1Cr18Ni9Ti不锈钢的马氏体相变量与孔蚀敏感性的相关性 …

研究了ＡＩＳＩ３２１亚稳态奥氏体不锈钢在－７０℃（液氮气氛）经不同程度拉伸形变得到的含有不同α‘－马氏体的试样在中性含氯离子介质中,材料的马氏体相变量与孔蚀敏感性的关系。孔蚀击蚀电位,位蚀诱导期和孔数的测试结果均表明,当α’－马氏体含量约小于５％和大于１５％时,经形变诱发马氏体相变的１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢在中性ＮａＣｌ溶液中,孔蚀敏感性随α‘－马氏体含量的增加而增大,当α’－马氏体含量在     

304不锈钢应变诱发相变对化学成分敏感性的研究

借助于X射线衍射技术,研究了304亚稳奥氏体不锈钢应变诱发马氏体相变倾向对化学成分的敏感性。液氮温度拉伸结果表明:C、Mn、Cr和Ni从标准范围的上限变化到下限,马氏体相变倾向显著增大,加工硬化明显提高。应变诱发α′马氏体相变倾向对C、Mn、Cr和Ni含量很敏感,要控制马氏体相变的发生,可通过优化C、Mn、Cr和Ni含量来实现。     

用交流阻抗法研究形变诱发马氏体相变的1Cr18Ni9Ti不锈钢在酸性NaCl溶液中的孔蚀敏感性

用交流阻抗法研究低温(-70℃)拉伸诱发马氏体相变的321不锈钢在酸性NaCl溶液中的孔蚀敏感性.结果表明:形变马氏体相(铁磁相)的存在,影响材料孔蚀的诱发和发展:低频离散型和低频实部收缩型频谱特征均说明有孔蚀诱发和发展的剧烈变化过程;界面电化学参数的变化规律进一步说明:当马氏体相含量小于6%和大于22%时,材料的孔蚀敏感性随马氏体相含量的增加而增大;当马氏体相含量约在6～22%范围时,孔蚀敏感性又随马氏体相增多而下降.根据马氏体相存在时孔蚀诱发和发展过程中,电极表面进行的吸附、溶解、成膜过程,提出本体系     

形变诱发马氏体对1Cr18Ni9Ti不锈钢应力腐蚀破裂的影响

通过低温(-70℃)拉伸方法,制备出具有不同马氏体(铁磁相)含量的1Cr18Ni9Ti(AISI321)奥氏体不锈钢试件。采用恒载荷法对双边缺口试样进行应力腐蚀试验,测定了不同马氏体含量的试样在氯化物介质中应力腐蚀破裂(SCC)的归一化门槛值。用SEM观察断口形貌。结果表明:当铁磁相含量小于5%时,材料的SCC敏感性随含量增加而减小;在5～15%范围内,SCC敏感性不断增加;在15～24%区域中,材料的SCC敏感性迅速下降;超过24%,SCC敏感性又有所上升。     

用交流阻抗法研究形变诱发马氏体相变的1Cr18Ni9Ti不锈钢在酸性NaC…

用交流阻抗法研究低温拉伸诱发马氏体相变的３２１不锈钢在酸性ＮａＣｌ溶液中的孔蚀敏感性。结果表明；形变马氏体相的存在，影响材料孔蚀的诱发和发展；低频离散型和低频实部收缩型频谱特征均说明有孔蚀诱发和发展的剧烈变化过程；界面电化学参数的变化规律进一步说明：当马氏体相含量小于６％和大于２２时，材料的孔蚀敏感性随马氏体相含量的增加而增大；当马氏体相含量约６－２２％范围时，蚀敏感性又随氏体相增多而下降。     

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 借助于X射线衍射，研究了C、Mn、Cr和Ni 含量对304奥氏体不锈钢拉伸力学性能和应变诱发 马氏体相变倾向的影响。结果表明：C、Mn、Cr和Ni在允许的成分范围内变化，应变诱发α′马氏体相变倾向差异很大，这导致屈服强度和抗拉强度复杂的变化，尽管应变诱发α′马氏体相变使加工硬化速率提高，相变可以诱发塑性，但相变速率较快，相变倾向较大的钢塑性反而下降，此外，由于室温变形还增大热诱发马氏体相变倾向，从而限制了C、Mn、Cr和Ni下限钢在高精度和低温环境下构件的应用。     

1Cr18Ni9Ti不锈钢形变诱发马氏体相变规律及其对孔蚀敏感性的影响

通过低温（－７０℃）拉伸制备不同马氏体相交量的１Ｃｒ１８Ｎｉ９Ｔｉ试样,用ＸＲＤ、ＴＥＭ及金相观察研究形变诱发马氏体相变的规律。用电化学方法研究。α’马氏体（铁磁相）含量对１Ｃｒ１８Ｎｉ９Ｔｉ钢在含Ｃｌ－溶液中孔蚀敏感性的影响。结果表明：随试样变形量加大,形变诱发马氏体中铁磁性的α’马氏体含量不断增大,而ε马氏体相的量始终较小。材料的孔蚀敏感性先随铁磁相含量的增大而增大;当铁磁相含量达到４．５８％以后,孔蚀敏感性反而渐降;当铁磁相含量超过２５．５％后,孔蚀敏感性又增加。     

激光电子散斑干涉技术监测奥氏体不锈钢在NaCl溶液中的点蚀敏感性

用动电位极化和电化学阻抗等方法检测1Cr18Ni9Ti、304和316三种奥氏体不锈钢在3.5%NaCl溶液中的点蚀敏感性;用恒电位下的计时电流法结合激光电子散斑干涉技术（ESPI）实时监测这三种材料在3.5%NaCl溶液中阳极极化过程的表面动态变化及点蚀感应时间(τ)。结果表明,当电极表面发生点蚀时,激光电子散斑干涉图上会出现由点蚀产物扩散引起的亮斑。1Cr18Ni9Ti和 304不锈钢的τ值分别是1 s和9 s,316不锈钢的τ值大于50 s。由此可以判断1Cr18Ni9Ti的点蚀敏感性最大,304居中,316的点蚀敏感性最小。此结果与动电位极化和电化学阻抗等电化学方法得出的结果一致。激光电子散斑干涉技术可以做为一种实验室方法监测金属早期点蚀敏感性。     

1Cr18Ni9Ti不锈钢形变诱发马氏体相变规律及其对孔敏感性…

通过低温（－７０℃）拉伸制备不同马氏体相变量１Ｃｒ１８Ｎｉ９Ｔｉ试样，用ＸＲＤ，ＴＥＭ及金相观察研究形变诱发马氏体相变的规律。用电化学方法研究α马氏体（铁磁相）含量对１Ｃｒ１８Ｎｉ９Ｔｉ钢在含Ｃｌ＾－溶液中孔蚀敏感性的影响，结果表明，随试样变形量加大，形变诱发马氏体中铁磁性的α马氏体含量不断增大，而ε马氏体相的量始终较小。材料的孔蚀敏感性失随铁磁相含量的增大而增大，当铁磁相含量达到４．５８％以后，     

超音速火焰喷涂Cr3C2/NiCr涂层抗加沙空蚀性分析

采用HVOF技术在1Cr18Ni9Ti不锈钢基体上制备了Cr3C2/NiCr涂层,借助XRD,TEM,SEM等方法分析了涂层的组织形貌及相组成.以1Cr18Ni9Ti奥氏体不锈钢作为对比材料,用磁致伸缩空蚀仪配备扬沙装置测试了涂层在清水以及含沙水中抗空蚀性能.结果表明,涂层呈层状结构,含有未熔颗粒和少量孔隙,涂层由Cr3C2,Cr7C3,Cr23C6及NiCr等相组成;在清水试验中,1Cr18Ni9Ti不锈钢抗空蚀性能良好,与空蚀过程中1Cr18Ni9Ti奥氏体不锈钢产生加工硬化有直接关系;在含沙40 kg/m3试验水中,Cr3C2/NiCr涂层呈现出较好的抗空蚀性能,与涂层自身相组成以及较高硬度有关.Cr3C2/NiCr涂层破坏总是从孔隙等薄弱环节开始,而1Cr18Ni9Ti奥氏体不锈钢的破坏起始于晶界和孪晶界.     

Effect of tensile deformation of austenite on the morphology and strength of lath martensite

A hot-rolled steel, 22SiMn2TiB, was employed to study the effect of austenite deformation on the microstructure and strength of the subsequently formed lath martensite. It was revealed that the sizes of the martensite packet, block and lath were refined by the tensile deformation of austenite at temperatures above 850 °C. With the increase of the deformation temperature, the packet size increased, whereas the block size decreased. The width of the lath was independent of the prior austenite grain size and the deformation temperature. The refinement of martensite blocks was considered to strengthen the ausformed martensite.     

热轧双相钢塑性变形和断裂行为的研究

文章利用SEM、TEM研究了热轧双相钢单向拉伸过程中不同变形量下的形变位错结构和断口组织特征。结果表明,双相钢中铁素体的塑性变形是由位错增殖、位错运动和交互作用、滑移带形成、位错缠结产生及其密度的增加、位错胞出现及细化等一系列演变构成;变形10%时,板条马氏体已产生塑性变形,其板条中出现形变带,并且随马氏体变形的继续,形变带不断形成和发展。变形颈缩时,双相钢中的微孔主要通过相界面结合力的丧失和马氏体断裂产生,而马氏体断裂主要出现在马氏体的尖角处。     

Crystallographic analysis of the FCC → BCC martensitic transformation in high-carbon steel

Based on the phenomenological crystallographic theory of martensitic transformations, the following crystallographic characteristics of the tetragonal martensite in high-carbon steel have been calculated: orientation relationships between the crystal lattices of the bct martensite and fcc austenite; the magnitude and direction of the macroscopic shear; the habit plane; the angle and the axis of rotation of the crystal lattice of the martensite. The calculation was performed for three variants of lattice deformation: Bain deformation; two-shear Kurdjumov-Sachs deformation; and the deformation we suggested upon the analysis of the fcc-bcc transformation. In the last variant, a minimum rotation of the crystal lattice of martensite is required; consequently, this variant is closest to the real mechanism of the martensitic transformation. An expression has been derived that describes the interrelation between the degree of tetragonality of the crystal lattice of martensite and the magnitude of the shear deformation of the lattice. It has been shown that the 12 crystal-lographically equivalent variants of shear upon the formation of the lattice of the tetragonal martensite form three groups in each of which the martensite has the same tetragonality axis. For each variant of the shear, we have two equivalent variants of deformation of the martensite with invariant lattice. This results in 24 variants of orientation relationships.     

82B盘条拉拔横裂纹断裂分析

采用金相显微镜、扫描电镜、显微硬度计等对 82B盘条钢拉拔横裂纹断裂试样进行了分析。结果表明：拉拔过程中产生白亮形变马氏体是盘条出现断裂的原因。对产生形变马氏体原因进行讨论，并提出了避免形变马氏体产生的措施。     

Ni—Ti—Nb宽滞后形状记忆合金的形变诱发马氏体相变及其可逆性

用透射电镜、高分辨电镜、不同温度下的拉伸试验以及电阻率－温度曲线测试研究了Ｎｉ－Ｔｉ－Ｎｂ合金形变诱发马氏体相变及其可逆性，分析了形变诱发马氏体的稳定性和可逆性与其变体界面结构之间的关系。结果表明，Ｎｉ－Ｔｉ－Ｎｂ合金在Ｍｓ－Ｍｓ＾σ温度区间加应力时发生应力诱发马氏体相变，而在Ｍｓ＾σ以上温度加应力时，发生应变诱发马氏体相变。形变对Ｎｉ－Ｔｉ－Ｎｂ合金的应力诱发马氏体界面结构有明显影响，随着拉伸变     

Effect of deformation by stress-induced martensitic transformation on the transformation behaviour of NiTi

It has been reported that martensite in near-equiatomic NiTi is thermally stabilised after a moderate deformation via martensite reorientation. This work continues the study by investigating the effect of deformation via stress-induced martensitic transformation on the transformation behaviour of the alloy. It was observed that the stress-induced martensite was also stabilised relative to the thermal martensite formed on cooling, as indicated by an increase in the critical temperature for the reverse transformation. Associated with the stabilisation, the heat effect, as determined by differential scanning calorimetry, and the temperature interval of the reverse transformation, were measured and found to decrease with increasing level of deformation. The experimental results also demonstrated that the stress-induced martensitic transformation was microscopically localised, as expected for a first-order phase transformation.     

Effect of Martensite Morphology on Tensile Deformation of Dual-Phase Steel

Three morphologies of martensite in dual-phase microstructure of 0.2% C steel were obtained by different heat treatment cycles. These morphologies consisting of grain boundary growth, scattered laths, and bulk form of martensite have their distinct patterns of distribution in the matrix (ferrite). In tensile testing martensite particles with these distributions behaved differently. A reasonable work hardening was gained initially during plastic deformation of the specimens. The control on ductility was found to depend on the alignment of martensite particles along the tensile axes. The increased surface area contact of martensite particles with ferrite, in grain boundary growth and scattered lath morphologies, facilitated stress transfer from ductile to hard phase. The ductility in the later part of deformation was dependent on the density of microvoids in the necked region. The microvoids are formed mostly by de-cohesion of martensite particles at the interface. The fracture of martensite particles is less prominent in the process of microvoid formation which predicts high strength of martensite.     

1Cr18Ni9Ti超高强度不锈钢丝的微观组织分析

分析了超高强度奥氏体不锈钢丝在多道次拉拔过程中的组织变化。结果表明，当拉拔变形量大于30％时，组织中开始出现形变马氏体，且变形量越大形变马氏体数量越多，尺寸越小：并分析了拉拔时产生形变马氏体的原因。     

Modified Law of Mixture to Describe the Tensile Deformation Behavior of Thermomechanically Processed Dual-Phase Steel

Low alloy steel containing 0.09 wt.% C was thermomechanically processed with various rolling reductions at intercritical temperature of 790 °C, followed by quenching in the iced brine solution. The flow of the material due to this plastic deformation increased the aspect ratio of the microstructure (α + γ) in the rolling than in the transverse directions. The strengths, both in the longitudinal and transverse directions of rolling were increased because of the development of substructure in ferrite, observed previously. The fibrous microstructure formed after rolling increased the surface area of contact of ferrite and martensite. During tensile deformation the fibrous dual-phase composite had positioned itself for better stress transfer from soft ferrite to hard martensite particles. These microstructural changes associated with hot deformation of the material were accommodated in current modifications in the law of mixture applied to dual-phase steel. A computer simulation was developed to present the deformation behavior of ferrite, martensite, and composite from the experimental tensile data (loads and strain). Different variables were introduced in the simulation for allowing the composite curves to pass through the experimental data points to demonstrate the tensile deformation behavior of ferrite and martensite. The systematic changes in these variables with degree of hot rolling in the intercritical region clearly described the deformation behaviour of ferrite and martensite individually.     

The influence of martensite volume fraction, shape and strength on the mechanical properties of granular structure steels

考虑马氏体岛的塑性变形, 采用Eshelby等效夹杂模型对粒状组织钢单向应力状态下的弹塑性变形行为进行了数值模拟.结果表明: 粒状组织钢的屈服强度及马氏体处于弹性变形阶段的加工硬化率均随马氏体岛的体积分数的增加而增加, 并呈一定的非线性; 马氏体岛的形状对粒状组织钢均匀变形阶段的应力-应变曲线影响较小; 马氏体岛的强度对粒状组织钢的屈服强度影响不大; 马氏体岛的体积分数越低, 马氏体岛越难发生塑性变形.