Posted by vintagengineer on 08/02/2017 21:29:48:
I was led to understand that EN stood for Emergency Number issued by the Government in the last war due to steel makers had all their own grades.
I have a copy of 'War Emergency British Standard Schedule 970:1942 – Wrought Steels", Price 5/- net, post free.
In the foreword it explains that it was prepared by the Iron and Steel Committee. This committee consisted of 34 Government, Scientific and Industrial Organisations ranging from the Admiralty to the Steel Castings Association, including several long gone authorities like the High Commissioner for India.
Standardisation was driven by the Technical and Advisory Committee of the Committee of Steel Control of the Ministry of Supply. MoS had been set up in 1939 to coordinate war supply to the Army, Navy and Air Force and it had very wide ranging powers, essentially controlling the British War Economy.
The first version of BS870 was issued in 1941. The 1942 standard defines 33 groups of steel intended for general engineering purposes and it stopped Industry 'doing it's own thing'. Before the war, many companies produced dozens of similar but different steels, all competing with each other. The need for a new steel standard had been recognised before the war. The earlier standard, BS5005:1924 hadn't, for example, kept up with the new steels used for car making. Work in this area was folded into the new system.
TAC numbers were used briefly before En numbers appeared. Consequently they feature conspicuously in the standard. For example, the 1942 version says of En1 and En1A "With little or no modification these specifications cover the essentials of the following classifications and specifications: TAC1, V.1, V.1A, SAE.1112, SAE1113, AMS.5010A". I wonder if anyone remembers TAC steel specifications: I'd never heard of them!
Dave
Edited By SillyOldDuffer on 08/02/2017 22:58:03
Edited By SillyOldDuffer on 08/02/2017 22:58:46