Comparison of Materials for TC4 Titanium Alloy, 304 Stainless Steel, 316 Stainless Steel, and Grade 8.8 Carbon Steel Fasteners
Comparison: TC4 Titanium Alloy (GR5) Density: 4.51 g/cm³, approximately 57% that of steel, offering significant weight reduction advantages Tensile Strength: ≥860 MPa, highest specific strength Hardness: HRC 30–34, relatively soft matrix; threads in grooves are prone to stripping Corrosion Resistance: Five stars. Extremely high corrosion resistance in atmospheric, rainwater, salt spray, and chloride ion environments; Not resistant to hydrofluoric acid or concentrated hydrochloric acid. Non-magnetic: Completely non-magnetic. High and low-temperature performance: Five stars. Stable performance between -200°C and 400°C; no brittle fracture at low temperatures. Fatigue resistance: Five stars. Resistant to alternating vibrations; unlikely to fracture under repeated vehicle vibrations. Risk of thread cold welding: High! Titanium-to-titanium contact is highly prone to seizing; anti-seize compound must be applied during assembly. Surface finishing: Can be sandblasted, polished, or color-anodized (blue/gold/purple). Price: Highest (expensive raw materials and processing costs). Typical Applications: Motorcycle/bicycle modifications, aerospace, precision instruments, and weight-reduction projects for coastal outdoor activities. Summary of Weaknesses: High cost; torque must be strictly controlled; titanium-to-titanium assemblies are prone to seizing.
Comparison Item: 304 Stainless Steel Density: 7.93 g/cm³ Tensile Strength: ≥520 MPa Hardness: Approximately HRC 20 Corrosion Resistance: 3 stars. Suitable for general indoor use and freshwater; prone to pitting and rusting in coastal salt fog environments. Non-magnetic: Weakly magnetic (may exhibit slight magnetism after machining). High and Low Temperature Performance: 3 stars. Acceptable at low temperatures; strength decreases significantly at high temperatures. Fatigue Resistance: 3 stars. Risk of Thread Cold Welding: Low. Surface Finishes: Polished, brushed; limited color options. Price: Moderate. Typical Applications: General equipment, indoor assembly, general outdoor use. Summary of Weaknesses: Prone to pitting corrosion in coastal salt fog; average strength.
Comparison: 316 Stainless Steel Density: 7.98 g/cm³ Tensile Strength: ≥480 MPa Hardness: Approximately HRC 20 Corrosion Resistance: 4 stars. Better resistance to chloride ions than 304, but there is still a risk of corrosion with long-term use in seawater. Non-magnetic: weakly magnetic. High and low temperature performance: 3 stars. Fatigue resistance: 3 stars. Risk of thread cold welding: low. Surface finishes: polished, brushed; limited color options. Price: slightly above average. Typical applications: seawater equipment, mildly corrosive chemical environments. Summary of weaknesses: Higher price than 304; no advantage in weight reduction.
Comparison Material: Grade 8.8 Carbon Steel Density: 7.85 g/cm³ Tensile Strength: ≥800 MPa Hardness: HRC 22–32; high hardness after quenching Corrosion Resistance: 1 star. Prone to rusting; must undergo galvanizing or blackening for rust prevention Non-magnetic: Magnetic High and Low Temperature Performance: 1 star. Prone to brittle fracture at low temperatures; strength decreases rapidly at high temperatures. Fatigue Resistance: 2 stars. Prone to fatigue fracture under vibrating conditions. Risk of Thread Cold Welding: Virtually none. Surface Finishes: Blackening, galvanizing; ordinary appearance. Price: Least expensive. Typical Applications: General machinery, non-weight-sensitive applications without corrosion protection requirements. Summary of Weaknesses: Heavy weight, poor rust resistance, rusts quickly in humid environments.
- For weight reduction and rust prevention: Prioritize TC4 titanium alloy screws—the top choice for motorcycle and bicycle modifications, with outstanding performance for long-term outdoor use near the ocean. Be sure to control torque during assembly, and use anti-seize compound when fastening titanium to titanium.
- For general indoor use with a limited budget, where only basic rust prevention is needed: Choose 304 stainless steel.
- For long-term exposure to seawater or mild chemical media: Prioritize 316 stainless steel.
- For general equipment mounting with no weight reduction or corrosion resistance requirements, and where low cost is the priority: Grade 8.8 carbon steel screws.
Among materials of the same specifications, TC4 titanium alloy is the lightest and far surpasses others in specific strength, salt spray corrosion resistance, and fatigue resistance; however, it is relatively expensive and has special assembly requirements. Carbon steel offers the best value for money but has poor rust resistance. 316 stainless steel has better resistance to chloride ions than 304, but it offers limited weight reduction.
TC4 titanium alloy screws are lightweight with high specific strength; they offer salt spray resistance and corrosion resistance, are non-magnetic and fatigue-resistant, and can be anodized to achieve a variety of finishes. They are suitable for motorcycle and bicycle modifications, as well as precision aerospace equipment. Disadvantages include a relatively high price, limited matrix hardness, a tendency for cold welding during titanium-to-titanium threaded assemblies, the need for controlled torque and anti-seize compound during assembly, and unsuitability for highly corrosive environments such as those involving hydrofluoric acid or concentrated hydrochloric acid.