共查询到20条相似文献,搜索用时 640 毫秒
1.
Aiming at the problem of poor corrosion resistance of aluminum alloy drill pipe materials in an alkaline environment, an innovative short basalt fiber/aluminum composite is prepared by vacuum hot-press sintering technique. Also, the corrosion behavior of the composites is investigated by hydrogen evolution and electrochemical tests. The results show that the corrosion resistance of 7075 aluminum alloy is significantly improved after adding 1.0 wt% short basalt fiber. According to the results of scanning electron microscopy and electrochemical impedance spectroscopy, the main component of basalt fiber, SiO2, reacts with the aluminum matrix to produce a large amount of Al2O3. Meanwhile, Si atoms diffuse into the metal melt. This reaction improves the strength and density of the oxide film of the composite material, thereby improving its corrosion resistance. 相似文献
2.
3.
Two of the most aggressive corrosion environments for steel structures are elevated temperatures and exposure in the marine tidal and splash zone areas. There are now cold applied tape based products available which protect steel pipe or pilings exposed in these environments. These two distinct coatings are cold-applied systems and may be used as coatings on original projects or as rehabilitation coatings. The elevated temperature coating is a three layer system comprised of a high temperature liquid adhesive (primer) and a tape made from a heat resistant multiple alloy polymer with a high temperature resistant adhesive. This high temperature pipeline coating has been proven effective by high temperature testing in 14 pipeline industry laboratories and by field experiences by 30+ pipeline operators all over the world. The upper temperature limit for this high temperature tape system is 121°C (250°F). The cold-applied coating for steel circular pilings in marine environments is a six layer composite module which combines corrosion inhibitors and high mechanical strength. The modules are drawn around the piling by a mechanical closure mechanism either above or below the tide level during installation. The technical aspects of formulation, construction and installation of this protective system will be discussed. 相似文献
4.
Hu Xiangzhao Kuang Lixin College of Resources Environment Civil Engineering Central South University of Technology Changsha P. R. China 《中国有色金属学会会刊》1998,(4)
SURVEYOFGEOLOGYLancangvolcanicbeltliesinthesouthwesternpartofYunnanProvince,P.R.Chinaandfromnorthtosouth,throughChanglin,Lan... 相似文献
5.
采用喷射成形技术制备7A04铝合金及玄武岩颗粒增强7A04铝合金复合材料,利用金相显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和能谱(EDS)分析复合材料微观组织和界面结构,对比研究复合材料的力学性能。结果表明:玄武岩颗粒在铝基体中弥散分布,并与铝基体形成强力结合界面,玄武岩颗粒边缘的SiO2不断被反应生成的Al2O3取代,形成一层几十纳米厚度的高温反应层,反应生成的Al2O3强化玄武岩颗粒与铝基体的结合界面;弥散分布的玄武岩颗粒促进基体中位错增殖、空位形成和析出相的析出,析出相主要以板状的η(MgZn2)相和亮白色条状或椭球状的T(Al2Mg3Zn3)相为主,结合界面、高位错密度及弥散分布的第二相显著提高复合材料的力学性能,添加玄武岩颗粒的7A04铝合金复合材料的屈服强度和极限拉伸强度分别达667 MPa和696 MPa,与未添加玄武岩颗粒的7A04铝合金相比分别提高10.4%和10.1%。 相似文献
6.
采取外层先离心浇注10号钢,再浇注内层1Cr18Ni9Ti得到离心复合空心管坯,管坯内外表面加工后进行热挤压和冷轧,试制出了47mm×4.5mm的碳钢/不锈钢复合钢管,对不锈钢离心复合管坯生产复合钢管工艺路线进行研究,并对复合管金相组织、性能及结合层质量等方面进行分析。结果表明,复合管内外层冶金结合良好,晶粒明显细化,终轧后晶粒由铸态时3.0~3.5级变为7.0~8.0级,复合管压扁、弯曲及热处理后晶界腐蚀检验合格。 相似文献
7.
在优化焊接工艺参数下实现了45钢径向环与37CrMnMo钢管的径向摩擦焊接.试验结果表明,径向环发生了强烈地塑性变形,焊缝表面有明显的氧化色,管体上具有很窄的热影响区.焊缝抗剪强度平均达401 MPa,略高于径向环母材.硬度从焊缝结合界面向两侧的径向环和管体母材逐渐降低.焊缝剪切断口平滑,呈现明显的剪切韧窝断裂特征,表明焊缝具有较好的塑韧性.接头金相组织分析结果表明,焊缝具有很窄的结合面,45钢径向环和37CrMnMo钢管体侧热影响区组织分别为铁素体+珠光体+贝氏体和贝氏体+少量马氏体,相比较母材产生了少量的马氏体组织,但焊缝中心及热影区的组织得到了细化. 相似文献
8.
In the area of heavy construction, welding processes are vital in the production and maintenance of pipelines and power plants.
The fusion welding process generates formidable welding residual stresses and metallurgical change, which increase the crack
driving force and reduce the resistance of brittle fracture as well as environmental fracture. This is a serious problem with
many alloys as well as A106 Gr B steel pipe. This pipe, used in petrochemical and heavy chemical plants, either degrades due
to corrosive environments, e.g., chlorides and sulfides, and/or becomes damaged during service due to the various corrosion
damage mechanisms. Thus, in this study, the sulfide corrosion fatigue strength of multi-pass welded A106 Gr B steel pipe was
evaluated in a 5.0 wt.% NaCl solution that was saturated with H2S gas at room temperature on the basis of NACE TM 0177-90.
The crack growth characteristics of the welded pipe were then assessed at the low limit of sulfide corrosion fatigue strength,
which was previously obtained from the sulfide corrosion fatigue (SCF) tests. From the results, in terms of the SCF, all the
specimens failed at the heat-affected zone, where a high welding residual stress distributes. It was found that the fatigue
crack grew at the low corrosion fatigue limit (σ
SCFun-notched), which was 32 % (160MPa) of the ultimate tensile strength (502MPa) of the welded specimens. 相似文献
9.
10.
11.
12.
M. A. Maleeva M. A. Petrunin L. B. Maksaeva T. A. Yurasova A. I. Marshakov 《Protection of Metals and Physical Chemistry of Surfaces》2016,52(7):1107-1113
Methods of optical in situ microscopy and scanning reflectometry were used to determine that localized corrosion defects (pitting) emerging on a pipe steel in a neutral solution simulate a neutral underfilm solution. The initial stages of this process were studied. The density, mean radius,and dimensions of corrosion spots (or pits) were determined. It was shown that the defects grew mainly into a depth that exceeded 100 μm after several hours and attained 600 μm after 33 days of corrosion tests. Similar behavior may lead to corrosion cracking under the cyclic mechanical stresses. The stress intensity factors realizable in steel in the event of localized corrosion defects were calculated, and the possibility of determining the danger of corrosion cracking initiation under stress of pipe steel was determined on the basis of both optical and electrochemical data. 相似文献
13.
14.
In the area of heavy construction, welding processes are vital in the production and maintenance of pipelines and power plants.
The fusion welding process generates formidable welding residual stress and metallurgical change, which together increase
the crack driving force and reduce the resistance against brittle fracturing and environmental fracturing. This is a serious
problem with many alloys, and it also arises in A106 Gr B steel pipes. This type of piping, which is used in petrochemical
and heavy chemical plants, either degrades due to the corrosive environment, e.g., those containing chlorides and sulfides,
and/or become damaged during service due to various corrosion damage mechanisms. Thus, in this study, after numerical and
experimental analyses of the welding residual stress of a multi-pass welded A106 Gr B steel pipe weld, the electrochemical
corrosion properties and environmentally induced cracking of an A106 Gr B steel pipe weld were assessed in a 5.0 wt.% NaCl
solution that was saturated with H2S gas at room temperature on the basis of NACE TM 0177-90. In terms of sulfide stress corrosion
cracking (SSCC) and sulfide corrosion fatigue (SCF), the low SSCC limit of smooth specimens, σSSCCsmooth, and the SCF limit, ΔσSCF, were 46 % and 32 % (160 MPa) of the ultimate tensile strength (502 MPa) of an A106 Gr B steel pipe weld, respectively. Further,
(Δσres)SCF was assessed under 75 MPa, which is 15 % of the tensile strength. 相似文献
15.
以铜/钢复合管为研究对象,利用AUTODYN有限元软件SPH和ALE法对爆炸焊接过程进行二维数值模拟,分析了焊接动态过程和边界效应问题,并对铜/钢复合管进行了爆炸焊接试验。结果表明,在爆轰波作用下,复管与基管发生倾斜碰撞,碰撞区域压力稳定在107 kPa的数量级,在碰撞区附近出现1条塑性变形带,且复管和基管上的剪切应力相反,界面形态随着爆炸波的传播从直线变为波状,这与试验中获得的T2/316L双金属复合管的实际界面形态一致,说明有限元模型能够有效模拟双金属复合管爆炸焊接过程。数值模拟过程中边缘动态参数值均小于正常值,存在边界效应,增加复管和炸药的长度可以消除边界效应。 相似文献
16.
17.
观察电厂12CrMoV钢管母材、熔合区、焊缝和热影响区等位置的金相组织,测试12CrMoV钢管母材的屈服强度、抗拉强度和伸长率,分析管道出现裂纹、引起泄漏的原因。结果表明:母材拉伸试验值(R_(eL)、R_m、A)均满足标准要求(12CrMoV/GB5310);沿断口侧焊接接头整个熔合区分布着大量密集氢气孔(夹杂),降低了焊接接头的机械性能,同时产生应力集中,在外部应力(蒸汽压力、管道振动等)的作用下致使焊缝开裂、泄漏。并针对上述问题提出了改进的方法。 相似文献
18.
19.
采用微合金化和热轧后超快冷等技术生产得到800 MPa级高韧直缝钢管钢,借助OM、SEM、TEM和室温拉伸等,研究了试验钢不同区域的组织与性能。研究表明,试验钢的热轧组织主要是粒状贝氏体+少量板条贝氏体;焊接热影响区粒状贝氏体体积分数减少到32.7%,板条贝氏体体积分数增加到30.5%,组织中出现针状铁素体和少量马氏体。试验钢热轧区主要以Ti为主进行复合微合金化,综合运用固溶强化、细晶强化、位错强化和析出强化,具有高的强韧性,屈服强度为804 MPa、抗拉强度为852 MPa、伸长率为21.5%。 相似文献