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针对高强度船板拉伸试样断口出现分层的问题,对典型断口分层试样和断口合格试样取样进行金相检验及扫描电镜能谱分析,结果表明,异常断口试样夹杂物级别高,试样心部组织晶粒粗大,带状组织明显且有裂纹,分析认为,2.0级以上的硅酸盐夹杂和MnS夹杂、28μm宽的珠光体带及Ti、Nb元素的富集是导致拉伸裂纹进而出现断口分层的主要原因。 相似文献
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高强船板拉伸断口分层分析 总被引:1,自引:0,他引:1
利用光学显微镜对高强船板拉伸断口分层试样进行显微组织检验,分析结果表明,高强船板拉伸断口分层与中心区域的成分偏析、夹杂物缺陷、轧后冷却过程中的组织应力有关,提出了降低拉伸断口分层率的措施。 相似文献
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通过金相显微镜、扫描电镜对船板钢拉伸试样断口的金相组织、低倍组织、形貌进行分析,确定船板钢拉伸试样断口缺陷是由铸坯中的夹杂物、中心偏析和轧制工艺中形成的带状组织引起的。结合生产实际,提出了连铸坯二冷区凝固末端强制冷却措施,使得柱状晶生长速度变慢,等轴晶增多,减少了钢水静压力,减轻了中心偏析,船板拉伸断口分层缺陷得到有效控制。 相似文献
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济钢船板分层缺陷形成机制分析 总被引:4,自引:0,他引:4
济钢A32高强船板拉伸试验后试样出现断口分层现象。利用金相显微镜、扫描电镜和能谱仪,对分层缺陷严重的部位进行了观察、检测和分析。结果表明:分层缺陷主要与铸坯偏析处的铌、钛碳化物和硫化物夹杂、带状组织有关。通过对炼钢和轧钢生产过程的观察,提出了改进冶炼和轧制工艺等相关措施,提出解决该问题的具体工艺措施并应用于实际生产。 相似文献
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高强船板拉伸试验断口分层的原因分析 总被引:8,自引:1,他引:7
高强船板拉伸试验后出现断口分层现象。利用低倍检测、扫描电镜能谱仪和金相显微镜,对断口以及平行于拉伸方向、垂直于钢板表面的剖面进行了观察、检测和分析,指出分层现象与板厚中心偏析处的硫化物夹杂、带状组织、未轧合孔洞有关。 相似文献
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Wenjun Shen Guoguang Cheng Chuangju Zhang Shisong Pan Lin Dai Xiaofeng Liu 《国际钢铁研究》2023,94(8):2300164
To investigate the cause for the low tensile plasticity in normal direction of high-strength low-alloy steel thick plate, tensile fracture observation, inclusion statistic, and microstructure observation of thick plate and solidification structure observation of continuous casting slab are carried out. The experimental results reveal that many MnS inclusions are only distributed on the platform of the tensile fracture and they only appear in the center of thick plate together with martensite and severe macrosegregation of elements C and Mn. It is concluded that the aggregated large-sized MnS inclusions are the direct cause for reducing the tensile plasticity. Stress concentration on a single MnS inclusion during tensile testing can occur and cause a limited brittle fracture area. Aggregation of MnS inclusions creates a large brittle fracture area, which significantly reduces the tensile plasticity. The root cause of the aggregation of MnS inclusions is the well-developed columnar crystals of continuous casting slab. The well-developed columnar crystals push high concentration of solutes into the residual liquid-phase zone in the center of continuous casting slab and create severe central macrosegregation which eventually lead to the appearance of aggregated large-sized MnS inclusions with martensite in the center of thick plate. 相似文献
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用物理检验方法,对高强度船体用结构钢的拉伸试验样断口分层的金相组织和断口形貌进行归类和分析。结果表明,拉伸试验样断口分层是由夹杂物和心部成分偏析造成的,严格控制钢材的纯净度和优化轧制工艺,可提高船体用结构钢的品质。 相似文献
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采用无匙孔搅拌摩擦焊对DP600镀锌钢和AZ31镁合金进行点焊搭接试验,利用扫描电镜观察其微观组织,分析拉伸断口推断其断裂过程.结果表明:镁-钢接头成形受转速与轴肩下压量影响敏感,可施焊工艺参数窗口小;在最优工艺参数下,接头成形良好,镁和钢相互嵌入锁合充分明显,具有典型"机械连接"特征;接头宏观形貌上,镁和钢分别呈多钩状互相嵌入对方并呈涡流状缠绕在一起;微观形貌上,由于搅拌针直接穿过钢板,钢侧搅拌针作用部分区域被撕裂与搅碎,镁、钢层叠交错分布,流向性明显,并存在少量由于镁蒸发造成的微观孔洞;拉断试验中,镁、钢分离起始于搅拌区外围不存在机械连接作用的区域,直至裂纹扩展至焊核区镁、钢互相缠绕部分钢的裂纹处,沿裂纹发生撕裂将钢板从镁板上剥离,断后在钢板的搅拌区域形成较大孔洞;接头横截面显微硬度显示,无论镁层钢层,其硬度分布均呈"W"型,符合普遍搅拌摩擦焊接头硬度分布特征. 相似文献
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针对低合金高强焊接钢HG70C(/%:0.069~0.077C、0.07~0.11Si、1.79~1.83Mn、0.011~0.012P、0.004~0.005S、0.121~0.123Ti、0.046~0.047Nb)8~12 mm板拉伸试验后试样断口出现分层的现象,利用金相显微镜、扫描电镜和能谱仪对断口形貌及分层附近区域进行了观察和分析,并且统计分析了实际生产中加热参数。结果表明,该钢种分层与热轧工艺无关,主要与中心珠光体偏析带及偏析处大颗粒Ti的碳氮化物有关,并且在铸坯中发现已有2μm左右的该类析出物颗粒存在,它们成为疲劳源导致拉伸断口分层。 相似文献
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Fracture initiation at hydrides in zirconium 总被引:2,自引:0,他引:2
M. P. Puls 《Metallurgical and Materials Transactions A》1991,22(10):2327-2337
The effect of hydride size and stress state on fracture initiation at hydrides in a reactor grade Zr material has been studied.
Uniaxial and triaxial states of stress were imposed by using smooth and notched tensile specimens, respectively. Crack initiation
at hydrides was monitored using acoustic emission (AE). The specimens contained, nominally, either 0.18 or 0.90 at. pct hydrogen.
Plate-or needle-shaped hydrides having different lengths were produced by varying the cooling rate to room temperature from
the hydrogenation temperature. Initial orientation of the plate normals of the hydrides with respect to the tensile axis was
mainly random. After deformation, the hydrides near the fracture surface were all oriented with their plate normals perpendicular
to the tensile axis direction. Regardless of the hydride size, fracture at hydrides commenced at stress levels just above
the proportional limit under uniaxial deformation. Average plastic strain values at initiation were ~0.2 pct. Slightly lower
values of plastic strain were needed to initiate fracture at hydrides under triaxial loading. Fracture of the hydrides was
always through-thickness and specimen fracture ductile. This is in contrast to previous results on hydride fracture obtained
using the pressure tube alloys. In these materials, the fracture of hydrides with their plate normal oriented parallel to
the tensile axis became less ductile as the hydride length increased. 相似文献