Dissertation > Industrial Technology > Metallurgy and Metal Craft > Casting > Iron casting > Gray cast iron castings

Improve the Mechanics Performance of the High Strength Grey Cast Iron

Author ZhangJie
Tutor YuHuaShun;LiuFuRong
School Shandong University
Course Materials Engineering
Keywords Gray cast iron Diesel engine Cylinder block Silicon -carbon ratio Copper alloying Inoculation Process Capability Control
Type Master's thesis
Year 2010
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Under production conditions, the elements of carbon and silicon, copper-chromium alloy, Inoculation Europe III diesel engine cylinder body microstructure and mechanical properties of experimental research. The experimental results indicate quite the case of the carbon equivalent, to improve the silicon to carbon ratio, the lower the percentage content of carbon, increase the percentage content of the silicon, the organization eutectoid austenite increases, reinforcement of the casting substrate. The reduction in the amount of graphite, thereby reducing the flake graphite on the cutting action of the metal body. The silicon element is increased, the amount of solid solution in the matrix to strengthen the ferrite in the pearlite, casting the tensile strength can be improved. When the carbon-silicon ratio of 0.68, the tensile strength may be raised to 336MPa. Copper can reduce the critical temperature of austenite transformation, refinement and to increase casting pearlite content. Since the production of the molten iron has a certain content of chromium, the presence of elements of tin, copper Add the change in the amount of castings pearlite content without significant impact. The copper content increased from 0.2% to 0.4%, significantly refined matrix organization pearlite spacing, the single cast test bars tensile strength increased from 285MPa to 310MPa. Copper on refinement of pearlite role is limited, when the copper content increases to 0.5%, the spacing of the pearlite is not changed significantly, the tensile strength decreased slightly, which may be copper segregates at the grain boundary of the eutectic , an increase of the brittleness of the grain boundaries weaken the strength of sake. Production practice shows, the inoculant addition method and the added time directly affects the the inoculant absorption situation, and gave birth to the absorbing state of the agent have a decisive impact on the casting performance. Experiments show that, inoculant added directly underwrite, is not conducive to nurture the absorption of agents, casting graphite morphology is poorly distributed, low tensile strength; stream inoculation using an iron to improve the material absorption, improve casting graphite morphology distribution, improve the tensile strength; 1/3 after first joined the inoculant, adding 25s, casting breeds best when the amount of iron; further extended to add time to the 35s when, later joined the inoculant floating in the hot metal surface oxidation burning not conducive to absorption, reduces the mechanical properties of the casting. As a production line for mass production, operation quality has an important impact on the stability of the product quality. In this paper, melting the pre-control through the implementation, the accurate weighing of the blast furnace processing materials, machinery control blast furnace processing materials added time and other measures, the single cast test bars tensile strength test results before and after the implementation. The results showed: cast test bar tensile strength test results after the implementation of the above measures, upper control limit change from 375MPa 335MPa from 280MPa to 296MPa lower control limit significant difference between the upper and lower reduced from 95MPa 39MPa, to optimize the performance of the casting control interval significantly improve the production process control capability, stable casting quality.

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