Fenomena Temper Embrittlement Pada Baja Martensitik AISI 410 Untuk Aplikasi Stem Gate Valve 20” Class 150 Grade WCB [Temper Embrittlement Phenomena of AISI 410 Martensitic Steel for Stem Gate Valve 20” Class 150 Grade WCB ]

Abstract

Temper embrittlement is a phenomenon that will decrease the toughness of steel due to tempering process at a certain temperature range. This phenomenon has been found in martensitic steel. This research is investigated the failure in stem gate valve of crude oil pipeline system. The stem gate valve material is made of stainless steel AISI 410. Several examinations were done to study cause of failure in stem gate valve such as visual inspection, chemical composition test using OES (optical emission spectrometer) and EDS (energy dispersive spectrometry), metallography observation by using optical microscopy (OM) and SEM (scanning electron microscopy), fractography using SEM, and Rockwell hardness test. Chemical composition test result on stem gate valve showed 13.65-13.67 wt.% Cr. The content of Cr in stem material is out from the required composition of AISI standard with the requirement of Cr amount 13.5 wt.%. Fractography result on the surface of failure stem area by SEM was observed intergranular crack followed by secondary crack. Its indicated that stem gate valve failure was caused by temper embrittlement due to tempering process.