马氏体与贝氏体组织GC—4超高强度钢的腐蚀疲劳裂纹扩展

本文研究了马氏体组织与贝氏体组织４０ＣｒＭｎＳｉＭｏＶＡ（ＧＣ－４）超高强度钢的腐蚀疲劳（ＣＦ）裂纹扩展特性及机理。结果表明，不显微组织状态下，ＧＣ－４钢在３．５ＮａＣｌ溶液中的ＣＦ裂纹扩展曲线上，都出现了类似于应力腐蚀的平台区，而且马氏体组织ＧＣ－４钢的平台区裂纹扩展速度远大于贝氏体组织。断口分析与理论研究表明，氢脆在ＧＣ－４钢的腐蚀疲劳中起重要作用。     

INTERFACE DEFORMATION CHARACTERISTICS OF BIMETAL FORMING

ＩＮＴＥＲＦＡＣＥＤＥＦＯＲＭＡＴＩＯＮＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＢＩＭＥＴＡＬＦＯＲＭＩＮＧ①ＰｅｎｇＹｉｎｇｈｏｎｇａｎｄＲｕａｎＸｕｅｙｕＮａｔｉｏｎａｌＤｉｅ＆ＭｏｌｄＣＡＤＥｎｇｉｎｅｒｉｎｇＲｅｓｅａｒｃｈＣｅｎｔｅｒ，Ｓｈａｎｇ...     

ELECTROCHEMICAL STUDIES ON THE MECHANISM OF GOLD DISSOLUTION IN THIOSULFATE SOLUTIONS

ＥＬＥＣＴＲＯＣＨＥＭＩＣＡＬＳＴＵＤＩＥＳＯＮＴＨＥＭＥＣＨＡＮＩＳＭＯＦＧＯＬＤＤＩＳＳＯＬＵＴＩＯＮＩＮＴＨＩＯＳＵＬＦＡＴＥＳＯＬＵＴＩＯＮＳＺｈｕ，Ｇｕｏｃａｉ；Ｆａｎｇ，Ｚｈａｏｈｅｎｇ；Ｃｈｅｎ，Ｊｉａｙｏｎｇ（ＩｎＳｔｄｕｔｅｏｆＣｈ...     

DESIGN AND PREPARATION OF SILICON NITRIDE COMPOSITE WITH HIGH FRACTURE TOUGHNESS AND NACRE STRUCTURE

ＤＥＳＩＧＮＡＮＤＰＲＥＰＡＲＡＴＩＯＮＯＦＳＩＬＩＣＯＮＮＩＴＲＩＤＥＣＯＭＰＯＳＩＴＥＷＩＴＨＨＩＧＨＦＲＡＣＴＵＲＥＴＯＵＧＨＮＥＳＳＡＮＤＮＡＣＲＥＳＴＲＵＣＴＵＲＥＹＨｕａｎｇ；Ｈ．ＮＨａｏ；Ｙ．Ｌ．ＣｈｅｎａｎｄＢ．Ｌ．Ｚｈｏｕ（１）Ｄｅ...     

焊接CGHAZ相变超塑性及对疲劳寿命的影响

采用热模拟方法，对ＥＨ３６ＭＯＤ钢焊接热影响区粗晶区（ＣＧＨＡＺ）的相变超塑性及其对疲劳寿命的影响进行了研究，研究结果证明；（１）采用热作用与拘束位移的方法，在模拟ＣＧＨＡＺ中确实在存着相变超塑性现象；（２）该超塑性应变值为１．０％时，其ＣＧＨＡＺ疲劳寿命比无相变超塑性的提高了１９％（３）微观分析表明，前者Ｍ－Ａ组元的形态为长条状与块状的混合体，其分布为铁素体（Ｆ）基体包围Ｍ－Ａ组元和Ｍ－Ａ组元包     

20G和2.25Cr—1Mo钢氢蚀后的疲劳性能

对２０Ｇ和２．２５Ｃｒ－１Ｍｏ钢经不同程度氢蚀后的常规力学性能与疲劳裂纹扩展行为进行了对比研究。并对氢蚀组织变化与裂纹扩展路径进行了显微观察。结果表明，氢蚀使２０Ｇ钢的疲劳裂纹扩展速率明显增大；扩展门槛值在氢蚀起始阶段显著降低，随后又呈增加趋势。对２．２５Ｃｒ－１Ｍｏ钢，由于元素Ｃｒ、Ｍｏ作用，其氢蚀程度远低于２０Ｇ钢，从而未造成疲劳裂纹扩展速率的明显改变。分析表明，氢蚀后疲劳裂纹扩展门槛值的上升     

阀片钢3Cr13的热处理工艺研究

研究了阀片钢３Ｃｒ１３经两种热处理后组织和性能的变化规律。试验结果表明，要求高硬度（５２ＨＲＣ）的阀片可采用１０５０℃油淬、２５０℃×２ｈ回火，或采用１０００℃加热、于２４０℃等温１５ｍｉｎ、３００℃×２ｈ回火；要求较低硬度（４０ＨＲＣ）的阀片，则可采用１０５０℃油淬、５５０℃×２ｈ回火的调质处理，或１０００℃加热、于２４０℃等温１５ｍｉｎ、５５０℃×２ｈ回火。弯曲疲劳模拟试验表明，高硬度的等温处理具有最长疲劳裂纹萌生期Ｎｏ和最高的疲劳强度，较低硬度的调质工艺也同样获得很高的Ｎｏ和良好的疲劳性能。     

INFLUENCE OF Fe DOPING ON ELECTROCHEMICAL PROPERTIES OF Ml(Ni,Co,Mn,Ti)_5 HYDROGEN STORAGE ALLOY

ＩＮＦＬＵＥＮＣＥＯＦＦｅＤＯＰＩＮＧＯＮＥＬＥＣＴＲＯＣＨＥＭＩＣＡＬＰＲＯＰＥＲＴＩＥＳＯＦＭｌ（Ｎｉ,Ｃｏ,Ｍｎ,Ｔｉ）５ＨＹＤＲＯＧＥＮＳＴＯＲＡＧＥＡＬＬＯＹ①ＣｈｅｎＬｉｘｉｎａｎｄＬｅｉＹｏｎｇｑｕａｎＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒ...     

20G和2．25Cr—1Mo钢氢蚀后的疲劳性能

对２０Ｇ和２．２５Ｃｒ－１Ｍｏ钢经不同程度氢蚀后的常规力学性能与疲劳裂纹扩展行为进行了对比研究。并对氢蚀组织变化与裂纹扩展路径进行了显微观察。结果表明，氢蚀使２０Ｇ钢的疲劳裂纹扩展速率明显增大；扩展门槛值在氢蚀起始阶段显著降低，随后又呈增加趋势，对２．２５Ｃｒ－１Ｍｏ钢，由于元素Ｃｒ，Ｍｏ的作用，其氢蚀程度远低于２０Ｇ钢，从而未造成疲劳裂纹扩展速率的明显改变，分析表明，氢蚀后疲劳裂纹扩展门槛值的上升可以归因于曲折开裂路径造成裂纹闭合效应的增加。     

NONLOCAL THEORY STUDY ON FRACTURE TOUGHNESS OF CERAMIC MATERIALS

ＮＯＮＬＯＣＡＬＴＨＥＯＲＹＳＴＵＤＹＯＮＦＲＡＣＴＵＲＥＴＯＵＧＨＮＥＳＳＯＦＣＥＲＡＭＩＣＭＡＴＥＲＩＡＬＳ￥Ｘ．Ｈ．Ｓｏｎｇ（ＣｅｎｔｒｅｆｏｒＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈａｎｄＡｎａｌｙｓｉｓ,ＷｕｈａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈ...     

环境介质对40Cr结构钢高周和超高周疲劳行为的影响

选用40Cr结构钢,分别在空气、水和3.5%NaCl水溶液中进行旋转弯曲疲劳实验,研究环境介质对该结构钢高周和超高周疲劳特性的影响.结果表明,40Cr钢在水环境中的疲劳强度比在空气中明显降低;在3.5%NaCl水溶液环境中的疲劳强度比在水中低.断面观察显示,在水和3.5%NaCl水溶液中,疲劳裂纹多源萌生;在稳态扩展阶段,裂纹沿品界扩展并存在广泛分布的沿晶二次裂纹.     

钢在中性水溶液中腐蚀疲劳的研究

本文对16Mn、08PVXt、440C和4340钢在蒸馏水和3.5％NaCl水溶液中的疲劳裂纹扩展速率(FCGR)进行了实验研究,并与一些钢在同类介质中的腐蚀疲劳(CF)实验结果进行了对比。结果表明:一般钢在前种介质中的疲劳寿命(FL)较后者长;08PVXt、440C及4340钢在蒸馏水中的FCGR较NaCl水溶液中高。而16Mn钢则有相反的结果。作者认为,这种情况是由于Cl~-在裂纹萌生和宏观裂纹扩展过程中起的不同作用所致。     

新型纳米强化马奥复相钢的应力腐蚀行为

采用慢应变速率拉伸以及WOL试样应力腐蚀试验研究一种含有逆转变奥氏体和纳米尺度多种析出相的新型纳米强化马奥复相钢在3.5%NaCl溶液的应力腐蚀行为。通过扫描电镜(SEM)、透射电镜(TEM)以及物理化学相分析观察了马奥复相钢的微观组织并解释了其应力腐蚀机理。结果表明,该马奥复相钢应力腐蚀敏感性较低,裂纹扩展速率较慢,抵抗裂纹能力强,抗应力腐蚀能力优异;Cl^-会促进马奥复相钢应力腐蚀开裂的发生,使得与在空气中的拉伸试验结果相比,在3.5%NaCl溶液中的抗应力腐蚀性能有一定损失;由于具有亚稳态逆转变奥氏体使得马奥复相钢具有好的塑韧性,并且弱化了应力集中,阻碍裂纹扩展;位错群共平面性较差,不容易产生腐蚀的敏感通道;碳化物以及Cu纳米第二相析出在600 ℃高温回火后,在提高了材料强度的同时,也可改善钢对应力腐蚀的敏感性。     

阳极电位下小幅载荷在腐蚀疲劳裂纹扩展中的作用

研究了A537钢在3.5%NaCl水溶液中,阳极溶解条件下以不同方式叠加在主载荷ΔP上的小幅载荷对疲劳裂纹扩展da/dN～ΔK曲线的影响,并与空气中的结果进行比较,讨论了阳极溶解影响小幅载荷行为的机理.结果表明:空气中幅度小于30%ΔP的小载荷叠加在主载荷底部时对裂纹扩展没有影响,而阳极溶解能使这些主载荷底部的小幅载荷对裂纹扩展过程产生重要作用,在阳极溶解条件下,即使是幅度为零的保持载荷(B0)对裂纹扩展也具有明显的加速作用;虽然阳极溶解对主载荷顶部的幅度为30%ΔP(T30)和70%ΔP(T70)的小载     

Hydrogen-assisted fatigue crack growth of AISI 316L stainless steel weld

The fatigue crack growth behaviors of AISI 316L stainless steel (SS) welds in air and gaseous hydrogen were evaluated, and further compared with the base plate. In air, the fatigue crack growth rate (FCGR) of the weld after heat-treatment at 1050 ^oC/1 h was similar to that of the base metal. Furthermore, all specimens became susceptible to hydrogen-accelerated crack growth. Mainly quasi-cleavage fracture related with the strain-induced martensite accounted for the accelerated crack growth in hydrogen. A smaller amount of martensite in the weld was responsible for the decreased susceptibility to hydrogen-enhanced fatigue crack growth relative to the base metal.     

CORROSION FATIGUE OF HSLA STEELS IN SALT SPRAY

The corrosion fatigue propagation behaviour of high strength low alloy Cr-Ni and Si-Mnsteels has been investigated in 3.5 %NaCl solution spryly at the frequencies of 0.1 and 5.5 Hz.It was shown that the fatigue crack initiation resistances of the two steels are significantly re-duced in salt spray;the fatigue crack growth rates of steels increase with the decrease of fre-quency and are much higher in salt spray than in air within low ΔK range.A critical stress in-tensity factor was observed for each steel and the crack growth stoppage will occur if the ΔKvalues are lower than it.It was found that the active dissolution makes great contribution tothe fatigue crack growth within low ΔK range.     

Fretting Corrosion Behavior of Zn-Al-Mg-RE Coating under Dry Friction and NaCl Solution

The fretting behavior of Zn-Al-Mg-RE coating prepared by high velocity arc spraying was studied for the first time in this paper.All specimens were fretted in air and 3.5%NaCl solution independently.The worn surfaces of the coating were investigated by scanning electron microscopy and X-ray energy dispersive spectroscopy.Fretting tests have shown that friction coefficient in 3.5%NaCl solution was similar to dry condition for Zn-Al-Mg-RE coating.Study of worn surfaces revealed the main mechanism in dry friction was the oxidative wear;while in 3.5%NaCl solution,the main mechanisms were delamination process and abrasive wear.     

The effects of hydrogen on fatigue crack growth behaviour of Ti-6Al-4V and Ti-4.5Al-3V-2Mo-2Fe alloys

The fatigue crack growth rates (FCGRs) of Ti-6Al-4V and Ti-4.5Al-3V-2Mo-2Fe alloys were determined in gaseous hydrogen, air, and a soft vacuum. In hydrogen and at a stress ratio of 0.1, the deflected crack path associated with the localized brittle fracture of the α-phase could account for the reduced FCGR of Ti-6Al-4V. At a higher stress ratio of 0.5, hydrogen embrittlement enhanced cracking and alleviated the effect of crack deflections in Ti-6Al-4V specimens, resulting in the FCGR in hydrogen similar to that in air. In contrast, the FCGR of Ti-4.5Al-3V-2Mo-2Fe was insensitive to both the environment and stress ratio.     

3.5%NaCl溶液对铝合金疲劳裂纹扩展特性的影响

对高强铝合金7050—T7451在模拟海水(3.5%NaCl溶液)的疲劳裂纹扩展特性进行了试验研究结果表明,3.5%NaCl溶液加速了7050—T7451铝合金的疲劳裂纹扩展速率da/dN.考虑应力比影响的有效应力强度因子面ΔKefT可以满意地表征不同环境中的的da/dN.裂纹面上的腐蚀产物较薄,对疲劳裂纹闭合的影响可以忽略不计.     

8090Al—Li合金的疲劳裂纹扩展

研究了8090型Al—Li合?疲劳裂纹扩展行为以及组织结构和环境的影响,结果表明,在空气中,自然时效和欠时效?现出最好的疲劳裂纹扩展阻力,其次是峰时效状态,而过时效状态的疲劳裂纹扩展阻力最低,在3.5%NaCl水溶液中,时效状态对疲劳裂纹扩展行为有着同空气中相同的影响规律,但在同样的时效条件下,在3.5%NaCl水溶液中的疲劳裂纹扩展阻力要比空气中的低,在相同的应力强度因子范围△K作用下,缺口短裂纹和物理短裂纹均表现出比长裂纹高的扩展速率,用位错的平面滑移性和循环滑移可逆性解释了时效的影响,用裂纹的闭合效应和裂纹尖端塑性区尺寸说明了长短裂纹扩展行为的差别。