P460NL1钢的焊接热影响区粗晶区组织和性能

Micros Structure and Property of the Coarse-Grained Zone in Weld P460NL1Steel by Thermal Simulation

利用焊接热模拟手段和冲击实验方法研究了国产新型低合金高强钢P46 0NL1焊接热影响区 (HAZ)粗晶区的组织和性能在连续冷却转变过程中的变化 ,发现随着 80 0℃到 5 0 0℃冷却时间 (t8/5)的增加 ,该区的组织、性能都随之而发生变化 ,当t8/5<2 0s时 ,热影响区粗晶区组织为贝氏体、铁素体和马氏体组织 ,它具有优良的综合机械性 ,但在焊前必须预热·当t8/5>2 0s ,t8/5<6 0s时 ,热影响区粗晶区组织为羽毛状上贝氏体、铁素体 ,其性能逐渐变坏·因而在实际生产中建议严格限制使用大的焊接线能量 ,以确保焊接热影响区的机械性能·

The coarse grained zone in the heat affected zone(HAZ) of a new high strength low alloy steel P460NL1 was studied using themally simulated specimens. It was found that with the increase of the cooling time from 800?℃ to 500?℃ ( t 8/5 ), the properties and microstructure are changed gradually. When ( t 8/5 )<20?s, the microstructure in the coarse grained zone in HAZ becomes acceptable. When cooling time from 800?℃ to 500?℃ is longer than 20?s, the granular bainite and ferite are fomed which results in poor mechanical properties. It is shown that the steel should be preheated before weld in order to avoid weld cool crack.