摘要
采用热模拟技术研究了X80管线钢粗晶区组织和低温韧性的变化规律,讨论了冷却时间、组织和性能之间的关系.结果表明,焊接粗晶区主要由板条束状贝氏体和粒状贝氏体组成.当t8/5在6～8 s时,粒状贝氏体含量较多,其分割作用使板条贝氏体的方向性减弱,使板条更为细小;M-A组元呈块状,尺寸较小且均匀分布在基体上,冲击韧度最优越;当t8/5增大或减小时,板条束状贝氏体的含量均增加,板条粗大,M-A组元在冷却速度较快时呈长条状,冷却速度较慢时呈块状且相对含量增加,尺寸增大,均使冲击韧度显著下降.
Microstructure and properties of coarse grain heat affected zone strongly influence the quality of welded joints. Thermal simulating technigue was adopted to study the rule and the relationship between microstructure and toughness in coarse grain beat affected zone of high-strength pipeline steel with different cooling time. The results showed that microstructure formed after thermal cycle mainly consisted lath bainite and granular bainite in coarse grain heat affected zone. The morphology of bainite and the shape, size and quantity of M-A(M:martensite, A:austenite) constituent have a great influence on impact toughness. When the cooling time is 6 to 8 seconds, the impact toughness is the highest for the formation of granular bainite which make the lath bainite finer for the function of partition, and block M-A constituent which is small and dispersed. The toughness will decrease when the value of cooling time is lower or higher. The reason of this phenomenon is that the percent of coarse lath bainite increase and M-A constituent is shaped of strip with cooling time of less than 6 s and block for that of greater than 8 s with big size and great quantity.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2005年第6期77-80,共4页
Transactions of The China Welding Institution
关键词
X80管线钢
热模拟
贝氏体
M—A组元
冲击韧度
Bainite
Cooling
Grain size and shape
Heat affected zone
Microstructure
Morphology
Optical microscopy
Scanning electron microscopy
Soldered joints
Steel pipe
Thermal cycling
Toughness
