Non-metallic inclusion and their effect on fatigue strength for case-hardened carbon steel in gears

• Steel is a very essential structural material and its production worldwide has shown significant increase over the last years. In steels there always exist a large number of inclusions which can have a degrading effect on the fatigue properties. This study is focused on the link between the characteristics of non-metallic inclusions and how they affect fatigue strength of the standardized case-hardened carbon steel 20MnCr5 and a version of this steel with a more favorable inclusion distribution, a so-called Clean steel. For the evaluation of the mechanical properties the test result from rotary bending tests are compared and an improvement by 37.5% in fatigue strength can be noted between the different steels. The new performed ultrasonic tests illustrate the difference in the size of defects in materials with different manufacturing processes and degree of reduction. By studying international and European standards for non-destructive testing and investigation of alloy compounds, the current material specification can be adjusted. © The Minerals, Metals & Materials Society 2018.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tribologi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Tribology (hsv//eng)

Nyckelord

Clean-steel

Inclusions

Mechanical properties

Standard

Steel

Ultrasonic test

Bending tests

Binary alloys

Carbon steel

Chromium alloys

Fatigue of materials

Fatigue testing

Hardening

Manganese alloys

Nondestructive examination

Standards

Clean steel

Degree of reduction

European Standards

Inclusion distribution

Manufacturing process

Material specification

Non destructive testing

Non-metallic inclusions

Ultrasonic testing

Maskinteknik

Mechanical Engineering

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