Melting points of common metals and alloys compared

Melting point of each material compared, converted to degrees Celsius. Bases differ, see the chart notes. Stainless 316 shows the union of two melting tables.

What are the melting points of common metals, and which is highest and lowest?

From the lowest: tin melts at 232 °C in high-purity pellets, lead at 328 °C for the element, pure zinc at 419.53 °C, aluminium at 660 °C, silver at 962 °C (99.95 percent bar), gold at 1,064.18 to 1,064.76 °C, copper at 1,083 to 1,085 °C, nickel at 1,455 °C and palladium at 1,555 °C.

The last decimals depend on the source, not on the metal. Gold is 1,064.76 °C in PubChem and 1,064.18 °C on a supplier datasheet. Copper is 1,083 °C for oxygen-free C10200 and 1,084.62 °C for the element, and palladium 1,554.9 °C in a handbook and 1,552 °C on one supplier's sheet. Purity, method and rounding explain such gaps, so quote the source.

The very high-melting metals come next: zirconium at 1,840 to 1,852 °C across the grades Zr 702, Zr 705 and Zircaloy-4, niobium at 2,350 to 2,477 °C from the C-103 alloy to the pure metal, molybdenum at 2,623 °C, tantalum at 3,017 °C and tungsten at 3,422 °C. The tungsten profile cites the ITIA for the highest of any metal; we checked only the profiles charted here.

Why do alloys melt over a range, and what are solidus and liquidus?

An alloy melts over a range because its elements do not all melt at one temperature, so it passes through a mushy state of solid and liquid. This is general engineering knowledge, not in our data, and so is every statement below that gives no number from a profile. Aluminium 6061 has a solidus of 582 °C and a liquidus of 652 °C. Brass C36000 runs from 954 °C to 1,049 °C, a wide interval, and bronze C95400 from 1,027 °C to 1,038 °C, a narrow one. The 6061 profile carries a datasheet comment that eutectic melting can be eliminated by homogenization (a long soak that evens out the composition), so the stored solidus is a typical figure, not a ceiling guaranteed for every lot.

Purity narrows the range and raises its start. Pure aluminium is stored at 660 °C, while alloy 1100-O, at least 99 percent aluminium, has a solidus of 640 °C and a liquidus of 660 °C. Commercial Nickel 200 melts at 1,435 to 1,446 °C against 1,455 °C for the element. Against pure zinc at 419.53 °C, Zamak 3 melts at 381 to 387 °C and ZA-8 at 375 to 404 °C.

Mixing can push the melt below both parents. Tin melts at 232 °C and lead at 328 °C, yet the eutectic solder Sn63Pb37 melts at 183 °C at a single point. Lead-free SAC305 melts at 217 to 220 °C.

Where the base metal is also charted, each alloy starts melting below it: brass C36000 at 954 °C against copper's 1,083 °C, Inconel 718 at 1,260 °C against nickel's 1,455 °C, and niobium alloy C-103 at 2,350 °C against pure niobium at 2,477 °C. The one exception is rolled titanium-zinc, 420 °C against pure zinc's 419.53 °C, level within rounding. That is what these profiles show, not a rule for all alloys.

Does the melting point matter for casting and welding?

Yes, because both processes start from liquid metal, and the span between liquidus and solidus decides how forgiving the job is. The metal is held above its liquidus, with some superheat, while it is poured or while the weld pool forms. As it cools, the freezing range governs hot tearing (cracks that open as the metal freezes) and shrinkage porosity. Our profiles hold the ranges but no pouring temperature, so they cannot say how hot to pour.

Zinc is the low-melting casting case: the zinc profile lists thin-walled die-cast parts among the best uses of its alloys. Bronze C95400 is the high-melting case: it is cast for bearings, gears and valve parts and melts over a narrow 1,027 to 1,038 °C, which tends to help sound castings.

In welding, the heat-affected zone, hot but below the solidus, is where many problems start. Stainless 304L carries a carbon limit of 0.030 percent because holding between 450 and 900 °C lets chromium carbide form and causes sensitisation. For 316 the band is 500 to 900 °C, far below its melting range.

Low-melting metals can also attack higher-melting ones: the nickel profile warns that Nickel 200 suffers intergranular attack when heated with sulfur or with lead, tin, zinc or bismuth, so shop soil and marking paint must come off first.

What is the maximum service temperature compared with the melting point?

It is hundreds of degrees lower, and only five of the profiles compared here store a service limit at all. Inconel 625 is stated for service to 1,800 °F, 982 °C, and Inconel 718 is quoted to 1,300 °F, 704 °C. Stainless 316 shows 750 to 925 °C, a range that overlaps the sensitisation band, so it is no clearance for long holds. Bronze C95400 is printed at 750 °F, 399 °C, for bar product; the source also says intermittent to 1,200 °F, so we cannot tell whether 750 °F is the continuous limit and do not rank it.

Stainless 304L needs care. Its 426 °C is an ASME code coverage limit, not a melting or oxidation limit, so its distance from melting says little. A separate CarTech figure gives a safe scaling temperature of 871 °C for continuous service. Both are true, so ask which one the drawing needs.

Among the 25 profiles compared here, none stores a limit for magnesium, zinc, brass, copper, titanium, carbon steel (steel 1018), lead or the aluminium grades charted. The melting range is not a substitute for one; the aluminium 5083 figures are under the third flow question.

Why must a part stay well below its melting point in service?

Strength, structure and surface all change long before melting. Zirconium Zr 702 has a typical yield of 321.1 MPa at room temperature and 97.2 MPa at 316 °C, though it melts at 1,852 °C. Copper battery foil is at least 300 MPa for 8 µm foil and 147 MPa at 180 °C, but the thickness of the hot row is not stated, so the pair is only an indication.

Structure changes next. Inconel 718 forms delta phase between about 700 and 1,000 °C and loses its strengthening phase, and Laves phase above about 1,000 °C weakens it significantly. After 2,000 hours near 1,200 °F, Inconel 625 hardens and its elongation falls from 54 to 30 percent. Cold-worked molybdenum sheet recrystallises (new soft grains replace the worked structure) in 1 hour at 925 °C and loses its strength.

Oxidation limits the very high-melting metals before melting does. Niobium begins to oxidise in air at 200 °C, the onset of a surface film and not a limit, and unprotected C-103 needs a coating above about 800 °C; a silicide coating raises usable temperature to about 1,400 °C. Molybdenum forms a volatile trioxide above 400 °C. Tungsten oxidises in air and must be protected when hot.

As general engineering knowledge, not in our data, creep becomes significant above roughly 0.4 of the melting temperature on the absolute (kelvin) scale. Stainless 316 starts melting at about 1,648 K, so that is about 660 K, or about 390 °C. Its stored 750 to 925 °C lies far above that, so load and life, not the melting range, decide whether it is usable.

Terms used

Solidus

the temperature at which an alloy starts to melt. Below it the alloy is fully solid.

Liquidus

the temperature above which an alloy is fully liquid. Between the two it is part solid, part liquid.

Eutectic

an alloy that melts at a single temperature, below the melting points of its parts, such as solder Sn63Pb37.

Incipient melting

melting that starts in a real lot below the stored solidus, where the composition is uneven.

Maximum service temperature

the highest temperature a supplier or code allows. Its basis varies: continuous or intermittent, a code limit, a typical range.

Creep

slow stretching of a metal under steady load at high temperature, which can end in rupture.

Superheat

how far molten metal is held above its liquidus while poured, so it stays fluid until the mould fills.

Heat-affected zone

the strip beside a weld that gets hot but does not melt, and can change structure.

Sensitisation

chromium carbide forming at grain boundaries in stainless steel held in a critical temperature band, which opens it to corrosion.

What to check before you order

1. Ask for solidus and liquidus with the grade, form and condition. Do not accept one number for an alloy unless the datasheet says it is a single melting point.
2. For service temperature, ask for a creep or rupture based limit at your load and life, and for its basis: continuous or intermittent, in air or vacuum, code limit, typical range or test, and your product form.
3. For casting, ask the foundry for the pouring temperature and freezing range. For solder, get the alloy designation with its melting range, for example Sn63Pb37 or SAC305. For brazing, check that the filler liquidus is below the base metal solidus.
4. For welded stainless and nickel alloys, ask for the filler, the interpass temperature (the metal temperature between weld passes) and whether the heat-affected zone will sit in a sensitisation band.

What do we not know yet?

• Solidus and liquidus are named separately for only 6061, brass C36000, bronze C95400 and alloy 1100-O, plus the zinc die-casting alloys. The other alloys carry one range as printed, and Invar 36 one number.
• No profile holds a pouring temperature, superheat, fluidity or solidification shrinkage for a metal; a search of all profiles found solidification only in a silicone product.
• Titanium grade 2 stores no melting point because its datasheet text was unclear, and there is no pure iron or pure magnesium profile, so the steel, AZ31B and Ti-6Al-4V ranges have no pure base metal to compare against. The database also holds other alloys, such as Hastelloy C276, Monel 400 and 17-4PH, that this article does not compare.
• Maximum service temperature is stored for only five of the profiles compared, each on a different basis, and the bronze C95400 basis is unclear.
• Pressure is not stated for the handbook melting points, and gold's purity is not stated.

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