国产压力容器用钢Q345R的低温韧性研究

基于实测的材料数据,运用缺陷评定的程序,针对ASME规范案例中关于我国常用压力容器用钢Q345R冲击韧性对豁免曲线的适用性问题的相关规定进行了探讨和分析。分析结果表明所用的Q345R正火板在低温下的冲击韧性与断裂韧性均优于ASME规范的要求值,ASME规范将Q345R归类于A曲线严重低估了材料本身的韧性。     

ASME规范和ISO标准关于金属材料高温强度计算方法的对比

通过对ASME规范关于高温拉伸强度性能背景技术资料的分析,对比了ASME规范第Ⅱ卷D篇表U与表Y-1中的抗拉强度、屈服强度的数据来源及计算方法与ISO标准的差异。结果表明,ASME规范与ISO标准对于高温强度规定有所不同。ASME规范第Ⅱ卷D篇表Y-1中的屈服强度数据趋向于保证值,在材料验收中不考核高温屈服强度,但可以通过考核室温屈服强度间接保证; ISO标准材料力学性能最低值的确定是基于屈服-温度的标准化数据导出的,拟合曲线代表屈服强度比随温度变化的平均值曲线,在材料验收时考核高温度。ASME规范第Ⅱ卷D篇表U中数据适用于设计计算,在高于室温时,表中抗拉强度值是通过将Smith比例和温度关系的拟合曲线提高10%的室温保证值得到的。     

RPV用钢美国常用断裂韧性KIC表达式的对比分析

为了有效评价经辐照后的反应堆压力容器的结构完整性,人们提出了多种表征反应堆压力容器用钢断裂韧性与温度之间的经验表达式.基于美国橡树岭国家实验室的断裂韧性测试数据,对目前常用的经验关系式进行了对比研究.结果表明,经修正后的ASME KIC曲线有最高保守性,未经修正的ASME KIC曲线在T-Tref低于-60℃时不够保守,主曲线5%下限具有足够的保守性,ASME Code Case N631提供的方法具有与ASME KIC曲线相似的保守性.     

RPV用钢美国常用断裂韧性KⅠC表达式的对比分析

为了有效评价经辐照后的反应堆压力容器的结构完整性,人们提出了多种表征反应堆压力容器用钢断裂韧性与温度之间的经验表达式。基于美国橡树岭国家实验室的断裂韧性测试数据,对目前常用的经验关系式进行了对比研究。结果表明,经修正后的ASME KⅠC曲线有最高保守性,未经修正的ASME KⅠC曲线在T-Tref低于-60℃时不够保守,主曲线5%下限具有足够的保守性,ASME Code Case N631提供的方法具有与ASME KⅠC曲线相似的保守性。     

国产S30408奥氏体不锈钢应变强化低温容器许用应力及应变确定

对奥氏体不锈钢低温压力容器常规设计与应变强化设计进行比较,可知应变强化技术可大幅提高奥氏体不锈钢材料的许用应力,减薄简体壁厚,减轻容器重量。根据预应变拉伸试验确定国产S30408奥氏体不锈钢应变强化压力容器的应变上限值,并建立国产S30408奥氏体不锈钢材料的ASME和双线性这两种应力应变曲线,对两者进行比较后,以ASME应力应变曲线为计算依据,考虑抗拉强度的影响,确定了国产S30408奥氏体不锈钢材料制造应变强化低温容器时的许用应力及其对应的应变。     

奥氏体不锈钢深冷容器疲劳设计曲线探讨

现行压力容器标准中奥氏体不锈钢疲劳设计曲线均基于常温疲劳试验数据拟合得来,并未考虑低温对奥氏体不锈钢强度、疲劳寿命的影响。本文提出一种基于常温疲劳设计曲线和深冷力学性能,获取奥氏体不锈钢深冷疲劳设计曲线的方法。首先,在试验研究基础上整理分析了文献中77 K和4 K温度下的奥氏体不锈钢疲劳试验数据,并按ASME BPVCⅧ-2采用的Langer模型表征疲劳试验曲线;其次,根据低温对奥氏体不锈钢强度和塑性的影响规律,分别对Langer模型中的疲劳极限和塑性应变项系数进行修正,建立低温下Langer模型系数与温度的关联关系,提出了深冷疲劳试验曲线计算公式;最后,通过对比文献中110 K温度下材料疲劳试验数据,初步验证了深冷疲劳曲线计算方法的有效性。     

轻水堆环境影响疲劳相关问题的研讨

美国核管会（NRC）在其管理导则RG 1．207中明确要求新建轻水堆核电厂设计中须考虑环境影响疲劳（Environmental Assisted Fatigue,EAF）问题。目前,我国新建核电厂在部件疲劳评价时尚未考虑EAF的影响。对环境影响疲劳的发展概况、疲劳裂纹和疲劳寿命的定义、ASME 设计疲劳曲线、现有ASME疲劳设计方法的保守性、美国环境影响疲劳设计方法等方面作了探讨,同时根据NUREG／CR 6909中Fen表达式,给出了典型材料在温度、溶解氧浓度和硫含量确定的情况下,Fen与应变速率的关系曲线。通过对以上相关问题的归纳和总结,以期加深业界对核电厂环境影响疲劳问题和现有ASME疲劳设计方法的认识。     

高压气瓶4130X钢低周疲劳特性及疲劳设计曲线探讨

针对大容积钢制无缝气瓶材料4130X钢,开展了应变控制下4130X钢的循环特性、应变幅-寿命关系、概率-应变幅-寿命关系和疲劳设计曲线研究,参考ASMEⅧ-2—2021和JB 4732—1995《钢制压力容器——分析设计标准》给出了4130X钢的疲劳设计曲线。获得的4130X钢疲劳设计曲线,与规范中793 MPa≤σ_uts≤892 MPa的疲劳设计曲线有一定的差异,略高于ASMEⅧ-Ⅱ(σ_uts≤552 MPa)和JB 4732—1995(σ_uts≤540 MPa)的疲劳设计曲线。4130X钢材料疲劳寿命设计可采用本文提出的疲劳设计曲线或保守地采用ASMEⅧ-Ⅱ(σ_uts≤552 MPa)和JB 4732—1995(σ_uts≤540 MPa)中对应材料的疲劳设计曲线。     

压力容器用碳钢和低合金钢板的低温韧性(二)

二、有关规范对最低使用温度下冲击韧性值的规定实际结构的最低使用温度视使用材料的厚度、应力状态、结构用途等不同而异。这里就国内外有影响的规范对材料在使用(或试验)温度下低温韧性的规定加以介绍。1.美国ASME锅炉压力容器规范Ⅷ—1对碳钢和低合金钢板冲击韧性要求如表3所示。     

基于Master Curve方法的Q345R钢断裂韧性研究

进行了国产Q345R钢在韧脆转变区的拉伸试验、夏比冲击试验和落锤试验,分别采用单温度法和多温度法获得1英寸厚CT试样的Master Curve曲线,并和ASME,API以及BS等规范中断裂韧性估算公式进行对比。结果表明,单温度法和多温度法获得的参考温度T_0基本一致,大约为-105℃。主曲线法能够很好地包络各种估算公式推断出的断裂韧性与温度关系曲线,并且在足够保守的前提下,比ASME的K_(IC)下包络线更具经济性和灵活性。     

Microstructure and mechanical properties of similar and dissimilar stainless steel electron beam and friction welds

Microstructure and mechanical properties of similar and dissimilar welds of austenitic stainless steel (AISI 304), ferritic stainless steel (AISI 430), and duplex stainless steel (AISI 2205) have been studied. Welding processes electron beam welding and friction welding were used. Optical, scanning electron microscopy, and electron probe microscopy were carried out to study the microstructural changes. Residual stress, hardness, tensile strength, and impact toughness testing were conducted to study mechanical behavior. Dissimilar metal electron beam welds of austenitic–ferritic, ferritic–duplex, and austenitic–duplex stainless steel welds contained coarse grains, which are predominantly equiaxed on austenitic, duplex stainless steel side, and they are columnar on the ferritic stainless steel side. Diffusion of elements was significant in electron beam welding and insignificant in friction welds. Austenitic–ferritic stainless steel exhibited tensile residual stress on the ferritic stainless steel side adjacent to the interface, compressive stresses on the austenitic stainless steel side that matches with the delta ferrite microstructure observed in this region. High compressive stresses were noted on duplex stainless steel side interface compared to austenitic stainless side interface. The highest tensile strength was observed in duplex–austenitic stainless steel joints. The impact strength and notch tensile strength of electron beam weldments are higher than the friction weldments. All electron beam and friction welds showed toughness lower than parent metals.     

直接由KIC／KIa～（T—RTNDT）的实测数据统计分析反应堆压力容器用钢断裂韧性值的概率分布

在反应堆压力容器的结构完整性评定中,ASME规范中选择材料大量断裂韧性数据的下包络线来确定断裂韧度,这在反应堆压力容器结构完整性的概率评定中会产生过于保守的结果。为此,利用三参数威布尔分布模型和对数正态分布模型分别对起裂韧性玩数据和动态止裂韧性KIa数据进行统计分析,并给出了断裂韧性的统计分布模型。     

Microstructure and mechanical properties of electron beam-welded AISI 409M-grade ferritic stainless steel

This paper deals with the microstructure and mechanical characterization of electron beam-welded AISI 409M-grade ferritic stainless steel joints. Single-pass autogenous welds free of volumetric defects were produced at a welding speed of 1,000?mm/min. The joints were subjected to optical microscopy, scanning electron fractography, microhardness, transverse and longitudinal tensile, bend and charpy impact toughness testing. The coarse ferrite grains in the base metal were changed into fine equiaxed axial grains and columnar grains as a result of characteristic rapid solidification of electron beam welds. Tensile testing indicates overmatching of the weld metal relative to the base metal. The joints exhibited acceptable impact toughness and bend strength properties.     

屈强比升高对管线钢使用安全性的影响

为了研究屈强比升高对管线钢使用安全性的影响,测试了5种常用钢材的工程应力及真应力-真应变曲线,计算了名义屈强比、真实屈强比和静力韧度。结果表明:随着钢强度级别的升高,名义屈强比会不断升高,材料的塑性指标有下降的趋势;真实屈强比在表征材料塑性变形余量方面比名义屈强比更客观,名义屈强比放大了屈强比升高的安全隐患;X80管线钢的屈强比虽然较高,但其抵抗变形的能力并未降低;对高强度管线钢规定过低的屈强比,会造成不必要的浪费。     

ASME应变强化本构模型及压力容器安全裕度分析

弹塑性有限元分析需要材料的真实应力—应变曲线,但利用ASME中的应变强化本构模型,按标准保证值和实测值分别建立的ASME真实应力—应变曲线存在较大的差异。运用ANSYS有限元软件模拟同一个1.4301奥氏体不锈钢压力容器模型在这两种材料参数下筒体应力、应变以及爆破压力的差异,并将模拟结果与试验结果对比。同时利用有限元模拟和爆破试验的爆破压力结果,分析奥氏体不锈钢应变强化压力容器在不同预应变下的安全裕度和实际安全裕度。结果表明：按保证值材料参数设计的压力容器,容器的实际塑性应变要比理论值小很多,用实测值材料参数设计大变形压力容器时应严格控制实际的应变值;应变强化压力容器的理论设计应变可达10%,但实际应变应在5%左右,容器才具有足够的安全裕度。     

合金元素对高强钢焊缝金属贝氏体形成及力学性能影响的研究进展

高强钢焊接过程中焊缝金属与母材的强韧匹配问题一直难以解决,因此急需细化合金元素调控体系,完善高强钢焊缝金属的强化增韧机理。贝氏体是高强钢焊缝金属中的重要组织,对其强韧性有重要影响,因此介绍了典型贝氏体的形成机理及分析方法,重点综述了合金元素对高强钢焊缝金属微观组织和力学性能的影响,得出高强钢焊接中各合金元素推荐值,进而丰富高强钢焊缝金属合金元素调控体系。     

Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods

The aim of the present study is to evaluate the abrasive wear resistance of some potential abrasion resistant steels exposed to different types of abrasive wear contact conditions typical of mining and transportation applications. The steels investigated, include a ferritic stainless steel, a medium alloyed ferritic carbon steel and a medium alloyed martensitic carbon steel.The abrasive wear resistance of the steels was evaluated using two different laboratory test methods, i.e. pin-on-disc testing and paddle wear testing that expose the materials to sliding abrasion and impact abrasion, respectively. All tests were performed under dry conditions in air at room temperature. In order to evaluate the tribological response of the different steels post-test characterization of the worn surfaces were performed using optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Besides, characterization of the wear induced sub-surface microstructure was performed using optical microscopy.The results show that depending on the abrasive conditions a combination of high hardness and toughness (fracture strain) is of importance in order to obtain a high wear resistance. In the pin-on-disc test (i.e. in sliding abrasion) these properties seem to be controlled by the as-rolled microstructure of the steels although a thin triboinduced sub-surface layer (5–10 μm in thickness) may influence the results. In contrast, in the paddle wear test (i.e. in impact abrasion), resulting in higher forces acting perpendicular to the surface by impacting stones, these properties are definitely controlled by the properties of the active sub-surface layer which also contains small imbedded stone fragments.     

Cryogenic fracture toughness evaluation for austenitic stainless steels by means of unloading compliance method

Most research to date concerning the cryogenic toughness of austenitic stainless steels has concentrated on the base metal and weld metal in weldments. The most severe problem faced on the conventional austenitic stainless steel is the thermal aging degradation such as sensitization and carbide induced embrittlement. In this paper, we investigate the cryogenic toughness degradation which can be occurred for austenitic stainless in welding. The test materials are austenitic stainless JN1, JJ1 and JK2 steels, which are materials recently developed for use in nuclear fusion apparatus at cryogenic temperature. The small punch (SP) test was conducted to detect similar isothermally aging condition with material degradation occurred in service welding. The single-specimen unloading compliance method was used to determine toughness degradation caused by thermal aging for austenitic stainless steels. In addition, we have investigated size effect on fracture toughness by using 20% side-grooved 0.5TCT specimens.     

低温高韧性药芯焊丝性能试验研究

对国产药芯焊丝 YJ5 0 7和 YJ5 0 2进行了焊接工艺试验 ,观察了药芯焊丝熔敷金属的显微组织 ,分析了药芯焊丝的熔敷金属化学成分。进行了药芯焊丝所焊焊接接头的低温冲击试验及焊接接头的常温拉伸试验。结果表明 ,国产药芯焊丝 YJ5 0 7和 YJ5 0 2具有良好的焊接工艺性能 ,其熔敷金属扩散氢含量较低 ;YJ5 0 7药芯焊丝的熔敷金属中含有一定量的镍 ,细化了先共析铁素体 ,提高了其低温韧性 ;YJ5 0 2药芯焊丝的熔敷金属含有一定量的钛和硼 ,易于形成针状铁素体 ,从而提高其低温韧性。     

High-resolution Transmission Electron Microscopy Characterization of the Structure of Cu Precipitate in a Thermal-aged Multicomponent Steel

High-dispersed nanoscale Cu precipitates often contribute to extremely high strength due to precipitation hardening,and whereas usually lead to degraded toughness for especially ferritic steels.Hence,it is important to understand the formation behaviors of the Cu precipitates.High-resolution transmission electron microscopy(TEM) is utilized to investigate the structure of Cu precipitates thermally formed in a high-strength low-alloy(HSLA) steel.The Cu precipitates were generally formed from solid solution and at the crystallographic defects such as martensite lath boundaries and dislocations.The Cu precipitates in the same aging condition have various structure of BCC,9 R and FCC,and the structural evolution does not greatly correlate with the actual sizes.The presence of different structures in an individual Cu precipitate is observed,which reflects the structural transformation occurring locally to relax the strain energy.The multiply additions in the steel possibly make the Cu precipitation more complex compared to the binary or the ternary Fe-Cu alloys with Ni or Mn additions.This research gives constructive suggestions on alloying design of Cu-bearing alloy steels.