In the present study,the market needs for the development of steel plates with excellent heat affected zone(HAZ) toughness are analyzed,and the mechanism of the decrease in the HAZ toughness during high-heat input wel...In the present study,the market needs for the development of steel plates with excellent heat affected zone(HAZ) toughness are analyzed,and the mechanism of the decrease in the HAZ toughness during high-heat input welding is discussed.The important countermeasure for improving the HAZ toughness is to employ the technology of oxide metallurgy,namely,to make use of fine inclusion particles for improving the microstructure of HAZ.The progress and theories of oxide metallurgy technologies developed in the Nippon Steel Corporation(NSC),the JFE Steel Corporation and the Kobe Steel Group are illustrated.Steel plates developed by these three companies with excellent HAZ toughness are introduced.展开更多
The microstructure evolution and impact-toughness variation of heat-affected zone(HAZ)in X80 highstrain pipeline steel were investigated via a welding thermal-simulation technique,Charpy impact tests,and scanning elec...The microstructure evolution and impact-toughness variation of heat-affected zone(HAZ)in X80 highstrain pipeline steel were investigated via a welding thermal-simulation technique,Charpy impact tests,and scanning electron microscopy observations under different welding heat inputs and peak temperatures.The results indicate that when heat input was between 17 and 25kJ·cm^(-1),the coarse-grained heat-affected zone showed improved impact toughness.When the heat input was increased further,the martensite-austenite(M-A)islands transformed from fine lath into a massive block.Therefore,impact toughness was substantially reduced.When the heat input was 20kJ·cm^(-1) and the peak temperature of the first thermal cycle was between 900 and 1300°C,a higher impact toughness was obtained.When heat input was 20kJ·cm^(-1) and the peak temperature of the first thermal cycle was 1300°C,the impact toughness value at the second peak temperature of 900°C was higher than that at the second peak temperature of 800°C because of grain refining and uniformly dispersed M-A constituents in the matrix of bainite.展开更多
为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输...为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输入并进行不同线能量焊接工艺模拟。结果表明:试验钢SHCCT冷速为1~10℃/s时,组织类型主要以粒状贝氏体为主,当冷速超过10℃/s时,开始出现板条贝氏体,并且随冷速的增加,相变开始和终了温度降低,贝氏体铁素体基体晶粒尺寸细化,由块状逐渐变为条状,维氏硬度增加。根据组织和硬度变化规律,初步推断高强高韧Q420qE钢适合焊接的热输入范围在45 k J/cm以下。展开更多
文摘In the present study,the market needs for the development of steel plates with excellent heat affected zone(HAZ) toughness are analyzed,and the mechanism of the decrease in the HAZ toughness during high-heat input welding is discussed.The important countermeasure for improving the HAZ toughness is to employ the technology of oxide metallurgy,namely,to make use of fine inclusion particles for improving the microstructure of HAZ.The progress and theories of oxide metallurgy technologies developed in the Nippon Steel Corporation(NSC),the JFE Steel Corporation and the Kobe Steel Group are illustrated.Steel plates developed by these three companies with excellent HAZ toughness are introduced.
文摘The microstructure evolution and impact-toughness variation of heat-affected zone(HAZ)in X80 highstrain pipeline steel were investigated via a welding thermal-simulation technique,Charpy impact tests,and scanning electron microscopy observations under different welding heat inputs and peak temperatures.The results indicate that when heat input was between 17 and 25kJ·cm^(-1),the coarse-grained heat-affected zone showed improved impact toughness.When the heat input was increased further,the martensite-austenite(M-A)islands transformed from fine lath into a massive block.Therefore,impact toughness was substantially reduced.When the heat input was 20kJ·cm^(-1) and the peak temperature of the first thermal cycle was between 900 and 1300°C,a higher impact toughness was obtained.When heat input was 20kJ·cm^(-1) and the peak temperature of the first thermal cycle was 1300°C,the impact toughness value at the second peak temperature of 900°C was higher than that at the second peak temperature of 800°C because of grain refining and uniformly dispersed M-A constituents in the matrix of bainite.
文摘为指导高强高韧Q420qE桥梁钢实际焊接工艺,采用Gleeble-3500热模拟试验机建立了试验钢的SHCCT曲线;针对各模拟样品,采用光学显微镜和透射显微镜观察了显微组织,测定了维氏硬度HV10,并利用Rykalin 2D模型根据冷速反推大致对应的焊接热输入并进行不同线能量焊接工艺模拟。结果表明:试验钢SHCCT冷速为1~10℃/s时,组织类型主要以粒状贝氏体为主,当冷速超过10℃/s时,开始出现板条贝氏体,并且随冷速的增加,相变开始和终了温度降低,贝氏体铁素体基体晶粒尺寸细化,由块状逐渐变为条状,维氏硬度增加。根据组织和硬度变化规律,初步推断高强高韧Q420qE钢适合焊接的热输入范围在45 k J/cm以下。
