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The axe heads are thought to have been manufactured before 1857 by transported convicts in a jail at Fremantle, Western Australia, which was then a remote and isolated British colony. They were of a type used to quarry and dress building blocks from a soft, local limestone and had been fabricated by joining on a central plane by forge welding two plates of puddled wrought iron, a central region being left unwelded to form a shaft hole. A section of crucible steel was then inset into the bit edge, also by forge welding (a process known as “steeling”). This procedure obviously required a high level of blacksmithing skill, and at least a reasonable level of skill had been achieved at the Fremantle jail. However, a number of fabrication abnormalities were present in the axe heads, drawing attention to some intrinsic deficiencies in the fabrication procedure. Examples are the difficulties of achieving weld bonding in regions adjacent to the shaft hole and that of avoiding “burning” in both wrought iron and steel during the steeling operation. High-carbon hypereutectoid steels had been used in the inserts, but they were in a normalized condition; that is, they had not been quench hardened as might have been expected if full advantage were to be taken of steeling. This may have been due to ignorance of quench-hardening heat treatment or to a lack of skill in its application, but it may have been by choice. It may have been realized that the properties of the normalized steel were adequate for the intended use, to which fact one of the axes examined bears witness, thus avoiding the hazards of quench hardening. Even in this event, it would be unnecessary and even undesirable to use insert steels with carbon contents as high as those actually used. Their use may have been due to ignorance in steel selection or it may simply indicate that smiths in such isolated communities had to use whatever materials happened to be at hand. |
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