Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

Steels - Endurance Limits and Fatigue Stress

Sponsored Links
  • Fatigue - when a material is subjected to repeated cycles of stress or strain and its structure breaks down and ultimately leads to fracture
  • Creep - when a material is subjected to a load for a very long time it may continue to deform until a sudden fracture occurs

Fatigue

Fractures due to fatigue is common in cyclic loaded parts like connected rods, crankshafts, turbine blades, railroad wheels and so on. Fractures occur at stress less than the material Yield Stress.

  • Yield strength is defined in engineering as the amount of stress (Yield point) that a material can undergo before moving from elastic deformation into plastic deformation.

Most steels have an endurance or fatigue limit about half the Tensile Strength.

  • Tensile Strength - (Ultimate Tensile Strength) - of a material is the limit stress at which the material actually breaks, with sudden release of the stored elastic energy.
Steels - Endurance Limits and Fatigue Stress
SteelBSTreatmentTensile Strength
- σu -
(MPa)

Endurance Limit
- σe -
(MPa)

σe / σu
0.4% Carbon BS970 080M40 Normalized 540 270 0.5
0.4% Carbon BS970 080M40 Hardened and tempered 700 340 0.49
Carbon, manganese BS970 150M19 Normalized 540 250 0.46
Carbon, manganese BS970 150M19 Hardened and tempered 700 325 0.53
3% Chrome molybdenum BS970 709M40 Hardened and tempered 1000 480 0.48
Spring steel BS970 735A50 Hardened and tempered 1500 650 0.43
18.8 Stainless Cold rolled 1200 490 0.41
  • 1 MPa = 106 Pa = 1 N/mm2= 145.0 psi (lbf/in2)
  • Fatigue limit, endurance limit, and fatigue strength are used to describe the amplitude (or range) of cyclic stress that can be applied to the material without causing fatigue failure.

Creep

The time dependent deformation due to heavy load over time is known as creep.

In general both stress and temperature influence on the rate of creep.Normally creep strength decreases with temperature.

Allowable creep strain can be specified - typical 0.1 %/year for steel bolts and piping

Sponsored Links

Related Topics

Mechanics

Forces, acceleration, displacement, vectors, motion, momentum, energy of objects and more.

Statics

Loads - forces and torque, beams and columns.

Related Documents

Barlow's Formula - Calculate Internal, Allowable and Bursting Pressure

Calculate pipes internal, allowable and bursting pressure.

Composition of Steels

Typical composition of AISI steels.

Compression and Tension Strength of some common Materials

Common materials and average ultimate compression and tension strength.

Engineering Materials - Properties

Some typical properties of engineering materials like steel, plastics, ceramics and composites.

Metals - Strength vs. Temperature

The influence of temperature on the strength of metals.

Metals and Alloys - Young's Modulus of Elasticity

Elastic properties and Young's modulus for metals and alloys like cast iron, carbon steel and more.

Modulus of Rigidity

Shear Modulus (Modulus of Rigidity) is the elasticity coefficient for shearing or torsion force.

Reliability of Machine Components

Mean Time Between Failure - MTB and reliability of machine components and systems.

Steel Bolts - SAE Grades

SAE steel bolts - grades ranging grade 1 to 8.2 - proof and tensile strength.

Steel Tempering Colors

The tempering process of hardening steel.

Stress

Stress is force applied on cross-sectional area.

Stress, Strain and Young's Modulus

Stress is force per unit area - strain is the deformation of a solid due to stress.

Threaded Bolts - Stress Area

Threaded bolts tensile stress area.

Threaded Rods - Loads in Imperial Units

Weight rating of threaded hanger rods.

US Bolts - Tensile Strength and Proof Loads

Tensile strength and proof loads SAE bolts.

Young's Modulus, Tensile Strength and Yield Strength Values for some Materials

Young's Modulus (or Tensile Modulus alt. Modulus of Elasticity) and Ultimate Tensile Strength and Yield Strength for materials like steel, glass, wood and many more.

Sponsored Links

Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.