Abstract：The present study focuses on the toughness properties in the weld heat-affected zone (HAZ) of 1000MPa grade high-performance steel, which is commonly used in construction machinery. Single and multi-pass HAZ were simulated by the Gleeble1500system. The microstructures and fracture surfaces were analyzed by scanning electron microscopy and transmission electron microscopy. The results of the crack propagation path showed that the crack propagation path of coarse-grained HAZ (CGHAZ) was shorter than fine-grained HAZ (FGHAZ), although both regions have identical lath bainite structures, because FGHAZ has smaller prior austenite grain and packet sizes, which can act as effective barriers to crack propagation. The crack propagation path of intercritically reheated CGHAZ (ICCGHAZ) was the shortest among local zones in the HAZ, due to rapid crack initiation and propagation via the massive martensite–austenite (M–A) constituent.
2019, Vol. 38 