钛合金改善X80管线钢中硫化物析出的研究

管线钢中的 MnS 对管线钢的韧性、焊接性能、应力腐蚀断裂等性能都有着不可忽视的影响.以不同 S 含量的 X80 管线钢为研究对象,通过加入不同的 Ti 含量控制 MnS 的生成,使其生成 Ti4 C2 S2 .运用 Factsage 软件模拟计算,探讨了 Ti 含量对 MnS 析出的影响,计算得到了不同 S 含量下 Ti4 C2 S2 析出时的临界 Ti 含量.在实验室条件下,制作了不同 Ti、S 含量下的试样,采用 SEM、EDS 观察不同条件下试样中夹杂物的形貌、尺寸和成分变化.研究表明,管线钢中加入 Ti 合金可以使 MnS 转化生成 Ti4 C2 S2 ,且 随 钢 中 S 含 量 的 提 高 其 要 求 转 化 生 成Ti4 C2 S2 的 Ti 含量也需提高.     

不同微观组织高强度管线钢冲击韧性的研究

采用示波冲击试验方法研究了具有不同微观组织高强度管线钢的夏比冲击性能。据该试验的位移-载荷曲线，描述了其断裂能量吸收特征、微观组织中脆性相的存在特点，并以此为依据论证了针状铁素体组织管线钢较铁素体珠光体组织管线钢具有更高的止裂能力。     

轧制工艺对高铌X80管线钢组织性能的影响

正X80管线钢具有高强度、高韧性、易焊接性及低温动态止裂性能,被广泛应用到西气东输干线工程中。Mo是生产高级别管线钢添加的主要微合金元素,添加Mo元素后管线钢的再结晶温度约为930℃,而生产要求其精轧入口温度低于920℃,这样才能保证精轧在未再结晶区轧制,不会出现混晶组织。据资料介绍:微合金元素Nb可以大幅度提高再结晶温度,当奥氏体中Nb含量增加时,能提高奥     

X80管线钢闪光对焊热模拟试验

X80管线钢是目前应用最广泛的油气运输材料，因需满足长时间、长距离的服役条件，要求其具有更高的焊接性能，而闪光对焊技术由于焊接质量好、效率高，可满足X80管线钢的焊接需要。利用Gleeble-3800热模拟试验机对X80管线钢进行了闪光对焊模拟试验，采用金相显微镜观察焊缝、热影响区及母材处金相组织，采用显微维氏硬度计测定了各区硬度，确定了最优焊接参数。结果表明：在Gleeble热模拟试验机进行闪光对焊模拟试验，模拟焊接效果良好；不同工艺参数下焊接接头焊缝处金相组织为贝氏体，热影响区组织为贝氏体和铁素体，母材为铁素体和珠光体组织；不同焊接参数下，试样热影响区硬度最高，焊缝区次之，母材硬度最低；为获得优异的焊接接头，最优焊接参数为闪光速度1 mm/s、闪光流量6 mm。     

承钢公司成功试炼X70、C700L两钢种

近日，承钢公司试炼管线钢X70、卷板C700L获成功，钢坯成分、气体含量、铸坯质量等指标均达到标准要求。管线钢X70是具有高强度、高韧性和良好焊接性能的高级别管线。提钒钢轧二厂在总结以往管线钢生产经验的基础上，于4月15日对X70钢组织试制，     

管线用高强韧性宽厚钢板的开发

本文回顾了舞钢高强韧性管线用宽厚钢板的研制开发过程，并结合生产工艺，对钢板性能作了全面分析，指导了钢管线钢的生产。舞钢X70级管线钢有较高的断裂韧性、良好的可焊性以及抗SSCC、HIC性能。舞钢正在进行技术改造，以进一步改善组织，提高性能、满足西气东输要求。     

良好低温韧性的X65MS耐酸管线钢卷的生产

在分析化学成分对抗腐蚀性能影响的基础上,介绍了邯钢通过成分控制和过程控制,采用转炉冶炼、炉外精炼技术,结合控制轧制和控制冷却技术,生产出抗酸腐蚀管线钢X65MS板卷。经检验,X65MS板卷具有良好的低温冲击韧性、DWTT性能、抗氢致裂纹(HIC)和抗硫化物应力腐蚀(SSCC)的性能。     

65公斤级抗硫化氢应力腐蚀用钢——25CrMoTi的研制

研究了合金元素,不同热处理方法和制度对试验钢机械性能和抗硫化氢应力腐蚀开裂性能的影响,研制成功综合机械性能、工艺性能皆好的65公斤级抗硫化物应力腐蚀开裂新钢种25CrMoTi,此钢在普通加热调质(900℃Q.+600～700℃T.)时,σy=635～750MPa,且抗SSCC;在工厂快速加热淬火(900～980℃)+760～790℃快速加热回火(或两相区快速再加热)时,σy=630～730MPa,且抗SSCC。     

100 t BOF-LF-VD-CC流程抗硫管线钢KS30的生产实践

抗硫管线钢主要用于加工石油、天然气的输送管道,对钢的强度、韧性、抗氢致裂纹(HIC)、抗硫应力腐蚀裂纹(SSC)和焊接性能等要求很高。结合石钢京诚生产抗硫管线钢的生产实践,对各成分的作用及影响进行了分析,并对抗硫管线钢KS30生产实践进行了介绍。在铁水P含量≤0.120%、铁水S含量≤0.050%的情况下,优选原辅料,可保证抗硫管线钢KS30成品P含量≤0.010%、S含量≤0.0015%、O含量≤0.0012%,轧材抗HIC、抗SSC性能全部合格     

合金元素对X80管线钢环焊接头组织和性能的影响

随着管道钢级提高，环焊缝断裂韧性控制难度不断增加。焊缝的成分是母材和填充金属成分的混合，因此，母材合金元素对最终焊缝的组织和性能具有重要影响。设计了10种不同合金元素含量的X80管线钢，并模拟现场环焊进行了相同工艺规范的焊接实验。采用扫描电子显微镜(SEM)对不同合金元素实验钢的环焊接头显微组织进行表征分析，同时测试了相应环焊缝的冲击韧性，探究了Mn、Cr和V 3种元素对X80管线钢环焊接头组织和性能的影响。结果表明，X80管线钢环焊过程中Mn会有部分溶入熔池，但是对焊缝的影响有限。Cr的稀释率很不稳定，母材中Cr含量越高，稀释率越低，整体在25%～50%范围。V的稀释率也较低，平均为17%。钢板中溶入焊缝的Mn只占焊缝总Mn量的极少一部分，不会对焊缝显微组织产生较大的影响，因此对焊缝冲击韧性没有影响。Cr元素在冷却相变过程中扩大了粒状贝氏体的形成区间，导致焊缝中出现大量粒状贝氏体组织，使得马奥组元(M/A)数量增加，颗粒尺寸增大，从而降低焊缝冲击韧性。母材钢板中溶入焊缝的少量V能够促进贝氏体铁素体相变，避免了焊缝中出现粗大的M/A颗粒，但对焊缝冲击韧性的影响不明显。     

Role of non-metallic inclusions in heat-treated steels for sour environment

Sulphide stress corrosion cracking (SSCC) studies on a set of three steels with different inclusion morphologies were conducted. Effect of heat treatment of the steels with and without rare-earth metal (RE) treatment upon SSCC resistance was studied. Threshold stress, corrosion rate and hydrogen content in the steels were determined. Quenched and tempered structure was found to improve the SSCC resistance only when the steel is RE treated. Corrosion rate and hydrogen content in the steels were found to decrease as the inclusion morphology is changed from elongated stringers to globular shape, which improves the SSCC resistance.     

Measuring Mechanical Behavior of Steel During Solidification: Modeling the SSCC Test

The submerged split chill contraction (SSCC) test can measure forces in a solidifying steel shell under controlled conditions that match those of commercial casting processes. A computational model of this test is developed and applied to increase understanding of the thermal-mechanical behavior during the initial solidification of steel. Determining the stress profile is difficult because of the complicated geometry of the experimental apparatus and the nonuniform temperature and strength across the shell. The two-dimensional axisymmetric elastic-viscoplastic finite-element model of the SSCC test features different mechanical properties and constitutive equations for delta-ferrite and austenite that are functions of both the temperature and the strain rate. The model successfully matches measurements of (1) temperature history, (2) shell thickness, (3) solidification force, and (4) failure location. In addition, the model reveals the stress and strain profiles through the shell and explains what the experiment is actually measuring. In addition to the strength of the shell, the measured force is governed by the strength of the junction between the upper and lower test pieces and depends on friction at the shell–cylinder interface. The SSCC test and the validated model together are a powerful analysis tool for mechanical behavior, hot tear crack formation, and other phenomena in solidification processes such as continuous casting.     

Suction Stress Characteristic Curve for Unsaturated Soil

The concept of the suction stress characteristic curve (SSCC) for unsaturated soil is presented. Particle-scale equilibrium analyses are employed to distinguish three types of interparticle forces: (1) active forces transmitted through the soil grains; (2) active forces at or near interparticle contacts; and (3) passive, or counterbalancing, forces at or near interparticle contacts. It is proposed that the second type of force, which includes physicochemical forces, cementation forces, surface tension forces, and the force arising from negative pore-water pressure, may be conceptually combined into a macroscopic stress called suction stress. Suction stress characteristically depends on degree of saturation, water content, or matric suction through the SSCC, thus paralleling well-established concepts of the soil–water characteristic curve and hydraulic conductivity function for unsaturated soils. The existence and behavior of the SSCC are experimentally validated by considering unsaturated shear strength data for a variety of soil types in the literature. Its characteristic nature and a methodology for its determination are demonstrated. The experimental evidence shows that both Mohr–Coulomb failure and critical state failure can be well represented by the SSCC concept. The SSCC provides a potentially simple and practical way to describe the state of stress in unsaturated soil.     

40CrNiMoA钢同质焊条焊接接头组织和性能研究

分析了焊接电流70A、80A、90A对40CrNiMoA钢焊缝接头组织和力学性能的影响。随着焊接电流的增大,焊缝外观质量较好。随着焊接电流的增大,熔池区温度升高,奥氏体晶粒尺寸增大,导致马氏体组织粗大。焊缝的显微组织为马氏体及少量残余奥氏体。焊缝的硬度远高于母材的硬度,且波动较大。热影响区的硬度从母材向沿焊缝方向逐渐升高。焊接接头纵向应力在焊缝中心为压应力,向外压应力减小。焊接颜色区边界处纵向应力为拉应力,且该点拉应力最大。焊接接头横向应力在焊缝中心为拉应力,向外逐渐增大,焊接颜色区边界处变横向拉应力达到最大。焊接电流和热输入增大,降低了材料的韧性,组织中铁素体增多及焊接残余应力是诱发脆性断裂的原因。焊接电流80A是40CrNiMoA同质焊条平板对接焊接工艺的最佳的焊接电流。     

高强度焊丝WER80的应用研究

介绍了以高强度、高韧性气保护焊丝WER80为材料,对焊丝熔敷金属及武钢HG785钢、HG980钢对接进行气保护焊接试验研究。采用富氩气体保护熔敷金属抗拉强度达到了810 MPa,-30℃冲击功达到106 J;匹配HG785钢气保护焊焊接接头抗拉强度达到815 MPa,-30℃冲击功大于90 J;匹配HG980钢气保护焊...     

Steels for pipes and pipelines

The development of steel grade up to X 80 quality was shown explaining metallurgical mechanisms used for thermomechanically rolled steels with improved toughness behaviour. The influence of the reduction of C-content for these TM-steels on the field welding behaviour was discussed. The development of steels with improved resistance against sour media was presented, showing the influence of purity degree, Mn- and C-content in combination with the steelmaking practice. The influence of residual stress on the SSCC resistance of SAW pipe was pointed out and a heat treatment process was presented reducing the residual stress and resulting in crack free spiral welded pipes under the most severe test condition of NACE-solution with pH-values of 2.7–3.5.     

Influence of the stress state on the structure and properties of welded steel and alloy structures

The residual stress due to welding in steel and alloy structures is analyzed. The greatest residual stress is produced by cooling of the welded structure. The results of calculations are in satisfactory agreement with the experimental deformation of the structure in welding on a test bench. The tests reveal the direction of the internal stress and permit assessment of the geometry of parts on the basis of a model of the temperature fields in the butt welding of steel and titanium-alloy workpieces. A coercimeter may be used to assess the stress state of the material and its defect content. By that means, it is possible to predict the structural state and properties of weld joints. The dynamics of welding deformation may be understood on the basis of the internal residual stress and the structural transformations produced by the welding process.     

热处理对GH3128合金接头组织及力学性能的影响

 核能已经逐渐取代化石能源成为新一代能源,作为重要构件的高温气冷堆中间换热器得到了广泛关注。由于GH3128合金具有较好的焊接性、较高的高温抗氧化性能和组织稳定性,有望成为超高温气冷堆中间换热器的候选材料,但基于换热器结构复杂性以及密封性的要求,焊接是其生产和制造的关键成形手段。采用脉冲钨极氩弧焊(GTAW)对GH3128合金2 mm板材进行对接焊,研究了热处理对焊接焊接接头显微组织以及应力的影响。结果表明,在优化焊接工艺参数下,固溶态板材接头表现出最高的强塑性,室温及高温拉伸断裂位置均为母材。由于热轧态与固溶态板材接头热影响区在焊接过程中产生残余应力,导致该区硬化,在高温变形过程中残余应力诱发热影响区μ相析出,对接头持久、蠕变性能造成不利影响。焊后热处理消除了接头热影响区的残余应力,减少了持久、蠕变过程中μ相的析出,接头持久寿命得以改善。在1 200 ℃下,残余应力可为焊后热处理过程中静态再结晶提供激活能,接头热影响区发生再结晶,硬度下降,接头塑性变形能力不协调,导致室温拉伸与950 ℃拉伸断裂位置均为焊接接头。对固溶态板材试样进行不同的焊后热处理,EBSD扫描结果分析发现,接头经过1 100 ℃×10 min热处理后,残余应力明显消失,温度升高至1 140 ℃后,热影响区开始发生再结晶。     

手工电弧焊接QU120钢轨实践

分析了Qu120钢轨在使用过程中接头断裂的成因，结合现场实际介绍了钢轨手工电孤焊接方法、焊接材料、焊接工艺、实际操作体会，可供同类型的钢轨整体焊接借鉴。     

提高ER70S-6焊丝钢质量的工艺措施

系统分析并确定了导致ER70S-6焊丝钢拉拔过程中发生断裂现象以及焊接过程飞溅率较高的原因。通过优化盘条化学成分含量、合金化物料种类,提高精炼渣二元碱度,细化精炼、连铸过程控制等措施,盘条全氧含量均值由0.005 5%降低到0.003 0%,氮含量均值由0.005 0%降低到0.004 0%,C类夹杂物级别均值由2.0级降低到1.0级,D类夹杂物级别均值由1.0级降低到0.5级,拉拔过程中断头率以及焊接飞溅量明显降低,满足了用户使用要求。