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液氮温度下奥氏体不锈钢强度试验研究 总被引:1,自引:0,他引:1
为研究低温和预应变对奥氏体不锈钢强度的影响规律,以奥氏体不锈钢S30408为例,对母材和9%预应变材料进行了液氮温度下恒定速率的拉伸试验。研究表明:材料屈服强度和抗拉强度规律均符合正态分布;在95%可靠度和90%置信度的条件下,母材和9%预应变材料屈服强度的标准值分别为383 MPa和449 MPa,抗拉强度的标准值分别为1521 MPa和1535 MPa;低温能够显著提高材料的屈服强度和抗拉强度,而预应变能够有效提高材料的屈服强度,但对于抗拉强度基本没有影响;低温会降低材料屈强比,而预应变则会提高屈强比。 相似文献
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将大口径X80管线钢试样拉伸至应变为0.5%~3.5%,卸载后分别进行室温及200,230,250℃时效处理,研究了拉伸预应变和时效温度对试验钢拉伸性能的影响;采用直缝埋弧焊在制管扩径率为0.5%~0.8%下对试验钢进行制管,研究了制管扩径率对试验钢拉伸性能的影响。结果表明:进行一定应变预拉伸+时效处理或制管扩径后,试验钢发生应变时效,其屈服强度增大,抗拉强度变化较小,屈强比增大;制管扩径率对屈服强度增量和屈强比增量的影响比拉伸预应变的更大;室温应变时效后,拉伸预应变是影响屈服强度和屈强比提高的主要因素;200~250℃应变时效对试验钢拉伸性能的影响比室温应变时效的大,200~250℃时效温度的变化对拉伸性能影响不大。 相似文献
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为了改善钢材的性能,需对其采用不同的方法进行处理。评价不同处理方法的效果是制定或改进钢材处理方法的基础。应用概率论与数理统计知识,构建了不同处理方法的效果评价体系。基于奥氏体不锈钢S30408在液氮温度时的有效拉伸试验数据,比较9%预应变与非预应变两种处理方法的效果。在双侧置信度为99%时,与非预应变处理方法相比,9%预应变处理方法明显提高了S30408材料在液氮温度下的屈服强度均值,降低标准差与变异系数的效果不显著; 9%预应变处理方法对在液氮温度下的抗拉强度均值、标准差与变异系数的改变效果不明显。液氮温度时奥氏体不锈钢S30408抗拉强度的变异系数明显小于屈服强度的变异系数。 相似文献
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X70管线钢拉伸性能试验研究 总被引:2,自引:0,他引:2
对X70系列大口径厚壁天然气管道材料不同取样方式和取向的拉伸试样进行试验,结果表明:X70管线钢具有连续屈服特征,无明显的屈服平台,延伸率非常大。其力学性能呈现明显的各向异性,横向拉伸的屈服强度、抗拉强度及弹性模量均比纵向拉伸的高。试样的截面形状和尺寸对抗拉强度有一定的影响,对屈服强度影响很小。由于材料内部的片状缺陷引起的沿厚度方向强度降低和横向拉应力的作用,断裂时在板状试样短边中心出现分层开裂。因此,在进行结构设计和安全评定时应充分考虑X70管线钢特殊的力学性能。 相似文献
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在CR1500HF热成形钢U形件不同位置取样,进行应变速率在1~500 s-1的拉伸试验,研究了不同位置拉伸性能的差异和应变速率对热压成形件拉伸性能的影响;建立材料拉伸有限元模型,模拟分析了该钢的高速拉伸性能和拉伸试样加持端应力分布.结果表明:该热压成形U形件侧壁位置的抗拉强度和屈服强度低于法兰和底部位置,在进行碰撞分析时需考虑部分位置因冷却不足强度降低的影响;随着应变速率的增加,U形件不同位置的屈服强度和抗拉强度均增大;由拉伸有限元模型模拟得到的真应力-真塑性应变曲线与combined S-H本构模型拟合得到的曲线吻合较好,应变速率1,500 s-1下真应力均方根误差分别为19.98,39.48 MPa;高速拉伸过程中拉伸试样夹持端大部分处于弹性变形阶段,应变片粘贴位置距试样圆弧处的距离应大于19 mm. 相似文献
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Bahadir Uyulgan Hakan Cetinel Tevfik Aksoy 《Journal of Mechanical Science and Technology》2011,25(9):2171-2177
In this study, 17Mn4 (P295GH) pressure vessels steel and AISI304 stainless steel were welded with ER309L austenitic consumable.
In experimental part of the study, tensile tests were conducted on welded plates and variation of hardness values along specimen
was measured. J-integral fracture toughness values were investigated for different crack locations. In order to determine
the regions where plastic deformation did not take place due to constraint, uni-axial tensile test was performed on welded
tensile specimen after attaching strain gauges. In numerical part of the study, finite element (FE) analyses were conducted
by fixing 2-D models precracked on different locations by using ANSYS software. In these models, stress triaxiality and plastic
deformation characteristics around crack tip were determined for each crack locations after stress — strain analyses. The
limitation on the extension of plastic deformation at diffusion line causes extra increase in stress triaxiality at crack
tip. 相似文献
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Chang-Kyun Oh Yun-Jae Kim Jong-Hyun Baek Young-Pyo Kim Woosik Kim 《International Journal of Mechanical Sciences》2007,49(12):1399-1412
This paper presents a phenomenological model of ductile fracture for the API X65 steel using the Gurson–Tvergaard–Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars, from which the parameters in the GTN model are calibrated. Comparison of experimental data of pre-strained, notched tensile and fracture toughness tests with finite element (FE) damage analyses show good agreements, suggesting the validity of the calibrated parameters. As application, the developed GTN model is applied to predict the pre-strain effect on deformation and fracture and the results are compared with experimental data. 相似文献
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为使船用钢CCS-B三明治板激光焊焊接接头在拉伸初期处于不同应力状态,设计了不同尺寸及缺口半径的试样,分别在平面应变、平面应力状态下获得不同的初始三向应力度,进而获得不同应力状态下的力学性能。试验结果表明:在进行拉伸试验时,试样无论是处于平面应力状态下还是平面应变状态下,随着初始三向应力度的减小,等效断裂应变增大,塑性变好;三向应力度与等效断裂应变之间均满足指数关系,即等效断裂应变随着三向应力度的增加呈现指数减小;断口形貌均为韧窝的韧性断裂形貌。 相似文献
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为了研究脉冲电流对SUS304极薄带拉伸变形的影响,进行了室温拉伸、通电拉伸以及通电空冷拉伸试验,分析了热效应和非热效应对宏观力学性能与微观组织的影响。结果表明,脉冲电流辅助SUS304极薄带拉伸变形过程中热效应和非热效应同时存在,热效应导致材料流变应力减小,非热效应抑制TRIP效应,促进TWIP效应,改变了材料的塑性变形机制;没有高强度马氏体协调塑性变形,导致试样过早发生失稳断裂,其中试样的抗拉强度降低12.2%,断裂延伸率下降44.7%;同时,非热效应使试样在较低温度下发生了回复和再结晶现象;脉冲电流诱导了SUS304极薄带由韧性断裂向韧脆性断裂模式的转变,并且促进了变形织构生成。 相似文献
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A lot of research has been focused on the necking process during the plastic deformation of sheet metals, but the localized necking is rarely distinguished form diffused necking by experiments, due to the limit of measurement equipment and method. Quenching and Partitioning (Q&P) steel is a 3rd generation advanced high strength steel (AHSS). Its good combination of high strength and ductility ensures potential application in automobile industry. Uniaxial tensile tests of QP980 steel sheet at five strain rates are performed to investigate the necking process and the effect of strain rate on necking behavior of Q&P steel. Digital image correlation (DIC) method is applied during tensile tests, and evolutions of major strain, minor strain and normal strain distributions along gauge section of the tensile specimens are obtained. The diffused and localized necking strains are determined according to SWIFT necking theory and HILL necking theory respectively. The test results indicate that with the increasing of strain rate in the investigated range, the diffused necking strain decreases from 0.152 to 0.120 and localized necking strain decreases from 0.245 to 0.137. Meanwhile, the difference of the two strains decreases form 0.096 to 0.017. Thus it can be concluded that strain rate has an influence on both necking strains during the deformation of QP980 steel sheet. Diffused and localized necking strains are determined by uniaxial tensile tests with the aid of DIC technique and the effect of strain rate on necking strains is evaluated. 相似文献
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采用慢拉伸应力腐蚀试验与应力腐蚀裂纹扩展试验,对AISI4340钢在含饱和氧和/或0.1 mol·L-1的100℃水中的应力腐蚀行为进行研究。结果表明:100℃水中存在的氧或C一均可以增大AISI4340钢的应力腐蚀倾向,但在含Cl-并除氧的100℃水中的应力腐蚀倾向不显著,慢拉伸断口依旧保留部分韧性断裂特征,而在含饱和氧的高温水中AISI4340钢发生完全脆性断裂,应力腐蚀倾向显著;氧或Cl-均可提高AISI4340钢在100℃水中的应力腐蚀裂纹扩展速率,氧与Cl-之间存在交互作用,二者共存显著提高了应力腐蚀倾向,并导致开裂后裂纹快速扩展。 相似文献