Hardening secondary

Thus, after the secondary hardening, either the secondary flow develops or the materials break. Note that breaks, in principle, can also take place in the region of strain times shorter than the relaxation time 0, and may not characterize the region of the secondary hardening . 

Heat Treatment Path Complexity Hardness Carbide Precipitations on Grain Boundaries Secondary Hardening Distortion, Specific Volume... 

Phthalic anhydride is the cheapest anhydride curing agent, but it has the disadvantage of being rather difhcult to mix with the resin. Liquid anhydrides (e.g., dodecenylsuccinic anhydride and nadic methyl anhydride), low-melting anhydrides (e.g., hexahydrophthalic anhydride), and eutectic mixtures are more easily incorporated into the resin. Since maleic anhydride produces brittle products, it is seldom used by itself and is used as a secondary hardener in admixture with other anhydrides. Dodecenylsuccinic anhydride imparts flexibility into the casting, whereas chlorendic anhydride confers flame resistance. 

As for cocoa butter various modifications exist for hard fat, but their consequences are much less pronounced [8fj. Therefore, control of temperature during melting and cooling comes far less precise than in cocoa butter. Nevertheless, the polymorphism of hard fat is responsible for some physical processes including the process of secondary hardening (ageing) as described in Sect. 11.4.8. It is hardly possible yet to trace back this process to certain phase transitions. 

The alloy carbide phases which precipitate and give rise to secondary hardening are listed in Table 3.1-76. 

Alloyed steels with secondary hardening effect Unalloyed and alloyed steels... 

Fig. 3.1-117 Isothermal (1 h) tempering curves of 4 typical tool steels. Curves 1 and 2 softening of AISI grade W (water-hardening) and O (oil-hardening) steels Curves 3 and 4 softening and secondary hardening of AISI grade A2 (air-hardening medium alloy) and M2 (Mo high-speed) steels [1.88]...

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