PSI - Issue 20

Sivtsev M.N. et al. / Procedia Structural Integrity 20 (2019) 148–153

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Sivtsev M.N. et al. / Structural Integrity Procedia 00 (2019) 000 – 000

Data is obtained on welding at low temperatures (-42 0 C) are presented in Table 3. Table 3. The welding modes and values sizes HAZ, at a temperature -42 0 C.

frequency of the pulsed control, Hz

HAZ weld surfaces, mm

Specimen number

Options

pulse duration, sec

pause duration, sec

0,3

0,25 0,27

1,82 1,49 1,17 1,53

2,5 2,4 2,2 2,5 2,6 2,8 3,8

№ 1 № 2 № 3 № 4 № 5 № 6 № 7

Option А APW

0,45 0,55

0,3

0,3

0,35 0,38

Option B APW

0,45 0,55

1,2

0,4

1,05

stationary mode

-

-

-

Fig. 3. The size distribution of the HAZ at -42 0 C: Specimens 1-6 pulsed mode with different pulse train frequencies, sample 7 - stationary regime (see Table 1 in.). At low temperatures, the use modes APW in the option A (-42 0 C) in the option A (+ 21 0 C), the difference in size of the HAZ is practically not observed. In the option B (-42 0 C) when the increase the pause duration of pulse observed increase in size HAZ as compared with welding in conditions at positive temperatures. The average size HAZ in welding a stationary mode of 0.5 times greater than the welding APW presented in all 6 modes. On the Fig. 4 shows a comparison of the size distribution of the HAZ at different temperatures (-42 0 C and 21 0 C). The results indicate the possibility of controlling the dimensions of the HAZ using various welding modes and controlling the duration pause of the pulse. Specimens 1-6 pulsed mode with different pulse train frequencies, sample 7 - stationary regime (see Table 1). Metallurgical studies have shown that in all weld seams structure of samples have a dendritic structure: in a zone adjacent to the transition zone in the form of columnar creation and closer to the outer surface of dendrites are disoriented structure. Fig.5. represented by the structure of the HAZ specimens surfacing at various ambient temperatures. The images obtained at grinding point metal structure of the HAZ. The grain size in the zone of normalization and incomplete recrystallization zone formed on the APW at + 21 0 C, decrease by 1.3 times (average grain diameter - 3.50 microns) compared with a grain size in the same zones obtained at stationary mode welding (average grain diameter - 4.50 microns) (Fig. 5.). In general fixed structure grinding to 23%. When APW at low temperature under -42 0 C, a decrease in grain size by 1.2 times (average grain diameter - 3.70 microns) in the aforementioned areas formed by adaptive pulse-arc welding as compared with the