A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brit...A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brittleness.A joint with good formability and tensile properties was obtained.The microstructure and element distribution of the joint were observed by metallographic microscopy,scanning electron microscopy and electron probe microanalysis.The shear resistance exhibited an initial increase,followed by a subsequent decrease,with an increase in heat input.It reached a maximum value of 2470 N at a welding energy of 267 kJ/m.The Fe-Ti brittle IMCs in TC4/DP780 joints are replaced by Fe-Cu phase and Cu-Ti phase,which reduces the brittleness at TC4/DP780 interface.The results show that the TC4/DP780 joint forms numerousα-Cu andγ-Fe solid solutions through the mutual diffusion and solid solution between H62 and TC4 layers of metals,which effectively inhibits the diffusion of Ti atoms and reduces the formation of brittle Ti-Fe IMCs.At the H62/TC4 interface,a composite layer composed of Cu-Ti IMCs and Cu-based solid solutions is formed.The composite layer grows dendritically from the TC4 alloy to the H62 interlayer.The microstructure at the TC4/DP780 interface changes from fine dendrites to coarse dendrites with the increase in Ti content and heat input.When the heat input is lower,the interfacial elements do not react sufficiently.When the heat input is excessive,microcracks appear at the TC4/DP780 interface,which limits the improvement of mechanical properties of TC4/DP780 joint.展开更多
研究了热镀锌DP780电阻点焊性能,并优化其点焊参数。通过测量焊接接头的熔核直径、熔透率、压痕深度,观察焊接接头显微组织,检测焊接接头硬度、抗剪力及正拉力等参数,综合评价热镀锌DP780点焊性能。结果表明:DP780热镀锌板因其合金含量...研究了热镀锌DP780电阻点焊性能,并优化其点焊参数。通过测量焊接接头的熔核直径、熔透率、压痕深度,观察焊接接头显微组织,检测焊接接头硬度、抗剪力及正拉力等参数,综合评价热镀锌DP780点焊性能。结果表明:DP780热镀锌板因其合金含量高的特点,点焊性能良好,但焊接工艺窗口较窄。当电极压力为3.5 k N,焊接电流为9.5 k A时,最佳焊接时间为300~400 ms,当焊接电流为10.5~11.5 k A时,焊接时间在200~400 ms均可。DP780热镀锌板点焊接头显微组织为马氏体和铁素体,这种焊接接头的组织决定了其塑性比仅有8%~30%,接头硬度值稍高。焊点的失效形式均为熔核剥离失效。展开更多
通过测量点焊接头的熔核直径、熔透率,检测接头抗剪力、硬度,分析接头显微组织构成及形态,评价DP780冷轧板电阻点焊性能,并给出试验条件下的可焊工艺范围,以及最优工艺参数。结果表明:DP780冷轧板点焊性能良好,当电极压力为3 k N时,焊...通过测量点焊接头的熔核直径、熔透率,检测接头抗剪力、硬度,分析接头显微组织构成及形态,评价DP780冷轧板电阻点焊性能,并给出试验条件下的可焊工艺范围,以及最优工艺参数。结果表明:DP780冷轧板点焊性能良好,当电极压力为3 k N时,焊接电流可取8~10 k A,焊接时间可取200~400 ms,但焊接电流10 k A,焊接时间400 ms不可取;电极压力为4 k N时,焊接电流可取8~9 k A,焊接时间可取200~400 ms,但焊接电流9 k A,焊接时间400 ms不可取;最优工艺参数为焊接电流9 k A,焊接时间300 ms,电极压力4 k N;熔核区显微组织为粗大板条状马氏体+铁素体,马氏体呈现柱状晶形态,热影响区显微组织为块状马氏体+铁素体;母材硬度(HV)为240,熔核区硬度(HV)为420。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52001141 and 52475360).
文摘A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brittleness.A joint with good formability and tensile properties was obtained.The microstructure and element distribution of the joint were observed by metallographic microscopy,scanning electron microscopy and electron probe microanalysis.The shear resistance exhibited an initial increase,followed by a subsequent decrease,with an increase in heat input.It reached a maximum value of 2470 N at a welding energy of 267 kJ/m.The Fe-Ti brittle IMCs in TC4/DP780 joints are replaced by Fe-Cu phase and Cu-Ti phase,which reduces the brittleness at TC4/DP780 interface.The results show that the TC4/DP780 joint forms numerousα-Cu andγ-Fe solid solutions through the mutual diffusion and solid solution between H62 and TC4 layers of metals,which effectively inhibits the diffusion of Ti atoms and reduces the formation of brittle Ti-Fe IMCs.At the H62/TC4 interface,a composite layer composed of Cu-Ti IMCs and Cu-based solid solutions is formed.The composite layer grows dendritically from the TC4 alloy to the H62 interlayer.The microstructure at the TC4/DP780 interface changes from fine dendrites to coarse dendrites with the increase in Ti content and heat input.When the heat input is lower,the interfacial elements do not react sufficiently.When the heat input is excessive,microcracks appear at the TC4/DP780 interface,which limits the improvement of mechanical properties of TC4/DP780 joint.
文摘研究了热镀锌DP780电阻点焊性能,并优化其点焊参数。通过测量焊接接头的熔核直径、熔透率、压痕深度,观察焊接接头显微组织,检测焊接接头硬度、抗剪力及正拉力等参数,综合评价热镀锌DP780点焊性能。结果表明:DP780热镀锌板因其合金含量高的特点,点焊性能良好,但焊接工艺窗口较窄。当电极压力为3.5 k N,焊接电流为9.5 k A时,最佳焊接时间为300~400 ms,当焊接电流为10.5~11.5 k A时,焊接时间在200~400 ms均可。DP780热镀锌板点焊接头显微组织为马氏体和铁素体,这种焊接接头的组织决定了其塑性比仅有8%~30%,接头硬度值稍高。焊点的失效形式均为熔核剥离失效。
文摘通过测量点焊接头的熔核直径、熔透率,检测接头抗剪力、硬度,分析接头显微组织构成及形态,评价DP780冷轧板电阻点焊性能,并给出试验条件下的可焊工艺范围,以及最优工艺参数。结果表明:DP780冷轧板点焊性能良好,当电极压力为3 k N时,焊接电流可取8~10 k A,焊接时间可取200~400 ms,但焊接电流10 k A,焊接时间400 ms不可取;电极压力为4 k N时,焊接电流可取8~9 k A,焊接时间可取200~400 ms,但焊接电流9 k A,焊接时间400 ms不可取;最优工艺参数为焊接电流9 k A,焊接时间300 ms,电极压力4 k N;熔核区显微组织为粗大板条状马氏体+铁素体,马氏体呈现柱状晶形态,热影响区显微组织为块状马氏体+铁素体;母材硬度(HV)为240,熔核区硬度(HV)为420。
