Knowledge

In the field of mechanical engineering, choosing the right materials is crucial for ensuring the performance, reliability and cost-effectiveness of products. Mechanical engineers need to have a thorough understanding of the properties, applications and limitations of various materials in order to make informed decisions during the design and manufacturing process. The following are 20 commonly used materials that mechanical engineers must know, including both metallic and non-metallic materials, each accompanied by a brief description.

I. Metal Materials

Steel No. 45 (High-Quality Carbon Structural Steel)

• Characteristics: Steel No. 45 is the most commonly used medium-carbon quenched and tempered steel, featuring excellent comprehensive mechanical properties. However, its hardenability is relatively low, and it is prone to cracking when quenched in water.

• Applications: It is frequently used to manufacture moving parts with high strength requirements, such as turbine impellers, compressor pistons, shafts, gears, racks, and worms.

2. Q235A (A3 steel, the most commonly used carbon structural steel)

• Characteristics: It has high plasticity, toughness and weldability, as well as certain strength and good cold bending performance.

• Applications: It is widely used in parts and welded structures with general requirements, such as tie rods, connecting rods, pins, shafts, screws, nuts, rings, brackets, bases, as well as in building structures and bridges.

3. 40Cr (Alloy Structural Steel)

• Characteristics: After quenching and tempering treatment, it has excellent comprehensive mechanical properties, good low-temperature impact toughness, low notch sensitivity, and ideal hardenability.

• Applications: It is mainly used for manufacturing medium-speed and medium-load parts, such as machine tool gears, shafts, worms, and splined shafts. It is also suitable for manufacturing heavy-load, low-impact parts that require wear resistance, such as worms and spindles.

4. HT200 (Gray Cast Iron)

• Characteristics: Carbon exists in the form of flake graphite, and it has certain mechanical properties, such as a tensile strength of at least 200 MPa, a flexural strength of 432 MPa, and a compressive strength of 725 MPa. It has good machinability and excellent vibration damping performance.

• Applications: It is commonly used to manufacture parts such as gearboxes, motor housings, machine tool beds, boxes, hydraulic cylinders, pump bodies, valve bodies, flywheels, cylinder heads, pulleys, and bearing covers.

5. Steel No. 35

• Characteristics: Moderate strength, good plasticity, high cold plasticity, and fair weldability.

• Applications: Suitable for manufacturing small cross-section parts and components that need to bear relatively large loads, such as crankshafts, levers, connecting rods, hooks, and rings.

6. 0Cr18Ni10 (304 Stainless Steel)

• Characteristics: It has an austenitic structure, excellent corrosion resistance, heat resistance, low-temperature strength and mechanical properties, good hot workability such as stamping and bending, no hardening during heat treatment, and no magnetism.

• Applications: It is widely used in food processing equipment, general chemical equipment, and equipment for the atomic energy industry, etc.

7. 65Mn (Spring Steel)

• Characteristics: Good elasticity and fatigue resistance.

• Applications: Commonly used for making small-sized flat and round springs, seat cushion springs, spring coils, etc.

8. Cr12 (Cold Work Die Steel)

• Characteristics: Good wear resistance and hardenability.

• Applications: Widely used for manufacturing cold working dies, punches, blanking dies, and other molds that are subject to relatively low impact loads.

9. DC53 (Japanese high-strength and high-toughness cold work die steel)

• Characteristics: High hardness and toughness after high-temperature tempering, excellent wire cutting performance.

• Applications: Suitable for the manufacturing of precision cold stamping dies, drawing dies, thread rolling dies, and other types of dies.

10. SKD11 (Toughness Chromium Steel)

• Characteristics: It features high toughness and wear resistance, effectively extending the service life of molds.

• Applications: It is commonly used in the manufacturing of cold working molds, cutting tools, and measuring tools with high precision requirements and long service cycles, such as drawing dies and cold extrusion dies.

11. ASP-23 (Powder Metallurgy High-Speed Steel)

• Characteristics: Extremely uniform carbide distribution, high wear resistance, high toughness, easy to machine, and stable in size after heat treatment.

• Applications: Used for punch dies, deep drawing dies, drill dies, milling cutters, and shearing blades, as well as various long-life cutting tools.

12. P20 (Plastic Mold Steel)

• Characteristics: Suitable for electrical discharge machining (EDM), pre-hardened at factory with HB270-300, and can be quenched to HRC52.

• Applications: Used for manufacturing plastic molds of various sizes with general requirements.

13. 718 (High-requirement plastic mold steel for large and small sizes)

• Characteristics: Particularly suitable for electrical discharge machining operations. Delivered pre-hardened to HB290-330, and can be quenched to HRC52.

• Applications: Commonly used in the manufacturing of high-requirement plastic molds.

14. Nak80 (High-mirror finish, high-precision plastic mold steel)

• Characteristics: Pre-hardened at factory with HB370-400, quenched hardness HRC52.

• Applications: Mainly used for manufacturing plastic molds with high mirror finish and high precision.

15. S136 (Corrosion-resistant and mirror-polished plastic mold steel)

• Characteristics: Pre-hardness at factory delivery is less than HB215, and quenched hardness is HRC52.

• Applications: Suitable for manufacturing plastic molds that require corrosion resistance and mirror polishing.

16. H13 (Commonly used die-casting mold material)

• Characteristics: It has excellent thermal stability and wear resistance.

• Applications: It is often used in die-casting molds for aluminum, zinc, magnesium and their alloys, as well as in hot forging dies and aluminum extrusion dies.

17. SKD61 (Advanced die-casting mold material)

• Characteristics: Significantly improved service life after electroslag remelting treatment.

• Applications: Suitable for manufacturing hot forging dies, aluminum extrusion dies, etc.

18. 8407 (Advanced die casting mold material)

• Characteristics: It features high strength and wear resistance.

• Applications: It is also frequently used in hot forging dies, aluminum extrusion dies, etc.

19. Cr12MoV (Alloy Tool Steel)

• Characteristics: It has high hardenability, hardness after quenching and tempering, wear resistance and strength.

• Applications: It is often used in various cold stamping dies and tools under complex shapes and heavy working conditions, such as punching dies, trimming dies, curling dies, deep drawing dies for steel plates, circular saws, standard tools and gauges, thread rolling dies, etc.

20. 0Cr18Ni9 (Another common type of stainless steel, similar to 304)

• Characteristics: Similar to 304 stainless steel, it has excellent corrosion resistance, heat resistance, low-temperature strength, and mechanical properties.

• Applications: It is also widely used in food equipment, chemical equipment, and atomic energy industrial equipment, among other fields.

II. Non-metallic Materials

1. GFRP (Glass Fiber Reinforced Plastic)

• Characteristics: High strength, lightweight, and corrosion resistance.

• Applications: Commonly used in manufacturing car bodies, ship hulls, wind turbine blades, etc.

2. PC (Polycarbonate)

• Characteristics: Excellent transparency, impact resistance and heat resistance.

• Applications: Widely used in the manufacture of safety glasses, CD/DVD discs, medical equipment, etc.

3. PVC (Polyvinyl Chloride)

• Characteristics: Low cost, good processability and weather resistance.

• Applications: Commonly used in the production of pipes, floor materials, wire insulation, etc.

4. Nylon

• Characteristics: Good wear resistance, elasticity and self-lubrication.

• Applications: Widely used in the manufacture of gears, bearings, pipes, ropes, etc.

5. Rubber

• Characteristics: Excellent elasticity, wear resistance and sealing property.

• Applications: Commonly used in the manufacture of tires, seals, shock absorbers, etc.

6. Ceramics

• Characteristics: High hardness, high melting point, and corrosion resistance.

• Applications: Commonly used in the manufacture of cutting tools, engine parts, artworks, etc.

7. Composite Materials

• Characteristics: Composed of two or more materials with different properties, it features high strength, low weight, corrosion resistance and other comprehensive properties.

• Applications: It is playing an increasingly important role in modern mechanical engineering and is used to manufacture various high-performance components.

Understanding the properties and applications of these materials helps mechanical engineers to more accurately select the appropriate materials during the design and manufacturing process, thereby optimizing product design and enhancing the performance and reliability of machinery. At the same time, with the advancement of technology and the continuous change of engineering demands, the research and application of new materials will also continue to drive the development of the mechanical engineering field.

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