论文部分内容阅读
通过焊接热模拟试验,模拟不同热输入下Q1100粗晶区的热循环过程。采用示波载荷冲击试验机检测焊接热模拟试样的冲击韧性,结合OM、SEM观察试样的显微组织和断口形貌;采用TEM观察和Lepera腐蚀,研究不同冷速下M-A组元数量、形貌和分布情况,分析不同热输入对粗晶区显微组织特征与冲击韧性的影响规律。研究结果表明,随焊接热输入的增大,粗晶区的组织由板条马氏体转变为板条马氏体+板条贝氏体的混合组织,最终转变为粗大的粒状贝氏体,原始奥氏体晶粒尺寸逐渐增大;-20℃下的冲击韧性呈现先增大后减小的趋势,焊接热输入为14.95 k J/cm时,相互交割的马贝混合组织使Q1100的粗晶区具有最优的韧性。M-A组元的形成和原奥晶粒尺寸的增大是大热输入下造成韧性下降的主要原因。
Through the thermal simulation test of welding, the thermal cycling of Q1100 coarse grain region under different heat input was simulated. The impact toughness of the welded hot simulation specimen was measured by oscillometric load impact tester. The microstructure and fracture morphology of the specimen were observed by OM and SEM. The TEM observation and Lepera corrosion test were used to study the effect of different cold conditions on the number of MA components, Morphology and distribution, analysis of different heat input on the coarse grain microstructure characteristics and impact toughness of the law. The results show that the microstructure changes from lath martensite to lath martensite + lath bainite and finally to coarse granular bainite with the increase of welding heat input. The initial austenite grain size increases gradually; the impact toughness increases first and then decreases at -20 ℃; when the welding heat input is 14.95 kJ / cm, the interlaced Mabe mixed tissues make the coarse Q1100 coarse Crystal zone has the best toughness. The formation of M-A element and the increase of the original austenite grain size are the main reasons for the decrease of toughness under the heat input.