THE EFFECTS OF ALLOY SEGREGATION AND YIELD STRENGTH ON HAZ TOUGHNESS AND SAFETY OF WELDED JOINTS
Several plates of normalised steel are examined to determine the influence of segregation on parent plate fracture properties and the relative influence of segregation and grain coarsened HAZ upon fracture properties in the HAZ. The effect of centreline segregation on parent plate fracture properties is assessed using Charpy impact and CTOD tests. These establish that segregation bands initiate brittle fracture with a shift in transition temperature of greater than 30 C and 20 C for the Charpy impact and CTOD tests respectively. The same tests are used to discover the influence of segregation on the fracture behaviour of the HAZ. At the fusion line the presence of grain coarsened HAZ is the predominant feature controlling brittle fracture initiation, and the influence of all segregation variables studied is marginal. A roller of quenched and tempered steel is evaluated and the fracture behaviour of parent plate and welded joints is analysed. The fracture behaviour of the HAZ is controlled by the presence of grain coarsening in the HAZ. The CTOD and wide plate tests indicate several differences in fracture behaviour in the higher strength steel and show an influence of weld metal yield strength and HAZ softening promoting a greater susceptibility to eventual brittle fracture initiation in the higher strength steel.
Bibliographic Reference: EUR 12485 EN (1990), 155 PP., MF, ECU 8, BLOW-UP COPY ECU 20 THE OFFICE FOR OFFICIAL PUBLICATIONS OF THE EUROPEAN COMMUNITIES, L-2985 LUXEMBOURG
Record Number: 1989128056400 / Last updated on: 1992-08-10
Original language: EN