@govind,
As of now, axisY supports number but not date-time. However you can work-around it by passing timestamp and formatting it in label and toolTip. Please take a look at this JSFiddle.
If you are still facing any issue, kindly share JSFiddle reproducing the issue so that we can understand the scenario better and help you out.
—
Manoj Mohan
Team CanvasJS