The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of differen...The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of different load ratios were obtained. The forming limit diagrams（FLDs） of DP590 steel sheet under biaxial tensile pre-strain and electromagnetic hybrid forming were established. Results showed that the biaxial tensile pre-strain had significant effects on the formability of DP590 steel. The pre-strain in a certain range improved the forming limit of DP590 steel under high rate, and the forming limit increased with the pre-strain. The prestrain in the same direction of high rate increased the forming limit of the final deformation under complex strain paths conditions, but the pre-strain in the vertical direction decreased the minor strain under the high strain rate.展开更多
在不同焊接参数下分别通过Φ3 mm E4303碳钢焊条(/%:≤0.12C、≤0.25Si、0.30～0.60Mn)和Φ1mm H10MnSi焊丝(/%:0.14C、0.65～0.95Si、0.80～1.10Mn)对3.8 mm DP590钢薄板(/%:0.07C、0.45Si、1.61 Mn)进行手工电弧焊接和CO_2气体保护焊...在不同焊接参数下分别通过Φ3 mm E4303碳钢焊条(/%:≤0.12C、≤0.25Si、0.30～0.60Mn)和Φ1mm H10MnSi焊丝(/%:0.14C、0.65～0.95Si、0.80～1.10Mn)对3.8 mm DP590钢薄板(/%:0.07C、0.45Si、1.61 Mn)进行手工电弧焊接和CO_2气体保护焊接,并利用ZEISS光学显微镜、LEICA显微硬度计分别对焊接接头的组织和显微硬度进行了观察和分析。结果表明,在焊缝区手工电弧焊焊缝组织为沿柱状晶分布的先共析铁素体和珠光体,CO_2气体保护焊为针状铁素体和少量贝氏体,在粗晶区手工电弧焊为贝氏体和先共析铁素体,CO_2气体保护焊为板条马氏体和贝氏体,且其粗晶区晶粒尺寸大于手工电弧焊;采用CO_2气体保护焊,选择较大的热输入,焊缝和粗晶区的魏氏组织消失;显微硬度最大值均出现在粗晶区,手工电弧焊的热影响区宽度小于CO_2气体保护焊。展开更多
运用超声波水浸聚焦入射法对1.5 mm的DP590双相钢单面点焊接头进行超声C扫描成像检测,分析不同焊接电流下的超声C扫图像特征及超声C扫描图像中不同区域对应的A扫信号的变化规律,并对点焊接头进行拉伸-剪切试验,测试接头的力学性能。结...运用超声波水浸聚焦入射法对1.5 mm的DP590双相钢单面点焊接头进行超声C扫描成像检测,分析不同焊接电流下的超声C扫图像特征及超声C扫描图像中不同区域对应的A扫信号的变化规律,并对点焊接头进行拉伸-剪切试验,测试接头的力学性能。结果表明:通过观察超声C扫描与超声A扫信号的变化,能够很好地观察点焊接头的内部形貌特征,检测到焊接缺陷的位置与大小;随着焊接电流的逐渐增大(12.5~14.5 k A),接头熔核直径呈递增趋势,对应的失效载荷均值从5549.5 N增加到9258.49 N;当焊接电流增加到15 k A时,接头的熔核直径增大,但由于焊接飞溅的产生,接头的失效载荷和能量吸收值都呈递减趋势。展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51205298 and 51475345)the China Postdoctoral Science Foundation(No.2014M552096)the Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(No.P2015-01)
文摘The effects of biaxial tensile pre-strain on the forming limit of DP590 high-strength steel under high strain rate were investigated. The stress-strain curves of DP590 steel sheet under the biaxial tensile of different load ratios were obtained. The forming limit diagrams（FLDs） of DP590 steel sheet under biaxial tensile pre-strain and electromagnetic hybrid forming were established. Results showed that the biaxial tensile pre-strain had significant effects on the formability of DP590 steel. The pre-strain in a certain range improved the forming limit of DP590 steel under high rate, and the forming limit increased with the pre-strain. The prestrain in the same direction of high rate increased the forming limit of the final deformation under complex strain paths conditions, but the pre-strain in the vertical direction decreased the minor strain under the high strain rate.
文摘在不同焊接参数下分别通过Φ3 mm E4303碳钢焊条(/%:≤0.12C、≤0.25Si、0.30～0.60Mn)和Φ1mm H10MnSi焊丝(/%:0.14C、0.65～0.95Si、0.80～1.10Mn)对3.8 mm DP590钢薄板(/%:0.07C、0.45Si、1.61 Mn)进行手工电弧焊接和CO_2气体保护焊接,并利用ZEISS光学显微镜、LEICA显微硬度计分别对焊接接头的组织和显微硬度进行了观察和分析。结果表明,在焊缝区手工电弧焊焊缝组织为沿柱状晶分布的先共析铁素体和珠光体,CO_2气体保护焊为针状铁素体和少量贝氏体,在粗晶区手工电弧焊为贝氏体和先共析铁素体,CO_2气体保护焊为板条马氏体和贝氏体,且其粗晶区晶粒尺寸大于手工电弧焊;采用CO_2气体保护焊,选择较大的热输入,焊缝和粗晶区的魏氏组织消失;显微硬度最大值均出现在粗晶区,手工电弧焊的热影响区宽度小于CO_2气体保护焊。
文摘运用超声波水浸聚焦入射法对1.5 mm的DP590双相钢单面点焊接头进行超声C扫描成像检测,分析不同焊接电流下的超声C扫图像特征及超声C扫描图像中不同区域对应的A扫信号的变化规律,并对点焊接头进行拉伸-剪切试验,测试接头的力学性能。结果表明:通过观察超声C扫描与超声A扫信号的变化,能够很好地观察点焊接头的内部形貌特征,检测到焊接缺陷的位置与大小;随着焊接电流的逐渐增大(12.5~14.5 k A),接头熔核直径呈递增趋势,对应的失效载荷均值从5549.5 N增加到9258.49 N;当焊接电流增加到15 k A时,接头的熔核直径增大,但由于焊接飞溅的产生,接头的失效载荷和能量吸收值都呈递减趋势。
