Prakt. Met. Sonderband 46 (2014) 243 
rature of the 2.2.3 SHORT-TERM TESTS AT 700 °C 
water. Base 
veld metal in To characterize the deformation and failure behaviour short-term creep rupture tests were 
3 h and the carried out at 700 °C on welds (cross weld specimens), weld metal and base material. The 
700 °C were cross weld specimens were examined in the as-welded condition, as well as after the post 
and after that weld heat treatment at 980 °C for 3 h followed by cooling in air. 
en according 
3. RESULTS AND DISCUSSION 
3.1. MECHANICAL TESTING 
The results of short-term creep tests carried out at 700 °C are shown in Fig. 1. The weld in 
as-welded condition shows the creep rupture strength comparable to that of the base 
material. After PWHT the strength of the weld increases slightly. However, the differences 
in the deformation behavior occur, both integral and local. The ductility of the weld metal 
and the base metal increases, if the welds are heat treated after welding at 980 °C. The 
cross weld specimen loaded in as-welded condition failed in the WM, after PWHT the 
location of fracture shifted into in the BM. 
0 — mm ——— 
oq aso | Alloy 617B; T=700°C Sa 
— 400 +20 % 
350 Oo 
300 : 
250. 
+ 200 
2 150 oO BM, without PWHT Location of 
A WM, without PWHT 1=BM 
ding by SiC m Weld, TIG orbital, without PWHT 3=WM 
amond paste 100 cr Weld, TIG orbital, with PWHT [4=HAz 
amples were to’ hd vo 
and etched in Rupture time / h 
| presence of 
N ERCIOSCODE Fig. 1: Results short-term creep tests at 700 °C 
3.2. MICROSTRUCTURE 
3.2.1 METALLOGRAPHIC INVESTIGATIONS 
jestigated by The hardness measurements (HV10) of all material states were performed on the cross 
a JEOL JEM sections. In the states without the PWHT the hardness in the WM was significantly higher 
ty metal foils compared to the BM in as welded and creep loaded conditions (A1: 148, W1: 202, A3: 
ction Pattern 329, W3: 357). After the PWHT the hardness differences were less (A2: 209, W2: 215, A4: 
339, W4: 313). After creep loading an increase of hardness could be observed in all 
articles were conditions. In the states without heat treatment the hardness is higher in the WM, in the 
as used. As heat treated condition in the BM. Fig. 2 shows microstructure in different areas of the 
equal area welded joint in as-welded condition and after creep loading. The microstructure in the initial 
valuated at a state consists of an austenitic matrix with randomly distributed carbides and carbonitrides 
of type Ti (C, N). The grain structure in the base material is inhomogeneous. The 
microstructure in the weld metal is dendritic. In the as-welded condition no welding defects