Mechanical Property Estimation of Similar Weld using Ball Indentation Technique

Harshit Kumar Khandelwal,Rahul Chhibber,Kamal Sharma

doi:10.4236/jmmce.2012.1111116

Harshit Kumar Khandelwal, Rahul Chhibber + Show 1 more

Open Access

https://doi.org/10.4236/jmmce.2012.1111116

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Abstract

A weld joint is composed of three principal zones viz., base metal, Heat Affected Zone (HAZ), and weld zone. Thus, the variation in mechanical behavior exists not only among these zones, but also from point to point in each individual zone. Being destructive in nature, the conventional method of mechanical testing cannot successfully used to estimate the variation in the mechanical behavior at different zones of the weld joint. Moreover, the conventional method of mechanical testing cannot characterize the material using small amount of material. In this respect, Ball Indentation (BI) methodology was considered to be useful approach, since it can characterize the mechanical properties of a material using very small amount of material in non destructive manner. The present work is an attempt to characterize the variation in the mechanical properties among each zone (global variation), and from point to point in each zone (local variation) of the similar weld joint used in nuclear application using BI approach. For this purpose, the similar weld joint of two SS-304 LN pipe lines was investigated using BI approach.

Highlights

Ball Indentation (BI) approach is based on multiple indentations at a particular location on the component using a spherical indenter in order to determine mechanical behavior at that location
The mechanical behavior of similar weld joint was characterized using a weld joint of two SS 304 LN pipelines. This weld joint comprised of three principal zones viz., two zones of SS 304 LN base metal and a weld zone, lying in between the two base metal zones. This investigation was carried out in order to study the gradients in the mechanical behavior of subzones of the similar weld joint viz., Weld, Heat Affected Zone (HAZ) and base metal zone
In order to study the gradients in mechanical behavior at these subzones, BI experiments were performed along the three principal zones of weld joint

Summary

Introduction

Pressurized Water Reactor (PWR) is the most widely used reactor type in the world, in which enriched (about 3.2% U-235) uranium dioxide is utilized as the fuel in zirconium alloy cans. The fuel is held in a steel vessel through which water at high pressure (at 16 MPa, to suppress boiling) is pumped to reactor vessel via cold lag pipeline to act as both a coolant and a moderator. After absorbing the heat from the core of reactor, high-pressure water is passed to a steam generator, via hot lag pipeline which raises steam in the usual way. Both hot lag and cold lag pipe lines are made of SS 304 LN material and have the similar weld joint.

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Experimentation

Comparison of Different Zones of Similar Weld Joint