Ferritic ductile iron (DI) GJS 400 and high-silicon strengthened ductile irons (HSSDIs) with 3.5 and 4.5 wt% of silicon contents were produced with different cooling rates, and the microstructures were analyzed to find the main microstructure parameters. The Y-blocks GJS 400 presented good nodularity, while the heavy section GJS 400 presented some graphite degeneracy with a lower nodularity. The 3.5 wt% HSSDI shown a good nodularity, while with increasing silicon content to 4.5 wt%, significant graphite degeneracy occurred with the appearance of chunky graphite. Samples were tensile tested and the tensile data were analyzed through the physical-based constitutive Voce equation, and the Voce parameters were plotted to produce a matrix assessment diagram (MAD). Y-blocks and heavy section GJS 400 data lied on two distinct lines in MAD, and they had, however, positive and negative intercepts which meant indeed two contradictory plastic behaviors. The intercept of the best fitting line of the GJS 400 Y-blocks data was positive and so consistent with the physical meaning of Voce equation, while the intercept of the best fitting line of the GJS 400 heavy section data was negative, which meant an unexpected opposite plastic behavior. Same behavior was reported for the investigated HSSDIs, resulting in positive intercept of the best fitting line in MAD for the 3.5 wt% HSSDI data and negative intercept for the 4.5 wt% HSSDI data. The uniform strain energy density (SED_U) that is the area below the tensile flow curve up to the uniform strain, i.e., the strain where necking begins, was also investigated. SED_U resulted to be almost constant for all the GJS 400 Y-blocks tensile flow curves and 3.5 wt% HSSDI, which was typical of a sound material, while in GJS 400 heavy section and 4.5 wt% HSSDI, SED_U changed significantly in a systematic way, indicating that metallurgical defects had affected the plastic behavior. So it was concluded that in the MAD the best fitting line of the tensile data with positive intercept was a possible indication of the material soundness, while the negative intercept was indication of defected material. The results suggested that the MAD analysis produced from tensile Voce parameters can be a useful and easy tool for industry not only to classify the production routes of DIs (Si content mainly and heat treatments), but also to identify possible microstructure poorness within a single DI grade.

中文翻译：

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通过拉伸数据分析鉴别铁素体球墨铸铁的完整性

在不同的冷却速率下生产了硅含量分别为3.5和4.5 wt％的铁素体球墨铸铁（DI）GJS 400和高硅强化球墨铸铁（HSSDIs），并对其微观结构进行了分析，以找到主要的微观结构参数。Y型块GJS 400表现出良好的球化度，而厚截面GJS 400表现出一些石墨变性，而球化度较低。3.5wt％的HSSDI显示出良好的球化度，而随着硅含量增加至4.5wt％，发生了显着的石墨简并并出现块状石墨。对样品进行拉伸测试，并通过基于物理的本构Voce方程分析拉伸数据，并绘制Voce参数以生成矩阵评估图（MAD）。Y块和GJS 400重截面数据在MAD中位于两条不同的线上，它们具有 但是，正向和负向截距实际上意味着两个相互矛盾的塑性行为。GJS 400 Y块数据的最佳拟合线的截距为正，因此与Voce方程的物理意义一致，而GJS 400重截面数据的最佳拟合线的截距为负，这意味着意外相反的塑性行为。对于所研究的HSSDI，报告了相同的行为，对于3.5 wt％的HSSDI数据，导致MAD中最佳拟合线的正向截距，而对于4.5 wt％的HSSDI数据则导致负向截距。均匀应变能密度（SED GJS 400 Y块数据的最佳拟合线的截距为正，因此与Voce方程的物理意义一致，而GJS 400重截面数据的最佳拟合线的截距为负，这意味着意外相反的塑性行为。对于所研究的HSSDI，报告了相同的行为，对于3.5 wt％的HSSDI数据，MAD中最佳拟合线的正向截距，对于4.5 wt％的HSSDI数据，导致负向截距。均匀应变能密度（SED GJS 400 Y块数据的最佳拟合线的截距为正，因此与Voce方程的物理意义一致，而GJS 400重截面数据的最佳拟合线的截距为负，这意味着意外相反的塑性行为。对于所研究的HSSDI，报告了相同的行为，对于3.5 wt％的HSSDI数据，MAD中最佳拟合线的正向截距，对于4.5 wt％的HSSDI数据，导致负向截距。均匀应变能密度（SED 5重量％的HSSDI数据。均匀应变能密度（SED 5重量％的HSSDI数据。均匀应变能密度（SED_U）是拉伸流动曲线下方直至均匀应变（即颈缩开始处的应变）的面积。结果表明，对于所有GJS 400 Y型块拉伸流曲线和3.5 wt％的HSSDI，SED _U几乎是恒定的，这是声音材料的典型特征；而对于GJS 400重截面和4.5 wt％的HSSDI，SED _U发生了系统性的显着变化，表明冶金缺陷已影响塑性性能。因此可以得出结论，在MAD中，具有正截距的拉伸数据的最佳拟合线是材料稳固性的可能指示，而负截距则是缺陷材料的指示。结果表明，由拉伸Voce参数产生的MAD分析不仅可以用于工业上对DIs的生产路线进行分类（主要是Si含量和热处理），而且可以识别单个DI内可能存在的微观结构缺陷，这对于工业而言是一种有用且容易的工具年级。