Carbide precipitation in HAZ of multipass welds in titanium containing and titanium free supermartensitic stainless steels Part 2 – Weld simulation studies

Abstract

Two pass weld simulation has been used to investigate the precipitation mechanism of carbides in the coarse grained heat affected zones (HAZ) of two supermartensitic stainless steels, one high grade steel containing titanium and the other medium grade alloy without titanium. Recently, a model for such carbide precipitation has been proposed. 1 According to this model, reheating of the HAZ in the martensitic stage is needed to provoke strong carbide formation. In the present work, the peak temperatures of the first and the second heating passes, the holding time during the second (reheating) pass and the holding temperature between the two passes have been varied in order to find the most favourable conditions for carbide precipitation in the two steels. In addition, measurements of the chromium content across prior austenite grain boundaries have been made for the titanium free steel.

Influence of tempering treatment on microstructure and pitting corrosion resistance of a new super ferritic–martensitic–austenitic stainless steels with 17%Cr

“…First, Cr carbide precipitation is prone to happen even if the steel is stabilised. 12 Second, the formation of interlath and intergranular austenite in the 2 XRD from specimens Q, QT650 and DT1 domains of martensite islands may also create Cr-rich and Cr-depleted zones. The reversed austenite has high Ni, but low Cr, Mo and W contents when compared to the adjacent tempered martensite.…”

Anodic behaviour of supermartensitic stainless steel weldments

“…Thus, top and single pass weldments are not susceptible to precipitation. 2,3 Pitting corrosion may occur due to the susceptible sites of chromium impoverishment as reported in the literature. [4][5][6] However, the literature 7 shows that the HAZ is not the most susceptible region in relation to pitting corrosion.…”