Hardening effects composites

Dispersion hardening or strengthening of a material means an increased resistance to deformation. The movement of dislocations in the metal facilitates metal deformation. Incorporated particles block the dislocation movement and thus strengthen the metal.4,11 12,21 Grain refinement of the metal due to the codeposition of particles has also been thought to contribute to the hardening effect, but this is not supported by experimental evidence. For several composites it was found that the grain structure of the metal matrix was not altered by the codeposition of particles. 

Effect of Hardener/Resin Composition on Degree of Cure. 

O.T and q. are the true tensile strength of the composite and the matrix respectively, A is the relative elongation, n characterizes the strain hardening effect of the matrix and B is a parameter that relates to the particle-matrix interaction. Equation (22) could be rewritten as follows ... 

Tjiptobroto and Hansen [12] investigated these composites with steel fibre reinforcement of 0.15 mmdiameter andGmm length, at contents in the range of 3-6% by volume. The flexural behaviour demonstrated high ductility, with a considerable strain hardening effect as shown in Figure 12.13. The strain capacity of the matrix was 150 microstrain and it increased to 2000 microstrain in the 12% fibre composite. 

Hardness, Impact Strength. Microhardness profiles on sections from explosion-bonded materials show the effect of strain hardening on the metals in the composite (see Hardness). Figure 8 Ulustrates the effect of cladding a strain-hardening austenitic stainless steel to a carbon steel. The austenitic stainless steel is hardened adjacent to the weld interface by explosion welding, whereas the carbon steel is not hardened to a great extent. 

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