Yes, like most head bolts today they are torque to yield bolts.
Added: If they didn't stretch, they would break off. They will stretch, then return to normal. That's why you re-tighten them after warming up the engine. Otherwise you'd have a head-gasket leak.
what is the head bolt torque settings on a ford focus 2007 tdci 2.0 diesel
The 2002 Ford Focus has 39.3 in. of front head room.
The 2006 Ford Focus has 39.1 in. of front head room.
The 2009 Ford Focus has 39.2 in. of front head room.
The 2005 Ford Focus has 39.1 in. of front head room.
The 2010 Ford Focus has 38.3 in. of rear head room.
The 2003 Ford Focus has 39.3 in. of front head room.
The 2012 Ford Focus has 38.0 in. of rear head room.
The 2013 Ford Focus has 38.0 in. of rear head room.
The 2011 Ford Focus has 38.3 in. of rear head room.
The 2010 Ford Focus has 39.2 in. of front head room.
The 2006 Ford Focus has 38.6 in. of rear head room.