C52100 Bronze

Alloy Designation

• International: UNS C52100, CDA 521, CuSn8 (EN Standard)

• Chinese: QSn8-0.3 (GB/T 4423-1992)

• Alias: 8% Tin-Phosphor Bronze, Instrument Bronze, characterized by high tin content (7.0%-9.0% Sn) and phosphorus strengthening (0.03%-0.35% P).

Key Features

C52100 excels in the tin-phosphor bronze series:

• Strength-Conductivity Balance: Tensile strength reaches 860-1035 MPa (hard temper) with 13-15% IACS conductivity, outperforming low-tin phosphor bronzes.

• Wear/Corrosion Resistance: Low friction coefficient (0.15-0.25), corrosion rate <0.015 mm/year in seawater/weak acids, resistant to stress corrosion cracking.

• Special Properties: Non-magnetic (μ<1.01), cryogenic toughness (effective at -200°C), spark-free upon impact.

• Process Adaptability: Excellent cold workability (≤30% deformation), but limited hot workability.

Product Forms & Dimensions

Table 1: Product Forms & Specifications

Form	Size Range	Temper	Standard
Sheet/Plate	Thickness: 0.1-150mm; Width: 400-1100mm	O60 (Soft), H08 (Hard)	ASTM B103
Strip	Thickness: 0.05-2.0mm; Width: 10-600mm	H04, H06	GB/T 4423
Bar (Round/Hex)	Diameter/Width: Ø5-200mm	Y2 (Half-hard), T6 (Aged)	ASTM B139
Wire	Diameter: Ø0.1-12mm	Soft, Half-hard	ASTM B103
Tube	OD: Ø3-150mm; Wall: 0.2-15mm	Annealed, Hard	GB/T 4423

Note: Custom profiles available with ±0.05mm tolerance.

Chemical Composition

Table 2: Chemical Composition (wt%, Cu bal.)

Element	Req.	Typical	Impurity Max	Function
Sn	7.0-9.0	8.0	–	Solid solution strengthening
P	0.03-0.35	0.15	–	Deoxidation, grain refinement
Fe	≤0.10	≤0.02	0.10	Reduces conductivity if excessive
Pb	≤0.05	≤0.005	0.05	Prevents hot shortness
Zn	≤0.20	≤0.10	0.20	Trace residual
Total Impurities	≤0.50	≤0.30	0.50	–

*Standards: ASTM B159M-2017, GB/T 5231-2012.*

C52100 Phosphor Bronze Properties

Physical Properties

Table 3: Physical Properties (20°C)

Property	Value Range	Unit	Test Method
Density	8.80-8.86	g/cm³	ASTM B193
Electrical Conductivity	13-15	%IACS	Annealed
Thermal Conductivity	36-50	W/(m·K)	Steady-state heat flow
CTE	18.20×10⁻⁶	K⁻¹	20-300°C
Elastic Modulus	110-115	GPa	Tensile test
Max Service Temp	200°C	–	–

Note: Non-magnetic properties suit precision instruments and explosion-proof applications.

Mechanical Properties

Table 4: Mechanical Properties (Room Temp, Bar Samples)

Property	Annealed (O60)	Half-hard (H02)	Hard (H08)	Test Standard
Tensile Strength	365-470 MPa	655-795 MPa	860-1035 MPa	ASTM E8
Yield Strength	150-200 MPa	450-550 MPa	750-850 MPa	ASTM E8
Elongation (δ₁₀)	≥40%	≥15%	≥5%	GB/T 228.1
Hardness (HV)	70-120	160-190	200-250	ASTM E92
Fatigue Strength (10⁷ cycles)	140 MPa	240 MPa	300 MPa	Rotating bending

*Note: Samples Ø5-12mm (longitudinal); cold working significantly improves elastic limit.*

Core Advantages

• Strength-Wear Balance: Hardness up to HV 250 (hard temper), 50% higher wear resistance vs. brass (PV limit: 2.5 MPa·m/s).

• Comprehensive Corrosion Resistance: Seawater corrosion rate <0.015 mm/year, resists microbial adhesion.

• Cryogenic Suitability: No brittleness at -200°C for superconducting/aerospace components.

• Cost Efficiency: 40% lower cost than beryllium copper, avoids toxicity issues, no solution treatment needed.

Applications

• Precision Springs: High-load contact springs, relay reeds, bellows (excellent stress relaxation resistance).

• Wear Parts: Bearing bushes, gear shafts, marine propeller sleeves (self-lubricating service).

• Electrical Contacts: High-reliability connectors, micro-motor brushes (balances conductivity/elasticity).

• Safety Equipment: Explosion-proof tools, spark-free drill bits (oil rigs, mining maintenance).

Processing Guidelines

• Hot Working: Strictly 650-750°C; >800°C causes grain growth, <650°C increases deformation resistance. Rapid cooling required post-rolling.

• Cold Working: ≤30% reduction per pass; intermediate anneal (600-650°C×1h). Acid-clean oxide layers before cold drawing.

• Welding: Avoid fusion welding (grain boundary embrittlement). Prefer brazing (BAg-5 filler) or diffusion bonding. Post-weld anneal at 500-550°C.

• Surface Treatment: Electroless nickel or chromate passivation for corrosion resistance. Prohibit lead-containing coolants to prevent SCC.

Key Application Scenarios

• Marine: Seawater pump seals (≥10-year design life), resists seawater corrosion/cavitation.

• Aerospace: Aircraft sensor springs (Airbus A350 certified), withstands high vibration.

• Electronics: 5G connector contacts (>100k mating cycles), ensures signal stability.

• Energy: Nuclear valve guides (resists radiation oxidation/fretting wear).

FAQ

Q1: C52100 vs. C51900 (QSn6.5-0.1)?

A1: Bronze C52100 has higher Sn (8% vs. 6.5%), 20% higher strength/wear resistance, but 15% higher cost. Use C51900 for general springs; C52100 for high-stress wear parts (bearings, gears).

Q2: Microcracks after cold working?

A2: Caused by excessive deformation/surface defects:

• Limit per-pass reduction to ≤25%;

• Acid-clean pre-processing;

• Intermediate anneal (620°C×1h).

Q3: Reliability of welded joints?

A3: Fusion welding risks embrittlement. Recommended:

• Brazing: BAg-5 filler (650-750°C), joint strength ≥300 MPa;

• Diffusion Bonding: 850°C×2h + 50 MPa pressure (precision components).

Q4: Performance stability at high temperatures?

A4: Maximum continuous service: 200°C; short-term exposure: 400°C. For >250°C, apply nickel plating.

Reference Standards

Standard	Code	Scope
USA	ASTM B103/B103M-2019	Plate, Sheet, Strip, Rolled Bar
	ASTM B139/B139M-2013	Rod and Bar
China	GB/T 4423-1992	Wrought Copper Alloy Bars
	GB/T 5231-2012	Chemical Composition & Product Forms
International	ISO 427:2016	Wrought Copper Alloys (CuSn8 equivalent)
	EN 12163:2016	Rod for General Purposes (CuSn8)
Japan	JIS C5210	Phosphor Bronze Strip for Electronics

Testing Standards

• Chemistry: ASTM E54 (Sn), ASTM E62 (P)

• Mechanical: ASTM E8 (tensile), ASTM E92 (Vickers hardness)

• Metallography: ASTM E112 (grain size)

Note: Data synthesized from ASTM, GB, JIS, and manufacturer specifications. Performance may vary slightly with processing. Conduct application-specific validation for critical uses.