The following excerpts come from:
Michael R. Notis, Vincent C. Pigott, Patrick E. McGovern,
K.H. Liu, and C.P. Swann. “The Metallurgical Technology: The Archaeometallurgy
of the Iron IA Steel,” in The Late Bronze and Early Iron Ages of Central
Transjordan: The Baq’ah Valley Project, 1977–1981, ed. Patrick E. McGovern
(University Museum Monograph 65; Philadelphia: University Museum, 1986),
272–278.
Among the most significant finds
in Cave A4 was a group of eleven complete pieces of iron jewelry— eight anklets
or bracelets and three rings—and forty fragments, dating to Iron IA. Three
basic types of anklet/bracelets are represented: (1) with terminals open, (2)
with ends overlapping and superimposed one above the other, and (3) with ends
overlapping side-by-side (see Ch. 7). Two types of rings can be distinguished,
each with a rectangular cross-section, but one had open ends, the other
overlapping ends. Waldbaum (1978) in her survey ofi ron artifacts recovered
from excavations in the eastern Mediterranean lists five objects from two LB II
Palestinian contexts, and about twenty more from various twelfth century B.C.
loci at seven Palestinian sites. The East Bank of the Jordan is represented
only by a pair of bracelets and pair of rings from a transitional LB/early Iron
Age tomb at Madaba (Harding 1953). They comprise one example each of an
open-ended and an overlapping, superimposed type, as defined above.
To these examples must now be
added an iron (steel) blade from Tomb 4 in the East Cemetery at Pella, dated to
the Middle Bronze Age (Smith et al. 1984), an unidentified fragment from an LB
II tomb on Jebel al-Nuzha near Amman (Dajani 1966c), part of a totally corroded
anklet or bracelet from the LB II Cave B3 (Ch. 7), and an early Iron Age knife
from Tomb 113 at Tell es-Sa‘idiyeh (Pritchard 1980: 20, fig.) 15.6).
With the excavation of Cave A4,
the number of iron artifacts from twelfth century B.C. Palestine has approximately
tripled, while for Transjordan it has been increased almost sevenfold. These
figures rep-resent a major statistical shift in the distribution of iron
artifacts in the Eastern Mediterranean. The Transjordanian plateau is clearly
of great importance in understanding the development and early history of iron
(steel) metallurgy. (p. 272)
Table from p. 273 (click to enlarge):
Anklet or Bracelet (A4.55;
Fig. 84.13, Pl. 29c)
The extent and inhomogeneity of
carburization of the metal in this artifact are illustrated in Pl. 48a. The
microstructure of A4.55 is extremely variable; overall it corresponds to that
of a hypoeutectoid steel, but there are regions with typically hypereutectoid
features. In addition, there are precipitated phase(s) of broadly varying size
in the proeutectoid ferrite and in the ferritic component region of the
pearlite (PI. 48b). To simplify the discussion, the nature of the precipitated
phases will be discussed after the other microstructural features have been
elucidated.
The morphological features of
proeutectoid ferrite and proeutectoid cementite have been classified into
several main categories: idiomorphic, allotriomorphic, and Widmanstatten (Dube
et al. 1958); further subdivisions have also been introduced within each main
category (Aaronson 1962). The composition temperature range for the formation
of each of the three main types of proeutectoid structural components are
described in these references; the different morphological features of the
proeutectoid phases in a given alloy may correspond to different undercooling
conditions through which the transformation has taken place. Thus, for a
hypoeutectoid steel, the idiomorphic ferrite forms with slight undercooling,
and the allotriomorphic ferrite and then the Widmanstatten ferrite form with
increasing degrees of undercooling in a given alloy (1.e., for a given carbon
content). A similar sequence 1s proposed for the formation of proeutectoid
cementite in hypereutectoid steels. The degree of undercooling required for a
specific morphological feature is also influenced by the austenite grain size,
with larger grain size extending the range of formation of the Widmanstatten
morphology. A steel with larger grain size has a greater tendency to form a
Widmanstatten structure, which is why Widmanstatten ferrite is frequently
observed in the microstructure of cast steel, or in overheated hot-worked
steels after normalizing treatments. (p.
273)
