科 技 石油规划设计 2002年9月 9
API SPEC 5L标准规定的占59.5%。这说明成型后屈服强度有明显的降低,进一步的统计显示成型后屈服强度下降情况见表1。
占总量百分比(%)
尹国耀. 包申格效应对X65钢管强度的影响. 石油规划设计,2002,13(5):9~10
屈服强度(MPa)
包申格效应对X65 钢管强度的影响
尹国耀
西北石油管道建设指挥部
*
摘 要 进口X65卷板制成钢管后屈服
强度有明显下降,卷板订货中应充分考虑钢管成型后屈服强度的这种变化。文章对该进口卷板制管前后屈服强度变化情况进行了试验分析,并就屈服强度变化存在的规律性问题进行了讨论。
主题词 钢板 钢管 制造 强度 拉伸试验 分析
卷板 钢管
图1 卷板和钢管屈服强度分布直方图
表1 拉伸实验结果统计
卷 板 钢 管 屈服
抗拉 屈服 抗拉 屈服 强度
项目 伸长率 伸长率
变化 强度 强度 强度 强度
(MPa)(MPa) (%) (MPa)(MPa)(%) (MPa) 平均值 最大值 最小值 平均偏差
548 574 531 9.2
465 486 445 8.1
40.5 43.8 36.8 1.2
552 580 529 8.6
445 466 426 6.4
39.5 42.4 37 1.1
-20 -20 -19 8.5
金属经过预先加载产生微量塑性变形,然后再同向加载,使变形抗力如弹性极限、屈服强度等升高;反向加载则弹性极限、屈服强度降低的现象称为包申格效应。带钢在制管和随后展平试样的过程中,经受拉、压反复变形,使钢管屈服强度与带钢屈服强度产生一定的差异,造成这种差异的主要原因为形变硬化和包申格效应。由于形变硬化和包申格效应发挥作用的不同,造成钢管屈服强度升降幅度的不同。实践表明,这种差别有时高达70 MPa。这种现象已引起广泛的重视,有必要对包申格效应影响钢管屈服强度的现象进行深入研究。本文着重对某管道用进口X65卷板的包申格效应进行分析。
卷板和钢管屈服强度分布见图2。卷板屈服强度的平均值为465 MPa,卷板屈服强度集中分布于接近卷板订货技术条件规定的下限值462 MPa处,呈非正态分布。钢管平均屈服强度为445 MPa,呈标准的正态分布。
成型前后卷板各部位屈服强度普遍下降,各部位下降程度也基本相同,表明卷板强度相对均匀。
60 占总量百分比(%)
50 40 30 20 10 400
420
440
460
480
500
520
钢管
卷板
包申格效应试验
对该批进口卷板中的7炉9卷共112组试验进行对比分析。由卷板制成钢管后屈服强度分布情况见图1。
由图1所示结果分析表明:板卷不符合API SPEC 5L标准规定的占1.8%,钢管屈服强度不符合
屈服强度(MPa)
图2 卷板和钢管屈服强度分布
沿卷板长度方向,不同部位的卷板和钢管力学性能测量结果见表2(以卷板头部为例)。
* 尹国耀,男,1943年生,教授级高级工程师、国家级有突出贡献专家。1965年毕业于西安石油学院开发系,长期从事管道设计、建设、管理工作,曾任西北石油管道建设指挥部副总工程师,曾两次获原中国石油天然气总公司科技进步二等奖,发表论文专著多篇。通信地址:陕西西安北郊张家堡,710021
10 石油规划设计 第13卷第5期 科 技
表2 卷板与钢管拉伸试验结果
卷 板 钢 管 屈服
强度 抗拉 屈服 抗拉 屈服
伸长率 伸长率 变化
强度 强度 强度 强度 (MPa) (MPa)(%) (MPa) (MPa) (%) (MPa)539 461 42 543 443 41.6 -18 536 458 42 542 433 41.2 -25 539 466 40.6 545 446 40.8 -20 536 460 41.4 544 429 40.8 -31 538 462 40 547 438 39.8 -24 539 457 41.2 - - - -
制管过程中的应力应变
卷板在制管成型过程中的应力应变对钢管的屈服强度有重要影响。卷板在制管成型过程中和随后压平拉伸试验的过程中,将经受拉压反复变形。从理论上讲,由于反向加载产生的包申格效应将使屈服强度降低,但实际上用压平试样测得的钢管屈服强度并非都表现为降低,这与卷板在制管过程中的形变强化能力有关,当形变强化效果大于包申格效应时,测得的屈服强度将增加,反之则降低。
包申格效应与位错运动受阻有关。在某滑移面上,运动着的位错穿过主滑移面与主滑移面相交的诸位错相遇,形成位错缠结或位错胞。这种位错结构在力学上是相当稳定的。如果在此时卸载并在随后同向加载,位错线不能显著运动,宏观上表现为屈服强度升高。但如卸载后施加反向载荷,位错做反向运动,在反向路径上,像林位错这样的障碍数量相对较少,因而位错可以在较低应力下移动,宏观上表现为屈服强度的下降。
2 形变量对屈服强度的影响
钢管形变量对屈服强度的影响与形变的程度范围有关。文献[1]对X60、X65、X70、X80、X100、X110一系列钢管的试验表明,在小于2%的应变范围内,随形变量的增加,则包申格效应越明显,钢管屈服强度的下降越大。同时随强度级别提高,钢管屈服强度下降也越明显。而从卷板到制成钢管的过程中,影响形变量的因素很多,这其中包括成型角的大小、弹复量大小的控制等。文献[2]和文献[3]的研究表明,弹复量大的钢管,其屈服强度下降幅度也大(见表3)。
表3 弹复量对屈服强度变化的影响
钢级
规格(mm)
∅426×7
弹复量
0~40 100~220 90~220 -10~30 90~220
成型后屈服强度 +20
-32
-30 -32 -79
X52 ∅426×7
∅508×7 ∅660×7.1 X60
∅660×8.7
影响钢管强度的因素
在实际生产和试验过程中,准确确定包申格效应影响的大小很困难,因为屈服强度的变化是包括包申格效应在内的诸多因素综合作用的结果。但大量的试验表明,成型后钢管屈服强度也存在一定的规律,现就其影响因素进行讨论。
1 卷板的屈服强度水平
卷板的屈服强度水平对其加工硬化能力和包申格效应有重要影响。通常,卷板的屈服强度增加,则加工硬化指数n趋于降低,加工硬化能力减小,包申格效应增强。屈服强度下降与卷板屈服强度关系表明随强度的增加,屈服强度下降明显增大。卷板屈强比越大,成型后屈服强度的下降也越大。同时,钢管屈服强度下降越明显,钢管屈强比也相应下降。所以,对于高强度或高屈强比的卷板,必须充分考虑包申格效应对屈服强度的影响。
3 显微组织对强度的影响
管线钢的显微组织大多为铁素体—珠光体,这种钢具有不连续的屈服行为,具有这种行为的钢,包申格效应较为明显。而针状铁素体钢中存在着高密度的可移动位错,易于实现多滑移,这种组织特征使得钢具有连续的屈服行为。在钢管成型及随后试样压平过程中,形变硬化的作用大于包申格效应,因而屈服强度不会有明显的下降。
当制造螺旋缝埋弧焊管时,由于在整个过程中形变量小于2%,所以当采用铁素体—珠光体钢或少珠光体钢时,其形变强化作用相对较小,因而大多表现为屈服强度下降。因此在卷板订货时,应充分考虑屈服强度的变化,并留出一定的余量。
该进口卷板成型后,屈服强度有明显的下降,最大下降幅度达56 MPa。屈服强度的下降有明显规律,即卷板屈服强度越高,屈服强度下降越大。造成这种屈服强度变化的原因与卷板和钢管制造工艺有关,因此在以后的订货中,应根据生产厂的生产工艺制订较为合理的卷板屈服强度范围。
参 考 文 献
[1] JOHN. P. ORTON. An Overview of Line Pipe
Micro-Alloying 75:334~347
[2] 吴淞等. 包申格效应对螺旋焊管强度的影响. 焊管,
1998,21(6):25~29
[3] 高惠临. 管线钢. 西安:陕西科学技术出版社,1995
收稿日期:2002-05-09
编辑:马三佳
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Wang Yong et al.
Based on analyzing difficulties to durably and effectively develop Cainan oilfield,the positive factors to durably and effectively develop the oilfield are illustrated. The potential of the oilfield is analyzed. The development trend of productivity and cost at the oilfield during next 4 years is predicted. The necessary measure to keep durative ,effective and stable production is pointed out. That is;Technique to improve recovery factor at the Sangonghe group should be studied with the advanced technology. Some special studies to improve recovery factor should be made, such as rational exploitation with natural energy at middle and high water-cut stage,Common Detector Gather(CDG )investigation and driving oil technology,experiment of polymer,and etc. The comprehensive management over the oilfield should be strengthened to assure durative and effective development of the oilfield.
Recovery Factor of C3 and Energy Consumption of Facility in Light Hydrocarbon Recovery Process from Natural gas
Pei Hong
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Dong Zhilin et al.
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Yin Guoyao
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Wang Fenglian
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Design for Integral Platform of Production and Repair in Chengdao Oilfield
Li Jing
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Development and Application of Simulating and Calculation Model for Whole Light Hydrocarbon Recovery Process
Peng Jin et al.
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Developing Communication Software of Data Interface at Application of Advanced Control Technique
Li Yanting et al.
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system and Distributed Control System (DCS) is realizable.
科 技 石油规划设计 2002年9月 9
API SPEC 5L标准规定的占59.5%。这说明成型后屈服强度有明显的降低,进一步的统计显示成型后屈服强度下降情况见表1。
占总量百分比(%)
尹国耀. 包申格效应对X65钢管强度的影响. 石油规划设计,2002,13(5):9~10
屈服强度(MPa)
包申格效应对X65 钢管强度的影响
尹国耀
西北石油管道建设指挥部
*
摘 要 进口X65卷板制成钢管后屈服
强度有明显下降,卷板订货中应充分考虑钢管成型后屈服强度的这种变化。文章对该进口卷板制管前后屈服强度变化情况进行了试验分析,并就屈服强度变化存在的规律性问题进行了讨论。
主题词 钢板 钢管 制造 强度 拉伸试验 分析
卷板 钢管
图1 卷板和钢管屈服强度分布直方图
表1 拉伸实验结果统计
卷 板 钢 管 屈服
抗拉 屈服 抗拉 屈服 强度
项目 伸长率 伸长率
变化 强度 强度 强度 强度
(MPa)(MPa) (%) (MPa)(MPa)(%) (MPa) 平均值 最大值 最小值 平均偏差
548 574 531 9.2
465 486 445 8.1
40.5 43.8 36.8 1.2
552 580 529 8.6
445 466 426 6.4
39.5 42.4 37 1.1
-20 -20 -19 8.5
金属经过预先加载产生微量塑性变形,然后再同向加载,使变形抗力如弹性极限、屈服强度等升高;反向加载则弹性极限、屈服强度降低的现象称为包申格效应。带钢在制管和随后展平试样的过程中,经受拉、压反复变形,使钢管屈服强度与带钢屈服强度产生一定的差异,造成这种差异的主要原因为形变硬化和包申格效应。由于形变硬化和包申格效应发挥作用的不同,造成钢管屈服强度升降幅度的不同。实践表明,这种差别有时高达70 MPa。这种现象已引起广泛的重视,有必要对包申格效应影响钢管屈服强度的现象进行深入研究。本文着重对某管道用进口X65卷板的包申格效应进行分析。
卷板和钢管屈服强度分布见图2。卷板屈服强度的平均值为465 MPa,卷板屈服强度集中分布于接近卷板订货技术条件规定的下限值462 MPa处,呈非正态分布。钢管平均屈服强度为445 MPa,呈标准的正态分布。
成型前后卷板各部位屈服强度普遍下降,各部位下降程度也基本相同,表明卷板强度相对均匀。
60 占总量百分比(%)
50 40 30 20 10 400
420
440
460
480
500
520
钢管
卷板
包申格效应试验
对该批进口卷板中的7炉9卷共112组试验进行对比分析。由卷板制成钢管后屈服强度分布情况见图1。
由图1所示结果分析表明:板卷不符合API SPEC 5L标准规定的占1.8%,钢管屈服强度不符合
屈服强度(MPa)
图2 卷板和钢管屈服强度分布
沿卷板长度方向,不同部位的卷板和钢管力学性能测量结果见表2(以卷板头部为例)。
* 尹国耀,男,1943年生,教授级高级工程师、国家级有突出贡献专家。1965年毕业于西安石油学院开发系,长期从事管道设计、建设、管理工作,曾任西北石油管道建设指挥部副总工程师,曾两次获原中国石油天然气总公司科技进步二等奖,发表论文专著多篇。通信地址:陕西西安北郊张家堡,710021
10 石油规划设计 第13卷第5期 科 技
表2 卷板与钢管拉伸试验结果
卷 板 钢 管 屈服
强度 抗拉 屈服 抗拉 屈服
伸长率 伸长率 变化
强度 强度 强度 强度 (MPa) (MPa)(%) (MPa) (MPa) (%) (MPa)539 461 42 543 443 41.6 -18 536 458 42 542 433 41.2 -25 539 466 40.6 545 446 40.8 -20 536 460 41.4 544 429 40.8 -31 538 462 40 547 438 39.8 -24 539 457 41.2 - - - -
制管过程中的应力应变
卷板在制管成型过程中的应力应变对钢管的屈服强度有重要影响。卷板在制管成型过程中和随后压平拉伸试验的过程中,将经受拉压反复变形。从理论上讲,由于反向加载产生的包申格效应将使屈服强度降低,但实际上用压平试样测得的钢管屈服强度并非都表现为降低,这与卷板在制管过程中的形变强化能力有关,当形变强化效果大于包申格效应时,测得的屈服强度将增加,反之则降低。
包申格效应与位错运动受阻有关。在某滑移面上,运动着的位错穿过主滑移面与主滑移面相交的诸位错相遇,形成位错缠结或位错胞。这种位错结构在力学上是相当稳定的。如果在此时卸载并在随后同向加载,位错线不能显著运动,宏观上表现为屈服强度升高。但如卸载后施加反向载荷,位错做反向运动,在反向路径上,像林位错这样的障碍数量相对较少,因而位错可以在较低应力下移动,宏观上表现为屈服强度的下降。
2 形变量对屈服强度的影响
钢管形变量对屈服强度的影响与形变的程度范围有关。文献[1]对X60、X65、X70、X80、X100、X110一系列钢管的试验表明,在小于2%的应变范围内,随形变量的增加,则包申格效应越明显,钢管屈服强度的下降越大。同时随强度级别提高,钢管屈服强度下降也越明显。而从卷板到制成钢管的过程中,影响形变量的因素很多,这其中包括成型角的大小、弹复量大小的控制等。文献[2]和文献[3]的研究表明,弹复量大的钢管,其屈服强度下降幅度也大(见表3)。
表3 弹复量对屈服强度变化的影响
钢级
规格(mm)
∅426×7
弹复量
0~40 100~220 90~220 -10~30 90~220
成型后屈服强度 +20
-32
-30 -32 -79
X52 ∅426×7
∅508×7 ∅660×7.1 X60
∅660×8.7
影响钢管强度的因素
在实际生产和试验过程中,准确确定包申格效应影响的大小很困难,因为屈服强度的变化是包括包申格效应在内的诸多因素综合作用的结果。但大量的试验表明,成型后钢管屈服强度也存在一定的规律,现就其影响因素进行讨论。
1 卷板的屈服强度水平
卷板的屈服强度水平对其加工硬化能力和包申格效应有重要影响。通常,卷板的屈服强度增加,则加工硬化指数n趋于降低,加工硬化能力减小,包申格效应增强。屈服强度下降与卷板屈服强度关系表明随强度的增加,屈服强度下降明显增大。卷板屈强比越大,成型后屈服强度的下降也越大。同时,钢管屈服强度下降越明显,钢管屈强比也相应下降。所以,对于高强度或高屈强比的卷板,必须充分考虑包申格效应对屈服强度的影响。
3 显微组织对强度的影响
管线钢的显微组织大多为铁素体—珠光体,这种钢具有不连续的屈服行为,具有这种行为的钢,包申格效应较为明显。而针状铁素体钢中存在着高密度的可移动位错,易于实现多滑移,这种组织特征使得钢具有连续的屈服行为。在钢管成型及随后试样压平过程中,形变硬化的作用大于包申格效应,因而屈服强度不会有明显的下降。
当制造螺旋缝埋弧焊管时,由于在整个过程中形变量小于2%,所以当采用铁素体—珠光体钢或少珠光体钢时,其形变强化作用相对较小,因而大多表现为屈服强度下降。因此在卷板订货时,应充分考虑屈服强度的变化,并留出一定的余量。
该进口卷板成型后,屈服强度有明显的下降,最大下降幅度达56 MPa。屈服强度的下降有明显规律,即卷板屈服强度越高,屈服强度下降越大。造成这种屈服强度变化的原因与卷板和钢管制造工艺有关,因此在以后的订货中,应根据生产厂的生产工艺制订较为合理的卷板屈服强度范围。
参 考 文 献
[1] JOHN. P. ORTON. An Overview of Line Pipe
Micro-Alloying 75:334~347
[2] 吴淞等. 包申格效应对螺旋焊管强度的影响. 焊管,
1998,21(6):25~29
[3] 高惠临. 管线钢. 西安:陕西科学技术出版社,1995
收稿日期:2002-05-09
编辑:马三佳
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