Table 1 shows the impact absorption energy of nodular cast iron V-notch samples at different ambient temperatures. The samples are taken from qt500-14 test block, and the Si content is 3.5%. It can be seen from table 9 that the impact absorption energy of the sample increases with the increase of ambient temperature. When the ambient temperature reaches 180 ℃, the impact absorption energy can reach about 20 J. Therefore, the author believes that high Si nodular cast iron are suitable for working in high temperature environment, so their impact absorption energy will be greatly increased, so as to improve the safety factor of the operating environment.
| Model of test block | Ambient temperature / ℃ | Impact absorption energy /j (1) | Impact absorption energy /j (2) | Impact absorption energy /j (3) | Impact absorption energy /j (average) |
| Y25 | -20 | 4 | 4 | 4 | 4 |
| Y25 | 20 | 5 | 5 | 5 | 5 |
| Y25 | 140 | 19 | 20 | 21 | 20 |
| Y25 | 180 | 20 | 21 | 22 | 21 |
Table 2 shows the impact absorption energy changes of V-notch specimens of nodular cast iron of different grades at different ambient temperatures.
| Cast iron grade | Model of test block | Impact absorption energy /j (-20°C) | Impact absorption energy /j (20°C) | Impact absorption energy /j (140°C) | Impact absorption energy /j (180°C) |
| QT600-10 | Y25 | 3 | 4 | 18 | 20 |
| QT500-15 | Y25 | 4 | 5 | 20 | 21 |
| QT500-7 | Y25 | 4 | 5 | 18 | 20 |
| QT450-18 | Y25 | 7 | 17 | 22 | 24 |
| QT450-10 | Y25 | 6 | 7 | 18 | 22 |
| QT400-18 | Y25 | 8 | 18 | 22 | 23 |
It can be seen from table 2 that the impact absorption energy levels of nodular cast iron of grades qt500-14 and QT500-7 at low temperature and normal temperature are the same, while the impact absorption energy levels of nodular cast iron of grades qt500-14, QT450-10 and qt400-18 at low temperature and normal temperature are quite different, but the impact absorption energy levels of the listed four grades of nodular cast iron measured at high temperature are the same. Therefore, the author believes that in terms of the impact resistance of materials, when the casting working environment temperature is above 140 ℃, high Si all ferrite qt600-10 can replace the mixed matrix QT600-3, qt500-14 can replace the mixed matrix QT500-7, and qt450-18 can replace the mixed matrix QT450-10. However, the impact resistance of High Silicon nodular cast iron produced with this kind of material at low and normal temperature is poor, which must be paid enough attention. Without special treatment, there will be certain potential safety hazards.
(1) Using FeSiMg alloy spheroidizing agent for impact spheroidizing and basi inoculant for inoculation, we can make full use of the solid solution strengthening effect of silicon and control the silicon content within a certain range. We can successfully produce nodular cast iron materials qt500-14 and qt600-10 whose mechanical properties and metallographic structure fully meet the requirements of EN 1563:2012 standard.
(2) Qt500-14 and qt600-10 materials can be fully applied to nodular cast iron operating in high temperature environment.
(3) Qt500-14 and qt600-10 materials are not suitable for nodular cast iron operating in low temperature environments.