FAST EVALUATION OF DISPERSED MICROSTRUCTU RE AND MECHANICAL-PROPERTIES OF CARBIDE FORMING STEELS

A possibility of a fast evaluation concerning the dispersed microstruc ture and the properties of C-, Cr- and Mn-alloy steels is presented. T he dispersed microstructure was adjusted by precipitation and coarseni ng from the martensitic initial condition. The quick recording coerciv e field strength He and microstructural parameters obtained from scann ing electronmicroscopic investigations were used in the relationship H -C-particle diameter dp relative to a microstructure fast evaluation. Due to the repeated nucleation the M(3)C carbides grow and coarse para llel and in particle generations. Thus always a particle size spectrum is obtained. A fast evaluation of properties is realized by the conne ction H-C- yield strength R(p 0,2) / tensile strength R(m) / hardness HV. Since H-C- reacts on the size of precipitated particles, and the c ourse H-C- time t / dp / particle volume (dp/2)(3) encloses two maxima , which both separate the precipitation (A) and coarsening stage (V), at any H-C-value one of the attaching possibilities (A or V) must be e xcluded. This can be reached by considering the obtained temperature a nd time limiting values. The magnetic measuring method with the struct ure-sensitive quantity H-C yields to an assertion relative to the micr ostructural condition within one minute. The error amounts to less tha n or equal to 0.5%. The application of the H-C-measurement is time- an d cost-economic. A special sample preparing is not necessary. The cond ition of the surface does not enter into the measuring result. The yie lded connections H-C- R(p 0,2) / R(m) / HV can be used like a standard referred to the tested grades of steel.