Different Steels

According to Tubal Cain's book "Model Engineer's Handbook" 070M20 used to be called EN3 and has a 15 - 20% higher UTS than 230M07 or EN1A. So if the part you're making is highly stressed then yes you might notice when it breaks sooner. Personally if I was designing a part that was highly stressed then I don't think I'd be using either of those steels anyway. 070M20 seems to be regarded as a general grade of lowish carbon steel, whereas 230M07 is a free machining low carbon steel.  

Keith

Edited By Keith Long on 27/01/2011 22:53:29

HI Martin

No need to apologise you've just saved me the effort of writing this out for myself, it very useful to have the properties brought together like that.

That table is very useful, could do with a wider circulation as this question keeps on cropping up and with the numerous classification systems for steels it isn't easy to find your way around the metals especially if you are a relative newcomer to this game.

Many thanks

Keith

Edited By macmarch on 28/01/2011 20:45:24

BS 970 has been generally superseded by European based standards – where will it all end?

BS970 Numbering system explained

The BS970 code number is constructed as follows;

a) The first three symbols are a number code indicating the type of steel:

000 to 199 Carbon and carbon-manganese steels. The number represents the manganese content x 100

200 to 240 Free cutting steels. The second and third number indicate the sulphur content x 100

250 Silicon Manganese valve steels

300 to 499 Stainless and heat resisting steels

500 to 999 Alloy Steels

b) The fourth symbol is a letter code .

A The steel is supplied to a chemical compostion determine by analysis of the batch sample.

H The steel is supplied to a hardenability specification

M The steel is supplied to a Mechanical Property specification.

S The steel is a stainless steel

c) The fifth and sixth symbol is a number is the actual mean carbon content x 100

In addition to the above coding a condition coding may be applied. indicating the tensile strength range after heat treatment. This is used in conjunction with a limiting section designation.

So that makes it all crystal clear doesn’t it

Edited By John Stevenson on 29/01/2011 17:50:28