EN9/070M55 steel,called ’55’ Carbon steel, is a common unalloyed medium steel as per British standard BS 970.It has carbon content with 0.50-0.60% which gives it tensile strength between 500-800Mpa when supplied in untreated condition or normalized condition.EN9 is also suitable in the hardened and tempered condition for tensile ranges of R(700-850Mpa),S(775-925Mpa),and T(850-1000Mpa). For further process,it can be flame or induction hardened to produce a high surface hardness with excellent wear resistance .This material has poor weldability, pre-heat treatment before welding  is recommended to prevent cracking.Annealing after welding is also suggested to minimize the risk of breaking.

en9 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
EN90.5-0.60.05-0.350.5-0.8≤0.06≤0.06
070M550.5-0.60.1-0.40.50-0.9≤0.05≤0.05

EN9 Series For Speical Applications:EN9K

GradeCSiMnPS
EN9K0.5-0.60.05-0.350.5-0.8≤0.05≤0.05

3. Equivalent Grade

  • BS 970-1991:070M55
  • AISI/ASTM A29:1050,1055
  • DIN Werkstoff No.: 1.0535,1.1209
  • BS & DIN European:C50,C55,CK55
  • JIS G4051: S50C,S55C

4. Mechanical Property


Condition
NormalizedHardened & Tempered
NRST
Ruling Section,inch421 1/81 1/8
Tensile Strength,Mpa≥695≥695≥775≥850
Yield Strength,Mpa≥355≥465≥510≥555
Elongation≥18%≥18%≥18%≥15%
Hardness,HBW201-255201-255223-277248-302

EN9 Round steel Lab Tesing Data with Normalizing condition

Diameter,mmTensile Strength MPaYield Strength MPaElongation %Hardness,HB
Φ360 78040520139-172
Φ43076540022184-203
Φ51075540023193-240
Φ60074041022184-232

5.Forging EN9/070M55 steel

Recommended Forging temperature:800℃- 1200℃,and final forging temperature should not below  800℃,EN9 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 temperaure  810-840ºC with several steps,keep proper holding time depend on the steel size, then followed by cooling in still air.

EN9 steel normalizing diagram

  EN9/070M55 Normalizing Diagram

  • Annealing

Heat the steel to the temperaure  770-810ºC,and enough soaking time for the steel heating, Cool slowly in the furnace.

  • Hardening

Hardening temperature is carried out from an austenitizing temperature of 810-840ºC, followed by oil quenching.

  • Tempering

Temperaure between 550°C to 660°C is recommended for tempering,and  one hour per inch  for holding time of heating.

7.Application

EN9 steel is widely used in engineering applications which require  higher strength and  wear resistance.

Typical Applications:

  • Gears
  • Shafts
  • Cylinders
  • Sprockets
  • Cams