工程机械用960QT钢焊接粗晶区组织及性能研究
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摘要
采用热模拟技术研究了960QT高强钢不同t_(8/5)条件下热影响区粗晶区(CGHAZ)的组织和性能,获得热影响区连续冷却转变曲线。得到的结果为:t_(8/5)在3～6s,硬度值变化不大,CGHAZ组织为板条马氏体。t_(8/5)=10 s,可见板条贝氏体,随着t_(8/5)的增加,组织中板条贝氏体逐渐增加,而板条马氏体逐渐减少,CGHAZ显微硬度逐渐降低。当t_(8/5)达到150 s后,组织中出现粒状贝氏体,显微硬度进一步降低。当t_(8/5)> 600 s后,显微组织以粒状贝氏体为主。利用实测热影响区t_(8/5)数据,建立了960QT钢t_(8/5)值与线能量(E)的关系式。t8/5为30 s时,粗晶区显微硬度(325 HV1)与母材相当(330 HV1)。焊接时应控制热输入,使t_(8/5)小于30 s,不预热条件下线能量应小于1.4kJ/mm。
The microstructure and property of the coarse grained heat affected zone( CGHAZ) of 960 QT steel was studied under t_(8/5) by using thermal simulation technology, and the continuous cooling transformation curve of the heat affected zone(SH-CCT diagram) was acquired. The results show that, the microstructure of the CGHAZ consists of lath martensite and the hardness values change little as t_(8/5) is 3～6 s. When t_(8/5)=10 s, lath bainite appears. With the increase of t_(8/5), the lath martensite reduces and lath bainite increases, and the microhardness of CGHAZ gradually reduces. When t_(8/5) reaches150 s, granular bainite in structure is found the microhardness is further reduced. As t_(8/5)>600 s, the CGHAZ mainly consists of granular bainite. Based on the measured heat affected zone t_(8/5), the relationship between t_(8/5) values and heat input E of steel 960 QT is established. As t_(8/5) is 30 s, the microhardness of CGHAZ(325 HV1) is equal to the base metal(330 HV1). So the heat input should be controlled to ensure that t_(8/5) is less than 30 s. Under non-preheating conditions, the heat input should be less than 1.4 kJ/mm.
The microstructure and property of the coarse grained heat affected zone( CGHAZ) of 960 QT steel was studied under t_(8/5) by using thermal simulation technology, and the continuous cooling transformation curve of the heat affected zone(SH-CCT diagram) was acquired. The results show that, the microstructure of the CGHAZ consists of lath martensite and the hardness values change little as t_(8/5) is 3～6 s. When t_(8/5)=10 s, lath bainite appears. With the increase of t_(8/5), the lath martensite reduces and lath bainite increases, and the microhardness of CGHAZ gradually reduces. When t_(8/5) reaches150 s, granular bainite in structure is found the microhardness is further reduced. As t_(8/5)>600 s, the CGHAZ mainly consists of granular bainite. Based on the measured heat affected zone t_(8/5), the relationship between t_(8/5) values and heat input E of steel 960 QT is established. As t_(8/5) is 30 s, the microhardness of CGHAZ(325 HV1) is equal to the base metal(330 HV1). So the heat input should be controlled to ensure that t_(8/5) is less than 30 s. Under non-preheating conditions, the heat input should be less than 1.4 kJ/mm.
引文
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[3]杨林,宋岱岳,刘洋,等.退火对BWELDY960QL焊接接头组织与性能的影响[J].沈阳工业大学学报,2013, 35(2):161-165.
[4]陈伟,闫强军,张仪杰.高强度工程机械用钢Q960E焊接试验研究[J].宽厚板,2018, 24(1):7-9.
[5]王芝玲,委福祥,于跟喜.强度匹配对WELDOX960钢焊接接头组织与性能的影响[J].热加工工艺,2014, 43(5):175-177.
[6]许红,李亚江,马群双,等.液压支架用Q890/Q960高强钢焊接裂纹敏感性研究[J].现代焊接,2014, 31(6):30-33.
[7]王芝玲.强度匹配对WELDOX960钢焊接接头组织与性能的影响[C]//中国职协2015年度优秀科研成果获奖论文集.2015.
[8]田德允,张瑞成,翁志刚,等.微合金高强钢焊接热影响区中粒状贝氏体微观结构的实验研究[J].金属学报,2000, 36(2):181-186.
[9]崔冰.工程机械用960MPa级高强钢焊接热影响区组织与性能研究[D].昆明:昆明理工大学,2016.
[10]曹志民,张贵锋,张建明,等.Q690C粒状贝氏体钢MAG焊接头中M-A组元的演变及其对热影响区冲击韧度的影响[J].机械工程学报,2014, 50(20):84-92.
[11]王爱华.焊接材料对海洋平台用高强钢接头组织和低温韧性的影响[J].热加工工艺,2015, 44(15):178-180.
[12]许冰,陈春焕,陈增有,等.WELDOX960E高强钢MAG焊焊接接头组织形态与力学性能研究[J].制造技术与机床,2013, 42(12):60-63.