To invisible formpart in Ax 2012 you can try below code in Job.
PartList partList;
Counter partCnt;
FormRun FormRun_part;
NumberOf NoOfParts;
super();
partList1 =new PartList(element);
NoOfParts =partList1.partCount();
for (partCnt =1; partCnt <= NoOfParts; partCnt++)
{
FormRun_part =partList1.getPartById(partCnt);
if (FormRun_part.name() ==formStr(YourFormName))
{
FormRun_part.design().controlName("YourControlName").visible(false);
}
}