共查询到18条相似文献,搜索用时 109 毫秒
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以我厂30MnSi盘圆为母材制作的PC钢棒在存储中发生比较严重的延迟断裂现象。以延迟断裂钢棒及30MnSi母材为研究对象,对延迟断裂的现象进行深入研究以寻找原因。并通过提高30MnSi母材Si的含量以改善母材的抗拉强度,以及提高钢棒厂热处理的回火温度以消除PC钢棒的内应力,最终解决了PC钢棒延迟断裂的问题。 相似文献
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对30MnSi PC钢棒进行了淬火回火处理,分析探讨了热处理工艺对高强度钢耐延迟断裂性能的影响.采用FIP试验作为PC钢棒耐延迟断裂性能的评价方法.研究发现,相同的回火工艺下30MnSi钢的耐延迟断裂性能随淬火温度的升高呈先升高后降低的趋势,950 ℃左右淬火其耐延迟断裂性能较好;在保证强度满足要求的前提下提高回火温度可以提高钢的耐延迟断裂性能.组织观察发现,经430 ℃左右回火后,30MnSi钢棒得到的回火索(屈)氏体组织均匀细小,碳化物弥散分布在马氏体板条界上,耐延迟断裂性能较好.可见,通过改变热处理制度改变组织形态,是改善30MnSi钢的耐延迟断裂性能的一种有效途径. 相似文献
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详细介绍了高强度预应力钢棒用钢30Si2MnA盘条的生产工艺流程,通过采用合理的化学成分设计和生产工艺优化,成功开发出满足用户要求的高强度、抗延迟断裂PC钢棒用钢盘条. 相似文献
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热处理工艺对30MnSi PC钢棒力学性能的影响 总被引:3,自引:0,他引:3
针对30MnSi 预应力混凝土用钢棒(简称PC钢棒)在实际生产中抗延迟断裂性能差、力学性能不稳、屈强比高等问题,从生产PC钢棒的技术关键热处理制度入手, 通过调质处理得到回火屈(索)氏体组织,分别绘出了淬火温度、回火温度与抗拉强度、伸长率、屈强比的关系曲线.系统地研究了热处理工艺参数对钢棒的组织及强韧性的影响规律并进行了理论分析.摸索出了生产30MnSi PC钢棒的合理工艺制度:当加热时间一定时,淬火温度920~960 ℃,回火温度控制在390~430 ℃时,能获得较好的综合力学性能. 相似文献
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针对Φ12 mm 30MnSi钢盘条为原料加工Φ10.7 mm钢棒时,成品钢棒在盘卷状态下放置一段时间发生脆性断裂的现象。分析了3支送检钢棒,其断口均具有典型的沿晶断裂特征,钢棒表面有明显的机械划伤。分析认为钢棒的断裂类型属于氢致延迟断裂,提出了减少钢棒氢致断裂的措施,建议该钢的生产应避开冬季。 相似文献
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φ9.0 mm的PC钢棒在生产过程中时常发生断裂.对断裂的PC钢棒进行宏观(低倍)、化学成分、金相组织及夹杂物检测,发现其组织存在严重的表面裂纹、块状碳化物和夹杂物是引起断裂的主要原因. 相似文献
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To investigate the effect of heat treatment on mechanical properties and delayed fracture resistance of high strength steel, 30MnSi prestressed concrete (PC) steel bars are quenched and tempered. Tensile results show that, after 950 °C quenching and about 430 °C tempering, 30MnSi PC steel bars have superior mechanical properties and delayed fracture resistance. Microstructural observation shows that 30MnSi steel bar is mainly composed of fine tempered sorbite (troostite) with carbide distributed along the lath martensite boundaries. It can be concluded that thermal refining is an effective way to improve mechanical properties and delayed fracture resistance of 30MnSi PC steel bar. 相似文献
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Measurements of transverse rupture strength are reported for AISI M2, AISI M 35, AISI T 15 and ASP 30 produced by conventional ingot metallurgy, sintering of cold pressed powders, and hot rolling of HIP billets. Also reported are the size distributions of undissolved carbides and the effects of hot reduction and austenitization temperature on these and on the transverse rupture strength of test bars from the centre and the periphery of the bar stock, and of test bars oriented longitudinally and transversally to the rolling direction. Fracture initiating defects were identified and their size measured by SEM fractography. The results are discussed in terms of a fracture mechanical model for transverse rupture strength. It is inferred that in ingot-derived materials, fracture is initiated by micro-cracks formed by subcritical crack growth within the carbide stringers. In powder metallurgy materials, large carbides or carbide clusters initiate fracture. The model explains the dependence of transverse rupture strength on carbide distribution, degree of hot working, austenitization temperature, and specimen orientation. It is emphasized that transverse rupture strength is suitable for characterizing the defect population of a tool steel, but not the fracture resistance of small stressed volumes such as the cutting edge of a tool bit. 相似文献
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对水平连铸磷铜排缺陷产生的原因进行了分析探讨,进而提出预防缺陷的措施,同时针对结晶器石墨内套的使用寿命,确定了合理的工艺技术条件,提高了磷铜排的产品质量。 相似文献
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PC钢棒在生产过程中出现镦头开裂。对开裂的镦头进行了化学成分、夹杂物及金相组织等检验。结果表明,镦头内部存在表面脱碳、块状碳化物和纵向夹杂物等缺陷是导致PC钢棒镦头开裂的主要原因。 相似文献
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W. C. Harrigan 《Metallurgical and Materials Transactions B》1974,5(3):565-572
Constant load creep tests were conducted with cast Ti-6Al-4 V bars in air and vacuum at 315† and 650†C. Some of the bars were
notched in their gauge section and heliarc-welded to simulate a weld repair in a casting. Results indicate that the welding
has little influence on the time to rupture of the bars. Fractographic analysis of the bars indicates minor differences in
the welded and unwelded fracture surfaces. However, these differences do not affect the microstructural influence on the creep
and fracture processes. The prior beta grain, size and the alpha platelet size are shown to control the creep fracture of
this alloy. These data show that weld repair of titanium castings for creep applications should be acceptable. 相似文献
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