File created with name [object formdata] but it must be name delivery.

Question

I work on asp.net core 2.2 Project with angular 7 . I face issue when download file

It created with Name [object FormData].xlsx but Name must be DeliveryGeneration_Output.xlsx .

on Angular 7

public uploadFile = (files) => {
const formData = new FormData();
formData.append('file', this.fileToUpload,this.fileToUpload.name);
this.http.post('https://localhost:44396/api/ApprovalQuality/', formData,{ responseType: 'blob' })
.subscribe((response: Blob) => saveAs(response, formData + '.xlsx'));
}

on Web API .Net Core 2.2

var memory2 = new MemoryStream();
using (var stream = new FileStream(exportPath, FileMode.Open))
{
stream.CopyTo(memory2);
}
memory2.Position = 0;
return File(memory2, "text/plain", Path.GetFileName(exportPath));

Path returned and Created

\\192.168.2.7\\ImportExport\\2\\Export\DeliveryGeneration_Output.xlsx

 

so why file name created with [object FormData].xlsx and not created with DeliveryGeneration_Output.xlsx

and How to solve this Issue ?