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A. K. Bhaduri ¹, S. J. Ray ¹, P. Rodriguez ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, IN

Abstract

A simple test procedure that can substitute the Charpy test for the estimation of ductile fracture toughness of the weakest region of a weld joint has been evolved. This approach explocits the conventional tension test with smooth round specimens, and stipulates that the post necking regime in this test is dominated by micro-void growth and coalescence processes. The method of computing two new toughness parameters from the load-elongation data of the tensile test is described. The effect of aging of the 2.25 Cr - 1 Mo steel HAZ in the Alloy 800/2.25 Cr - 1 Mo steel dissimilar metal joint (welded with inconel 182 electrodes) was studied to demonstrate the application, efficacy and sensitivity of these estimates of fracture toughness.

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P. Rodriguez ¹, T. P. S. Gill ¹

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102, IN

Abstract

The weldability of any material can be classified into two categories namely, weldability for fabrication and weldability for service. While the weldability for service aspects have received considerable attention from research workers in India, the weldability for fabrication has been a neglected field. This paper reviews the above two aspects of weldability as applied to common fabrication materials. The available information has been critically analysed and areas where further research efforts should be directed are outlined.

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S. K. Albert ¹, T. P. S. Gill ¹, P. Rodriguez ¹, S. L. Mannan ¹, S. D. Kulkarni ²

Affiliations
1 Indira Gandhi Centre for Atomic Research, Kalpakkam, IN
2 Indian Institute of Technology, Powai, Mumbai, IN

Abstract

Hardness variation in the Cr-Mo steel weld metal as a function of Cr content and weld cooling rate was studied Chromium in the weld metal was varied by adding known amount of high purity Cr into the weld pool produced by a stationary arc. The cooling rate of the weld was measured by plunging W-Rh thermocouple in to the weld pool just at the time of extinguishing the arc and measuring the variation in temperature as a function of time using a X-t recorder. The microstructural studies revealed that in the low Cr steels the structure varied from fully martensitic to a mixture of bainite and martensite as the weld cooling rate decreased while for weld metal with Cr content higher than 5 wt% the structure remained fully martensitic irrespective of the cooling rate. The measured hardness of the weld metal for different Cr contents and cooling rates was compared with that predicted by Yurioka's and Hart's formulae. It was found that Yurioka’s formula can be used to predict the hardness of the weld metal with reasonable accuracy. It was further noticed that there is a reduction in the maximum hardness at Cr content above 5wt% and it is attributed to the presence of delta ferrite in the weld metal.

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