Issue 66

A. Shelar et alii, Frattura ed Integrità Strutturale, 66 (2023) 38-55; DOI: 10.3221/IGF-ESIS.66.03

the microstructure shows coarsening of carbides. Thus, it can be stated that the critical radius for the different alloy carbides and closely distributed parallel orientation of martensite lath in double tempering with a reduced % of retained austenite gives optimum mechanical properties. The aging parameter can be studied for getting the optimized critical radius for the carbides which would suggest better heat treatment boundary conditions.

Untreated H13 Steel

T1

T2

T3

T4

Figure 7: d) Nano-size carbide precipitations at 200nm, morphology observed by SEM Untreated H13 steel , T1, T2, T3, T4

Phase analysis The XRD plot obtained is shown in figure 8 and the values obtained for microstrain and dislocation density were evaluated by using Xpert highscore software as mentioned in table 9. The values for all the specimens were compared at relative intensity 100% and it was found that dislocation density varies from 4.3825E-05 to 1.9832E-03 for the ferrite and the value for microstrain varies in the range 8.47E-5 to 4.365E-3. The carbides peak cannot be matched due to less % of alloying elements.

Figure 8: XRD plot for specimen at different tempering conditions.

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