The vast majority – probably 90% - of golf clubs sold are made by casting – which involves pouring molten metal into a mould to produce a golf club head.
The nature of casting allows manufacturers to be more creative in their – the process particularly lending itself to the creation of cavity back clubs and the ability to push weight to the outside of the head which helps prevent it twisting on off-centre hits.
You will hear manufacturers shouting about their use of cast 17-4 stainless steel. No, we didn’t know what it meant either until we looked it up. It means that 17% of the make-up is chromium – and 4% nickel. And that, apparently, is very good news. 17-4 stainless steel is strong, durable, very hard, and doesn’t corrode easily.
You'll also hear about 431 Stainless steel which is 25% softer than 17-4 – and would claim to give slightly better ‘feel’ . It’s worth noting, however, that the harder the face, the faster the ball comes off it. So everything is a compromise.
Source: Golfbidder, Chessington, Surrey