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Search Results: 1 - 10 of 11 matches for " CTOD "
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HEAT-AFFECTED ZONE FRACTURE TOUGHNESS OF HIGH STRENGTH STEELS EVALUATED USING THE WEAKEST LINK MODEL
ZL Zhou,NE Hannerz,
Z.L.
,Zhou,and,N.E.,Hannerz

金属学报(英文版) , 1997,
Abstract: A probabilistic model is derived based on the weakest link theory to evaluate the specimen thickness effect and the size effect of coarse-grained heat-affected zone (CGHAZ) on CTOD toughness values in heat-affected zones (HAZ) of high strength steels. The scatter of CTOD fracture toughness values in heterogeneous weldments is predicted using this model. The specimen thickness has influence on the CTOD toughness values of HAZ. With increase in the specimen thickness the estimated and experimental mean CTOD values decrease while the lower boundary CTOD values remain almost unchanged. The size of CGHAZ has strong negative effect on the mean CTOD values of HAZ. The estimated mean CTOD values and lower boundary CTOD values agree with experimental CTOD testing results of HAZ notched specimens. The facture toughness scatter is dependent on the Weibull shape parameter a and specimen thickness.
金属焊缝ctod试样疲劳裂纹前沿平直度研究
苗张木
武汉理工大学学报 , 2002,
Abstract: ?在金属厚板焊缝ctod试样中预制前沿平直的疲劳裂纹,是ctod试验的一个关键难题。通过实验,研究了疲劳裂纹前沿平直度st与疲劳载荷比f之间的关系,发现两者高度正相关,为预制具有平直裂纹前沿的疲劳裂纹提供了有效的途径和方法
Dynamic Plastic Fracture
塑性动态断裂实验研究

Zhu Xi Hua Tianrui,
朱锡
,华天瑞

实验力学 , 1990,
Abstract: Dynamic plastic fracture properties of ductile material under explosive loading are tested. In our experiments the following properties are measured: a)The crack propagation procedure and its speed in plastic flow field; b)The dynamic plastic fracture toughness CTOD and its variation with different. crack propagation speeds. In addition, micro-analyses arc also made for specimen fractures corresponding to different crack propagation speeds.
INFLUENCE OF LOCAL BRITTLE ZONE ON THE FRACTURE TOUGHNESS OF HIGH-STRENGTH LOW-ALLOYED MULTIPASS WELD METALS
INFLUENCE OF LOCAL BRITTLE ZONE ON THE FRACTURETOUGHNESS OF HIGH-STRENGTH LOW-ALLOYEDMULTIPASS WELD METALS

ZL Zhou,SH Liu,
Z.L.Zhou
,S.H.Liu

金属学报(英文版) , 1998,
Abstract: In this paper, toughness properties and microstructurc of low-alloyed multipass welds with yield strength above 700MPa have 6een studied using the weld thermal simulation and throughout thickness CTOD fracture mechanics tests. Impact testing of thermal simulated specimens showed that the primary weld metal and the fine gmmed weld metal had good toughness, while the coarse grained weld metal had the lowest toughness value as the local brittle zone (LBZ) in multipass weld metals. Cleavage fracture in CTOD testing of thick multipass weld metals was initiated from martensite-austenite (MA) phases in the LBZ. MA phases were distributed at the prior austenite grain boundaries and around ferrite grains. As the size of the local brittle zone along the fatigue crack front increases, CTOD frncture toughness of multipass weld metals decreases. The weakest link theory was used to evaluate effect of the local brittle zone on fracture toughness of thick multipass weld metals. The estimated curves agree well with the eaperimental data.
钢结构厚板对接焊缝的低温断裂韧性试验
王元清,周晖,石永久,胡宗文,陈宏
哈尔滨工业大学学报 , 2012, DOI: 10.11918/j.issn.0367-6234.2012.06.026
Abstract: 随着钢板厚度的增加,焊接难度加大,且存在焊接裂纹缺陷的可能性也增大.为防止钢结构厚板焊接接头的脆性断裂,采用三点弯曲试样,以裂纹尖端张开位移(CTOD)为指标,对厚度为150mm的Q345B钢板对接焊缝低温下的断裂韧性进行试验研究.分析了焊缝金属和热影响区断裂韧性CTOD值δm随温度的变化关系,并用Boltzmann函数对断裂韧性-温度曲线进行拟合,结合试样断口的扫描电镜图分析了断裂的微观机理.试验结果表明:焊缝金属和热影响区的CTOD值δm随温度的降低而降低,从20℃~-60℃,降幅分别达78%和91%;热影响区CTOD值δm比焊缝金属和母材均要小.试验积累了厚板对接焊缝的断裂韧性数据,为低温地区钢结构厚板对接焊缝脆性断裂的预防提供了技术基础.
X100高强管线钢焊接接头的断裂韧性
毕宗岳,杨军,牛靖,张建勋
金属学报 , 2013, DOI: 10.3724/SP.J.1037.2012.00703
Abstract: 采用裂纹尖端张开位移(CTOD)实验对X100高强管线钢焊接接头母材、焊缝和热影响区(HAZ)进行了断裂韧性测试研究,并使用SEM和TEM对CTOD试样近断口区组织及夹杂物进行了观察.结果表明,温度对X100高强管线钢焊接接头断裂韧性有显著影响.在同一温度下,条件启裂值δ0.2和δ0.2BL均呈现母材最大、热影响区次之、焊缝最小,即母材低温断裂韧性最优、热影响区次之、焊缝最差,但随温度降低,其断裂韧性均下降.母材试样近断口区显微组织为粒状贝氏体(GB)和少量准多边形铁素体(QF)及板条贝氏体铁素体(BF),细小粒状M-A组元弥散分布于贝氏体铁素体板条界处;焊缝试样近断口区组织为针状铁素体(AF),M-A组元形态多样,尖角明显;热影响区粗晶区近断口组织为粒状贝氏体和平行排列的板条状贝氏体铁素体,M-A组元呈方形、楔形、条形分布于晶内、晶界和板条界处.大尺寸尖角型M--A组元是导致焊缝和热影响区粗晶区断裂韧性差的主要原因之一,而较高的夹杂物分布则使焊缝具有较低的断裂韧性.
桥梁钢q370qe焊缝断裂韧性ctod试验研究
余启明,吴卫国,苗张木,李方敏,朱铭
武汉理工大学学报 , 2009,
Abstract: ?依据英国标准bs7448断裂韧度试验标准和dnv?os?c401,对桥梁用钢q370qe进行了ctod(裂纹尖端张开位移)试验,分别测试了在低温(-20℃)和常温(20℃)条件下不同厚度的母材、热影响区、焊缝的ctod断裂韧度,实验结果表明,在同种物理条件下,焊缝的韧性比母材和热影响区试件差。
Efecto del tama o de probeta y orientación en la resistencia a la tracción y a la tenacidad a la fractura
Terán, J.,González, J. L.,Hallen, J. M.,Martínez, M.
Revista de Metalurgia , 2007,
Abstract: In this work, an experimental research was conducted to determine size and orientation effects on tension and toughness properties through CTOD-R curves, using standard and miniature specimens taken from a structural steel plate. Compliance function estimation for the miniature size samples through load-displacement curves was considered. Experimental and statistical results showed that size and orientation affect tension and toughness properties. The miniature tension test specimens showed strength values slightly greater than the standard ones but with less ductility. Miniature specimen CTOD-R curves showed sensibility to load changes and measurement method of crack aperture and crack length. Inconsistency in fracture toughness for specimen orientation longitudinal circumferential (LC) regarding size effect was also observed. Short orientations showed less strength and toughness than the other directions. Este trabajo se dirigió a determinar el efecto de tama o y orientación en las propiedades de tracción y tenacidad a la fractura mediante las curvas CTOD-R, utilizando probetas estándar y miniatura de una placa de acero estructural. El estudio requirió la estimación de la función flexibilidad de las probetas miniatura a partir de la curva carga versus desplazamiento. Los resultados experimentales y estadísticos muestran que tanto el tama o como la orientación afectan las propiedades mecánicas y la tenacidad a la fractura. Las probetas miniatura de tracción mostraron valores de resistencia ligeramente mayores que las estándar pero una menor ductilidad. Las curvas CTOD-R de las probetas miniatura mostraron ser sensibles a las variaciones de carga y al método de medición de la abertura y longitud de la grieta. Asimismo, se observó inconsistencia del efecto de tama o en la tenacidad a la fractura en la orientación longitudinal circunferencial (LC), siendo las orientaciones cortas menos resistentes y tenaces que las otras direcciones.
高应变梯度异形板J参量和δ_t的实验测定
赵勇李泽震王印培曾广欣
力学学报 , 1988, DOI: 10.6052/0459-1879-1988-5-1988-050
Abstract: 在能较好模拟压力容器接管区应变场的16MnR异形板上,采用多试样法和显微摄影法测定出高应变梯度区弹-塑性断裂J参量和CTONδ_t曲线,并通过多重回归和参数分析求出了J参量估算式和关系式J=mσ_yδ_t,为将小试样与实物容器接管结构试验研究紧密相联开拓出一条较新的途径。
厚钢板焊接接头CTOD断裂韧度的温度影响
苗张木,吴卫国,陶德馨,李永信
重庆大学学报 , 2006, DOI: 10.11835/j.issn.1000-582X.2006.06.010
Abstract: 大型厚壁钢结构建造中,研究温度对焊接接头断裂韧度的影响十分重要.笔者对65mm厚S355ML钢板,编制自动埋弧焊(WPS017)工艺和手工电弧焊(WPS016,WPS016A)工艺,对其焊接接头进行常温(15℃)和低温(-20℃)裂纹尖端张开位移(CTOD)评定.发现自动埋弧焊(WPS017)接头焊缝低温CTOD最小值比常温低13.9%,焊缝低温CTOD均值比常温低8.0%;热影响区CTOD断裂韧度值高于焊缝和母材,且对温度变化不敏感.手工电弧焊接头焊缝低温CTOD最小值只有常温的34.5%,焊缝低温CTOD均值只有常温的25.9%;热影响区低温CTOD断裂韧度也很低.在常温(15℃)下,自动埋弧焊焊缝CTOD值比手工电弧焊焊缝CTOD值大得多;在低温(-20℃)下,自动埋弧焊的焊缝和热影响区的CTOD值,都远远大于手工电弧焊CTOD值.
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