84 Y GoNG et al Table 1 Chemical compositions and heat treatment conditions of T92 and HR3C samples(wt%) Elements P s Si N 0.21 0.011.63 ASME 0.07-0.138.50- 0.30-0600.15-0.250.040.09≤0.40 0.30-0.60<0.020<0.010<0.500.03-0.07<0.041.50-2.000.001-0.006 SA-213 12400120.0010390.24 ASME 3.00-2700 0.20-0.601700-23.00≤2.000.030≤0.030≤1.500.15-0.35 TP310HC T92: 1050C x 20 min(normalizing)+760C x 60 min(tempering). HR3C: solution-treated at 1110.C minimum reep rupture performances of them and their welded (a) joints, let alone the dissimilar steels welded joints between them. Therefore, a thorough assessment of the compre hensive properties, particularly the creep properties of T92/HR3C dissimilar steels welded joints, seems pretty urgent. In this paper, besides various conventional mechanica tests including tensile test, bending test and hardness sur- ey, optical microscope(OM)was also applied to inspect the metallographic microstructures across the dissimilar steels welded joint between T92 and HR3C. Moreover, creep rupture test was particularly employed under dif- ferent load stresses at 625 oC to investigate the creep features of the joints, whose fractograph was then ob- served by using scanning electron microscope (SEM)as ell. Furthermore, the residual stress distribution of the element method(FEM), which was a tentative approach (b) to evaluate residual stress of the dissimilar steels welded joint between these two novel materials through the com the degradation curves of T92/HR3C dissimilar steels yelded joints were reported, but also the mechanism of voids initiating creep rupture was concretely discussed which may have critical significance in both service-life prediction and future heat-resistant steels preparation fo boiler components EXPERIMENTAL 20题 Tested materials were nominal T92 and hr3C heat- Fig. 1 Metallographic microstructures of tested base materials (a) resistant steels with scales of 480D x 8.4 mm thick 92,1500×(b)HR3C,200× and 48. D x 10.16 mm thick, respectively. Chemical compositions as well as heat treatment conditions of their crostructure of T92 sample is presented in Fig. la, which base materials are listed in Table 1, which are in accor- displays a typical tempered lath martensitic microstruc- dance with the requirements of ASME SA-213 T92 and ture. Similarly, metallographic microstructure of HR3C TP310HCbN specifications. Etched in agent of picric sample was also obtained after being etched in the agent acid(2, 4, 6-trinitrophenol)1. 25 g, HCI 20 ml, ethanol of CuSO4 4 g, HCl 20 ml and ethanol 20 ml for 20 s 10 ml and H2O 10 ml for 40 s, the metallographic mi- As is shown in Fig. 1b, HR3C presents a fine-grained @2010 Blackwell Publishing Ltd Fatigue Fract Engng Mater Struct 34, 83-9684 Y. GONG et al. Table 1 Chemical compositions and heat treatment conditions of T92 and HR3C samples (wt%) Elements C Cr Mo V Nb Ni Mn P S Si N Al W B T92 Sample 0.11 8.76 0.36 0.21 0.059 0.25 0.46 0.016 0.002 0.39 0.044 0.01 1.63 0.0033 ASME 0.07–0.13 8.50–9.50 0.30–0.60 0.15–0.25 0.04–0.09 ≤0.40 0.30–0.60 ≤0.020 ≤0.010 ≤0.50 0.03–0.07 ≤0.04 1.50–2.00 0.001–0.006 SA-213 T92 HR3C 0.06 24.63 / / 0.49 20.29 1.24 0.012 0.001 0.39 0.24 / / / Sample ASME ≤0.10 23.00–27.00 / / 0.20–0.60 17.00–23.00 ≤2.00 ≤0.030 ≤0.030 ≤1.50 0.15–0.35 / / / SA-213 TP310HCbN Heat treatment conditions: T92: 1050 ◦C × 20 min (normalizing) + 760 ◦C × 60 min (tempering). HR3C: solution-treated at 1110 ◦C minimum. creep rupture performances of them and their welded joints, let alone the dissimilar steels welded joints between them. Therefore, a thorough assessment of the compre￾hensive properties, particularly the creep properties of T92/HR3C dissimilar steels welded joints, seems pretty urgent. In this paper, besides various conventional mechanical tests including tensile test, bending test and hardness sur￾vey, optical microscope (OM) was also applied to inspect the metallographic microstructures across the dissimilar steels welded joint between T92 and HR3C. Moreover, creep rupture test was particularly employed under dif￾ferent load stresses at 625 ◦C to investigate the creep features of the joints, whose fractograph was then ob￾served by using scanning electron microscope (SEM) as well. Furthermore, the residual stress distribution of the welded joint after welding was calculated by using finite element method (FEM), which was a tentative approach to evaluate residual stress of the dissimilar steels welded joint between these two novel materials through the com￾putational simulation method. Finally, based on the anal￾ysis results, not only the creep rupture performances and the degradation curves of T92/HR3C dissimilar steels welded joints were reported, but also the mechanism of voids initiating creep rupture was concretely discussed, which may have critical significance in both service-life prediction and future heat-resistant steels preparation for boiler components. EXPERIMENTAL Tested materials were nominal T92 and HR3C heat￾resistant steels with scales of 48O D × 8.4 mm thick and 48.26O D × 10.16 mm thick, respectively. Chemical compositions as well as heat treatment conditions of their base materials are listed in Table 1, which are in accor￾dance with the requirements of ASME SA-213 T92 and TP310HCbN specifications.30 Etched in agent of picric acid (2, 4, 6-trinitrophenol) 1.25 g, HCl 20 ml, ethanol 10 ml and H2O 10 ml for 40 s, the metallographic mi￾Fig. 1 Metallographic microstructures of tested base materials (a) T92, 1500× (b) HR3C, 200×. crostructure of T92 sample is presented in Fig. 1a, which displays a typical tempered lath martensitic microstruc￾ture. Similarly, metallographic microstructure of HR3C sample was also obtained after being etched in the agent of CuSO4 4 g, HCl 20 ml and ethanol 20 ml for 20 s. As is shown in Fig. 1b, HR3C presents a fine-grained c 2010 Blackwell Publishing Ltd. Fatigue Fract Engng Mater Struct 34, 83–96