Some posts have indicated that we may have some sections of the future SSN built in Barrow and then shipped to Osborne to be mated to locally produced sections - this leads to thoughts about the type of steel to be used.
The steel currently used in Astute class SSN’s is similar in strength to the HY80 used in the LA class. The Virginia class uses HY100 which is stronger but is difficult to weld. The Collins class used a steel originally produced in Sweden but was further improved by Bisalloy and this product is slightly stronger than HY100 with very good blast/bulge capability, good corrosion resistance and is relatively easy to weld. This article discusses the development work for an improved steel to be used in the previously planned Attack class SSK’s.
Deep dive into underwater material advances - Australian Defence Magazine
Obviously, the most suitable steel to be used would be sourced from Bisalloy/Bluescope so, if sections are to produced in Barrow, we would have to send the steel to them and then train them wrt the handling differences - not insurmountable but still something that has to be planned.
On another matter, our submariners have been operating the Collins class which has the aft control surfaces in an X configuration whereas both the Astute and Virginia have the conventional + configuration. The advantages of the X configuration is that they can be smaller (less drag), provide better controllability/depth maintenance in shallow water and better control when conducting high speed turns. The Columbia, SSNX, Dreadnought & SSNR classes are all planned to have X configuration controls so, if we were to purchase hybrid Astute class SSN’s we would be going backwards as far as controllability - as well as having no vertical launch capability. I know that it’s important to get the SSN’s as quickly as possible (with no capability gap) but I do hope that our government does decide on the type that gives us the best capability for the entire service life of these very expensive boats.