I have been using [attr.disabled]
because I still like this template driven than programmatic enable()/disable() as it is superior IMO.
Change
<md-input formControlName="id" placeholder="ID" [disabled]="true"></md-input>
to
<md-input formControlName="id" placeholder="ID" [attr.disabled]="true"></md-input>
If you are on newer material change md-input
to mat-input
.