Preparation of samples for mechanical properties and machinability of gray cast iron

The multi-element alloy additive is developed and designed by China Yituo on the basis of previous application experience according to the influence of Alloying on the mechanical properties and processability of gray cast iron at home and abroad and research results. The raw materials used in the design are: high carbon ferrochromium with 68% chromium, medium carbon ferromanganese with 80% manganese and 1# rare earth alloy with 25% rare earth, Multicomponent alloy additive is obtained by melting in medium frequency induction furnace. Its actual composition is 38.70% Cr, 13.50% Si, 8.50% Mn, 5.30% RE, and the rest is Fe. Finally, the prepared multi-element alloy additive alloy block is broken into 0.5 – 2.0 mm particles for use.

The sample is melted in 250 kg acid medium frequency induction furnace, and the raw material and mass ratio are pig iron / reheating material / scrap = 50 / 10 / 40. The alloying of gray cast iron adopts multi-element alloy additive and pure Cu respectively, and the addition amount is 0.4 wt.%. Multicomponent alloy additives are added into the 50 kg ladle for alloying, and pure Cu is added into the smelting furnace for alloying. Three kinds of inoculants, 75sife, SRSI and basi, were selected. They were inoculated in the ladle in front of the furnace, and the addition amount was 0.5 wt.%. The particles of the inoculant are between 15 − 17 mm, and the inoculation treatment temperature is about 1495 ℃. After adding the inoculant, stir and stay for about five minutes.

Four groups of samples are cast in one test, which are called sample 1, sample 2, sample 3 and sample 4 respectively. The alloying and inoculant of the four groups of samples. Each group is poured separately Φ 100 mm × One 350 mm cylindrical specimen (as shown in Fig. 1) for testing cutting performance, one stepped specimen for section sensitivity test (as shown in Fig. 2), and four tensile specimens for testing strength. The mechanical properties and machinability of gray cast iron obtained by alloying with multi-element alloy additives and Cu alloying treatment with the same inoculant 75sife were compared between sample 1 and sample 4, and the mechanical properties and machinability of gray cast iron obtained by alloying with the same multi-element alloy additives and inoculation with different inoculants were compared between sample 1, sample 2 and sample 3.

In order to better compare the effects of alloy addition and inoculant on the mechanical properties and processability of gray cast iron, three repeated tests were carried out. In order to avoid the effects of carbon content and other impurities, gray cast iron samples poured in the same furnace were selected for research. In order to test the effect of alloying on the processability of gray cast iron under the same strength, In the three tests, gray cast iron samples with the same inoculant and different alloying treatment but the same strength were selected for research.