Table partition existing table where partition key is not part of the primary key

Main objective: Add partitioning to table to make deletion of old orders non-blocking/quicker (and also understand partitioning)

I have an existing table Order, like this:

CREATE TABLE Order (    OrderId INT,    OrderDate Datetime,    Quantity INT,    CONSTRAINT [PK_OrderId] PRIMARY KEY CLUSTERED (    [OrderId] ASC) ON [PRIMARY];

This table contains 50 million rows from the last 10 years.I only need the last 5 years data.

I have a partition function like this:

CREATE PARTITION FUNCTION OrderPF (datetime)AS RANGE RIGHT FOR VALUES ('2014-01-01')

I have a partition scheme like this:

CREATE PARTITION SCHEME OrderPS AS PARTITION OrderPF ALL TO ([PRIMARY]) 

My question is how to proceed?I still want a primary key on the table.

Does the [OrderDate] column have to be a part of the clustered index? (Main question)

CREATE UNIQUE CLUSTERED INDEX IX_Order ON Order(OrderDate,OrderId) ON OrderPS(OrderDate) ;

If so, do I then have to create an extra non-clustered Primary Key purely on [OrderId]?

ALTER TABLE Order ADD CONSTRAINT PK_OrderId PRIMARY KEY NONCLUSTERED (Id) ON [PRIMARY];

Is this the correct approach?