Contact deterioration, arc forming on high power DC switcher
From the datasheet, it looks to be intended for a 24V system. There is a huge difference in switching 24VDC and 48VDC. You need a relay with either:

A much larger contact gap, so the arc self extinguishes.
An arc quench magnet, which pushes the arc off to the side.

You need a relay rated to switch 48VDC at 200A, which this one is not.
While there is considerable debate about the effectiveness, it is possible that using two relays with the contacts in series, might be effective in the short term, until you choose a relay properly specified for your application. The series connection lengthens the total arc length when opened, and may cause the arc to extinguish before contact damage occurs.