The process scheme is put into production after being determined by casting CAE simulation, and all valve castings are qualified and delivered to customers for use. The chemical composition test results are shown in Table 1, the mechanical property test results are shown in Table 2, and the metallographic test results and ferrite test results are shown in Table 3 and table 4.
Heat number
Sample No
C
Si
Mn
S
P
Cr
Ni
Mo
Nb
C13-206
3C688
0.06
0.71
0.71
0.007
0.02
18.3
9.52
0.07
0.049
C13-210
3C748
0.07
0.74
0.67
0.005
0.02
18.91
9.33
0.08
0.059
Sample No
So/mm2
Temperature / ℃
ReL/MPa
Rm/MPa
ALo/%
Z/%
Executive standard
3C688
124.49
room temperature
290
530
46.5
66.0
ASTM A351
3C748
124.69
room temperature
275
515
53.5
59.5
ASTM A351
Heat number
Sample No
A
B
C
D
Austenite grain size
Microstructure
Executive standard
C13-206
3C688
0.5
0.5
0.5
1.0
3.0
Austenite + ferrite
ASTM E381
C13-210
3C748
0.5
0.5
0.5
2.0
5.0
Austenite + ferrite
ASTM E381
Heat number
Sample No
Ferrite content f /%
C13-206
3C688
4.5 4.6 5.0 4.6 4.8 5.0
C13-210
3C748
4.9 5.0 5.5 4.8 5.5 5.4
Intergranular corrosion results are qualified (sulfuric acid copper sulfate method). After the valve casting surface is polished to meet the flaw detection requirements, it shall be polished according to ASME B16 34. 100% radiographic inspection was conducted for the full volume of valve castings, no crack defects were found, and the casting defects such as air hole, shrinkage cavity and sand inclusion met the requirements of grade 2; 100% liquid penetrant testing is conducted on the surface of valve castings according to ASTM e165. There are no crack casting defects. The length of any linear display is not more than 2 mm, the size of a single circular casting defect is not more than 4 mm, and the cumulative length of dense casting defects (referring to concentrated defects with a size less than 0.5 mm) is at any 100 mm × Not more than 2 mm in an area of 100 mm.