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AISI 1045 Medium Carbon Steel

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Machining
Welding
Heat Treatment
Forging
Annealing
Normalizing
Stress Relieving
Hardening
Tempering
Applications

Introduction

AISI 1045 steel is a medium tensile steel supplied in the black hot rolled or normalized condition. It has a tensile strength of 570 - 700 MPa and Brinell hardness ranging between 170 and 210.

AISI 1045 steel is characterized by good weldability, good machinability, and high strength and impact properties in either the normalized or hot rolled condition.

AISI 1045 steel has a low through-hardening capability with only sections of size around 60 mm being recommended as suitable for tempering and through-hardening. However, it can be efficiently flame or induction hardened in the normalized or hot rolled condition to obtain surface hardnesses in the range of Rc 54 - Rc 60 based on factors such as section size, type of set up, quenching medium used etc.

AISI 1045 steel lacks suitable alloying elements and hence does not respond to the nitriding process.

Chemical Composition

Element Content
Carbon, C 0.420 - 0.50 %
Iron, Fe 98.51 - 98.98 %
Manganese, Mn 0.60 - 0.90 %
Phosphorous, P ≤ 0.040 %
Sulfur, S ≤ 0.050 %

Physical Properties

Physical Properties Metric Imperial
Density 7.87 g/cc 0.284 lb/in3

Mechanical Properties

Mechanical Properties Metric Imperial
Hardness, Brinell 163 163
Hardness, Knoop (Converted from Brinell hardness) 184 184
Hardness, Rockwell B (Converted from Brinell hardness) 84 84
Hardness, Vickers (Converted from Brinell hardness) 170 170
Tensile Strength, Ultimate 565 MPa 81900 psi
Tensile Strength, Yield 310 MPa 45000 psi
Elongation at Break (in 50 mm) 16.0 % 16.0 %
Reduction of Area 40.0 % 40.0 %
Modulus of Elasticity (Typical for steel) 200 GPa 29000 ksi
Bulk Modulus (Typical for steel) 140 GPa 20300 ksi
Poissons Ratio (Typical For Steel) 0.290 0.290
Shear Modulus (Typical for steel) 80 GPa 11600 ksi

Machining

AISI 1045 steel has good machinability in normalized as well as the hot rolled condition. Based on the recommendations given by the machine manufacturers, operations like tapping, milling, broaching, drilling, turning and sawing etc. can be carried out on AISI 1045 steel using suitable feeds, tool type and speeds.

Welding

Certain facts about welding of AISI 1045 steel are:

  • AISI 1045 steel is readily welded when correct procedure is followed.
  • Welding AISI 1045 steel in through-hardened, tempered and flame or induction hardened condition is not recommended.
  • Low hydrogen electrodes are preferred for welding AISI 1045 steel.
  • The workpiece is
    • Pre-heated at 200°C–300°C (392°F - 572°F)
    • Maintained at the same temperature during welding
    • Cooled slowly using sand, ashes etc and
    • Stress relieved at 550°C - 660°C (1022°F - 1220°F).

Heat Treatment

AISI 1045 is subjected to the following processes:

  • Forging
  • Annealing
  • Normalizing
  • Stress relieving
  • Hardening
  • Tempering

Forging

  • Heat to 850°C - 1250°C (1562°F - 2282°F)
  • Hold until the temperature is uniform
  • Cool in furnace

Annealing

  • Heat to 800°C - 850°C (1472°F - 1562°F)
  • Hold until the temperature is uniform
  • Cool in furnace.

Normalizing

  • Heat to 870°C - 920°C (1598°F-1688°F)
  • Hold until the temperature is uniform
  • Soak for 10 - 15 minutes
  • Cool in still air

Stress Relieving

  • Heat to 550°C - 660°C (1022°F - 1220°F)
  • Hold until the temperature is uniform
  • Soak for 1 hour per 25mm of section
  • Cool in still air

Hardening

  • Heat to 820°C - 850°C (1508°F - 1562°F)
  • Hold until the temperature is uniform
  • Soak for 10 - 15 minutes per 25mm of section
  • Quench in water or brine

Tempering

  • Re-heat to 400°C - 650°C (752°F - 1202°F ) as required
  • Hold until the temperature is uniform
  • Soak for 1 hour per 25mm of section
  • Cool in still air

Applications

AISI 1045 is widely used for all industrial applications requiring more wear resistance and strength. Typical applications of AISI 1045 are as follows:

Gears Pins Rams
Shafts Rolls Sockets
Axles Spindles Worms
Bolts Ratchets Light gears
Studs Crankshafts Guide rods
Connecting rods Torsion bars Hydraulic clamps
Date Added: Jul 2, 2012 | Updated: Jun 11, 2013
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