| 摘要 |
FIELD: metallurgy; thermal treatment of large-size slabs out of gray pearlitic pig-iron. ^ SUBSTANCE: the invention is dealt with metallurgy, in particular, with a thermal treatment of large-size slabs out of gray pearlitic iron and may be used in production of cylinder cartridges for powerful ship diesel engines. Technical result of the invention is an increase of strength, hardness and wear resistance of the gray pearlitic iron formed in large-sized slabs. The method of thermal treatment of the large size slabs out of gray pearlitic iron provides for, that composition of the slabs contains the following elements in the ratio: C + 2 Si = 5.0 - 6.2 and 0.8 Cu + 4V = 0.8 - l. 7 (mass %); carbon 2.9 - 3.5; silicon 0.9 - 1.5; manganese 0.5-1.0; phosphorus 0.15- 0.5; chromium, nickel, molybdenum, titanium in the sum - 0.1- 0.8; vanadium - up to 0.32; boron - up to 0.04; copper - up to 1.55; sulfur - up to 0.1; iron - the rest. The thermal treatment is conducted in two cycles. The first cycle provides for the heating up to 550-580 and up to 820-860 with speeds accordingly ^ 80-100/hour and 130-180/hour. The temperature leveling of cross-sections takes no more than 25 minutes, accelerated refrigerating from 820 - 860 to 470 - 520 at a speed of 370-580/hour; in the second cycle - heating from 470-520 C up to 820-860 with speed of 130-180/hour; alignment of temperature of cross-sections and refrigerating from 820-860 up to 470-520 on modes of the first cycle at final refrigerating up to 200-300 with cooling rate of no more than 50/hour and further at random speed. ^ EFFECT: increase of strength, hardness and wear resistance of the gray pearlitic iron formed in large-sized slabs. ^ 1tbl |
