Issue 49

A. Abdelhalim et alii, Frattura ed Integrità Strutturale, 49 (2019) 350-359; DOI: 10.3221/IGF-ESIS.49.35

1050 °C. Then they are cooled to the deformation temperature, which is between 700 °C and 1050 °C. Tab. 1 Show detailed chemical compositions and Figs. (3–4) present starting microstructure. The average grain size is about 40 µm.

% C

% S

% P

% Al 0.017

% Si 0.22

% Mn

% V 0.053

% Nb 0.080

% Ti 0.041

0.044

0.012

0.012

1.45

Table 1 : The detailed chemical compositions

Figure 2 : Experimental procedures for the compression tests of CMn (Nb-Ti-V) micro alloyed steel.

Figure 3 : Microstructure of the raw steel casting

Figure 4 : Raw casting sample quenched after austenization at 1300 °C.

Experimental Results Figs. (5–7) show real stress-strain curves resulted from hot compression at different temperatures (from 700 °C to 1050 °C) and strain rates values of 0.0146 s -1 , 0.0029 s -1 and 0.000734 s -1 . their paces suggest classifying them in three types a, b and c, according to the different ranges of temperature: o The stress increases rapidly and decreases with a significant slope (700 °C and 750 °C) (type a); o The stress increases rapidly until reaching a plateau (800 °C and 850 ° C) (type b);

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