采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头...采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.展开更多
Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a...Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a wave-front breaking on the shore of our historical ways of thinking and acting,increasingly unfit for our human circumstances.This challenge to humanity is not new.In 1970 the French term‘problematique’was coined to refer to a set of 49 interrelated global problems;the classic description of wicked and tame problems was published soon after,yet little progress has been made towards answering the question:what purposeful action will aid human flourishing,create and sustain a viable space for humanity,in our ongoing co-evolution with the Anthropocene-Biosphere?A case for innovation in our ways of knowing and doing is made based on arguments that our social world is constrained by:(i)explanations we accept that are no longer relevant to our circumstances;(ii)outdated historical institutions(in the institutional economics sense)that contribute as social technologies to a broader human created and ungoverned technosphere;(iii)inadequate theory-informed practices,or praxis,and(iv)governance-systems no longer adequate for purpose.Practitioners of knowledge science and systems science are urged to act reflexively to critically evaluate the traditions-of-understanding out of which they think and act.展开更多
文摘采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.
文摘Since 2019 humanity has been subjected to the perturbations of pandemic,economic disruption,war,civil unrest and changes in whole-Earth dynamics associated with a human-induced Anthropocene.Each perturbation is like a wave-front breaking on the shore of our historical ways of thinking and acting,increasingly unfit for our human circumstances.This challenge to humanity is not new.In 1970 the French term‘problematique’was coined to refer to a set of 49 interrelated global problems;the classic description of wicked and tame problems was published soon after,yet little progress has been made towards answering the question:what purposeful action will aid human flourishing,create and sustain a viable space for humanity,in our ongoing co-evolution with the Anthropocene-Biosphere?A case for innovation in our ways of knowing and doing is made based on arguments that our social world is constrained by:(i)explanations we accept that are no longer relevant to our circumstances;(ii)outdated historical institutions(in the institutional economics sense)that contribute as social technologies to a broader human created and ungoverned technosphere;(iii)inadequate theory-informed practices,or praxis,and(iv)governance-systems no longer adequate for purpose.Practitioners of knowledge science and systems science are urged to act reflexively to critically evaluate the traditions-of-understanding out of which they think and act.
