LG2 / C83600 gunmetal bushes for pumps, valves and water
The 85-5-5-5 alloy: 85 % copper with 5 % each of tin, zinc and lead. Pressure-tight, corrosion resistant in fresh water, steam and mild chemicals, and the easiest bearing alloy to machine, LG2 is the British and Commonwealth default for general bronze bushes, BC6 / CAC406 the Japanese, Rg5 the German, БрО5Ц5С5 the Russian, ZCuSn5Pb5Zn5 the Chinese. A light-duty bearing alloy: 207 N/mm² minimum tensile and 55 – 65 HB, for pump, valve and general machinery bushes where the medium matters more than the load.
Leaded gunmetal (leaded red brass in US terminology) is a tin-zinc-lead bronze cast to ASTM B505 / B271 as C83600 and to EN 1982 as CuSn5Zn5Pb5-C (CC491K). In bushings it is chosen for water service, pressure-tightness and machinability; for load it is a step below SAE 660.
- Composition (ASTM B505): Cu 84 – 86, Sn 4 – 6, Pb 4 – 6, Zn 4 – 6, Ni ≤ 1 %
- Minimums (B505): tensile 207 N/mm² (30 ksi), yield 97 N/mm² (14 ksi), elongation 15 %; typical 255 / 117 N/mm², 30 %, 60 HB; EN CC491K GZ / GC: Rm 250, Rp0.2 100, A 13 %, 65 HB
- Density 8.83 g/cm³, machinability 84 – the highest of the bearing bronzes
- Corrosion resistant in fresh water, steam, mild acids and alkalis; not for seawater under load (use aluminium bronze)
- Contains 5 % lead – not for drinking water; lead-free alternative CuSn10 or C90500
Chemical composition
LG2 / C83600 · CuSn5Zn5Pb5
| Element | Range (% by mass) | Nominal (%) |
|---|---|---|
| Cu | 84.0–86.0 | 85 |
| Sn | 4.0–6.0 | 5 |
| Pb | 4.0–6.0 | 5 |
| Zn | 4.0–6.0 | 5 |
| Ni | ≤ 1.0 | — |
* Typical values per ASTM B505 / B271, EN 1982 and GB/T 1176 for the cast alloy; not a guarantee for a specific part. Test certificates (chemical analysis, hardness) are supplied on request with the order.
Tensile strength · Hardness · Density
| Grade | Alloy | Family | Tensile strength standard minimum (MPa) | Yield strength (0.5 % ext. / Rp0.2) standard minimum (MPa) | Elongation (%) | Hardness (HB) | Tensile strength typical (MPa) | Density (g/cm³) | Machinability (C36000 = 100) |
|---|---|---|---|---|---|---|---|---|---|
| LG2 / C83600* | CuSn5Zn5Pb5 | gunmetal (leaded red brass) | 207 | 97 | 15 | 55–65 | 255 | 8.83 | 84 |
* Typical values per ASTM B505 / B271, EN 1982 and GB/T 1176 for the cast alloy; not a guarantee for a specific part. Test certificates (chemical analysis, hardness) are supplied on request with the order.
Also known as
| Parameter | LG2 / C83600CuSn5Zn5Pb5 |
|---|---|
| UNS / ASTM | C83600 |
| SAE | SAE 40 |
| EN 1982 | CuSn5Zn5Pb5-C · CC491K |
| DIN (old) | Rg5 · 2.1096 |
| BS 1400 | LG2 |
| JIS H5120 | CAC406 (BC6) |
| GB/T 1176 | ZCuSn5Pb5Zn5 |
| ГОСТ 613 | БрО5Ц5С5 |
| PN (Poland) | B555 |
| Also known as | CDA 836 · 85-5-5-5 · "ounce metal" · leaded gunmetal · IS 318 LTB2 (IN) |
* Typical values per ASTM B505 / B271, EN 1982 and GB/T 1176 for the cast alloy; not a guarantee for a specific part. Test certificates (chemical analysis, hardness) are supplied on request with the order.
LG2 vs SAE 660 – sold side by side, not the same alloy
Australian, British, South African and Indian stockists sell LG2 and SAE 660 as interchangeable general bronzes, and for light duty they are. Chemically they differ: LG2 has 5 % tin and 5 % zinc, 660 has 7 % tin and 3 % zinc, and 660 is about 10 HB harder and 15 % stronger in typical values. In a pump gland, a valve stem guide or a slow lightly loaded pin either works; on a heavily loaded pin or under shock 660 lasts longer, and LG2 wins where pressure-tightness, water corrosion and machining cost dominate. Indian IS 318 LTB2 is the same 5-5-5 class; JIS CAC406 (old BC6) too.
| Criterion | LG2 / C83600 | C93200 / SAE 660 | Phosphor bronze CuSn10P |
|---|---|---|---|
| Composition | Cu 85, Sn 5, Pb 5, Zn 5 | Cu 83, Sn 7, Pb 7, Zn 3 | Cu 89, Sn 10, P 0.8 |
| Min. tensile, N/mm² | 207 (B505) / 250 (EN GZ) | 207 (B505) / 260 (EN GZ) | 310 |
| Hardness HB | 55 – 65 | 65 – 75 | ≥ 90 |
| Load | light | medium | high |
| Water, steam corrosion | very good, pressure-tight | good | good |
| Emergency lubrication | fair (5 % Pb) | good (7 % Pb) | none |
| Machinability | 84 | 70 | lower (≈ 40) |
| Shaft | plain steel or stainless | plain steel | hardened |
| Typical use | pumps, valves, marine fittings, light pivots | general machinery pins and bushes | heavy gear and press bushes |
For your enquiry:Drawing says LG2, BC6 / CAC406, Rg5 or 85-5-5-5? We machine C83600 / CC491K – say if 660 may be substituted.
When gunmetal is the right bush
Pumps: shaft sleeves, throat bushes, wear rings and bearing bushes in water, condensate and mild chemicals, where the alloy's pressure-tightness and resistance to fresh-water corrosion matter and the load is modest. Valves: stem bushes and guides, gland followers, seat rings. General machinery and marine fittings: light pivots, lever bushes, rudder and tiller fittings in fresh water. Also the alloy to quote when the drawing says LG2 and the position is not heavily loaded.
Not the right bush for heavy pins (660, C86300), seawater under load or cavitation (aluminium bronze), high wear with a hard shaft (tin bronze), or lead-free positions (CuSn10, C90500) – its 5 % lead exceeds drinking-water limits like all leaded grades.
Names for the 85-5-5-5 gunmetal
One alloy, many names – all interchangeable:
| System | Designation |
|---|---|
| UNS / CDA / SAE | C83600 · CDA 836 · SAE 40 · "85-5-5-5" · "ounce metal" |
| ASTM | B505 (continuous), B271 (centrifugal), B584 (sand), B62 (valve castings) |
| EN 1982 | CuSn5Zn5Pb5-C · CC491K |
| DIN (old) | Rg5 · G-CuSn5ZnPb · 2.1096 |
| BS 1400 | LG2 (leaded gunmetal) |
| IS 318 (India) | LTB2 |
| JIS H5120 | CAC406 (old BC6) |
| GB/T 1176 | ZCuSn5Pb5Zn5 |
| ГОСТ 613 | БрО5Ц5С5 |
| PN (Poland) | B555 |
Where LG2 bushes are used
Water, pressure and light load:
- Water and condensate pumps: shaft bushes, throat bushes, wear rings
- Valves: stem guides, gland bushes, seat rings
- General machinery: light pivots and lever bushes, especially to UK, Australian, South African and Indian drawings
- Marine fittings in fresh water and above the waterline
- Food and textile machinery where lead is permitted
- Replacement bushes for CAC406 / BC6 positions in Japanese and South-East Asian equipment
Forms and sizes in LG2
All ISO 4379 sleeve and flanged sizes, thrust washers and parts to drawing. Stock is bought per order as continuous-cast bar or tube; typical lead times are close to those of C93200.
Frequently asked questions
Is LG2 the same as SAE 660?
No. LG2 is the 85-5-5-5 gunmetal (C83600, CC491K); SAE 660 is the 83-7-7-3 leaded tin bronze (C93200, CC493K). Stockists sell them as interchangeable general bronzes and for light duty they are, but 660 is harder and stronger and lasts longer on loaded pins, while LG2 is more pressure-tight and cheaper to machine.
What is gunmetal used for in bushings?
Pump shaft bushes and wear rings, valve stem guides, gland followers, light pivots and marine fittings – positions with water or steam, modest load and a plain steel or stainless shaft. Its name comes from cannon founding; today it is the standard valve and pump casting alloy.
Is BC6 / CAC406 the same as LG2?
Yes – JIS CAC406 (formerly BC6) is the Japanese 5-5-5 gunmetal, the same class as LG2, C83600 and CC491K. Japanese and South-East Asian machines specify it for general bushes; we machine C83600 for those positions.
Can I use LG2 for a heavily loaded pin?
Better not. At 55 – 65 HB and 207 N/mm² minimum tensile it is the softest grade here; on an excavator or press pin it deforms and wears fast. Use SAE 660 for general pins, C86300 or aluminium bronze for heavy ones.
Is LG2 lead-free?
No – 4 – 6 % lead. For drinking-water and food positions the lead-free tin bronzes CuSn10 or C90500 replace it; for pressure-tight lead-free castings the industry uses CuSn5Zn5Bi or silicon bronzes, which we do not machine into bushings.
Quote LG2 / C83600 bushes
Send sizes or drawing, quantity and the medium the bush works in – we confirm the alloy and quote.