PSI - Issue 43

Michal Krbaťa et al. / Procedia Structural Integrity 43 (2023) 270 – 275 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

272

3

Primary carbide M 6 C

a)

b)

Martensite

Primary carbide MC

10um

Primary carbide M 6 C

d)

Martensite

c)

Bainite

Primary carbide MC

10um

f)

Carbide M 3 C

Pearlite

e)

Primary carbide MC

10um

Fig. 3. Experimental expansion curves and the resulting microstructure of X37CrMoV5-1 steel: a) dilatation curve 1 °C /s; b) microstructure 1 °C /s; c) dilatation curve 0,1 °C /s; d) microstructure 0,1 °C /s; e) dilatation curve 0,0 1 °C /s; f) microstructure 0,01 °C /s The dilatation curve (Fig. 3a) represents a cooling rate of 1 °C/s. Only one phase transformation is visible in a given dilation curve. This represents a change in the austenitic structure at the beginning of the martensitic transformation of M s , which began at 350 °C. The fine primary carbide particles contained in the structure are based on molybdenumM 6 C (Fe 3 Mo 3 C) and vanadiumMC as reported by the authors (Huber et al. 2019, Dlouhý et al. 2015). Vanadium carbides are smaller than molybdenum carbides and are more common in the structure. Also, according to