核电站关键设备异种钢焊接接头16MND5/309L熔合线组织性能研究
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摘要
目前国内主流在役核电堆型为二代压水堆型,关键设备的接管与安全端的焊接均采用异种钢焊接接头,其接头形式为:在接管端堆焊不锈钢隔离层(ER309L+ER308L),再用不锈钢焊材(ER308L)与不锈钢安全端进行对接焊。分析研究国内二代核电技术制造的16MND5/309L/308L/Z2CND18-12N异种钢焊接接头16MND5/309L侧熔合线的金相组织、冲击性能、显微维氏硬度分布、微曲线能谱及断口形貌。结果表明,16MND5/309L侧熔合线冲击性能普遍偏低,部分区域存在脆性断裂,断裂位置一般位于熔合线附近的马氏体带上,以沿晶断口为主,马氏体带整体分布不均匀,且宽度范围无明显规律。16MND5/309L侧熔合线附近硬度值最高,硬度值向16MND5/309L界面两侧呈递减趋势,且在16MND5侧靠近熔合线附近(约0.5～1 mm)出现明显的硬度降低区域。16MND5/309L界面处产生碳迁移和脆性过渡层(马氏体带)明显,在熔合线两侧产生一个增碳层和脱碳层,造成16MND5/309L侧熔合线冲击韧性严重下降。
At present,the domestic mainstream nuclear power reactor type is the second-generation pressurized water reactor type. The nozzle and safety end of the key equipment are welded with different types of steel welded joints. The joint type is: the surfacing of stainless steel isolation layer(ER309L+ER308L) is conducted at the nozzle end, and then the butt welding of stainless steel welding consumables(ER308L) and stainless steel safety end is conducted. The metallurgical structure,impact properties,micro Vickers hardness distribution,micro-curve energy spectrum and fracture morphology of 16MND5/309L side bond line of 16 MND5/309L/308L/Z2CND18-12N dissimilar steel welded joints made by domestic second generation nuclear power technology are analyzed. The results show that the impact performance of the 16MND5/309L side bond line is generally low,and there are brittle fractures in some areas. The brittle fracture is generally located in the martensite zone near the bond line,mainly along the crystal fracture,and the overall distribution of the martensite zone is not uniform,and the width range has no obvious rule. The hardness value of the 16MND5/309L side bond line is the highest,and the hardness value reduces towards both sides of the 16MND5/309L interface,and a significant hardness reduction area appears near the bond line(about 0.5～1 mm) on the 16MND5 side. The carbon migration and brittle transition layer(martensite zone) at the interface of 16 MND5/309L are obvious,and a recarburization layer and a decarburization layer are formed on both sides of the bond line,resulting in a serious decline in the impact toughness of the 16MND5/309L side bond line.
At present,the domestic mainstream nuclear power reactor type is the second-generation pressurized water reactor type. The nozzle and safety end of the key equipment are welded with different types of steel welded joints. The joint type is: the surfacing of stainless steel isolation layer(ER309L+ER308L) is conducted at the nozzle end, and then the butt welding of stainless steel welding consumables(ER308L) and stainless steel safety end is conducted. The metallurgical structure,impact properties,micro Vickers hardness distribution,micro-curve energy spectrum and fracture morphology of 16MND5/309L side bond line of 16 MND5/309L/308L/Z2CND18-12N dissimilar steel welded joints made by domestic second generation nuclear power technology are analyzed. The results show that the impact performance of the 16MND5/309L side bond line is generally low,and there are brittle fractures in some areas. The brittle fracture is generally located in the martensite zone near the bond line,mainly along the crystal fracture,and the overall distribution of the martensite zone is not uniform,and the width range has no obvious rule. The hardness value of the 16MND5/309L side bond line is the highest,and the hardness value reduces towards both sides of the 16MND5/309L interface,and a significant hardness reduction area appears near the bond line(about 0.5～1 mm) on the 16MND5 side. The carbon migration and brittle transition layer(martensite zone) at the interface of 16 MND5/309L are obvious,and a recarburization layer and a decarburization layer are formed on both sides of the bond line,resulting in a serious decline in the impact toughness of the 16MND5/309L side bond line.
引文
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[11]袁义帆,卢煦,杨星红.16MND5/309L/308L/Z2CND18-12N异种金属焊接件的组织和性能[J].理化检验:物理分册,2014(6):404-408.
[12]Ming Hongliang,Zhang Zhiming,Wang Jianqiu.Microstructural characterization of an SA508-309L/308L-316L domestic dissimilar metal welded safe-end joint[J].Materials Characterization,2014,97(11):101-115.
[2]周灵军.异类异种钢焊接问题及对策[J].化工机械,2011(3):375-376
[3]刘海云,吴宇.异种钢焊接接头熔合区马氏体带的化学成分和组织结构[J].太原理工大学学报,1999(6):598-601.
[4]王爱珍,张太超,赵红岩.异种钢熔合区马氏体脆性层的消除[J].焊接学报,2001(4):58-62.
[5]王家淳,吴家桢.超低碳奥氏体不锈钢带极电渣堆焊接头的熔合区特征[J].焊接,1999(6):13-15.
[6]王海涛,王国珍,轩福贞,等.核压力容器异种金属焊接接头延性断裂行为数值研究[J].核动力工程,2012(5):36-40.
[7]杨世柏,潘春旭,杨红霞.母材碳含量对A/F钢焊接熔合区断口形态的影响[J].武汉交通科技大学学报,1995(3):223-227.
[8]潘春旭,孙国正.异种钢焊接性的研究现状和进展[J].水利电力机械,1998(3):42-47.
[9]杜兵,李彦.异种钢接头熔合区的脆化与断裂行为[J].焊接学报,1998(1):8-12.
[10]王昱成,李卫东.异种钢熔合区马氏体相变过程及组织[J].焊接学报,1999(3):147-152.
[11]袁义帆,卢煦,杨星红.16MND5/309L/308L/Z2CND18-12N异种金属焊接件的组织和性能[J].理化检验:物理分册,2014(6):404-408.
[12]Ming Hongliang,Zhang Zhiming,Wang Jianqiu.Microstructural characterization of an SA508-309L/308L-316L domestic dissimilar metal welded safe-end joint[J].Materials Characterization,2014,97(11):101-115.