In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered （Q＆.T） steel welds. Flux cored arc wel...In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered （Q＆.T） steel welds. Flux cored arc welding （FCAW） process were used making welds using austenitic stainless steel （ASS） and low hydrogen ferritic steel （LHF） consumables. The diffusible hydrogen levels in the weld metal of the ASS and LHF consumables were determined by mercury method. Residual stresses were evaluated using X-ray stress analyzer and implant test was carried out to study the cold cracking of the welds. Results indicate that ASS welds offer a greater resistance to cold cracking of armour grade Q＆T steel welds.展开更多
An AZ31 HP magnesium alloy was laser beam welded in autogenous mode with AZ61 filler using Nd-YAG laser system.Microstructural examination revealed that the laser beam weld metals obtained with or without filler mater...An AZ31 HP magnesium alloy was laser beam welded in autogenous mode with AZ61 filler using Nd-YAG laser system.Microstructural examination revealed that the laser beam weld metals obtained with or without filler material had an average grain size of about 12 μm.The microhardness and the tensile strength of the weldments were similar to those of the parent alloy.However,the stress corrosion cracking （SCC） behaviour of both the weldments assessed by slow strain rate tensile （SSRT） tests in ASTM D1384 solution was found to be slightly inferior to that of the parent alloy.It was observed that the stress corrosion cracks originated in the weld metal and propagated through the weld metal-HAZ regions in the autogenous weldment.On the other hand,in the weldment obtained with AZ61 filler material,the crack initiation and propagation was in the HAZ region.The localized damage of the magnesium hydroxide/oxide film formed on the surface of the specimens due to the exposure to the corrosive environment during the SSRT tests was found to be responsible for the SCC.展开更多
The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking suscepti- bility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show t...The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking suscepti- bility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show that the hardenability characteristics and cold cracking susceptibility of the steel are very low. The results also indicate that a crack-free weldment can be obtained during the welding of this type of steel even at an ambient temperature as low as -5 ℃ as well as in an absolute humidity lower than 4 000 Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or higher absolute humidity.展开更多
Super 304 H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power...Super 304 H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of the material. Stress corrosion cracking susceptibility of Super 304 H parent metal and gas tungsten arc(GTA) welded joints were studied by constant load tests in 45% boiling Mg Cl2 solution. Stress corrosion cracking resistance of Super 304 H stainless steel was deteriorated by GTA welding due to the formation of susceptible microstructure in the HAZ of the weld joint and the residual stresses. The mechanism of cracking was found to be anodic path cracking, with transgranular nature of crack propagation. Linear relationships were derived to predict the time to failure by extrapolating the rate of steady state elongation.展开更多
This paper introduces the process and result of fatigue test of steel (Z direction steel) welded T tubular joints used in offshore engineering. Detailed measurement of stress concentration factor, stress distribution,...This paper introduces the process and result of fatigue test of steel (Z direction steel) welded T tubular joints used in offshore engineering. Detailed measurement of stress concentration factor, stress distribution, fatigue life and crack development has been performed. Through analysis, an empirical formula of stress concentration factor for T tubular joints, fatigue S-N curve and crack propagation rule are obtained.展开更多
核电站乏燃料水池覆面板焊缝与母材交界面处的裂纹会严重影响设备的运行安全。考虑焊缝的真实特性,提出采用交流电磁场检测(alternating current field measurement,ACFM)技术来检测焊缝裂纹,以提高裂纹检测的灵敏度。首先,采用COMSOL...核电站乏燃料水池覆面板焊缝与母材交界面处的裂纹会严重影响设备的运行安全。考虑焊缝的真实特性,提出采用交流电磁场检测(alternating current field measurement,ACFM)技术来检测焊缝裂纹,以提高裂纹检测的灵敏度。首先,采用COMSOL软件建立了焊缝裂纹检测模型,分析了焊缝裂纹区域的磁场特征信号;其次,在实验试件焊缝与母材交界面处预置与数值仿真一致的人工裂纹,进行焊缝裂纹ACFM实验;最后,制作了焊缝裂纹检测系统,并进行了其性能测试。仿真、实验和测试结果表明:ACFM方法能够有效识别焊缝与母材交界面处平行于焊缝方向的裂纹,而不能识别垂直于焊缝方向的裂纹;通过焊缝裂纹检测系统测试得到的裂纹检测长度的偏差小于探头检测实验的偏差,但两者比较接近,证明了焊缝裂纹检测系统设计的合理性。ACFM能够实现乏池覆面板对接焊缝裂纹的定量化检测,满足现场高灵敏度的使用要求。展开更多
基金Armament Research Board (ARMREB),New Delhi for funding this projectwork (Project No MAA/03/41)
文摘In this investigation, an attempt has been made to study the influence of welding consumables on the factors that influence cold cracking of armour grade quenched and tempered （Q＆.T） steel welds. Flux cored arc welding （FCAW） process were used making welds using austenitic stainless steel （ASS） and low hydrogen ferritic steel （LHF） consumables. The diffusible hydrogen levels in the weld metal of the ASS and LHF consumables were determined by mercury method. Residual stresses were evaluated using X-ray stress analyzer and implant test was carried out to study the cold cracking of the welds. Results indicate that ASS welds offer a greater resistance to cold cracking of armour grade Q＆T steel welds.
文摘An AZ31 HP magnesium alloy was laser beam welded in autogenous mode with AZ61 filler using Nd-YAG laser system.Microstructural examination revealed that the laser beam weld metals obtained with or without filler material had an average grain size of about 12 μm.The microhardness and the tensile strength of the weldments were similar to those of the parent alloy.However,the stress corrosion cracking （SCC） behaviour of both the weldments assessed by slow strain rate tensile （SSRT） tests in ASTM D1384 solution was found to be slightly inferior to that of the parent alloy.It was observed that the stress corrosion cracks originated in the weld metal and propagated through the weld metal-HAZ regions in the autogenous weldment.On the other hand,in the weldment obtained with AZ61 filler material,the crack initiation and propagation was in the HAZ region.The localized damage of the magnesium hydroxide/oxide film formed on the surface of the specimens due to the exposure to the corrosive environment during the SSRT tests was found to be responsible for the SCC.
文摘The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking suscepti- bility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show that the hardenability characteristics and cold cracking susceptibility of the steel are very low. The results also indicate that a crack-free weldment can be obtained during the welding of this type of steel even at an ambient temperature as low as -5 ℃ as well as in an absolute humidity lower than 4 000 Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or higher absolute humidity.
文摘Super 304 H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of the material. Stress corrosion cracking susceptibility of Super 304 H parent metal and gas tungsten arc(GTA) welded joints were studied by constant load tests in 45% boiling Mg Cl2 solution. Stress corrosion cracking resistance of Super 304 H stainless steel was deteriorated by GTA welding due to the formation of susceptible microstructure in the HAZ of the weld joint and the residual stresses. The mechanism of cracking was found to be anodic path cracking, with transgranular nature of crack propagation. Linear relationships were derived to predict the time to failure by extrapolating the rate of steady state elongation.
文摘This paper introduces the process and result of fatigue test of steel (Z direction steel) welded T tubular joints used in offshore engineering. Detailed measurement of stress concentration factor, stress distribution, fatigue life and crack development has been performed. Through analysis, an empirical formula of stress concentration factor for T tubular joints, fatigue S-N curve and crack propagation rule are obtained.
文摘核电站乏燃料水池覆面板焊缝与母材交界面处的裂纹会严重影响设备的运行安全。考虑焊缝的真实特性,提出采用交流电磁场检测(alternating current field measurement,ACFM)技术来检测焊缝裂纹,以提高裂纹检测的灵敏度。首先,采用COMSOL软件建立了焊缝裂纹检测模型,分析了焊缝裂纹区域的磁场特征信号;其次,在实验试件焊缝与母材交界面处预置与数值仿真一致的人工裂纹,进行焊缝裂纹ACFM实验;最后,制作了焊缝裂纹检测系统,并进行了其性能测试。仿真、实验和测试结果表明:ACFM方法能够有效识别焊缝与母材交界面处平行于焊缝方向的裂纹,而不能识别垂直于焊缝方向的裂纹;通过焊缝裂纹检测系统测试得到的裂纹检测长度的偏差小于探头检测实验的偏差,但两者比较接近,证明了焊缝裂纹检测系统设计的合理性。ACFM能够实现乏池覆面板对接焊缝裂纹的定量化检测,满足现场高灵敏度的使用要求。
