Nickel based superalloy Inconel 718 and low alloy steel EN24 are welded by continuous drive friction welding in annealed condition and then post-weld heat treated (PWHT). The welds exhibit low strength and high toughness in the as welded condition. Post-weld heat treatment applicable to either Inconel 718 or EN24, led to reduction in toughness and increase in strength. Toughness degradation after PWHT as per Inconel 718 was predominant. The observed trends in mechanical properties are explained on the basis of observed microstructure, fracture behaviour, electron probe microanalysis and X-ray diffraction. © 2009 Institute of Materials, Minerals and Mining.

M. Kamaraj

Department of Metallurgical and Materials Engineering

Budaraju Srinivasa Murty

DISSIMILAR METAL WELDS

EN24

Fracture behaviour

HIGH TOUGHNESS

Inconel 718

LOW ALLOY STEELS

Nickel- based superalloys

POST WELD HEAT TREATMENT

POST-WELD HEAT TREATED

X- RAY DIFFRACTION

DISSIMILAR METALS

Electron probe microanalysis

Fracture

Friction

Friction welding

Mechanical properties

Photodegradation

tribology

Welds

Welding

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Continuous drive friction welding of Inconel 718 and EN24 dissimilar metal combination

Materials Science and Technology

The disposal of used automobiles tyres is a major environmental concern of the day. Annually, there are 1.2 billion tyres seeking disposal issues globally. Concrete as a major construction material can potentially adopt processed rubber waste—derived from tyres as a partial replacement for aggregates. The present study is focused on mechanical and thermal properties of concretes with rubber as partial replacement to well-graded conventional aggregates. The study includes replacement of 10, 20, 30 and 100% of coarse aggregate with waste tyre aggregates and was compared with conventional M30 grade concrete. Concretes were subjected a thermal cyclic heating of 50 °C for a period of 7 days. The results showed that the weight of the rubber concrete is reduced by 12% compared to the conventional concrete and the strength of the concrete reduces with the increase in rubber content. At ambient temperatures, the rubber concrete was found thermally stable. The compressive strengths were found increasing after cyclic heating of 50 °C for a period of 7 days. This effect may be due the effect of Portland pozzolana cement which has 30% of fly ash in it. From this study, it can be concluded that rubber waste concretes can be a potential candidate for structural and non-load bearing structures at ambient temperatures. © 2019, Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

On Mechanical and Thermal Properties of Concretes with Rubber as Partial Replacement to Well-Graded Conventional Aggregates

This research work articulates the microstructural features of the dissimilar weldments involving Ni based superalloy Inconel 718 and martensitic stainless steel, AISI 416 that is difficult to weld. Autogenous tungsten inert gas (TIG) welding was carried out with and without using flux to fabricate these bimetallic combinations. Microstructure at the fusion zones and the interfaces were characterized using optical and scanning electron microscopy. The results depicted the presence of fine martensite at the heat affected zone (HAZ) of AISI 416 and the formation of unmixed zone containing secondary phases at the HAZ of Inconel 718. Similarly, the formation of Nb rich eutectics along with sulfides was witnessed at the fusion zone of both the weldments. Owing to the low heat input witnessed during the flux assisted TIG welding, the Nb segregation was found to be minimal. Tensile studies reported that the fracture occurred at the fusion zone in both the cases. It was inferred from the tensile studies that the joint strength of the weldments with flux addition was greater than the ones without flux. This study demonstrated that dissimilar joints with complete penetration could be achieved in single pass using the TIG welding process with the aid of flux.

Materials & Design

Effect of flux addition on the microstructure and tensile strength of dissimilar weldments involving Inconel 718 and AISI 416

Journal	Materials Science and Technology
ISSN	02670836
Open Access	No