MICROSTRUCTURE AND LOCAL BRITTLE ZONE PHENOMENA IN HIGH-STRENGTH LOW-ALLOY STEEL WELDS
MICROSTRUCTURE AND LOCAL BRITTLE ZONE PHENOMENA IN HIGH-STRENGTH LOW-ALLOY STEEL WELDS
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DOI：
10.1007/bf03350956
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发表时间：
1991-01-01
期刊：
影响因子：
--
通讯作者：
LEE, DY
中科院分区：
文献类型：
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作者：
KIM, BC;LEE, S;LEE, DY
研究了高强度低合金(HSLA)钢焊接接头组织与局部脆性区(LBZ)现象的关系。通过模拟热影响区(HAZ)试验和焊接接头试验，研究了LBZ对韧性的影响。通过缺口圆拉伸试验和随后的扫描电子显微镜(SEM)分析，还确定了与微孔洞和解理微裂纹形成有关的微观机械过程。多道焊接头HAZ中的LBZ是过临界再加热的粗晶HAZ，其性能受有效晶粒度和高碳马氏体岛等冶金因素的强烈影响。实验结果表明，随着马氏体岛数量的增加，夏比能单调下降，证实了马氏体岛是控制HAZ韧性的主要组织因素。此外，在马氏体岛和铁素体基体的界面处还发现了微空洞和微裂纹的萌生，从而导致韧性的降低。这些结果表明，粗晶HAZ中的LBZ现象可以用马氏体岛的形态和数量来解释。
This study is concerned with a correlation between the microstructure and the local brittle zone (LBZ) phenomena in high-strength low-alloy (HSLA) steel welds. The influence of the LBZ on toughness was investigated by means of simulated heat-affected zone (HAZ) tests as well as welded joint tests. Micromechanical processes involved in microvoid and cleavage micro-crack formation were also identified using notched round tensile tests and subsequent scanning electron microscopy (SEM) analyses. The LBZ in the HAZ of a multipass welded joint is the intercritically reheated coarse-grained HAZ whose properties are strongly influenced by metallurgical factors such as an effective grain size and high-carbon martensitic islands. The experimental results indicated that Charpy energy was found to decrease monotonically with increasing the amount of martensitic islands, confirming that the martensitic island is the major microstructural factor controlling the HAZ toughness. In addition, microvoids and microcracks were found to initiate at the interface between the martensitic island and the ferrite matrix, thereby causing the reduction in toughness. These findings suggest that the LBZ phenomena in the coarse-grained HAZ can be explained by the morphology and the amount of martensitic islands.