回火温度对9Ni钢低温韧度的影响研究

为了研究不同回火温度对9Ni钢低温韧度的影响,利用OM、SEM、TEM对试验钢微观组织和断口形貌进行观察分析,研究表明:在550~600℃范围内回火,9Ni钢强度和韧度达到最佳匹配,且其他各项性能也达到最佳;回转奥氏体、碳化物及回转奥氏体诱发马氏体相变等均对低温韧度产生重要影响。     

液化天然气储罐用超低温9Ni钢的研究及应用

9Ni钢是目前国内为缓解能源压力,建设液化天然气储罐所必须国产化的重要基础原材料.论述了9Ni钢的成分、组织结构与性能的关系.深入分析了9Ni钢的低温韧化机制,认为除了回转奥氏体外可能还有其它重要控制冈素,诸如奥氏体/铁索体界面结构、杂质元素含量等.提出应通过细化晶粒、提高钢的纯净度、添加合金元素等手段来改善9Ni钢的低温韧性,提高屈服强度,实现节约成本的目的.     

从拉伸应力-应变曲线分析06Ni9钢强韧性配合

06Ni9钢是适合于制作液化天然气储罐的低温钢，要求具有优良的强韧性配合。作者选择了4组06Ni9钢典型的拉伸应力-应变曲线，分析了曲线类型与其强韧性之间的关系。研究表明如果成分一定，拉伸曲线上有明显的屈服点和屈服平台，那么其强韧性配合良好，能够满足性能指标要求。同时认为屈服强度取决于回火后偏聚于刃型位错周围的碳原子浓度，而低温冲击韧度则取决于回转奥氏体及其中所含合金元素的数量和浓度。     

9Ni钢纯净化生产实践

介绍了鞍钢9Ni钢的工艺路线和技术特点。采用转炉双联法、LF/VD双渣法及精炼合成渣技术可使钢中有害元素P+S+N+H+O总和平均降低到0.008 4%;采用电磁搅拌、动态二冷和多点矫直技术减少了连铸坯内部和表面缺陷;采用温度为200~300℃的铸坯缓冷和铸坯修磨工艺保证了轧后钢板表面质量。     

QLT处理9%Ni钢低温拉伸性能的研究

 对QLT处理后的9%Ni钢在室温和低温下进行拉伸试验,采用X射线法对拉伸前后样品中的奥氏体含量进行了测试,利用透射分析拉伸试样断口附近的显微组织,研究了低温拉伸过程中逆转变奥氏体/马氏体对QLT处理9%Ni钢拉伸变形行为的影响。研究表明：QLT处理9%Ni钢在20~-196℃系列温度拉伸时,随试验温度的降低,强度和均匀伸长率均提高、屈强比降低。逆转变奥氏体在拉伸时发生相变而改善了9%Ni钢的低温塑性。     

硼含量及奥氏体化温度对P20B钢淬透性的影响

 为提高P20B钢的淬透性,通过端淬试验研究了硼含量及奥氏体化温度对P20B钢淬透性的影响。结果表明,当硼含量在0000 9%~0002 3%范围时,P20B钢的淬透性得到提高;当硼含量超过0004 0%时,P20B钢的淬透性反而下降。奥氏体化温度在820~920 ℃范围时,随温度升高,P20B钢的淬透性显著提高。     

低温奥氏体钢的强度计算

研究了低温奥氏体钢的强度随温度及合金元素含量的变化规律。对大量试验结果用计算机处理得到了定量计算的系列表达式。经验证,计算结果是令人满意的,可用于低温奥氏体钢的设计和强度计算。     

电渣重熔对奥氏体钢低温韧性的影响

测定了77K下22Mn-13Cr-5Ni-0.25N奥氏体钢电渣重熔前后的冲击韧性、氢含量及夹杂物含量,并利用扫描电子显微镜和透射电子显微镜研究了电渣重熔对该钢低温韧性的影响,结果表明：电渣重熔使钢中氢和夹杂物含量显下降,有利于抑制γ→ε转变,减小应力集中,从而提高了该,多的低温韧性。     

Effect of Tempering Temperature on Microstructure and Mechanical Properties of Steel Containing Ni of 9 %

  Mechanical properties of quenching, intercritical quenching and tempering (QLT) treated steel containing Ni of 9% were evaluated from specimens subject to various tempering temperatures. The detailed microstructures of steel containing Ni of 9% at different tempering temperatures were observed by optical microscope (OM) and transmission electron microscope (TEM). The volume fraction of austenite was estimated by XRD. The results show that high strength and cryogenic toughness of steel containing Ni of 9% are obtained when the tempering temperature are between 540 and 580 ℃. The microstructure keeps the dual phase lamellar structure after the intercritical quenching and there is cementite created in the Ni rich constituents when tempering temperature is 540 ℃. When tempering temperatures are between 560 and 580 ℃, the reversed austenites (γ′) grow up and the dual phase lamellar structure is not clear. The γ′ becomes instable at 600 ℃. When tempered at temperature ranging from 500 to 520 ℃, the increase of dislocation density in the lamellar matrix makes both tensile strength and yield strength decrease. When tempered at 540 ℃ and higher temperature, the yield strength decreases continuously because the C and alloying elements in the matrix are absorbed by the cementite and the γ′, so the yield ratio is decreased by the γ′. There are two toughness mechanisms at different tempering temperatures. One is that the precipitation of cementite absorbs the carbon in the steel which plays a major role in improving cryogenic toughness at lower temperature. Another is that the γ′ and the purified matrix become major role at higher tempering temperature. When the tempering temperature is 600 ℃, the stability of γ′ is decreased quickly, even the transformation takes place at room temperature, which results in a sharp decrease of Charpy V impact energy at 77 K. The tempering temperature range is enlarged by the special distribution of cementite and the lamellar structure.     

液化天然气储罐用超低温9Ni钢的研究与应用

 9Ni钢是我国目前为缓解能源压力,建设液化天然气储罐所必须国产化的重要基础原材料。在本文中,作者较为详细地论述了9Ni钢的成分、组织结构与性能之间的关系,深入分析了该钢低温韧化机制,认为除了回转奥氏体之外可能还有其他重要的控制因素,诸如奥氏体∕铁素体界面结构﹑杂质元素含量等。提出应通过细化晶粒、提高钢的纯净度、添加合金元素等手段来改善9Ni钢的低温韧度,提高屈服强度,实现节约成本的目的。     

Reheating Austenitizing Temperature of Spring Steel 60Si2MnA for Railway

The microsturctural transformation of austenite grain, pearlite interlamellar spacing, and lamellar cement ite thickness of spring steel 60Si2MnA for railway were studied in the hot-rolled and reheated states. Furthermore, the effect of microstructural characterization on its final mechanical properties was discussed. The results showed that as far as 60Si2MnA, the pearlite interlamellar spacing determined the hardness, whereas, the austenite grain determined the toughness. Compared with microstructure and mechanical properties in the hot rolled state, after reheating treatment at 950 ℃, its average grain sizes are apparently fine and the pearlite interlamellar spacing and lamellar cementite thickness coarsen to some extent, but both hardness and impact toughness increase to HRC 48 and 8.5 J, respectively. In the course of making spring, the optimum reheating austenitizing temperature for the 60Si2MnA steel is 950 ℃.     

超低温环境压力容器用途超厚3.5Ni钢板的研发

通过调整成分,增加有利于提高淬透性的元素含量,采用合理的控制轧制工艺以及两次正火工艺,成功开发了厚度达150 mm的08Ni3DR(3.5Ni)钢板,钢板的-101℃冲击韧性达到了较高水平。     

热处理工艺对高强度含铜9Ni钢组织和性能的影晌

随着液化天然气（LNG）储罐朝着大型化发展,在不增加容器壁厚的情况下,必须提高钢板强度。在传统9Ni钢中添加Cu,通过析出强化,使其强度水平得到显著提高。提出一种新型含1．25％Cu（质量分数）9Ni钢。试验钢经过控轧直接淬火（DQ）;研究了DO材料分别经过1）QLT（奥氏体（γ）单相区淬火（Q）＋两相区（α＋γ）淬火...     

High Temperature Oxidation Resistance of 9Ni Steel

Oxidation rates and scale/steel interface configuration of 9Ni steels were investigated at 1000--1 250 ℃ in air. The results revealed that Cu addition caused high temperature oxidation resistance to deteriorate. High tempera ture oxidation rates increased and scale/steel interface configuration became complicated due to Cu addition. Scale/ steel interface appeared to be network above certain temperature. Temperature required to form network scale/steel interface dropped more than 100 ℃ for 1.5% Cu-containing steel. （Fe,Ni,Cu）x Oy in inner oxidation layer dissocia ted to Fe-Ni-Cu phase and released active oxygen which can react with base steel easily. So the inner oxidation layer became the second source of oxidizing agent besides atmosphere. Internal stress at austenite grain boundary caused local oxide to fragment. So the scale/steel interface appeared to be network. Liquid Si-rich phase formed at sufficient ly high temperature. Penetration of the liquid Si-rich phase along austenite grain enhanced austenite grain oxidizing.     

铌对9%Ni钢焊条熔敷金属组织和性能的影响

 研制9%Ni钢焊条的难点在于满足熔敷金属强度和塑性指标的前提下提高其低温韧性。本文在9%Ni钢焊条熔敷金属力学性能分析的基础上,采用彩色金相分析、扫描电镜分析、X射线衍射分析技术研究了Nb对9%Ni钢焊条熔敷金属组织和性能的影响。试验结果表明,熔敷金属中Nb的加入,形成了共格有序的金属间化合物γ'相(Ni3Nb)作为强化相,使熔敷金属得到有效的强化,但当Nb含量过高时,会形成是脆性的金属间化合物Laves相,导致熔敷金属低温韧性下降。Nb含量较低时,随着Nb含量的增加,熔敷金属强度和塑性显著提高,同时低温韧性下降很少。当Nb含量达到3.5(wt%)时,熔敷金属的强度和塑性继续提高,但低温韧性指标明显下降。     

热处理工艺对LNG用高Ni低温钢韧性的影响

为改善LNG用高Ni钢板的力学性能,采用正火＋回火、淬火＋回火和淬火＋淬火＋回火三种工艺对其进行热处理。性能检测及组织观察结果显示,由于正火的冷却速度较慢,影响了正火＋回火处理后钢板潜能的释放;而淬火＋回火处理则解决了这个问题,钢板低温韧性大幅提高;淬火＋淬火＋回火处理使钢板的低温韧性进一步改善。