Steels continued high-tensile

An further alternative approach being developed worldwide is to replace the steel completely by fibre-reinforced plastics (FRP), which consist of continuous fibres as carbon, glass or aramid, set in a suitable resin to form a composite rod or grid. These materials have high tensile strength, low density and are non-magnetic they can be used both for new structures and for repair of existing ones. The mechanical properties of FRP are determined by the amount and type of fibre, while the durability will be a function of both the resin and the fibre. 

There is another interesting difference between the two irons. Ni-Hard (nominally 1 A Cr, 4 A Ni, 3C) has a matrix of the iron carbide that suiTounds the areas of the steel constituent. This brittle matrix provides a continuous path if a crack should start thus the alloy is vulnerable to impact and is weak in tension. In contrast, HC 250 (nominally 25 Cr, 2 AC) has the steel portion as the matrix that contains island crystals of chromium carbide. As the matrix is tougher. HC 250 has more resistance to impact and the tensile strength is about twice as high as that of Ni-Hard. jMoreover, by a suitable annealing treatment the... 

Fig. 3.12 A model of high-modulus carbon fibres, composed of ribbons of packets of hexagonal carbon atom layers ( Fig. 5.8), oriented nearly parallel to the fibre axis. Continuous carbon fibres have exceptional mechanical properties Young s modulus up to 830 GPa and tensile strength up to 5 GPa, higher than steel...

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