Submerged arc welding （SAW） is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subseq...Submerged arc welding （SAW） is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress.展开更多
A fuzzy model was presented to predict the weldment shape profile of submerged arc welds （SAW） including the shape of heat affected zone （HAZ）. The SAW bead-on-plates were welded by following a full factorial desi...A fuzzy model was presented to predict the weldment shape profile of submerged arc welds （SAW） including the shape of heat affected zone （HAZ）. The SAW bead-on-plates were welded by following a full factorial design matrix. The design matrix consisted of three levels of input welding process parameters. The welds were cross-sectioned and etched, and the zones were measured. A mapping technique was used to measure the various segments of the weld zones. These mapped zones were used to build a fuzzy logic model. The membership functions of the fuzzy model were chosen for the accurate prediction of the weld zone. The fuzzy model was further tested for a set of test case data. The weld zone predicted by the fuzzy logic model was compared with the experimentally obtained shape profiles and close agreement between the two was noted. The mapping technique developed for the weld zones and the fuzzy logiemodel earl be used for on-line control of the SAW process. From the SAW fuzzy logic model an estimation of the fusion and HAZ can also be developed.展开更多
Cable welding wire（CWW）CO2gas shielded welding is an innovative process arc welding with high efficiency,high quality and low consumption,in which cable wire is used as consumable electrode.CWW CO2gas shielded weldi...Cable welding wire（CWW）CO2gas shielded welding is an innovative process arc welding with high efficiency,high quality and low consumption,in which cable wire is used as consumable electrode.CWW CO2gas shielded welding and submerged arc welding（SAW）are used for contrast studies on processing property of high strength steel A36used in ship structure.The results show that the shapes of weld seam,using CWW CO2gas shielded welding and SAW,are good and no weld defect such as air hole,flaw,slag inclusion,incomplete fusion,lack of penetration and so on are found in the weld seam.Because the rotating of arc during CWW CO2gas shielded welding process has a strong stirring effect on molten pool,the grain in the heat affected zone（HAZ）of the joints,using CWW CO2 gas shielded welding,is small.Tensile failure positions of joints by CWW CO2gas shielded welding and SAW are all in the base metal,but tensile strength of CWW CO2gas shielded welding joint is higher than that of SAW joint by an average of 2.3%.The average impact energy of HAZ,using CWW CO2gas shielded welding and SAW,is almost equal,but the average impact energy of the weld seam using CWW CO2gas shielded welding is increased by 6%,and the average impact energy of the fusion line is increased by 7%.The 180°bending tests for the joints of CWW CO2 gas shielded welding and SAW are all qualified,and the joints hardness is all less than HV 355,but hardness of CWW CO2gas shielded welding wire welding joint near the fusion line is obviously lower.It can be concluded that the properties of CWW CO2gas shielded welding are better than those of the SAW joint,and CWW CO2gas shielded welding is suitable for welding high strength steel A36used in ship structure.展开更多
埋弧焊交流方波电弧电信号存在畸变,影响焊接过程电弧稳定性和焊缝成形质量,针对于此,在对采集的埋弧焊交流方波电弧电流信号进行小波包降噪后,利用局部均值分解(local mean decomposition,LMD)对电弧电流信号进行自适应分解,获得若干...埋弧焊交流方波电弧电信号存在畸变,影响焊接过程电弧稳定性和焊缝成形质量,针对于此,在对采集的埋弧焊交流方波电弧电流信号进行小波包降噪后,利用局部均值分解(local mean decomposition,LMD)对电弧电流信号进行自适应分解,获得若干个具有真实物理意义的PF(product function)分量,并对PF分量集进行Hilbert变换及能量熵计算。结果表明,利用小波消噪与LMD能有效得到埋弧焊交流方波电流波形畸变的不同频率成分及其幅值在时间特征尺度上的变化特征,在此基础上通过Hilbert变换及能量熵计算可以有效提取反映焊接过程电弧稳定性和焊缝成形质量的电弧特征信息。展开更多
基金Supported by the Indian Institute of Technology Guwahati under Grant No:SG/ME/PB/P/01
文摘Submerged arc welding （SAW） is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress.
基金Supported by the IIT Roorkee Project under Grant No. FIG-A Scheme-A
文摘A fuzzy model was presented to predict the weldment shape profile of submerged arc welds （SAW） including the shape of heat affected zone （HAZ）. The SAW bead-on-plates were welded by following a full factorial design matrix. The design matrix consisted of three levels of input welding process parameters. The welds were cross-sectioned and etched, and the zones were measured. A mapping technique was used to measure the various segments of the weld zones. These mapped zones were used to build a fuzzy logic model. The membership functions of the fuzzy model were chosen for the accurate prediction of the weld zone. The fuzzy model was further tested for a set of test case data. The weld zone predicted by the fuzzy logic model was compared with the experimentally obtained shape profiles and close agreement between the two was noted. The mapping technique developed for the weld zones and the fuzzy logiemodel earl be used for on-line control of the SAW process. From the SAW fuzzy logic model an estimation of the fusion and HAZ can also be developed.
基金Sponsored by National Natural Science Foundation of China(51275224,51005106)Prospective Joint Research Project ofJiangsu Province of China(BY2012184)
文摘Cable welding wire（CWW）CO2gas shielded welding is an innovative process arc welding with high efficiency,high quality and low consumption,in which cable wire is used as consumable electrode.CWW CO2gas shielded welding and submerged arc welding（SAW）are used for contrast studies on processing property of high strength steel A36used in ship structure.The results show that the shapes of weld seam,using CWW CO2gas shielded welding and SAW,are good and no weld defect such as air hole,flaw,slag inclusion,incomplete fusion,lack of penetration and so on are found in the weld seam.Because the rotating of arc during CWW CO2gas shielded welding process has a strong stirring effect on molten pool,the grain in the heat affected zone（HAZ）of the joints,using CWW CO2 gas shielded welding,is small.Tensile failure positions of joints by CWW CO2gas shielded welding and SAW are all in the base metal,but tensile strength of CWW CO2gas shielded welding joint is higher than that of SAW joint by an average of 2.3%.The average impact energy of HAZ,using CWW CO2gas shielded welding and SAW,is almost equal,but the average impact energy of the weld seam using CWW CO2gas shielded welding is increased by 6%,and the average impact energy of the fusion line is increased by 7%.The 180°bending tests for the joints of CWW CO2 gas shielded welding and SAW are all qualified,and the joints hardness is all less than HV 355,but hardness of CWW CO2gas shielded welding wire welding joint near the fusion line is obviously lower.It can be concluded that the properties of CWW CO2gas shielded welding are better than those of the SAW joint,and CWW CO2gas shielded welding is suitable for welding high strength steel A36used in ship structure.
文摘埋弧焊交流方波电弧电信号存在畸变,影响焊接过程电弧稳定性和焊缝成形质量,针对于此,在对采集的埋弧焊交流方波电弧电流信号进行小波包降噪后,利用局部均值分解(local mean decomposition,LMD)对电弧电流信号进行自适应分解,获得若干个具有真实物理意义的PF(product function)分量,并对PF分量集进行Hilbert变换及能量熵计算。结果表明,利用小波消噪与LMD能有效得到埋弧焊交流方波电流波形畸变的不同频率成分及其幅值在时间特征尺度上的变化特征,在此基础上通过Hilbert变换及能量熵计算可以有效提取反映焊接过程电弧稳定性和焊缝成形质量的电弧特征信息。
