摘要
为了实现焊接时焊缝金属的纯净化与晶粒细化,减小焊缝的裂纹率。通过碳当量计算公式,判断X80管线钢的淬硬倾向;通过小铁研试验计算了在25℃、50℃、100℃和150℃的预热温度下X80管线钢的焊接裂纹率;利用金相方法分析了裂纹的性质和不同预热温度时焊接接头熔合区的金相组织。结果表明:X80管线钢淬硬倾向较小,焊后一般不需要热处理,小铁研试验出现的裂纹为冷裂纹;随着预热温度的升高,裂纹率显著降低;焊接接头熔合区显微组织为粒状贝氏体+板条贝氏体+铁素体,随着预热温度的升高,线能量的降低,晶粒粗化现象得到缓解,粒状贝氏体组织增加,降低了冷裂纹敏感性。
In order to purify the welding metal,refine the grain and decrease the ratio of the cracks in the wehting metal,the formula of Ceq was employed to judge the hardening tendency.The ratio of the crack of welding X80 pipeline alloy steel was calculated by Tekken type cracking test at the preheating temperature of 25 ℃ .50 ℃ , 100 ℃ and 150℃ ,respectively.Optic microscope was utilized to analyze the properties of the cracks and the microstructure of the melting area of the welding joint at different preheating temperature. The results show that it is unnecessary to conduct post heat due to the low hardening tendency for X80 pipeline steel.The cracks occur in Tekken type cracking test are cold cracks.The ratio of cracks decreases with the increase of the preheating temperature.The microstructure of the melting area of the welding joint is granular bainite,lathing bainite and ferritc.With the increase of preheating temperature and the decrease of the line energy, the phenomena of grain coarsen alleviates, the number of the granular bainite increases and the sensitivity of the cold cracks rcduees.
出处
《电焊机》
2008年第10期66-69,共4页
Electric Welding Machine
