Carbon tools

MARTENSITE. The chief constituent of hardened carbon tool steels. It is a solution of carbon or FeiC in /(-iron. or and exceedingly line-grained or-iron with carbon or l cmolecular dispersion. Carbon content up to I easily obtained bv quenching small bodies of liypereutectoid steel in cold water more difficult to obtain in low-carhun steels. 

Figure 6. Above a tool for the superplastic forging of titanium, made entirely from carbon/carbon composites (15) Below aircraft exhaust manifold formed from titanium by superplastic forging with the carbon/carbon tool.

A short length of 3 mm rod is joined to the end of the 5 mm stirrer shaft as shown in Fig. 8.6a the limbs of this 3 mm rod are bent and cut off as shown in (b) and joined to the shaft as shown in (c). A small, pointed flame should be used to avoid distorting the shaft. The holes should be shaped with a pointed carbon tool and should be of such a size that the links will pass through easily (see Fig. 8.6d). The shaft end is then flame annealed and set up to cool. 

There is a considerable possibility that the carbon tools will be damaged they must be given careful treatment. 

When the basic bowl is formed to your general specifications, apply flame around its perimeter until it gets red hot, then work it on your pad and push on the bowl gently, all the while turning the carbon tool with your fingers. 

For coated and uncoated cemented carbon tools, the limiting factor on surface quality is the material buildup. Build-up edges as well as flank buildup cause very rough surfaces. 

The most common types of steels are plain low-carbon, high-strength low-aUoy, medium-carbon, tool, and stainless. 

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