低碳贝氏体高强钢Q690CFD焊接粗晶区组织韧性

Microstructure and Toughness in the Coarse Grain Region of Low Carbon Bainite High Strength Steel Plate for Q690CFD

利用Gleeble-2000热模拟试验机对低碳贝氏体高强钢Q690CFD进行不同焊接工艺下的热模拟试验,研究焊接条件下热影响区粗晶区(CGHAZ)组织、韧性及其变化规律。结果表明:CGHAZ组织为板条马氏体;CGHAZ韧性在800～500℃随冷却时间增大而降低;在合适的条件下焊接,CGHAZ可获得很好低温韧性。同时对粗晶区进行了不同温度的焊后处理,研究焊后热处理后组织、韧性变化规律。随着热处理温度的提高,粗晶区冲击韧性呈降低趋势。在250～500℃范围内进行焊后热处理,可以获得优异的冲击韧性。应尽量避免在500℃以上长时间保温处理。

The microstructure and toughness of the coarse-grained heat-affected zone（CGHAZ） of low carbon bainite high strength steel for Q690CFD with different welding processes were investigated by thermal simulation with a Gleeble-2000 thermal simulator.The experimental results indicate that the lath martensite is the dominate microstructure of the CGHAZ,and the toughness of CGHAZ decreases with cooling time increase at 500～800 ℃.With the stress relief（SR） temperature increasing,the impact toughness of the CGHAZ decreases.The CGHAZ has good toughness when the SR temperature at 250～500 ℃.