In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sin...In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sink effect on weld strength. In this work, the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.展开更多
Transforming China into an innovation-driven economy has been one of the top priorities of the Chinese Government. This paper examines the policy choices involved in the extended national innovation performance framew...Transforming China into an innovation-driven economy has been one of the top priorities of the Chinese Government. This paper examines the policy choices involved in the extended national innovation performance framework for creating an open innovation system. Innovation capabilities, incentives and institutional frameworks are examined. The paper argues that China should continue to increase its investment in R ＆D and in education, and that there should also be an attempt to strengthen the incentive system at the macro, meso and micro levels. This strengthening may include reforms to： release the power of competition and guide resources towards innovative sectors; adopt appropriate human resource management, such as appraisal and remuneration systems; create effective policies for research funding management; and evaluate the efficiency of research to encourage the creativity of researchers, managers and employees. The paper also discusses the space for industrial policy in the 21st century.展开更多
China＇s remarkable economic growth has produced dramatic structtral and socioeconomic change. Economic growth has solved many problems but the accompanying changes in the economy and society have brought new problems...China＇s remarkable economic growth has produced dramatic structtral and socioeconomic change. Economic growth has solved many problems but the accompanying changes in the economy and society have brought new problems to the fore. This has been recognized by China＇s Government in the recent emphasis that it has placed on the need to create a ＂harmonious society.＂ The new leadership will wish to devise new policies for the current challenges and those ahead.展开更多
文摘In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sink effect on weld strength. In this work, the effect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel (DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium (air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the effect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.
文摘Transforming China into an innovation-driven economy has been one of the top priorities of the Chinese Government. This paper examines the policy choices involved in the extended national innovation performance framework for creating an open innovation system. Innovation capabilities, incentives and institutional frameworks are examined. The paper argues that China should continue to increase its investment in R ＆D and in education, and that there should also be an attempt to strengthen the incentive system at the macro, meso and micro levels. This strengthening may include reforms to： release the power of competition and guide resources towards innovative sectors; adopt appropriate human resource management, such as appraisal and remuneration systems; create effective policies for research funding management; and evaluate the efficiency of research to encourage the creativity of researchers, managers and employees. The paper also discusses the space for industrial policy in the 21st century.
文摘China＇s remarkable economic growth has produced dramatic structtral and socioeconomic change. Economic growth has solved many problems but the accompanying changes in the economy and society have brought new problems to the fore. This has been recognized by China＇s Government in the recent emphasis that it has placed on the need to create a ＂harmonious society.＂ The new leadership will wish to devise new policies for the current challenges and those ahead.
