I understand that about the Rocinante, but what about larger Martian warships? The Donnager, the huge warship that carried the Roci (when it was called the Tachi) has its hull punched through by a weapon and someone gets his head blown off. Though it may have been a railgun in that case, not that I'm sure what that is in The Expanse.. an energy weapon?

The warship that carries Gunny and her Marines gets attacked by kinetic projectiles on Ganymede and someone is similarly killed by projectiles punching through it.

My impression is that they may have anti-spalling measures, but close combat in The Expanse means spraying the enemy ship with your PDCs until something breaks down and the defenses get overrun. I get that impression from the (very cool) fight with the stealth ship protecting the station with the Protogen scientists. They rake the enemy ship with bullets until it simply stops working and drifts away, its crew dead.