In-service property prediction of X80 self-shielded flux-cored (FCAW) girth weld metal based on strain ageing kinetics

Figures & data

Figure 1. (a) schematic of sampling location and (b) size of tensile specimen.

Table 1. Aging temperature and period for the strain aging.

Prestrain	Aging temperature	Aging period
1%	150°C	0.5 h/1 h/3 h
	100°C	1 h/3 h/6 h
	80°C	1 d/3 d/7 d
	50°C	30 d/90 d/120 d

Figure 2. Schematic of through thickness tensile specimen and sampling location of CVN specimen.

Figure 3. Schematic of calculation method of ΔY [15].

Table 2. Yield strength variations before and after strain ageing.

Strain aging conditions			σs before SA (MPa)	σs after SA (MPa)	ΔY (MPa)	$\overline{\mathrm{\Delta }Y}$ (MPa)
Prestrain	Aging Temp. (℃)	Aging period
1%	150	0.5 h	557.6	589.2	31.6	50.4
			595.7	647.1	51.4
			551.7	609.8	58.1
			562.4	622.8	60.4
		1 h	547.6	614.2	66.6	75.4
			533.4	621.4	88.0
			553.0	629.8	76.8
			561.1	631.1	70.0
		3 h	563.9	632.6	68.7	84.9
			596.4	685.7	89.3
			523.3	606.9	83.6
			549.9	647.9	98.0
	100	1 h	575.7	629.8	54.1	46.1
			583.4	631.1	47.7
			583.1	621.5	38.4
			578.9	623.0	44.1
		3 h	550.4	642.9	92.5	79.5
			573.5	653.1	79.6
			556.3	631.2	74.9
			599.4	670.2	70.8
		6 h	554.1	632.5	78.4	83.9
			591.4	677.6	86.2
			528.6	629.1	100.5
			507.9	578.5	70.6
	80	1 day	586.1	646.4	60.3	61.7
			560.0	632.1	72.1
			600.5	663.4	62.9
			557.5	608.8	51.3
		3 days	633.2	695.0	61.8	70.3
			579.2	636.0	56.8
			500.9	584.5	83.6
			560.4	639.2	78.8
		7 days	542.5	634.8	92.3	83.7
			503.7	588.7	85.0
			546.1	640.7	94.6
			565.3	628.1	62.8
	50	30 days	560.1	632.8	72.7	62.0
			595.7	664.5	68.8
			596.1	646.4	50.3
			591.7	648.0	56.3
		90 days	534.7	616.8	82.1	85.0
			530.6	625.2	94.6
			575.5	645.5	70.0
			539.4	624.6	85.2
		120 days	534.0	628.1	94.1	91.6
			553.3	638.3	85.0
			525.2	65.2	100.0
			524.1	608.3	84.2

Figure 4. Trend of strength variation at different strain aging conditions.

Table 3. Charpy impact toughness variations before and after strain ageing.

Prestrain	Aging Temp. & period	CVN/J			$\overline{CVN}$/J	ΔCVN
*	*	153.8	128.8	193.8	158.8	*
1%	150°C + 1 h	85.0	41.3	60.0	62.1	−96.7
	150°C + 3 h	46.7	67.0	65.0	59.6	−99.2
	100°C + 1 h	115.0	65.0	86.3	88.8	−70.0
	100°C + 3 h	62.5	90.0	78.5	77.0	−81.8
	100°C + 6 h	61.0	75.0	53.5	63.2	−95.6
	80°C + 1 day	168.7	71.3	121.2	120.4	−38.4
	80°C + 3 days	76.2	78.8	87.5	80.8	−78.0
	80°C + 7 days	77.5	88.0	70.6	78.7	−80.1
	80°C + 15 days	58.0	80.5	64.0	67.5	−91.3
	80°C + 30 days	53.5	72.0	55.8	60.4	−98.4
	50°C + 15 days	102.5	135.0	57.5	98.3	−60.5
	50°C + 30 days	140.0	31.3	138.7	93.3	−65.5
	50°C + 90 days	65.0	79.0	62.4	68.8	−90.0
	50°C + 120 days	59.3	51.5	68.0	59.6	−99.2

Figure 5. Correlation of strength (ΔY) and toughness (ΔCVN) variation during strain aging.

Figure 6. Fitting curve of strain aging kinetics.

Rashid MS. Strain-aging of vanadium, niobium or titanium-strengthened high-strength low-alloy steels. Metall Trans A. 1975;6(7):1265–1268. doi: 10.1007/BF02658536

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