Assessment of fatigue life and crack growth resistance of friction stir welded AISI 409M ferritic stainless steel joints

The present investigation is aimed at to study the effect of four welding processes namely friction stir welding, gas tungsten arc welding, laser beam welding and electron beam welding on fatigue behavior of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. The fatigue life and fatigue crack growth behavior were evaluated using hourglass and centre cracked tension (CCT) specimens respectively. A 100 kN servo hydraulic controlled fatigue testing machine was used under constant amplitude uniaxial tensile load with stress ratio of 0.1 and frequency of 15 Hz. Fatigue properties are correlated with the tensile, impact toughness, micro hardness, microstructure, fracture surface morphology and residual stress of the welded joints. It is found that the joint fabricated by friction stir welding process showed superior fatigue life and fatigue crack growth resistance compared to other joints. This is mainly due to the synergetic effect of dual phase ferritic-martensitic microstructure, superior tensile properties and favorable residual stress, which inhibit the growth of cracks compared to other joints.

Download Full-text

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.577-578.429 ◽

2013 ◽

Vol 577-578 ◽

pp. 429-432 ◽

Cited By ~ 1

Author(s):

Yukio Miyashita ◽

Kyohei Kushihata ◽

Toshifumi Kakiuchi ◽

Mitsuhiro Kiyohara

Keyword(s):

Fatigue Crack ◽

Fatigue Life ◽

Fatigue Strength ◽

Magnesium Alloy ◽

Crack Initiation ◽

Crack Growth ◽

Fatigue Crack Initiation ◽

Fatigue Tests ◽

Crack Growth Resistance ◽

Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

Download Full-text