A first step towards computational design of W-containing self-healing ferritic creep resistant steels

Figures & data

Table 1. Search range (in wt.%) for alloying elements and the homogenisation temperatures (in ⁰C).

	C	Cr	Mn	Si	W	Fe	Thomog
Min.	0	8	0	0	0	Balance	800
Max.	0.1	20	5	5	3		1200

Table 2. Room temperature strengthening coefficient for alloying elements dissolved in ferrite (MPa per at. %) [34,35].

Element	C	Si	Mn	Mo	W	Cr
Ci	1103.45	25.80	16.90	15.90	31.8	2.60

Figure 1. Experimentally observed incubation times for Laves phase precipitation at several temperatures as reported for nine commercial steels [39–42].

Figure 2. The composition distribution of all potentially feasible compositions normalized to the total composition search range in Table 1. The density of column patterns represents the number of solutions meeting the criteria.

Figure 3. PH factor of M₂₃C₆ carbides after 10⁵s at 550°C versus SSS factor of those solutions meeting all go/no-go criteria. The values of existing commercial steels, indicated by star symbols, are also put on the plot to compare to the identified possible solutions to the current state of the art steels.

Figure 4. PH factors of M₂₃C₆ precipitates as strengthening particles at 10⁵s (a) and the SSS factors (b) versus driving force of Laves phase as self-healing agents meeting all go/no-go criteria at a temperature of 550°C.

Table 3. Compositions of three selected alloys (in wt.%) and their PH factor, SSS factor driving force for Laves phase formation and estimated healing initiation times at 550°C.

	C	Cr	Mn	Si	W	Thomog/^0C	PH@10^5s M23C6	SSS	DF of Laves/J.mol^−1	tinit /days
1	0.026	12	0.81	0.32	1.45	1200	8.65 · 10^6	69	2964.2	~ 1000
2	0.023	12	0.32	0.65	2.23	1200	8.55 · 10^6	75	4218.4	~ 75
3	0.023	13.03	0.01	0.97	3.0	1200	8.71 · 10^6	80	4848.8	~ 10

Figure 5. PH factors of M₂₃C₆ precipitates as strengthening particles at 10⁵s versus driving force of Laves phase as self-healing agents meeting all go/no-go criteria at the temperature of 600°C (a) and 650°C (b).

Figure 6. Properties values for SSS factor and Laves phase driving force on the Pareto front at different temperatures.

Cahn RW, Haasen P. Physical metallurgy. Vol. 2. Amsterdam: North-Holland; 1996.

 Google Scholar

Leslie WC. Iron and its dilute substitutional solid solutions. Metall Mater Trans B. 1972;3(1):5–26.

 Web of Science ®Google Scholar

Nakahashi M, Komatsu S, Nakamura S, et al. On the precipitation of Laves phase in 12Cr-Mo-V-W steel heated for a long time. J Jpn I Met. 1983;47(5):426–431.

 Web of Science ®Google Scholar

Hosoi Y, Wade N, Kunimitsu S, et al. Precipitation behavior of laves phase and its effect on toughness of 9Cr-2Mo ferritic-martensitic steel. J Nucl Mater. 1986;141:461–467.

 Web of Science ®Google Scholar