细晶组织耐候钢热影响区粗晶区的组织和性能

 采用焊接热模拟技术研究了焊接热循环对细晶组织09CuPCrNi钢热影响区粗晶区 (CGHAZ)显微组织和性能的影响。结果表明，在800~500 ℃冷却时间t8/5≤8 s时，该钢CGHAZ组织为贝氏体和少量马氏体。随着t8/5延长，在原奥氏体晶界上逐渐析出先共析铁素体，当t8/5＞18 s时，显微组织由大量铁素体和珠光体组成，且原奥氏体晶粒明显粗化，先共析铁素体含量增加。在-20 ℃和0 ℃下，t8/5对冲击吸收功影响较小，在-40 ℃时，随着t8/5延长，冲击吸收功下降显著，而且随着t8/5延长，CGHAZ硬度逐渐下降，但硬度值均高于母材，焊接热影响区相对于母材未出现软化倾向。

Microstructure and Mechanical Properties of Coarse Grain Heat Affected Zone of Fine Grained Antiweathering Steel

The effects of welding thermal cycle on the microstructure and mechanical properties of the coarse grained heat affected zone (CGHAZ) of fine grained antiweathering steel are studied by using thermal simulation test. The results indicate that the HAZ microstructure of the steel is bainite and a little martensite when the cooling time from 800 ℃ to 500 ℃ (t8/5) is less than 8 s. With longer t8/5, proeutectoid ferrite gradually occurs on the original austenite grain boundary. When t8/5 is longer than 18 s, the microstructure consists of ferrite and pearlite, and the original austenite grain size is obviously coarsened with increased proeutectoid ferrite. With longer t8/5, the impact toughness of CGHAZ at -20 ℃ and 0 ℃ decreases slowly; but the -40 ℃ toughness decreases remarkably. The hardness of CGHAZ is decreased gradually with longer t8/5, but it is higher than that of base metal. There is no softened zone in HAZ.