【摘要】 Q690低合金高强钢基体含碳量及合金元素含量较高,淬硬倾向较大,给实际焊接带来一些困难。为了研究冷却时间t_8/5（从800?℃至500?℃的冷却时间）对焊接热影响区显微组织及冲击韧性的影响,利用Gleeble-3800热模拟试验机,对Q690高强钢在不同热循环条件下进行焊接热影响区热模拟试验。结果表明:随着t_8/5的增大,过热区和不完全相变区-20?℃冲击功先增加后下降,当t_8/5=15?s时,冲击功均达到峰值（过热区为184?J,不完全相变区为163?J）,正火区-20?℃冲击吸收功均在较高水平,均值在197?J以上。综合分析,Q690钢种在实际焊接时,t_8/5应控制在15?s左右,这样得到的产品的组织和性能可以能达到最佳水平。更多还原

【Abstract】 Q690?low-alloy?high-strength?steel?has?higher?carbon?content?and?alloy?element?content,?and?has?a?greater?tendency?to?harden,?which?brings?some?difficulties?to?actual?welding.?In?order?to?study?the?effect?of?cooling?time?t_8/5?（cooling?time?from?800?℃?to?500?℃）?on?the?microstructure?and?impact?energy?of?welding?heat?affected?zone,?the?Gleeble-3800?thermal?simulation?test?machine?was?used?to?conduct?the?thermal?simulation?test?of?the?welding?heat?affected?zone?of?Q690?high-strength?steel?under?different?thermal?cycle?conditions.?The?results?show?that?with?the?increase?of?t_8/5,?the?-20?℃?impact?absorption?energy?in?the?overheating?zone?and?the?incomplete?phase?change?zone?first?increases?and?then?decreases,?when?t_8/5=15?s,?the?impact?energy?reaches?the?peak?value?（184?J?in?the?overheating?zone?and?163?J?in?the?incomplete?phase?change?zone）,?and?the?-20?℃?impact?absorption?energy?in?the?normalizing?zone?is?at?a?relatively?high?level?and?average?above?197?J.?According?to?comprehensive?analysis,?in?actual?welding?of?Q690?steel,?t_8/5?should?be?controlled?at?about?15?s,?and?the?microstructure?and?physical?properties?should?reach?the?best?level.更多还原