Consturuction of Analysis System for Deformation Behavior during Solidification of Metallic Materials

在追求高质量、高生产率的金属加工过程中，凝固裂纹是最难克服的障碍变量之一。因此，我们研究了碳钢和铜锡合金在凝固过程中和凝固后的变形行为。我们对碳含量高达0.8wt%的样品和硫含量较高的样品进行了高温拉伸试验。研究了应变速率对0.6wt%C试样凝固过程中力学性能的影响。作为高温拉伸试验的结果，对于高碳样品和高硫样品，ZST（零强度温度）被确定为对应于约0.7的固体分数的温度，这与先前的实验结果相同。相反，根据数值分析，即使在凝固完成的温度以下也观察到很小的延展性，并且ZDT无法确定。ZDT不对应于1的固体分数的原因似乎是与先前测试的样品相比样品的低纯度。例如，具有硫和磷两者更包含约。然而，导致ZDT下降的机制仍然无法解释。随着应变速率的增加，拉伸强度增加，应变速率为10^ /s时，拉伸试样的位移量在5 mm左右，<-3>而应变速率为10 ^0 -10^ /s时，拉伸试样的位移量很小<-2>。对于铜锡合金，在低于固相线的温度范围内，在10^0-10^ /s的应变速率下测量了变形行为<-4>。得到了拉伸强度、流变应力和伸长率与试验温度、应变速率和应变的回归方程。

For metals processings which aim at higher quality and higher productivity, solidification crack is one of the worst obstruction variables to overcome. Therefore we investigated the deformation behavior of carbon steels and copper-tin alloys during and after solidification. We carried out high temperature tensile tests for samples which have higher carbon contents to 0.8wt% and for samples which have higher sulfur contents. We also investigated the influence of strain rate on mechanical properties during solidification of 0.6wt%C samples. As a result of the high temperature tensile test, ZST(Zero Strength Temperature) was determined to be the temperature which corresponds to the solid fraction of about 0.7 for both high carbon samples and high sulfur samples as is same with the previous experimental results. On the contrary little ductility was observed even below the temperature at which solidification completes according to the numerical analysis, and ZDT could not be determined. The reason why ZDT does not correspond to the solid fraction of 1 seems to be the low purity of the samples compared with the previously tested samples. For example, having both sulfur and phosphorus are more contained for about. However the mechanism of causing the ZDT drop remains unexplained. The increase of strain rate gave rise of the tensile strength, and around 5mm displacement was measured under strain rate of 10^<-3>/s though little displacement was observed under strain rate of 10^0-10^<-2>/s. Consequently it is concluded that the mechanical properities depend on the strain rate even in the solidification temperature range.As for copper-tin alloys deformation behavior under strain tate of 10^0-10^<-4>/s was measured at the temperature range below the solidus. Regression equations for tensile strength, flow stress and elongation are obtained in relation to testing temperature, strain rate and/or strain.