So far, all I've been able to determine is that they were part of the 18th Division. The division was part of the OKH Reserves. I can't find specifics yet.
Did not find any battle details, did find this German site. Not that good with all those words there about 1940 ( one sentence ) but I guess they were in reserve? If the site is correct, too, that is. http://www.lexikon-der-wehrmacht.de/Gliederungen/Infanterieregimenter/IR51-R.htm