GH901合金的蠕变裂纹扩展

我们对GH135合金的高温长期实验结果表明,存在一个“开裂界限”K_(It)(或称K_(Ihcc))。当应力强度因子K_I相似文献   

CRACK GROWTH BEHAVIOR IN TITANIUM ALLOY TC11AT ROOM AND HIGH TEMPERATURES

１．ＩｎｔｒｏｄｕｃｔｉｏｎＡｌｔｒａｄｉｔｉｏｎａｌａｎａｌｙｔｉｃａｌｍｅｔｈｏｄｓｏｆｔｈｅｆａｔｉｇｕｅｌｉｆｅｆｏｒａｅｒｏｅｎｇｉｎｅｃｏｍｐｏｎｅｎｔｓｒｅｌｙｏｎｓｐｅｃｉｍｅｎｏｒｆｕｌｓｃａｌｅｃｏｍｐｏｎｅｎｔｓｔｅｓｔｓ,...     

Al-Cu-Mg-Ag耐热铝合金高温蠕变行为

在100-210℃和150-300 MPa的条件下,研究了Al 5.3Cu-0.8Mg-0.5Ag-0.3Mn-0.15Zr耐热铝合金的蠕变行为,探讨了时效状态对合金高温性能的影响.结果表明:在相同蠕变条件下,欠时效态合金的稳态蠕变速率远远低于峰时效态合金.在210℃/200 MPa 下,欠时效态合金的蠕变断裂时间为7...     

IN718合金蠕变的补偿效应

研究了Ｐ,Ｓ和Ｂ含量不同的ＩＮ７１８合金的蠕变性能。结果表明,普通多晶体的蠕变存在补偿效应。一无素通过影响表现蠕变激活能Ｑ和指九前因子ε０,从而影响稳态蠕变速弯ε＝ε０ｅ－Ｑ／ＲＴ,各度验合金的Ｑ与ε０遵守补偿定律Ｑ＝ＲＴｃｌｎε０＋Ｑ０,式中常数Ｑ０＝６８．１２ｋｊ／ｍｏｌ,补偿温度Ｔｃ≈８１０℃,Ｔｃ可能近皇ＩＮ７１８合金δ相快速形成的临界温度。     

晶界碳化物对Fe-Cr15-Ni25合金蠕变裂纹扩展行为的影响SCIEI

在两种不同晶界状态下研究了Fe-Cr15-Ni25合金的蠕变裂纹扩展行为。单相合金的空洞在晶界三叉点处形核,而对晶界上有碳化物析出的合金,空洞在晶界碳化物上形核。晶界碳化物阻碍了空洞的长大和连接,因而大大提高了蠕变裂纹扩展抗力。     

少量Mg和Zr对一种Ni-Cr-Ti型变形合金蠕变裂纹长大行为的影响

采用电位法测定单边切口试样700℃下的蠕变裂纹生长,并测定裂纹起始寿命和断裂寿命(t_(rc)和t_r)。用能量率积分(C~*)描述稳态蠕变条件下裂纹顶端附近的场。给出裂纹长大速率与C~*的函数关系,预报的裂纹起始时间与实测值相符。发现合金中加入少量Mg和Zr可以大大延长蠕变裂纹起始寿命和蠕变断裂寿命。     

EFFECT OF GRAIN BOUNDARY CARBIDE ON CREEP CRACK GROWTH IN Fe-Cr15-Ni25 ALLOY

Creep crack growth behavior of Fe-Cr15-Ni25 alloys with different grain boundary featureshas been studied.Cavities nucleate at triple junctions of grain boundaries for the single phasealloy and at grain boundary carbide for the alloy with grain boundary carbide.Grain bounda-ry carbide particles are obstacles to cavity growth and coalescence,and therefore increase thecreep crack growth resistance greatly.     

EFFECT OF SULPHURIZING-OXIDIZING ENVIRONMENT ON CREEP CRACK GROWTH OF Ni-BASE SUPERALLOY GH30

An investigation was made on the creep crack growth behaviour under static load at 1023 Kfor Ni-base superalloy GH30 exposed to air and air+10% SO_2.The results showed that inthe region of low stress intensity factor,the creep crack growth rate is higher in air+10%SO_2 than in air only,while in the high region,it is reverse.The fractograph of specimens hasbeen analyzed,and the mechanism of creep crack growth together with the influences of sul-phur and oxygen has been discussed as well.     

INFLUENCE OF GRAIN SHAPE AND CARBIDE ON CREEP CRACK GROWTH IN HK40

The influence of two different grain shapes and carbides in the HK40 alloy,the material foruse of furnace tube,on the rate of creep crack growth has been investigated.The resistance tocreep crack growth of the material with columnar grains is inferior than that with equiaxialgrains when the load line is perpendicular to the columnar grain axis.The influence of secon-dary carbide on the rate of creep crack propagation depends upon the Brain shape.     

EFFECTS OF TRACE Zr ON FATIGUE CRACK GROWTH RATE OF HIGH DAMPING Zn-Al ALLOY

ＥＦＦＥＣＴＳＯＦＴＲＡＣＥＺｒＯＮＦＡＴＩＧＵＥＣＲＡＣＫＧＲＯＷＴＨＲＡＴＥＯＦＨＩＧＨＤＡＭＰＩＮＧＺｎ－ＡｌＡＬＬＯＹ￥ＺｈｏｕＳｈａｎｃｈｕ；ＬｕｏＢｉｎｇｈｕｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉｎｅｅ...     

硫-氧化环境对GH30镍基高温合金蠕变裂纹扩展行为的影响SCIEI

研究了GH30镍基高温合金在静载荷下在1023K不同气氛中的蠕变裂纹扩展行为。结果表明:低应力强度因子区域,在10％SO_2+空气中的da/dt比空气中的高;高应力强度因子区域的da/dt,则与上述相反。对断口进行了分析,并讨论了蠕变裂纹扩展机制以及硫、氧的影响。     

NiAl—Cr（Zr）金属间化合物合金的高温蠕变

研究了多相金属间化合物NiAl-33．5Cr－0．5Zr合金的显微组织和高温拉伸蠕变行为。铸态合金由β-NiAl和α-Cr组成共晶胞及沿共晶胞界分布的NiAlZr（Heusler)相组成。热等静压处理后,胞界处的Ni2AlZr相转变为富Zr相。蠕变曲线表现为较短的减速蠕变阶段和较长的稳态蠕变阶段,不同温度、负荷下的蠕变应变几乎相同,均为45％左右,且蠕变后的显微组织变化不大。蠕变变形机制为错滑移和攀移控制下的动态回复与动态再结晶,不是单独由扩散所控制。蠕变断裂数据符合Monkman-Grant关系。     

EFFECT OF Mg AND Zr ADDITION ON CREEP CRACK GROWTH BEHAVIOUR OF A Ni-BASE SUPERALLOY

The creep crack growth(CCG)and the time to carck initiation and rupture of specimen(t_(rc)and t_r)were measured by means of electrical potential method on single edge notchedspecimens at 700℃.The field near the crack tip under steady-state creep was represented byenergy rate integral(C~*),and the CCG rate as a function of C~* has been obtained.Theagreement between the predicted and observed t_(rc)values is quite good.It was found that theaddition of small amount of Mg and Zr in the alloys causes t_(rc)and t_r of the specimens to in-crease significantly.     

晶粒形状和碳化物对HK40蠕变裂纹扩展的影响SCIEI

对两种晶粒形状的HK40炉管材料,研究了晶粒形状及碳化物对蠕变裂纹扩展速率的影响。发现当加载方向与柱状晶轴向垂直时,柱状晶材料的蠕变裂纹扩展抗力低于等轴晶材料。二次碳化物对裂纹扩展速率的影响依赖于晶粒形状。     

EFFECIS OF TEMPERATURE AND OVERLOAD RETARDATION ON CORROSION FATIGUE CRACK GROWTH OF HIGH STRENGTH STEEL

The fatigue crack growth rate (CGR) of ultra high strength steel 30CrMnSiNi2A in distilledwater at 18,35 and 55℃ were measured.It was confirmed that the temperature is strongly af-fected on the corrosion fatigue CGR of ultra high strength steel.An expression concerning theeffects of Δ K and temperature on the CGR was proposed.The fact that the apparentactivation energy (36.6 kJ/mol) resulted from regressive analysis of CGR data was similarto the activation energy of hydrogen diffusion in γ-Fe,strongly supporting the theory ofhydrogen-assisted crack growth.The overload retardation effect was greatly reduced in cor-rosion fatigue crack growth,especially at lower frequency,e.g.,0.1 Hz.This phenomenonmight be due to the increase of the SCC component of CGR after an overload.     

THE SEGREGATION OF SULFUR AND PHOSPHORVS IN NICKEL-BASE ALLOY 718

1.IntroductionSurfaceandinterfacialsegregationiscurrentlyaveryactiveareaofresearch.Thisphenomenonhasbeenstudiedextensivelyinbinaryandternaryalloysll--31.Commercialsteelsandsuperalloysarecomplexsystemswithmanyelementalspecies.Whileimpuritysegregationhasbeenwidelystudiedinsteels,comparativelylittleisknownaboutthesuperalloys.Cleansuperalloyproductionisvanguardofthesuperalloyindustryandcleanlinesshasbeenbasicallyconsidetedintwocategories:inclusionsanddetrimentalelementsco.t.oll4].Sulfurandphospho…     

高强度钢腐蚀疲劳裂纹扩展的温度效应和过载迟滞效应

通过在18,35和55℃蒸馏水中疲劳裂纹扩展试验,证明了超高强度钢30CrMnSiNi2A腐蚀疲劳具有强烈的温度效应,得到了ΔK值和温度对裂纹扩展速率影响的复合表达式。由于扩展速率数据拟合得到的表观激活能值(36.7kJ/mol)十分接近于氢在γ-Fe中的扩散激活能值,支持了氢助裂纹扩展的观点。对大气中疲劳裂纹扩展具有重要价值的过载迟滞效应,在腐蚀疲劳时显著地减小,在0.1Hz的低频率下尤其明显。     

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.     

DEVELOPMENT OF INCONEL~ ALLOY 783，A LOW THERMAL EXPANSION，CRACK GROWTH RESISTANT SUPERALLOY

ＤＥＶＥＬＯＰＭＥＮＴＯＦＩＮＣＯＮＥＬ~ＡＬＬＯＹ７８３,ＡＬＯＷＴＨＥＲＭＡＬＥＸＰＡＮＳＩＯＮ,ＣＲＡＣＫＧＲＯＷＴＨＲＥＳＩＳＴＡＮＴＳＵＰＥＲＡＬＬＯＹＪ．Ｈ．Ｔｈｎｄｅｒｍａｎｎ（ＩｎｃｏＡｌｌｏｙｓＩｎｔｅｒｎａｔｉｏｎａｌ,Ｉｎｃ．...     

热处理对莫来石短纤维增强ZL107合金高温循环蠕变行为的影响

研究了经峰时效（Ｔ５）及过时效（Ｔ５＋３００℃）处理的莫莱石纤维增强ＺＬ１０７复合材料在３００℃时的拉－拉循环蠕变的行为,实验结果表明：两种热处理状态下,复合材料都显示出循环蠕变减速现象,峰时效状态下,循环蠕变与静态蠕变相比表现出低的表观激活能非热空位机制作用较大,而过时效状态下,循环蠕变与静态蠕变相比表现出的高的表观激活能,滞弹怀机制作用较大