Microstructural evolution and mechanical properties of weld joints of centrifugally cast furnace tubes with different contents of Ti and W are investigated via field emission scanning electron microscopy (FESEM) equipped with energy-dispersive X-ray spectroscopy, tensile testing machine and creep testing machine. The results show that high temperature performance of weld joints of 25Cr35NiNb+MA (micro alloy) and 35Cr45NiNb+MA furnace tube with addition of Ti and W is significantly higher than that of the weld joints without Ti and W. Micro alloying element Ti significantly affects the microstructures of weld joints. The microstructure of the original welded joints with high Ti content is NbTiC, and it partially transformed to G phase (Ni16Nb6Si7) during aging, which has poor creep resistance. Both NbTiC and NbC are present in the original welded joints with low Ti content, which totally transformed to G phase after high temperature aging. Micro alloying element W could improve high temperature performance of weld joints by solid solution strengthening.
[1] 连晓明, 陈学东, 吕运容, 等. 高温时效对25Cr35Ni-Nb合金碳化物的影响[J]. 压力容器, 2011, 28(8):1-5 Lian Xiaoming, Chen Xuedong, Lü Yunrong, et al. Influence of high temperature aging on the carbides of 25Cr35Ni-Nb alloys[J]. Pressure Vessel Technology, 2011, 28(8):1-5, doi:10.3969/j.issn.1001-4837.2011.08.001
[2] 陈涛, 陈学东, 艾志斌, 等. 长期服役后乙烯裂解炉管KHR45A高温氧化现象研究[J]. 压力容器, 2010, 27(1):1-4 Chen Tao, Chen Xuedong, Ai Zhibin, et al. Investigation on oxidation phenomena of KHR 45A alloy fuenace tube in ethylene pyrolysis after long term service at high temperature[J]. Pressure Vessel Technology, 2010, 27(1):1-4, doi:10.3969/j.issn.1001-4837.2010.01.001
[3] 耿鲁阳, 巩建鸣, 姜勇. 对多起乙烯裂解炉HP型炉管失效原因发分析总结[J]. 压力容器, 2011, 28(12):48-53 Geng Luyang, Gong Jianming, Jiang Yong. Failure analysis for several accidents of HP type ethylene pyrolyzing tubes[J]. Pressure Vessel Technology, 2011, 28(12):48-53, doi:10.3969/j.issn.1001-4837.2011.12.009
[4] 郑显伟. 我国乙烯裂解炉辐射炉管的使用状况[J]. 压力容器, 2013, 30(5):45-52 Zheng Xianwei. Status of using of ethylene pyrolysis furnace tube in china[J]. Pressure Vessel Technology, 2013, 30(5):45-52, doi:10.3969/j.issn.1001-4837.2013.05.009
[5] 陈涛, 陈学东, 艾志斌, 等. 35Cr45NiNb+微合金裂解炉管焊缝开裂原因分析[J]. 金属热处理, 2015, 40(增刊):365-370 Chen Tao, Chen Xuedong, Ai Zhibin, et al. Failure analysis of cracked weld joint of 35Cr-45Ni-Nb+Micro alloy ethylene pyrolysis furnace tube[J]. Heat Treatment of Metals, 2015, 40(增刊):365-370
[6] 陈涛, 陈学东, 吕运容, 等. 国产乙烯裂解炉管抽样检测状况[J]. 压力容器, 2014, 31(3):45-55 Chen Tao, Chen Xuedong, Lü Yunrong, et al. Status of sampling testing of ethylene pyrolysis furnace tubes in China[J]. Pressure Vessel Technology, 2014, 31(3):45-55, doi:10.3969/j.issn.1001-4837.2014.03.008
[7] Chen Tao, Chen Xuedong, Lian Xiaoming, et al. Effect of Ti additions on microstructure and mechanical properties of centrifugally cast 25Cr-35Ni-Ni alloy[C]//Proceedings of the ASME 2016 Pressure Vessels & Piping Division Conference, Vancouver, BC, Canada, 2016.
[8] 阳大云, 张炫, 金涛, 等. 钴、钨和钛对镍基单晶高温合金持久性能的影响[J]. 稀有金属材料与工程, 2005, 34(8):1295-1298 Yang Dayun, Zhang Xuan, Jin Tao, et al. The influence of cobalt, tungsten and titanium on stress-rupture properties of nickel-base single crystal superalloy[J]. Rare Metal Materials and Engineering, 2005, 34(8):1295-1298, doi:10.3321/j.issn:1002-185X.2005.08.029
[9] Liu Chunjiao, Chen Xuedong, Chen Tao, et al. Phase transformation of Nb in carburized zone of 25Cr35NiNb+MA alloy after service[J]. Procedure Engineering, 2015, 130:693-700. doi:10.1016/j.proeng.2015.12.165
[10] Bogdan Piekarski. Effect of Nb and Ti additions on microstructure, and identification of precipitates in stabilized Ni-Cr cast austenitic steels[J]. Materials Characterization, 2001, 47(3):181-186.
[11] Nunes F. Microstructural changes caused by yttrium addition to Nb, Ti-modified centrifugally cast HP-type stainless steels[J]. Materials Characterization, 2007, 58(2):132-142. doi:10.1016/j.matchar.2006.04.007
[12] 阳大云, 金涛, 赵乃仁, 等. 钴、钨和钛对镍基单晶高温合金铸态组织的影响[J]. 航空材料学报, 2003, 23(z1):17-20 Yang Dayun, Jin Tao, Zhao Naireng, et al. The influence of cobalt, tungsten and titanium on the as-cast microstructure of single crystal nickel-base single superalloys[J]. Journal of Aeronautical Materials, 2003, 23(z1):17-20, doi:10.3969/j.issn.1005-5053.2003.z1.005
[13] Chen Tao, Chen Xuedong, Lü Yunrong, et al. Effects of trace Pb on creep and fracture of 25Cr35Ni-Nb alloy[C]//ASME PVP2015, Boston, USA, July, 2015.
[14] Chen Tao, Chen Xuedong, Ye Juan. Sulfur effects on high-temperature creep and fracture behavior of 25Cr35Ni-Nb alloys[J]. Journal of Pressure Vessel Technology, 2014, 136, 041407(1-7).
