| As a very important mechanism part, the spring is widely used. It has the function of buffering, damping, accumulation energy, coupling, poling, sealing, driving, etc. So it must bear pulling, bending, squeezing, twisting and collision. In order to produce the high quality spring steel, the metallurgy quality must be controlled, and amount of large inclusion or nondeformable inclusion in steel must be reduced.The cleanliness of 60Si2Mn produced by the route of electric arc furnace-ladle furnace-four strands billet caster in bayi steel was systematically studied.①After sampling in each process, the cleanliness of 60Si2Mn produced by the route of electric arc furnace-ladle furnace-four strands billet caster in bayi steel was systematically studied by metallographical observation, oxygen analysis, sample electrolysis, EPMA, rare earth oxides tracing, etc. Content of total oxygen are 95×10-6 of liquid steel after LF refining, 94×10-6 of liquid steel in tundish and 54×10-6 in billet respectively. The amount, size distribution and type of inclusion at different stage were investigated, and the source and origins of the large inclusion was also found. Based on research result, some useful suggestions were presented aim at the main factors which affect the cleanliness of billet, and the flow control device in tundish was optimized. Due to the purification process, the amount of harmful inclusion was decrease, and the quality of spring steel was greatly improved, and the content of total oxygen was reduced to 28×10-6 from 54×10-6.②The statistics of extreme value is introduced in this paper, and applied to the data processing of the experiment. The predicted result shows that maximum inclusion in steel is consistent with the maximum inclusion size observed by SEM. So the law can offer the judgment of the maximum size of the inclusion in production and the suggestion for steel making.③The fluid flow behavior of liquid steel in the following tundishs (without flow control devices, with"V"weir) is calculated respectively by employing the finite volume software FLUENT. By the simulation result, the suitable flow control device is favorable to the flow pattern. The weir make the flow move to the surface after it run out, this could extend the route of the flow, add the opportunity of inclusion float up, and make flow field above the outlet more placidity. The temperature distribution in tundish is more uniformity after the fluid control is equipped; the difference in...
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