PSI - Issue 32

T.V. Lomaeva et al. / Procedia Structural Integrity 32 (2021) 295–298 Lomaeva/ Structural Integrity Procedia 00 (2019) 000–000

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The development of industry is inextricably linked with the use of materials that meet high operational requirements for reliability and quality. These materials fully include titanium alloys, which have a number of valuable properties. They have high specific strength, heat resistance, corrosion-mechanical strength and resistance, non-cold brittleness, non-magnetic, passiveness in relation to organic and many inorganic acids (sulfuric, nitric, hydrochloric, etc.) and alkalis and a number of other characteristics (see Koryagin et al. (2000), Zhuchkov et al. (1989), Raikhelson (2018)). The above properties determine the increasing use of these alloys in various industries for the manufacture of critical parts that are subjected to alternating loads during operation when exposed to sufficiently high temperatures. The process of plastic deformation in titanium alloys is the most interesting. Unlike most construction materials, chip shrinkage in titanium alloys can be “negative”. That is, thinning of the shavings can occur. In some cases, this can be dangerous, since the formation of thin chips and, moreover, dust in the process of chip formation leads to its ignition with intense combustion (see NPAOP (1962)). Therefore, when assigning processing modes when cutting titanium alloys, one should take into account the possibility of ignition of chips during machining by cutting. In (see Lomaeva, (2021)), the research results of the effect of cutting speed on chip shrinkage when turning parts made of ВТ -6 titanium alloy are presented. The authors found that with an increase in the cutting speed from 10 m/min to 40 m/min, the chip shrinkage coefficient smoothly decreases from 2 to 1, and then becomes less than 1, i.e. chip shrinkage becomes “negative”.

Table 1 . Transverse chip shrinkage factor vs. cutting speed(see Lomaeva, (2021))

a chip

ξ

V, m/min

a material to be removed

1

2

3

Mean

9.42

0.22

0.225

0.21

0.218

0.106

2.058

11.9

0.19

0.18

0.195

0.188

0.106

1.775

15

0.17

0.15

0.16

0.16

0.106

1.508

23.5

0.115

0.12

0.14

0.125

0.106

1.178

30.1

0.12

0.11

0.125

0.118

0.106

1.115

37.7

0.1

0.11

0.1

0.103

0.106

0.974

47.1

0.1

0.1

0.105

0.101

0.106

0.958

59.3

0.09

0.095

0.095

0.093

0.106

0.879

Fig. 1. Dependence of transverse chip shrinkage factor on cutting force when machining titanium alloy BT6 (Russian State Standard GOST 19807-91) (depth of cut t = 1.5 mm, feed per revolution So = 0.15 mm/rev) (see Lomaeva, (2021)).