EN8/080M40 steel,as ’40’ carbon steel, is a common unalloyed medium carbon steel as per British standard BS 970.It has medium carbon content with 0.36-0.44% which gives it medium tensile strength.EN8 steel is generally supplied in untreated condition or normalized condition,and also suitable in the hardened and tempered condition for tensile ranges of 625-775 Mpa(Q),and 700-850Mpa(R). For further process,it can be flame or induction hardened to produce a good surface hardness(50-55HRC) and moderate wear resistance.With good homogenous metallurgical structures which gives stable machining properties, EN8 material can be easily machined  in any condition.

EN8 forged round steel

1.Supply Form & Size & Tolerance

Hot Forged Round bar:Φ80-Φ1000mm

Hot Forged Square bar: Max Thickness:500mm

Flat bar/Blcoks:Thickness :120-800mm ,Width:120-1500mm

Surface FinishBlack-Forged Black-Rolled Turned   GrindingPolishedPeeledCold Drawn
Tolerance(0,+5mm)(0,+1mm)(0,+3mm)Best h9Best h11Best H11Best H11

2.Chemical Composition

GradeCSiMnPS
EN80.35-0.450.05-0.350.60-1.0≤ 0.06≤ 0.06
080M400.36-0.440.1-0.40.60-1.0≤ 0.05≤ 0.05

EN8 Series For Speical Applications:EN8A,EN8B,EN8C,EN8D,EN8E,EN8K

GradeCSiMnPS
EN 8A0.33-0.380.05-0.350.70-0.9≤0.06≤0.06
EN 8B0.35-0.400.05-0.350.70-0.9≤0.06≤0.06
EN 8C0.38-0.430.05-0.350.70-0.9≤0.06≤0.06
EN 8D0.40-0.450.05-0.350.70-0.9≤0.06≤0.06
EN 8E0.35-0.400.05-0.350.9-1.1≤0.06≤0.06
EN 8K0.35-0.450.05-0.350.6-1.0≤0.05≤0.05

EN8 Series For Free Cutting:EN8M,EN8AM,EN8BM,EN8CM,EN8DM

GradeCSiMnPS
EN 8M0.35-0.45≤0.251.0-1.3≤0.060.12-0.20
EN 8AM0.33-0.38≤0.250.9-1.3≤0.060.12-0.20
EN 8BM0.35-0.40≤0.250.9-1.3≤0.060.12-0.20
EN 8CM0.38-0.43≤0.250.9-1.3≤0.060.12-0.20
EN 8DM0.40-0.45≤0.250.9-1.3≤0.060.12-0.20

3.Relevant Standards

USAEN/DINJapan
1040/1045C40/CK40/C45/CK45/1.0511/1.1186/1.1189S40C/S45C

4. Mechanical Property


Condition
NormalizedHardened & Tempered
NQR
Tensile Strength,Mpa≥540≥540≥620≥700≥700
Yield Strength,Mpa≥ 280≥540≥435≥495≥495
Elongation≥20%≥20%≥22%≥20%≥20%
ISO V Impact,J≥28≥20≥34≥54≥34
Hardness,HBW152-207152-207179-229201-255201-255

EN8 Round steel Lab Tesing Data with Normalizing condition

Diameter,mmTensile Strength MPaYield Strength MPaElongation %Hardness,HB
Φ46067537525179-187
Φ51062036028135-167
Φ60061535527124-156

5.Forging EN8/080M40 steel

Forging temperature around 1200℃,but don’t forge below  800℃,EN8 steel should be cooled as slowly as possible in still air(may get fine grain) or in sand after forged.

6.Heat Treatment

  • Normalizing

Heat the steel to the temperature 830-860ºC ,keep the temperature depend on the steel size, then followed by cooling in still air.

EN8 steel normalizing diagram

  EN8/080M40 Normalizing Diagram

  • Annealing

Heat EN8 steel  slowly to 680-710°C, keep the temperature stable . Cool slowly in the furnace.

  • Hardening

Hardening of this grade is carried out from an austenitizing temperature of 820-860ºC followed by oil or water quenching.

  • Tempering

Carbon steel EN8 or 080m40 can be tempered at a heat of between 550°C to 660°C,heating for about 1 hour for every inch of thickness, then cool in oil or water.

7.Application

EN8 steel is widely used in industries which is used in applications where better properties than mild steel are required.

Typical Applications:

  • Automotive parts
  • Connecting rods
  • Studs, bolts
  • Axles, spindles
  • General engineering components