In metallurgy and other materials testing, fracture toughness is a property, denoted KIc, which describes the ability of a material containing a crack to resist fracture, and is one of the most important properties of any material for virtually all design applications. 

A fracture toughness test characterizes the resistance of a material to fracture in a neutral environment and in the presence of a sharp crack. 

The KIC test and the KIC value

In contrast with Charpy Impact Toughness, which can only be used to compare the notch toughness of materials or to determine a metal’s compliance with a specification, the KIC test, sometimes referred to as KIC, or K1C, is used to determine the fracture toughness of metallic materials. Most often associated with ASTM E399, the Linear-Elastic Plane Strain Fracture Toughness test, or KIc value, can be used directly, across a range of temperatures, to determine design, life calculations and crack growth, or remaining life calculations.

The CTOD test and the S value

Crack Tip Opening Displacement is a measure of the physical opening of the fatigue crack tip at the point of failure. Typically used to measure the toughness of materials that tear before failure. All tests can be carried out from -129ºC (-200ºF) to 200ºC ( 400ºF)

The JIC test

This is a determination of toughness using the energy expended in fracturing the sample.

The JR test

Using single or multiple samples, a value of J at the point of the initiation of tearing is determined.

Preventing brittle fracture

Fracture mechanics lab testing derives a value that can be used in design work to ensure that the fabrication does not fail by brittle fracture. Additionally, in relation to fatigue testing and corrosion rates,  Element experts can use it to determine life, or remaining life, of a fabrication. 

What industries use this test?

Element is qualified to conduct the machining, fatigue pre-cracking, and fracture toughness determination, or FTD, of bend or compact-tension samples from every type of product, including large and complex structures—such as buildings, bridges, ships, aircraft, windmill towers, nuclear reactors, pressure vessels, and press bodies.

Element's Engineered Mechanics and Metallurgical Engineering experts can help solve fracture toughness problems specific to many industries—from ground vehicle, aerospace, and defense suppliers to the power generation sector and nuclear and wind power industries.

Applied mechanics and engineering

Using fracture mechanics, Element engineers quantitatively establish allowable stress levels for new structures, and inspection requirements for structures used beyond their initial design life. Element tests both high-strength ferrous and nonferrous materials in the company’s computer-controlled servo-hydraulic test frames.Element fracture mechanics lab experts can help you solve fracture toughness problems in your industry—from ground vehicle, aerospace, and defense suppliers to the power generation sector and nuclear and wind power industries. Element has the mechanical and metallurgical engineering expertise and experience to recommend and conduct tests, analyze complex data, and consult with you on brittleness and toughness issues.



American Petroleum Institute

API STD 1104

ASTM International

ASTM A 923, ASTM C1018, ASTM C1609 / C1609M, ASTM E 399, ASTM E1290, ASTM E1820, ASTM F 541

British Standards Institute

BS 7448

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