共查询到19条相似文献,搜索用时 296 毫秒
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对含Nb、Ti船板钢的中板表面微裂纹进行了试验研究,结果表明:中板表面微裂纹不是轧制时新产生的裂纹,而是由坯料裂纹扩展形成的,轧制过程中对裂纹有延伸作用,影响裂纹形核的主要因素有钢中C、P、S、Nb、Al含量和各种应力。 相似文献
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37Mn2钢属于裂纹敏感性较强的中碳锰钢,生产过程中发现部分铸坯上下表面中间部位存在严重的表面纵裂纹,采用微Ti处理后铸坯表面纵裂纹明显减少.本文通过低倍、金相显微镜、透射电镜(TEM)等实验技术,研究了微量元素Ti对37Mn2钢铸态组织和性能的影响.结果表明,Ti可以显著改善37Mn2钢的铸态组织和性能,减少铸坯表面纵裂纹. 相似文献
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针对S355NL钢连铸过程中铸坯角部产生的严重横裂纹缺陷,通过光学显微镜、扫描电镜等对铸坯角部横裂纹形貌特征、微观组织及析出进行分析,结果表明:微合金元素的碳氮化物、夹杂物在低温下沿奥氏体晶界析出,脆化了晶界,降低了强度,在受到应力作用时,造成应力集中,是角部横裂纹产生的主要原因。采取提高铸坯表面温度及其均匀性、降低钢中氮含量、减少夹杂物含量等措施,解决了铸坯角部横裂纹缺陷问题。 相似文献
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S. Semboshi T. J. Konno N. Masahashi S. Hanada 《Metallurgical and Materials Transactions A》2006,37(4):1301-1309
Fracture behavior of pure niobium (Nb) by several hydrogenation procedures has been investigated to elucidate the fundamental
mechanisms of hydrogen pulverization, which can then be used to produce fine Nb powders with high purity. Concentric cracks
and microcracks were introduced in recrystallized Nb specimens, leading to pulverization, when they absorb hydrogen enough
to form a large volume of the face-centered orthorhombic β-NbH phase. This hydride phase exhibits anisotropic expansion of
Nb lattice and embrittlement. Thus, the fracture of Nb plates occurs in the following sequence: hydrogen absorption, the formation
of the ordered hydride phase, strain generation arising from the phase transformation, and crack nucleation and propagation.
The authors also show that Nb powders less than 1 μm were prepared by hydrogenation and ball-milling at a temperature below
203 K, in which hydrogen was removed by dehydrogenation at above 724 K. Thus, fine and contamination-free Nb powders can be
effectively fabricated by using hydrogenation, ball-milling, and dehydrogenation procedures. 相似文献
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中厚板表面微裂纹成因分析 总被引:6,自引:0,他引:6
简要介绍了武钢三炼钢厂生产的连铸坯轧制中厚板钢板表面产生微裂纹的情况 ,并对微裂纹的成因进行了调查和分析 ,根据攻关试验的结果 ,采取了相应的措施 ,基本消除了钢板表面的微裂纹 相似文献
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在大方坯连铸中,经常出现的缺陷是表面网状裂纹.由于铸坯表面存在网状裂纹导致轧制过程中出现严重的纵裂纹.通过微观检测、热模拟等手段分析了表面网状裂纹产生的原因及机理,由实验结果可以看出,表面网状裂纹沿异常粗大的奥氏体晶粒开裂,其实质是奥氏体晶间裂纹;异常粗大的奥氏体晶粒、残余元素Cu的富集以及AlN、BN等氮化物和先共析铁素体薄膜的析出是导致该钢种产生晶间裂纹的主要原因;大的奥氏体晶粒是残余元素富集以及氮化物和先共析铁素体薄膜析出的先决条件,因此表面网状裂纹是第Ⅱ和第Ⅲ脆性区间相互作用的结果,经常出现在存在凹陷和鼓肚的部位;异常粗大的奥氏体晶粒产生的主要原因是高的过热度和不均匀冷却. 相似文献
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《钢铁冶炼》2013,40(4):305-311
AbstractRolled plates from continuously cast slabs at Bhilai Steel Plant have been frequently rejected due to the formation of irregular shaped fine surface cracks. These cracks originate from fine transverse cracks located below oscillation marks/surface depressions of the cast slabs. The random occurrence of this defect from heat to heat was of major concern to Bhilai Steel Plant where slabs are cast of special grades such as boiler, microalloying, and high tensile quality. The mechanism of formation of this defect was identified through a detailed metallographic study of defect bearing slabs and plates and analysis of rejection patterns with respect to various important process parameters. The crack formation mechanism was verified through a process perturbation trial. A defect potential index was developed to explain the random occurrence of these cracks. The index incorporated parameters which influence crack formation in the Bhilai casters. A significant reduction in this type of cracking was observed, based on the recommendations made in this study 相似文献
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采用金相分析方法对低合金高强度钢(/%:0.16~0.18C,0.20~0.40Si,1.42~1.55Mn, ≤0.025P, ≤0.012S,0.015~0.025Nb,0.100~0.115V,0.010 0~0.0150N)连铸板坯窄面微裂纹的产生机理进行了分析研究。结果表明:板坯窄面表层显微组织不合理如奥氏体晶粒粗大、奥氏体晶界处先共析铁素体膜的形成以及第二相质点在奥氏体晶界处的偏析等是微裂纹产生的机理。通过优化连铸板坯窄面冷却工艺,将窄面冷却水量增加35%;细化了晶粒,抑制了铁素体膜的产生,改变了第二相质点析出,改善了铸坯表层组织,消除了铸坯窄面微裂纹缺陷。 相似文献
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分析了成分为(%):0.14~0.17C,0.45~0.55Si,1.25~1.45Mn,0.08~0. 10V,0.03~0.05Nb H 型 钢BS55C表面裂纹形成原因。结果表明,该钢凝固时纵裂的敏感性较大,700~950℃范围内的塑性较低,使H 型钢表面易产生裂纹。由168炉Nb-V微合金化H 型钢BS55C生产数据分析得出,采用LF精炼,控制钢中S≤ 0.015%、P≤0.020%,优化浇铸水口,采用弱二次水冷工艺,避免在700~900℃范围矫直,可有效减少Nb-V微 合金化H 型钢的表面裂纹 相似文献