Fracture toughness and microstructure of HAZ in thick quenched and tempered high strength low alloy steels

作     者：Zhou, ZhiLiang 

作者机构：Dalian Railway Inst China 

出 版 物：《International Journal for the Joining of Materials》 (Int J Joining Mater)

年 卷 期：1997年第9卷第4期

页      面：153-158页

核心收录：

主　　题：Heat affected zone 

摘      要：Heat-affected zones (HAZ) of high-strength quenched and tempered steels were investigated by means of CTOD fracture toughness tests on multipass weldments. The relation between toughness properties and microstructure was established by thorough examination of microstructure in the vicinity of the fatigue precrack and at the origin of the cleavage crack. HAZ fracture toughness is related to the total size of the coarse grained HAZ along the fatigue precrack front. The fracture toughness decreases with increase in the size of coarse grained HAZ. Initiation of the cleavage fracture is associated with martensite islands in the coarse grained HAZ. Martensite islands, large prior austenite grain size and coarsened structures all contribute to the low toughness of coarse grained HAZ. To improve the HAZ fracture toughness it is necessary to minimize the coarse grained HAZ or to increase the toughness of this region by improving microstructure.