Procedure development to estimate the nodularity of cast iron using ultrasonic testing equipment

瓦比钢铁公司专门从事铸铁零件的设计和开发。镁在铸造过程中用作球化剂。熔体中镁的含量决定了铸铁的球化率，而球化率又决定了铸件的机械性能。目前的工艺包括在钢水包中向钢水中添加镁，在工艺的上游。该技术的挑战在于，Mg在短时间内从钢包挥发，从而导致从浇注开始到结束的球化率较低，从而导致铸件的机械性能较差。目前测量球化率的方法是从钢包中取样进行金相分析，解决这个问题的建议是改变铸造工艺，以便在钢倒入单个模具的同时向钢中加入镁。初步的文献综述已经确定了研究表明，一种非破坏性的测试方法，将提供更快的结果，通过测量的声速ofsound使用超声波的铸铁球化率的可行性。然而，没有关于瓦比钢铁公司使用的铸造合金类型的现成数据。该项目建议使用已经完成的纯研究来开发一种特定的测试方法和实验数据，将无损测量与材料的实际金相条件相关联。

Wabi Iron and Steel Corp. specialize in the design and development cast iron parts. Magnesium (Mg) is used as a spheroidizer inthe casting process. The amount of Mg in the melt determines the nodularity of the cast iron, which in turn determines themechanical properties of the casting. The present process involves the addition of Mg to the molten steel in ladle, far upstream inthe process. The challenge with this technique is that the Mg volatilizes from the ladle within a short period of time, thus, leading tolower nodularity from the beginning of the pour to the end hence, inferior mechanical properties of the casting. The current processof measuring the nodularity is through metallographic analysis by taking a sample from the ladle.The proposed solution to this problem is to change the casting process in order to add Mg to the steel at the time that it is pouredinto the individual molds. A preliminary literature review has identified research that show the feasibility of a non-destructive testmethod that would provide faster results for determining nodularity of cast iron through the measurement of the acoustic speed ofsound using ultrasonic sound waves. However, there is no data readily available for the type of casting alloy being used by WabiIron and Steel. This project proposes to use the pure research that has been done to develop a specific test method andexperimental data that correlates the nondestructive measurements with actual metallographic condition of the material.