Weld bead morphology plays an important role in welding procedure specification and welding process planning.In order to obtain the quantitative relationship between process parameters and weld morphology of DH36 mari...Weld bead morphology plays an important role in welding procedure specification and welding process planning.In order to obtain the quantitative relationship between process parameters and weld morphology of DH36 marine steel plate,grey correlation method was used to study multiple morphology characteristics simultaneously.Eighteen experimental runs were proposed according to orthogonal method.With grey correlation theory,three response objectives,aspect ratio,depth of penetration and weld were transformed into a single grey correlation grade(GRG).The process parameters were quantitatively correlated to the GRG value and optimized with the target of maximum aspect ratio,minimum depth of penetration and maximum weld area.The results show that the optimized weld bead morphology is better than other weld bead morphology.The relative error of the predicted GRG with respect to the actual value is 5.06%,which further verifies the accuracy of the established model.The microstructure and hardness analysis suggests that the optimized welded joint has obtained required mechanical properties.The research outcomes provide a theoretical basis for multi-objective optimization of arc welding morphology in practical applications.展开更多
对厚1.5mm规格DH590钢板进行激光束焊焊接试验,研究该钢板的激光束焊焊接特性以及焊接接头性能。结果表明,1.5 mm规格的DH590+Z钢板单板的最大焊接速度为6.8 m/min,搭接板最大焊接速度为3.2m/min;连续搭接试验的平均最大抗剪力为41.6 k...对厚1.5mm规格DH590钢板进行激光束焊焊接试验,研究该钢板的激光束焊焊接特性以及焊接接头性能。结果表明,1.5 mm规格的DH590+Z钢板单板的最大焊接速度为6.8 m/min,搭接板最大焊接速度为3.2m/min;连续搭接试验的平均最大抗剪力为41.6 k N,断续搭接试验的平均最大抗剪力为18.9 k N,焊接接头的平均最大抗拉力为12.5 k N;焊接接头焊缝区的显微硬度分布均匀,热影响区不存在明显的软化点;对焊接接头进行X光探伤检测,未发现气孔和裂纹缺陷,焊缝质量良好。展开更多
对近年来汽车车身用新型冷轧薄板的研发进展进行了综述,重点介绍了国内外增强成形性双相钢(Dual phase steel with improved formability,DH)、锌铝镁镀层钢板和高鲜映性汽车外板的技术思路、产品优势和应用情况.DH钢中适量稳定性较高...对近年来汽车车身用新型冷轧薄板的研发进展进行了综述,重点介绍了国内外增强成形性双相钢(Dual phase steel with improved formability,DH)、锌铝镁镀层钢板和高鲜映性汽车外板的技术思路、产品优势和应用情况.DH钢中适量稳定性较高的残余奥氏体大幅提高了断后延伸率及加工硬化率,在解决冲压开裂、实现车身轻量化方面效果显著;锌铝镁镀层特殊的相结构决定了其优异的耐蚀性能和成形性能,在汽车内板和外板得到广泛应用;成形零件的表面波纹度是评价高鲜映性汽车外板的重要指标,首钢开发了表面波纹度演变机理及控制技术,解决了钢板表面粗糙度与波纹度协同控制难题.指出了这些新型冷轧薄板要关注的生产和应用方面问题,如DH钢中较高Al、Si含量导致的连铸生产困难和表面质量问题、高合金含量带来的性能波动问题、高强度级别产品的氢脆问题和镀层板焊接的液态金属脆性(Liquid metal embrittlement,LME)问题等;锌铝镁镀层钢板焊接、涂装、粘接、成形等基础数据还不健全,高耐蚀性能还需得到更多用户检验及认可;高鲜映性汽车外板还需要进一步减少表面缺陷的数量、尺寸,进一步压制长波的表面轮廓.展开更多
Friction stir spot welding was successfully applied to the 1.2-mm-thick DH590 dual-phase steel plates by using a polycrystalline cubic boron nitride rotating tool.During welding,the rotation speed ranged from 600 to 1...Friction stir spot welding was successfully applied to the 1.2-mm-thick DH590 dual-phase steel plates by using a polycrystalline cubic boron nitride rotating tool.During welding,the rotation speed ranged from 600 to 1000 r/min and the penetration depth ranged from 0.1 to 0.3 mm.In the spot joints,the size of the stir zone increased with the increase in rotation speed as well as the penetration depth of the tool.Comparing with the banded ferrite and martensite structure of the base metal,a mixed microstructure of ferrite and tempered martensite,refined bainite structure and coarse martensite structure were found in the heat-affected zone,thermomechanically affected zone and stir zone of the joints,respectively.Two kinds of interfacial shapes were formed between the upper and lower steel plates,and the formation of the bonded interface was dominated mainly by the penetration depth of the rotating tool rather than the rotation speed.It was revealed that the joints with straight interfaces showed higher shear tensile loads comparing with those with hook-like interfaces.Shear tensile tests showed that the maximum shear tensile load reached about 15.56 kN when the rotation speed and penetration depth were set as 800 r/min and 0.3 mm,respectively.The specimen was fractured through plug failure mode with a total elongation of about 5.6 mm.展开更多
Grade A （GA） and high strength steel DH36 ship steels possessing different chemical compositions were used, and strength properties of GA steel and DH36 steel were compared. Additionally, 4 types of dual phase （DP...Grade A （GA） and high strength steel DH36 ship steels possessing different chemical compositions were used, and strength properties of GA steel and DH36 steel were compared. Additionally, 4 types of dual phase （DP） steels with different martensite volume fractions （MVFs） were produced from GA steel by means of heat treatment and they were compared with other steels through conducting mierostructure, microhardness, tensile and impact tests. The fracture surfaces of specimens （DH36, GA and DP steels） exposed to tensile and Charpy impact tests were investigated by scanning electron microscope. Furthermore, it was found that the specimens quenched from 800 and 900℃ had better strength than DH36 steel. The tensile test results indicated that the tensile strength of DP steel water quenched from 900℃ was 3 times that of GA steel and twice that of DH36 steel.展开更多
基金Natural Science Foundation of Fujian Province(Grant No.2020J01873)Technology Major Project of Fujian Province(Grant No.2020H03018).
文摘Weld bead morphology plays an important role in welding procedure specification and welding process planning.In order to obtain the quantitative relationship between process parameters and weld morphology of DH36 marine steel plate,grey correlation method was used to study multiple morphology characteristics simultaneously.Eighteen experimental runs were proposed according to orthogonal method.With grey correlation theory,three response objectives,aspect ratio,depth of penetration and weld were transformed into a single grey correlation grade(GRG).The process parameters were quantitatively correlated to the GRG value and optimized with the target of maximum aspect ratio,minimum depth of penetration and maximum weld area.The results show that the optimized weld bead morphology is better than other weld bead morphology.The relative error of the predicted GRG with respect to the actual value is 5.06%,which further verifies the accuracy of the established model.The microstructure and hardness analysis suggests that the optimized welded joint has obtained required mechanical properties.The research outcomes provide a theoretical basis for multi-objective optimization of arc welding morphology in practical applications.
文摘对厚1.5mm规格DH590钢板进行激光束焊焊接试验,研究该钢板的激光束焊焊接特性以及焊接接头性能。结果表明,1.5 mm规格的DH590+Z钢板单板的最大焊接速度为6.8 m/min,搭接板最大焊接速度为3.2m/min;连续搭接试验的平均最大抗剪力为41.6 k N,断续搭接试验的平均最大抗剪力为18.9 k N,焊接接头的平均最大抗拉力为12.5 k N;焊接接头焊缝区的显微硬度分布均匀,热影响区不存在明显的软化点;对焊接接头进行X光探伤检测,未发现气孔和裂纹缺陷,焊缝质量良好。
文摘对近年来汽车车身用新型冷轧薄板的研发进展进行了综述,重点介绍了国内外增强成形性双相钢(Dual phase steel with improved formability,DH)、锌铝镁镀层钢板和高鲜映性汽车外板的技术思路、产品优势和应用情况.DH钢中适量稳定性较高的残余奥氏体大幅提高了断后延伸率及加工硬化率,在解决冲压开裂、实现车身轻量化方面效果显著;锌铝镁镀层特殊的相结构决定了其优异的耐蚀性能和成形性能,在汽车内板和外板得到广泛应用;成形零件的表面波纹度是评价高鲜映性汽车外板的重要指标,首钢开发了表面波纹度演变机理及控制技术,解决了钢板表面粗糙度与波纹度协同控制难题.指出了这些新型冷轧薄板要关注的生产和应用方面问题,如DH钢中较高Al、Si含量导致的连铸生产困难和表面质量问题、高合金含量带来的性能波动问题、高强度级别产品的氢脆问题和镀层板焊接的液态金属脆性(Liquid metal embrittlement,LME)问题等;锌铝镁镀层钢板焊接、涂装、粘接、成形等基础数据还不健全,高耐蚀性能还需得到更多用户检验及认可;高鲜映性汽车外板还需要进一步减少表面缺陷的数量、尺寸,进一步压制长波的表面轮廓.
文摘Friction stir spot welding was successfully applied to the 1.2-mm-thick DH590 dual-phase steel plates by using a polycrystalline cubic boron nitride rotating tool.During welding,the rotation speed ranged from 600 to 1000 r/min and the penetration depth ranged from 0.1 to 0.3 mm.In the spot joints,the size of the stir zone increased with the increase in rotation speed as well as the penetration depth of the tool.Comparing with the banded ferrite and martensite structure of the base metal,a mixed microstructure of ferrite and tempered martensite,refined bainite structure and coarse martensite structure were found in the heat-affected zone,thermomechanically affected zone and stir zone of the joints,respectively.Two kinds of interfacial shapes were formed between the upper and lower steel plates,and the formation of the bonded interface was dominated mainly by the penetration depth of the rotating tool rather than the rotation speed.It was revealed that the joints with straight interfaces showed higher shear tensile loads comparing with those with hook-like interfaces.Shear tensile tests showed that the maximum shear tensile load reached about 15.56 kN when the rotation speed and penetration depth were set as 800 r/min and 0.3 mm,respectively.The specimen was fractured through plug failure mode with a total elongation of about 5.6 mm.
文摘采用Thermecmastor-Z热模拟试验机研究了试验钢在800~1150℃、应变速率0.01~10 s-1的热压缩变形行为,并观察变形后显微组织。基于试验数据分析,确定了试验钢在奥氏体区的热变形方程,建立试验钢在0.8真应变下的热加工图。结果表明:试验钢的流变应力和峰值应变随变形温度的升高而减小;试验钢在奥氏体区的热变形激活能为385.91 k J/mol。根据试验钢功率耗散及流变失稳判据确定最佳热加工工艺参数为热变形温度范围1050~1150℃和应变速率0.01~0.1 s-1。在该范围内,试验钢发生完全动态再结晶,功率耗散系数为17%~32%。
文摘Grade A （GA） and high strength steel DH36 ship steels possessing different chemical compositions were used, and strength properties of GA steel and DH36 steel were compared. Additionally, 4 types of dual phase （DP） steels with different martensite volume fractions （MVFs） were produced from GA steel by means of heat treatment and they were compared with other steels through conducting mierostructure, microhardness, tensile and impact tests. The fracture surfaces of specimens （DH36, GA and DP steels） exposed to tensile and Charpy impact tests were investigated by scanning electron microscope. Furthermore, it was found that the specimens quenched from 800 and 900℃ had better strength than DH36 steel. The tensile test results indicated that the tensile strength of DP steel water quenched from 900℃ was 3 times that of GA steel and twice that of DH36 steel.
