This is the war armour of Lord Buckhurst, made in 1587 at the Royal Armourers’ Workshops in Greenwich, England. The Royal Armourers’ Workshops was set up by Henry VIII at the beginning of the 16th century to provide himself and his Court with the finest quality armour. Read more here.
Iron armour could be carburized or case hardened to give a surface of harder steel.
Related reading: Materials 1 (metals); Materials 2 (ores), Materials 3 (resins)