The default behavior is whenever you click on any attachment in the work object, it will download the attachment and not view the attachment.
To address your requirement you can configure a custom pdf viewer, which will display the pdf attached in a modal dialog. The steps to configure this has been explained by John and Rett in the below link:
But after the pdf displayed i checked the elements by pressing F12 key
<object class="inline" data="/WWSE/PRServlet/PGPHEhFfGOmgyaVVojR1QqY3wycqXmkQ*/!@ec1c09d2a6ae53681ef2aa6b396d8d35!PS1__TABTHREAD3?pyActivity=BGC-CWS-WWS-Data-OrderSearchResult.ShowPDF width="850" height="850" <="" object=""> <span style="display: none;" uitype="Rule-HTML-Section" id="pzFlowActionUITypeRef" uiref="ShowPDF"></span> <!-- When there is an interest page with no dot, show HTML for that page --> </object>
As shown above we are getting "!@ec1c09d2a6ae53681ef2aa6b396d8d35!PS1__TABTHREAD3" in place of pdf name so the same is getting displayed on screen
How to customize this to display the correct pdf name?