PSI - Issue 59

Olexandr Ivanov et al. / Procedia Structural Integrity 59 (2024) 622–628 Olexandr Ivanov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

624

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Table 1. Chemical composition of 08 kp steel, wt. %. Fe Mn C Cu

Ni

Cr

As

Si

S

P

Bal.

0.25-0.50

0.05-0.1

≤0.30

≤0.30

≤0.1

≤0.08

≤0.03

≤0.04

≤0.035

Table 2. Chemical composition of sample electrodes. Sample Fe B

C

Ti

Mo

1 2 3 4

55.50 57.35 56.65 61.17

22.23 21.31 21.66 19.40

5.57 5.34 5.43 4.86

15.02 11.20

1.67 4.80 9.76

6.50 1.46

13.11

Welding parameters. Welding was carried out in manual mode with parameters as follows: direct current, 150 A, 30 V, reverse polarity. Steel 40 (DSTU 7809:2015) hot rolled strip 10  10 mm (DSTU 4747:2007) was used as a substrate for hardfacing. Chemical composition of steel 40 presented in table 3. Hardfacing was carried without any special preparation or preheating of substrate surface. Hardfacing was made in three layers for ensuring higher amount of deposited material during structure investigation as well as for testing the technological parameter of coherence between deposited layers. Cooling was done on air (20 C ° ), open environmental, without additional influence.

Table 3. Chemical composition of steel 40, wt. %. Fe Mn C Cu

Ni

Cr

Si

S

P

bal.

0.50-0.80

0.37-045

0.17-0.37

≤0.30

≤0.30

≤0.25

≤0.04

≤0.035

Material investigation. Experimental hardfacings were prepared by polishing of the top surface (third welded layer) and etching surface. Surface morphology was observed with scanning electron microscopy (SEM; Zeiss Evo 40XVP) and material chemical composition was examined with X-ray diffraction (XRD). PMT-3 hardness meter with digital camera attached to its lens was used for additional microstructure investigation. Testing. Hardness of the hardfacing was determined by Ro ckwell method, “C” scale. Hardness was measured by average value based on three measurement taken on top surface (third hardfaced layer). Relative tribological tests were carried out in conditions of fixed, non-fixed abrasive wear and impact abrasive loads. Tribological test with fixed abrasive was done by sliding the hardfacing sample with abrasive wheel 64C F46 L7V (GOST 52781-2007) with 300 mm diameter and 30 mm width. Parameters of testing as follows: pressure 2 kN, 400 m sliding distance, 25 min -1 rotating speed. Test with non-fixed abrasive was done by sliding the rubber wheel 50 mm diameter, 15 mm width under pressure 2.4 kN with hardfacing sample with continuous abrasive feeding into sliding zone. Test with impact-abrasive load was done with special laboratory stand by continuous hits (200 hits) with striker with load of 2 kN on the hardfacing covered with 10 mm of abrasive material. In all testing abrasive material SiO 2 (DSTU B V.2.7-131:2007) with grade 0.05-0.1 mm was used. For comparative analysis serial production electrodes and relit T3 (Ukraine) were used (Table 4). Table 4. Serial production electrodes used for comparative tests, their chemical composition and hardness of hardfacing (according to developers). Electrode (country of production) Alloying system Hardness, HRC C Cr Mo Mn Si V Lastek 2400 (Belgium) 4.0-5.0 20.0-24.0 - 0.5-1.0 - 9-10 60-68 Hardalloy 155 (USA) 5.50 32 4.50 0.40 1.00 59-63 Super 20 (Sweden) 39(Cr-Mo-C-W-Si-Mn) 60-65