Excel 2010 Macro Specify a Chart Type
Excel 2010 has 70 built-in chart types. To change a chart to one of the 70 types, use the ChartType property. This property can be applied to a chart or to a series within a chart.
An example that changes the type for the entire chart:
ActiveChart.ChartType = xlBubble
To change the second series on a chart to a line chart:
ActiveChart.Series(2).ChartType = xlLine