Page 240 - Mechanical Engineer's Data Handbook

228 MECHANICAL ENGINEER’S DATA HANDBOOK

6.5 British Standard specification of steels

The relevant standard is BS 970 ‘Wrought Steels’. The 300-449 : Heat-resistant, stainless and valve steels
standard is in six parts: 500-999: Alloy steels
Part 1 Carbon and carbon manganese steels including Letter
free-cutting steels The letters A, M, H and S indicate if the steel is sup-
Part 2 Direct hardening alloy steels plied to - chemical analysis, mechanical properties,
Part 3 Steels for Case Hardening hardenability requirements, or is stainless, respect-
Part 4 Stainless, heat resisting and spring steels ively.
Part 5 Carbon and alloy spring steels
Part 6 SI metric values (for use with Parts 1 to 5) Last two digits
These give 100 times the percentage of carbon, except
Each steel is designated by six symbols: for stainless steels.
First three digits
000-199: Carbon and carbon-manganese steels. Example
Digits represent 100 times the percentage of manga-
nese. 070M20: A plain carbon steel with 0.2% carbon and
200-240: Free cutting steels. Second and third digits 0.7% manganese. The mechanical properties, i.e.
represent 100 times the percentage of sulphur. tensile strength, yield strength, elongation and hard-
250: Silicon-manganese steel ness, are given in the standard.

6.6 Non-ferrous metals

6.6. I Copper and copper alloys etc. Copper is available in the form ofwire, sheet, strip,
plate, round bar and tube.
ElectrolYticallY r&ned copper (99.95% Pure) is used Copper is used in many alloys, including brasses,
for components requiring high conductivity. Less Pure bronzes, aluminium bronze, cupronickel, nickel-silver
copper is used for chemical plant, domestic plumbing, and &ryllium+opper.
Composition and mechanical properties of some copper alloys

Mechanical properties
0.1%
Composition (YO) proof Tensile
stress strength Elongation Vickers
Type and uses Cu Zn Others Condition (Nmm-’) (Nmm-’) (YO) hardness
~~
Muntz metal: 60 40 - Extruded 110 350 40 15
die stampings,
and extrusions
Free-cutting brass: 58 39 3 Pb Extruded 140 440 30 100
high-speed
machining