SAE 1040 carbon steel

Introduction

We manufacture forging ingots, billets, and blooms in carbon steel specifically for SAE 1040, designed for medium strength engineering applications where good toughness, strength, and machinability are required.

SAE 1040 is a medium carbon, unalloyed steel with a carbon content of approximately 0.40%. It offers a balance of moderate strength and good toughness, making it suitable for general engineering, automotive, and agricultural components subjected to moderate mechanical loads.

This grade responds well to heat treatment, including normalizing, quenching, and tempering, to achieve desired mechanical properties.

Chemical composition

Element Content (%) Function / effect
Carbon (c) 0.37 – 0.44 Provides moderate strength and hardness
Manganese (mn) 0.60 – 0.90 Improves toughness and hardenability
Phosphorus (p) 0.040 max Limited to improve toughness
Sulphur (s) 0.050 max Improves machinability when controlled
Silicon (si) 0.15 – 0.35 Acts as deoxidizer and increases strength
Chromium (cr) Nil Not intentionally added
Nickel (ni) Nil Not present
Molybdenum (mo) Nil Not present
Other elements — No significant alloying additions

Mechanical properties (typical – normalized / quenched & tempered)

  • Tensile strength: 570 – 700 MPa
  • Yield strength: 330 – 410 MPa
  • Elongation: 16 – 22 %
  • Hardness: 150 – 200 HB

Heat treatment

  • Annealing: improves softness and machinability
  • Normalizing: refines grain structure and improves mechanical properties
  • Quenching: heating to 820 – 860°c followed by rapid cooling for hardness
  • Tempering: relieves internal stresses and improves toughness

Key features and benefits

  • Good balance of strength and toughness
  • Reliable performance under moderate loads
  • Cost-effective and readily available
  • Good machinability in annealed condition
  • Suitable for forging and machining

Typical applications

  • Shafts and axles
  • Gears and pins
  • Automotive components
  • Agricultural tools
  • General engineering parts

Equivalent Steel Grades

  • SAE 1040 (Aisi/SAE Standard)
  • En8 (En Standard – Closest Equivalent)
  • Din 1.0511 (German Standard)

Why Choose SAE 1040 For Your Application?

SAE 1040 Offers A Reliable Balance Of Strength, Wear Resistance, And Affordability. Its Ability To Be Heat Treated Allows Manufacturers To Achieve Improved Mechanical Properties, Making It Suitable For Components Subjected To Moderate To High Loads. It Is Widely Available And Easy To Process, Making It A Practical Choice For Engineering Applications.

Comparison table for similar grades

Grade Carbon (%) Strength level Typical applications
SAE 1035 0.32 – 0.39 Medium–low Light engineering parts
SAE 1040 0.37 – 0.44 Medium Shafts, gears
SAE 1045 0.43 – 0.50 Medium–high Automotive parts
45 c8 0.40 – 0.50 Medium–high General engineering
C 45 0.40 – 0.50 Medium–high Heavy duty parts

Summary

SAE 1040 carbon steel is a versatile medium carbon grade providing a good balance of strength, toughness, and machinability. It is suitable for a wide range of general engineering and automotive applications where moderate load-bearing capability is required.