POST method returns FileContentResult but save as dialog is not launched in browser

Hello,

  I've written a POST method in Web API project. 

This POST method looks like

[HttpPost]
        [ActionName("downloadfile")]
        public System.Web.Mvc.FileContentResult DownloadImportedFile(string id)
        {
            try
            {
               byte[] fileContent =  ... //some logic to get the file content into byte array
                var fileContentResult = new System.Web.Mvc.FileContentResult(Encoding.UTF8.GetBytes(fileContent, "text/xml");
                fileContentResult.FileDownloadName = "myFile.xml];
                return fileContentResult;
            }

}

On the client side, I'm using HTML and AngularJS. 

var data = {
                JobId: "This_Is_My_Id"
            };

$http.post(url, data, config);

The fileContentResult is properly populated with byte array and the POST method returns value perfectly. But on the browser side

save as dialog is not launched.

Please help.

Thanks,

Saswat