation.
- **Elongation (δ):** The percentage increase in length before fracture. Measured as δ5 (short gauge length) or δ10 (longer gauge length).
- **Reduction in Area (Ψ):** The percentage decrease in cross-sectional area at the point of fracture.
**Impact Toughness:**
- **Impact Absorption Work (Ak):** The energy absorbed during impact before fracture, measured in joules (J).
- **Impact Toughness (ak):** Impact work divided by the cross-sectional area at the notch, measured in J/cm².
Common tests include Charpy U-notch (AkU) and Charpy V-notch (AKV).
**Related Bearings Knowledge:**
- Analysis of Bearing Steel in Special Environments (Part II)
- Methods for Smoothing Centrifugal Pump Bearings
- Use of Aviation Bearings in Aircraft and Helicopters
This article is linked from http://
Please cite China Bearing Network: http://
Previous: Causes of Oscillation in Rolling Bearings of Oscillating Screens Affecting Y-Bearings
Source: Bearing Network | Time: 2013-03-14