DC rating for specific AC rated relay
Usually, the contact current rating is independent of the contact rated voltage.

The application is limited by the contact resistance, and for all types is listed as:


  Contact resistance (Initial) Max. 30 m\$\Omega\$


The maximum current in the contacts is a heating limited function, and therefore the DC capacity will be the same as the RMS capacity.

I would not use this part anywhere close to the rated capacity (calculate \$I^2 R\$ to see why).

[Update with comment from JimmyB]

Who quite rightly states that the break current can be much lower for DC than AC, which is another reason to not use this anywhere near the stated rated current.

The test for contact resistance is a DC test:


  (By voltage drop 6 V DC 1A)


so the only current guaranteed to be safe is that test current.