Use of instrumented indentation testing to study local mechanical properties of 304L SS welded joints subjected to low-cycle fatigue loadings

The AlSi8Cu3 and AlSi7MgCu0.5 cast aluminium alloys of different composition and heat treatment were investigated to verify their applicability as cylinder heads in the car engines [1]. Creep tests under the step-increased stresses at different temperatures, and low cycle fatigue (LCF) tests for a range of strain amplitudes and temperatures were carried out. The results exhibit a significant influence of the heat treatment on the mechanical properties of the AlSi8Cu3 and AlSi7MgCu0.5. An interesting fact is that the properties strongly depend on the type of quenching. Lower creep resistance (higher strain rates) and lower stress response during fatigue tests were observed for the air quenched materials in comparison to those in the water quenched. Cyclic hardening/softening were also observed during the LCF tests due to the heat treatment applied. The mechanical properties determined during the tests can be used to identify new constitutive equations and to verify existing numerical models.

Download Full-text

Low-cycle fatigue behaviour of laser welded high-strength steel DOMEX 700 MC

MATEC Web of Conferences ◽

10.1051/matecconf/201815705013 ◽

2018 ◽

Vol 157 ◽

pp. 05013 ◽

Cited By ~ 2

Author(s):

Peter Kopas ◽

Milan Sága ◽

František Nový ◽

Bohuš Leitner

Keyword(s):

Fatigue Life ◽

Welded Joints ◽

High Strength Steel ◽

Fatigue Testing ◽

Low Cycle Fatigue ◽

High Strength ◽

Fatigue Behaviour ◽

Total Strain Amplitude ◽

Cycle Fatigue ◽

Fatigue Life Analysis

The article presents the results of research on low cycle fatigue strength of laser welded joints vs. non-welded material of high-strength steel DOMEX 700 MC. The tests were performed under load controlled using the total strain amplitude ɛac. The operating principle of the special electro-mechanic fatigue testing equipment with a suitable clamping system was working on 35 Hz frequency. Fatigue life analysis was conducted based on the Manson-Coffin-Basquin equation, which made it possible to determine fatigue parameters. Studies have shown differences in the fatigue life of original specimens and laser welded joints analysed, where laser welded joints showed lower fatigue resistance. In this article a numerical analysis of stresses generated in bending fatigue specimens has been performed employing the commercially available FEM-program ADINA.

Download Full-text

Investigation of low-cycle fatigue of welded joints in light alloys

Strength of Materials ◽

10.1007/bf01527795 ◽

1972 ◽

Vol 4 (11) ◽

pp. 1320-1322

Author(s):

V. A. Strizhalo ◽

A. A. Il'in ◽

Yu. A. Kuzema

Keyword(s):

Welded Joints ◽

Low Cycle Fatigue ◽

Cycle Fatigue ◽

Light Alloys

Download Full-text

Low Cycle Fatigue Analysis of Marine Structures

Volume 3: Safety and Reliability; Materials Technology; Douglas Faulkner Symposium on Reliability and Ultimate Strength of Marine Structures ◽

10.1115/omae2006-92268 ◽

2006 ◽

Cited By ~ 2

Author(s):

Xiaozhi Wang ◽

Joong-Kyoo Kang ◽

Yooil Kim ◽

Paul H. Wirsching

Keyword(s):

Welded Joints ◽

Low Cycle Fatigue ◽

Prediction Method ◽

Local Stress ◽

Cyclic Plasticity ◽

Cycle Fatigue ◽

Stress Concentrations ◽

Damage Prediction ◽

Marine Structure ◽

Number Of Cycles

There are situations where a marine structure is subjected to stress cycles of such large magnitude that small, but significant, parts of the structural component in question experiences cyclic plasticity. Welded joints are particularly vulnerable because of high local stress concentrations. Fatigue caused by oscillating strain in the plastic range is called “low cycle fatigue”. Cycles to failure are typically below 104. Traditional welded joint S-N curves do not describe the fatigue strength in the low cycle region (< 104 number of cycles). Typical Class Society Rules do not directly address the low cycle fatigue problem. It is therefore the objective of this paper to present a credible fatigue damage prediction method of welded joints in the low cycle fatigue regime.

Download Full-text