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采用20和40 mm厚的ZL114A两种试样,对比研究了稀土变质和锶变质对砂型铸造ZL114A合金试样力学性能和组织的影响。结果表明:不变质、稀土变质和锶变质等三种方案的试样抗拉强度差异较小(在5%以内),而伸长率差异较大。锶变质后的试样(T6状态)伸长率最高,比其它两种方案高出28%以上。通过对比三种方案伸长率最小的试样组织发现,锶变质试样的共晶硅组织细化最明显,且试样聚集性的孔洞类缺陷又较少,这对试样的伸长率提升有很大作用。稀土变质后的试样组织中会形成一些树枝状或片层状化合物Al REMg Si相,且聚集性的孔洞类缺陷较多,这类组织反而降低了试样的伸长率。
The effects of rare earth deterioration and strontium modification on the mechanical properties and microstructure of the sand casting ZL114A alloy were studied by using 20 and 40 mm thick ZL114A specimens. The results show that there is little difference (less than 5%) in the tensile strength of specimens without any deterioration, rare earth deterioration and strontium deterioration, while the elongation is quite different. Strontium deterioration of the sample (T6 state) the highest elongation, 28% higher than the other two programs above. By comparing the microstructure of the three specimens with the lowest elongation, it is found that the refinement of the eutectic silicon structure of the strontium metamorphic specimen is the most obvious, and the hole-like defects of the sample aggregation are less, which shows that the elongation of the specimen Enhance the great role. Some rare earth demetallic samples will form some dendritic or lamellar compounds Al REMg Si phase, and the accumulation of holes more defects, but these organizations reduce the elongation of the sample.