Well Sam I don't have the honour of being able to say I have an ONC or HNC Mech E to my name (congratulations BTW) but I have placed an awful lot of small pieces of tool steel of differing varieties into a quench in order to heat treat them to specified and very defined limits. Despite my lack of academic prowess, for some fourteen years I had the pleasure of running the machine shop for a company that produced electric terminals on multistage progression press tools.
In my experience of such it is not essential – to the average home ME – to know what the technical aspects are behind the process but knowing what and what not to do on a practical level is. To me this is far more important to be aware of in obtaining an acceptable result in those conditions. Each to his own though – I guess I'm far more interested in knowing 'how' it works than 'why' but I stress – in the home workshop environment.
The heat treatment of parts I was responsible for making were mainly punches and anvils/dies in a variety of tool steels for small press tools and parts for the progression press tools. Many of these were quite thin and liable to distort if not handled carefully but they were hung from MS cages – about 10/12 per cage and four cages at a time in the two ovens to be brought to temp. Each cage would be quenched by hand. Sometimes this could be on a daily basis but usually on a weekly one – apart from the silver steel parts previously mentioned I don't recall we ever had a failure
The punches were usually BO1 and the dies from a different steel. All were then ground to fine limits on thickness and width and the punches then form ground in blocks to create the punch/die profile.
I have never felt that the technical aspect has ever been a help in producing a well heat treated part in the home workshop – but that's just my approach, others of course may see it through different eyes
Best – Tug