Tungsten melts at 3410°C or 3400°C in Bushong; other references give up to 3422°C

Tungsten melts at 3410°C in Bushong’s radiography textbook, which also prints 3400°C in its anode section and target table (11th ed., PDF pp.127, 130-131). Other references vary: a 2015 toxicology review gives 3422 ± 15°C, and a 2025 materials paper gives 3410°C. Both call it the highest of any metal.

ARRT® doesn’t publish a value, and we found nothing showing that any one figure is the registry’s. These numbers are close enough that the reason for the high melting point matters more than the last digits. If you need one for class, use your program’s textbook.

Why do x-ray tubes use tungsten?

Over 99% of the electrons’ energy becomes heat at the anode, so the target has to handle it. Bushong gives three reasons for tungsten:

• Atomic number 74. This makes x-ray production efficient and the x-rays energetic.
• Heat conduction. It moves heat away from the focal spot.
• High melting point. It stands up to high tube current without pitting.

Tungsten is the choice for general radiography, but it isn’t the only target. Mammography tubes use other metals.

Target	Atomic number	Melting point in Bushong’s table
Tungsten	74	3400°C
Molybdenum	42	2600°C
Rhodium	45	3200°C (Bushong’s figure. The NIOSH Pocket Guide lists 3571°F, about 1966°C, so don’t memorize this one)

The filament is tungsten too, with a little thorium added. See what causes filament burnout.

What else is in the anode?

• Rhenium is usually alloyed with the tungsten to add strength against fast rotation and repeated heating and cooling.
• Molybdenum or graphite layers under the target on high-capacity tubes make the disc lighter and easier to spin.
• The stem is narrow and usually molybdenum, which Bushong describes as a poor heat conductor. Both limit the heat moving toward the rotor.

How does heat damage an anode?

Too much heat in one exposure can melt and pit the surface, which makes output lower and uneven. Heating it too fast, as with a maximum technique on a cold anode, can crack it. Severe melting can also vaporize tungsten onto the enclosure.

A tube rating chart shows which single exposures are safe.

The Image Production guide puts this in context. Then read the Equipment Operation and QA chapter and try the equipment practice questions.