The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are...The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical,refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Tie6Ale4 V and SS304 L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Tie6Ale4 V and SS304 L into which pure oxygen free copper(OFC) was introduced as interlayer were investigated. Boxe Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Tie6Ale4 V and SS304 L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XRD analysis.展开更多
The selection of process parameter in the gas tungsten arc （GTA） welding of titanium alloy was presented for obtaining optimum grain size and hardness. Titanium alloy （Ti-6Al-4V） is one of the most important non-f...The selection of process parameter in the gas tungsten arc （GTA） welding of titanium alloy was presented for obtaining optimum grain size and hardness. Titanium alloy （Ti-6Al-4V） is one of the most important non-ferrous metals which offers great potential application in aerospace, biomedical and chemical industries, because of its low density （4.5 g/cm^3）, excellent corrosion resistance, high strength, attractive fracture behaviour and high melting point （1678℃）. The preferred welding process for titanium alloy is frequent GTA welding due to its comparatively easier applicability and better economy. In the case of single pass （GTA） welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one needs to carefully balance various pulse current parameters to reach an optimum combination. Four factors, five level, central composite, rotatable design matrix were used to optimize the required number of experimental conditions. Mathematical models were developed to predict the fusion zone grain size using analysis of variance （ANOVA） and regression analysis. The developed models were optimized using the traditional Hooke and Jeeve＇s algorithm. Experimental results were provided to illustrate the proposed approach.展开更多
As titanium alloy is chemically reactive,it is very difficult to join by conventional welding techniques.Titanium alloys can easily pick up nitrogen and oxygen from the atmosphere.In the fusion welding method,brittle ...As titanium alloy is chemically reactive,it is very difficult to join by conventional welding techniques.Titanium alloys can easily pick up nitrogen and oxygen from the atmosphere.In the fusion welding method,brittle intermetallic compounds are formed when joining titanium alloy and stainless steel,which decrease the mechanical behavior of the couples.Hence,for joining of titanium alloy,diffusion bonding is recommended.This work dealt with the measurement of feasible process parameters for diffusion bonding of Ti-6Al-4V and AISI 304 stainless steel with silver as an intermediate layer.The quality of the bonds was confirmed by the lap shear test and microstructural analysis.With the experimental results obtained,diffusion bonding windows were constructed and this will act as reference maps to identify the process parameters for obtaining defect free bond.Bonding was successful in the temperature range of 750-800 °C.Maximum lap shear strength was achieved under a bonding pressure of 5 MPa and holding time of 90 min.展开更多
The effects of pulsing current parameters on weld pool geometry namely front height, back height, front width and back width of pulse current gas tungsten arc welded （GTAW） titanium alloy was analysed. Four factors,...The effects of pulsing current parameters on weld pool geometry namely front height, back height, front width and back width of pulse current gas tungsten arc welded （GTAW） titanium alloy was analysed. Four factors, five levels, central composite design were used to develop empirical relationships, incorporating pulsed current parameters and weld pool geometry.展开更多
The selection of process parameters for obtaining optimal tensile properties in the pulsed current gas tungsten arc welding is presented. The tensile properties include ultimate tensile strength, yield strength and no...The selection of process parameters for obtaining optimal tensile properties in the pulsed current gas tungsten arc welding is presented. The tensile properties include ultimate tensile strength, yield strength and notch tensile strength. All these characteristics are considered together in the selection of process parameters by modified taguchi method to analyse the effect of each welding process parameter on tensile properties. Experimental results are furnished to illustrate the approach.展开更多
A method to decide near optimal settings of the process parameters in friction welding was proposed.The success of the friction welding process is based on various input parameters like friction pressure,friction time...A method to decide near optimal settings of the process parameters in friction welding was proposed.The success of the friction welding process is based on various input parameters like friction pressure,friction time,upset pressure and upset time and output parameters like tensile strength,hardness and material loss.Ti-6Al-4V and SS304L(SS) materials were joined by friction welding process using interlayer techniques.The Box-Behnken design and response surface methodology(RSM) were applied to deciding the number of experiments to be performed and identify the optimum process parameters for obtaining better joint strength.The results were highly encouraging.Join strength of 523 MPa was obtained at a friction pressure of 12 N/mm^2,upset pressure of40 N/mm^2,friction time of 1.2 s and upset time of 7 s.展开更多
This paper presents an experimental study on the resistance spot weldability of SPRC35（steel plate re-phosphorised cold rolled） sheets.The sheets were joined by using resistance spot welding as lap joint.The weld nu...This paper presents an experimental study on the resistance spot weldability of SPRC35（steel plate re-phosphorised cold rolled） sheets.The sheets were joined by using resistance spot welding as lap joint.The weld nugget diameter and tensile shear force were investigated.Tensile-shear tests were applied to the welded specimens to understand the tensile shear force that the joint can withstand.Empirical relationships were developed for both nugget diameter and tensile shear force.Use of automatic mode, will increase the dependence on the use of equations to predict the nugget diameter.The developed models have been checked for their adequacy and significance by the F test and t test respectively.The results obtained from the empirical relationships have been optimized and also tested using conformity test runs.展开更多
The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecula...The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecular weight,and the polydispersivity index of the synthesized PCS are SiC_(1.94)H_(5.01)O_(0.028),1135,and 1.66,respectively,which can be attributed to the higher reaction temperature used for polymerization.The polymer to ceramic conversion of PCS was completed at 900℃with a ceramic yield of 85%.The crystallization started at 1100℃,and at 1200℃,well resolved peaks ofβ-SiC were formed with small amount ofα-cristobalite.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)studies indicated the presence of nanocrystallineβ-SiC.展开更多
文摘The basic principle of friction welding is intermetallic bonding at the stage of super plasticity attained with self-generating heat due to friction and finishing at upset pressure. Now the dissimilar metal joints are especially popular in defense, aerospace, automobile, bio-medical,refinery and nuclear engineerings. In friction welding, some special alloys with dual phase are not joined successfully due to poor bonding strength. The alloy surfaces after bonding also have metallurgical changes in the line of interfacing. The reported research work in this area is scanty. Although the sound weld zone of direct bonding between Tie6Ale4 V and SS304 L was obtained though many trials, the joint was not successful. In this paper, the friction welding characteristics between Tie6Ale4 V and SS304 L into which pure oxygen free copper(OFC) was introduced as interlayer were investigated. Boxe Behnken design was used to minimize the number of experiments to be performed. The weld joint was analyzed for its mechanical strength. The highest tensile strength between Tie6Ale4 V and SS304 L between which pure copper was used as insert metal was acquired. Micro-structural analysis and elemental analysis were carried out by EDS, and the formation of intermetallic compound at the interface was identified by XRD analysis.
文摘The selection of process parameter in the gas tungsten arc （GTA） welding of titanium alloy was presented for obtaining optimum grain size and hardness. Titanium alloy （Ti-6Al-4V） is one of the most important non-ferrous metals which offers great potential application in aerospace, biomedical and chemical industries, because of its low density （4.5 g/cm^3）, excellent corrosion resistance, high strength, attractive fracture behaviour and high melting point （1678℃）. The preferred welding process for titanium alloy is frequent GTA welding due to its comparatively easier applicability and better economy. In the case of single pass （GTA） welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. Many considerations come into the picture and one needs to carefully balance various pulse current parameters to reach an optimum combination. Four factors, five level, central composite, rotatable design matrix were used to optimize the required number of experimental conditions. Mathematical models were developed to predict the fusion zone grain size using analysis of variance （ANOVA） and regression analysis. The developed models were optimized using the traditional Hooke and Jeeve＇s algorithm. Experimental results were provided to illustrate the proposed approach.
基金All India Council for Technical Education (AICTE),New Delhi,India,for the financial support rendered under the Grant No:8023/ RID/RID/RPS-76/2010-11
文摘As titanium alloy is chemically reactive,it is very difficult to join by conventional welding techniques.Titanium alloys can easily pick up nitrogen and oxygen from the atmosphere.In the fusion welding method,brittle intermetallic compounds are formed when joining titanium alloy and stainless steel,which decrease the mechanical behavior of the couples.Hence,for joining of titanium alloy,diffusion bonding is recommended.This work dealt with the measurement of feasible process parameters for diffusion bonding of Ti-6Al-4V and AISI 304 stainless steel with silver as an intermediate layer.The quality of the bonds was confirmed by the lap shear test and microstructural analysis.With the experimental results obtained,diffusion bonding windows were constructed and this will act as reference maps to identify the process parameters for obtaining defect free bond.Bonding was successful in the temperature range of 750-800 °C.Maximum lap shear strength was achieved under a bonding pressure of 5 MPa and holding time of 90 min.
文摘The effects of pulsing current parameters on weld pool geometry namely front height, back height, front width and back width of pulse current gas tungsten arc welded （GTAW） titanium alloy was analysed. Four factors, five levels, central composite design were used to develop empirical relationships, incorporating pulsed current parameters and weld pool geometry.
文摘The selection of process parameters for obtaining optimal tensile properties in the pulsed current gas tungsten arc welding is presented. The tensile properties include ultimate tensile strength, yield strength and notch tensile strength. All these characteristics are considered together in the selection of process parameters by modified taguchi method to analyse the effect of each welding process parameter on tensile properties. Experimental results are furnished to illustrate the approach.
文摘A method to decide near optimal settings of the process parameters in friction welding was proposed.The success of the friction welding process is based on various input parameters like friction pressure,friction time,upset pressure and upset time and output parameters like tensile strength,hardness and material loss.Ti-6Al-4V and SS304L(SS) materials were joined by friction welding process using interlayer techniques.The Box-Behnken design and response surface methodology(RSM) were applied to deciding the number of experiments to be performed and identify the optimum process parameters for obtaining better joint strength.The results were highly encouraging.Join strength of 523 MPa was obtained at a friction pressure of 12 N/mm^2,upset pressure of40 N/mm^2,friction time of 1.2 s and upset time of 7 s.
文摘This paper presents an experimental study on the resistance spot weldability of SPRC35（steel plate re-phosphorised cold rolled） sheets.The sheets were joined by using resistance spot welding as lap joint.The weld nugget diameter and tensile shear force were investigated.Tensile-shear tests were applied to the welded specimens to understand the tensile shear force that the joint can withstand.Empirical relationships were developed for both nugget diameter and tensile shear force.Use of automatic mode, will increase the dependence on the use of equations to predict the nugget diameter.The developed models have been checked for their adequacy and significance by the F test and t test respectively.The results obtained from the empirical relationships have been optimized and also tested using conformity test runs.
文摘The polycarbosilane(PCS)precursor for SiC with high molecular weight and medium molecular weight distribution was synthesized from polydimethylsilane at normal pressure.The chemical formula,the number average molecular weight,and the polydispersivity index of the synthesized PCS are SiC_(1.94)H_(5.01)O_(0.028),1135,and 1.66,respectively,which can be attributed to the higher reaction temperature used for polymerization.The polymer to ceramic conversion of PCS was completed at 900℃with a ceramic yield of 85%.The crystallization started at 1100℃,and at 1200℃,well resolved peaks ofβ-SiC were formed with small amount ofα-cristobalite.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)studies indicated the presence of nanocrystallineβ-SiC.
