复杂铝合金圆盘的等温精密锻造英文文献和中文翻译(9)

Fig。 10。 The curves of logarithmic stress versus logarithmic strain rate: (a) ε¼ 0。6 and (b) ε¼ 0。8。

Fig。 11。 Power dissipation map of 7A09 aluminum alloy: (a) ε¼ 0。6, 3D map; (b) ε¼ 0。6, isoline map; (c) ε¼ 0。8, 3D map and (d) ε¼ 0。8, isoline map。

of 7A09 aluminum alloy within the instability ﬂow zone。 In the present study, the hot processing map is used for optimizing the process parameters to guarantee the stable ﬂow zone of the metal material, such as the strain rate and the deformation temperature。 In the case of large plastic deformation, when the strain rate is less than

0。1 s−1, 7A09 aluminum alloy shall exhibit the more stable ﬂow。 In

addition, it seems that 7A09 aluminum alloy is characterized by steady ﬂow in the temperature range from 300 1C to 460 1C。 The

processing map lays a certain foundation for the optimum working conditions on the basis of ﬂow stress, strain rate and deformation temperature。 The establishment of the processing map based on the microstructural defects shall be investigated in the future。

6。Finite element simulation

DEFORM3D commercial ﬁnite element code was used for simulating isothermal precision forging of rotating disk based on ring preform and pentagram preform。 The deformation

temperature is determined as 430 1C and the die moves at the velocity of 0。1 mm s−1 during ﬁnite element simulation。

Fig。 14 indicates ﬁnite element simulation results of isothermal plastic forming of rotating disk forging based on the different preforms。 Fig。 14(a) indicates the distribution of the equivalent strain derived from ﬁnite element simulation of isothermal forging of rotating disk forging based on ring preform。 For the sake of better understanding the deformation mechanism of the forged sample, the forming process of the forged sample can be pided into three stages, namely upsetting, forming of inner ear and forming of outer ear。 At the upsetting stage, the metal mainly ﬂows along the radial direction and the ring wall of the forged sample thickens gradually。 At the second stage, the inner ear impressions are ﬁrstly ﬁlled with the metal since they are nearer to the preform, and simultaneously the metal continues to ﬂow inside to form the ﬂash。 At the third stage, as the upper die continues to move down, the resistance force from the ﬂash gutter of the inner ears gets larger and larger。 As a result, the metal is forced to ﬂow into the outer ear impressions along the radial

Fig。 12。 Instability processing map of 7A09 aluminum alloy: (a) ε¼ 0。6, 3D map; (b) ε¼ 0。6, isoline map; (c) ε¼ 0。8, 3D map and (d) ε¼ 0。8, isoline map。

Fig。 13。 Hot processing map of 7A09 aluminum alloy: (a) ε¼ 0。6 and (b) ε¼ 0。8。

direction to form ﬁve outer ears。 The ﬁnal simulation results reveal that four outer ear impressions are not full of metal。 Fig。 14

(b)indicates the distribution of the equivalent strain derived from ﬁnite element simulation of isothermal forging of rotating disk forging based on pentagram preform。 The shape of pentagram preform causes ﬁve outer ear impressions to be covered with the sufﬁcient metal, so the metal mainly ﬂows into the impressions along the axial direction。 According to the ﬂow characteristic of the metal, the forming process of the forged sample can also be pided into three stages, namely local forming, forming of outer ears and forming of inner ears。 At the local forming stage, the metal ﬂows into the impressions along the axial direction by means of backward extrusion。 With the increase in the plastic strain, the metal ﬂows outside along the radial direction until the outer ear impressions are completely ﬁlled and the corresponding ﬂash is ﬁnished。 Consequently, the resistance force from the ﬂash gutter of the outer ears causes the metal to ﬂow into the inner ear impressions along the radial direction。 Finally, the inner ears are 复杂铝合金圆盘的等温精密锻造英文文献和中文翻译(9):http://www.youerw.com/fanyi/lunwen_96941.html