The organization I work for sends material out for heat treating, plating, etc.…, but we DO NOT sub our process to another organization or allow another organization to send the product to our customer. All materials sent out for special processing is returned and further worked in-house. All work is also done at our one (1) location so orders are not subbed to sister facilities.
Is it a viable statement to say that “Control of Work Transfers” is not applicable to our situation?"
Transfer of work, as mentioned in clause 8.1, is referring to moving a process which is normally done in one place to another. As per the note it can be from your facility to a supplier, from one supplier to another, etc. In other words, it is in changing the original plan of where work will be done, and the requirements are that when you do this you have a process in place to ensure that the original conformity of the products or services is not maintained and risks are managed. When you are talking about sending a product out to be heat treated or plated as a regular function, this would fall under clause 8.4, Control of externally provided processes, products and services.
From your explanation it could be argued that this transfer of work is not applicable to you, but if you do choose to do this in the future you would need to plan the transfer and not just move work without assessing the risks.
Since the reason for this requirement is to ensure process validation is maintained when work is transferred, you can learn more on process validation in this article: What is process validation in AS9100 Rev D?, https://advisera.com/9100academy/blog/2017/10/02/what-is-process-validation-in-as9100-rev-d/