RadControls for WPF

The axes of the RadChart display a label for each of the major ticks

You can specify custom Axis Items Labels by either specifying a XCategory or by manually setting TickPoint's labels.

XCategory is used when the data is not sequential, i.e. values on the X Axis have no meaning, for examle when the chart presents information for different companies (whose names are placed on the X axis) or other entities. In case X value is present in the data, and something else should be placed on the X axis, you need to go through the RadChart.DefaultView.ChartArea.AxisX.TickPoints collection and set Label for each TickPoint. Since the XCategory is already described in another help article - Categorical Charts this topic will demonstrate the second approach:

CopyC#
DataSeries lineSeries = new DataSeries();
            lineSeries.LegendLabel = "Monthly Sales";
            lineSeries.Definition = new LineSeriesDefinition();
            Random r = new Random();
            for (int i = 0; i < 12; i++)
            {
                lineSeries.Add(new DataPoint() { YValue = i + r.Next(0,20) });
            }

            radChart.DefaultView.ChartArea.DataSeries.Add(lineSeries);

            string[] months = new string[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun" ,"Jul", "Aug", "Sep", "Oct", "Nov", "Dec", };

            for (int i = 0; i < months.Length; i++)
            {
               radChart.DefaultView.ChartArea.AxisX.TickPoints[i].Label = months[i];
            }
CopyVB.NET
Dim lineSeries As New DataSeries()
lineSeries.LegendLabel = "Monthly Sales"
lineSeries.Definition = New LineSeriesDefinition()
Dim r As New Random()
For i As Integer = 0 To 11
 lineSeries.Add(New DataPoint() With { _
  .YValue = i + r.[Next](0, 20) _
 })
Next
radChart.DefaultView.ChartArea.DataSeries.Add(lineSeries)
Dim months As String() = New String() {"Jan", "Feb", "Mar", "Apr", "May", "Jun", _
 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}
For i As Integer = 0 To months.Length - 1
 radChart.DefaultView.ChartArea.AxisX.TickPoints(i).Label = months(i)
Next

The result is: