马氏体型不锈钢

它的显微组织为马氏体。这类钢中铬的质量分数为11.5％～18．0％,但碳的质量分数最高可达0．6％。碳含量的增高,提高了钢的强度和硬度。在这类钢中加入的少量镍可以促使生成马氏体,同时又能提高其耐蚀性。这类钢的焊接性较差。列入国家标准牌号的钢板有1Cr13、2Cr13、3Cr13、1Cr17Ni2等。     

高铬不锈钢的热处理问题

前言 高铬钢通常是指铬含量≥12％～14％并含有碳及其他合金元素的钢。这种钢通常要进行两种类型的热处理：含碳量0．1％～0．2％C的奥氏体钢,用1150℃淬火 高温退火;而马氏体钢则用1050℃淬火 低温回火热处理。     

热轧带钢用高强度贝氏体钒微合金钢

本案目的是探讨通过钒微合金化及适当配用基本合金成分生产低碳贝氏体,使热轧带钢钢和屈服强度达到高于600MPa的具体条件是什么。实验室研究所选工艺条件以及碳和氮含量均与一般电炉所炼钢（最终含碳量0．04％及氮含量0．010％——均为重量百分数）经传统或紧凑式轧机轧成8mm热轧带钢生产条件相同。实验表明,只有采用1．4％锰,1．O％铬及0．25％钼（均为重量百分数）这样的基本合金成分才能在400℃温度下卷取中形成全贝氏体金相组织。决定热轧带钢钢种贝氏体强度的关键因素,首先是贝氏体转变温度,其次是对高密度位错贝氏体中铁素体回复的阻止。研究结果证明,钒微合金化能有效阻止贝氏体的铁素体回复,从而保持原生贝氏体强度。其中主要原因是位错结构上的细钒碳氮化物沉淀物阻止贝氏体中马氏体回复,实际沉淀强化只起很小的作用。在0．08％V加0．010％-0．02％N时,屈服强度高达750—790blPa,而不加钒的对照钢在其它成分相同条件下仅为680MPa。在将铬含量增加至2％时屈服强度达到840—880MPa。这要归功于基本合金元素水平较高,使贝氏体转变温度降低所致。     

新型不锈钢

日本一家公司生产了一种新型不锈钢，它含有较高的耐蚀性强的元素铬和钼，只含有极低的会产生腐蚀的元素碳和氮，因而具有极好的耐腐蚀性。其主要成分为：铬25％、钼5％、氮0．005％、碳0．003％，其余为铁。这种不锈钢的耐腐蚀性要比普通不锈钢强1倍以上，经用海水做实验，浸泡三四年也未产生腐蚀现象，是种极好的耐蚀性材料。     

以孕育处理通过电渣重熔开发超高强度钢

在一项较早的工作中已开发出了一种命名为0．3c—CrMoVESR（0．3C—1．0Mo-0．3V）的超高强度钢，这是一种通过将碳含量从0．15增加到0．28％和通过电渣精炼（ESR）并在ESR期间以铌或者锆对该钢进行孕育处理而得到的改进型AFNOR15CDV6钢。根据淬火速度，该钢铸态热处理后的极限拉伸强度（UTS），0．2％屈服应力（PS），百分延伸和夏氏U型缺口试件冲击能值分别在1550～1560MPa，1500～1520MPa，8～12．5％和370～790kJm^-2的范围内变动。所报道的0．3C—CrMoV钢的显微组织由马氏体和贝氏体组成。在现行的研究中，通过增加0．3C—CrMoV钢的铬含量到4％及将该钢经过ESR以钛进行孕育处理，其UTS和0．2％PS分别进一步增加到1740～1760MPa和1570～1610MPa。有意思的是随着UTS和PS的增长其百分延伸率也同时增长了14％，而其夏氏U型缺口试件冲击能值无任何跌落。此钢的力学性能随着铬含量的增加而提高可以归因于其马氏体和贝氏体混合显微组织中马氏体的体积百分数增加之故。     

合金材料

新型含钼合金钢美国专家研制成一种强度高、韧性大、耐腐蚀、不易断裂、使用寿命长的合金钢。这种钢是在锦粘合金用中添加适量的钥、格和碳制成的，它的抗拉强度为1980兆帕，屈服强度为1670兆帕，洛氏硬度为55，伸展率为15％，具有广泛用途。成本低的铬钢不锈钢镍基不锈钢是一种耐蚀性强的钢材，但价格较贵。新日本制铁公司生产了一种新型的钻铂不锈钢，它具有与谋基不锈钢同样的耐蚀性，而价格却低得多。铬用不锈钢的主要添加成分是：铬22％、用2％、用0．4％、铝0．4％。与含铅13％的普通铬不锈钢相比，新型不锈钢的硬度稍大，但仍可以进…     

不同变形量对0Cr21Ni6Mn9N不锈钢力学性能的影响

研究了不同变形量对不同氮含量的OCr21Ni6Mn9N不锈钢力学性能的影响。结果表明,不同氮含量的0Cr21Ni6MngN不锈钢都具有很强的加工硬化特性,冷变形使强度和硬度得到大幅度提高,但塑性会有所降低。氮的质量分数为0．20％～0．48％的0Cr21Ni6MngN不锈钢,控制变形量在20％以下,屈服强度可达到745MPa以上,同时保持伸长率在25％以上。分析表明,不同变形后钢的屈服强度与产生同等变形量的真应力具有很好的对应关系,且两者随变形量的变化规律基本相同。该钢的加工硬化行为明显分为两种情况,应变水平低于约20％时,强度提高幅度很大,而应变水平高于约20％后,强度提高幅度相对较小了,其原因是变形机制不同。     

生产无磁性钢的限制因素

高氮Cr-Mn钢在奥氏体不锈钢领域变得越来越重要。这类钢主要用锰、铬和氮（在某些情况下用钼和碳）进行合金化，因此具有高的强度、良好的延性和耐腐蚀性，被广泛地应用于油田行业和医疗领域。在大多数情况下这类钢必须是严格顺磁的：其组织必须完全是稳定的奥氏体，所以必须避免铁素体和马氏体。因此，奥氏体的稳定性及其预测是顺利生产Cr-Mn-N钢的重要因素。此外，奥氏体的稳定性也是研究者们所关注的，因为氮是高度耐腐蚀Cr—Mn—N钢中稳定奥氏体组织的最重要的合金化元素。由于氮在标准状态下呈气态，因此，一熔体中可以调节的氮含量是严格受到限制的，并主要取决于环境中的氮分压，合金的化学成分和所采用的加工温度。     

船舶用马氏体高强度不锈钢

为提高海上运输效率 ,日本船舶正向大型化和高速化方向发展 ,船舶构件大多使用焊接性能良好的马氏体不锈钢。新日铁公司采取调整成分和金相组织方法研制出焊接性和韧性良好的马氏体高强度不锈钢。这种新型不锈钢的成分为 :铬 1 3.2 % ,镍5.4% ,钼 1 % ,铌 0 .1 % ,碳 0 .0 1 % ,余量为铁。用这种钢轧制的厚度为 2 0ｍｍ和 2 0 0ｍｍ的厚钢板 ,经机械、冲击、疲劳和焊接等多项试验 ,其结果各项性能均可达到或超过目标值 ,是一种良好的船舶用不锈钢。船舶用马氏体高强度不锈钢@李惠萍…     

含氮奥氏体不锈钢的敏化行为

通过65％硝酸浸泡法和电化学动电位再活化法定量评价18—8奥氏体不锈钢的晶间腐蚀倾向，并利用分析电子显微镜确定晶界的贫铬区，利用透射电子显微镜及电子衍射技术确定晶界析出物的结构。试验结果表明：适量增加氮含量可提高18—8奥氏体不锈钢的耐晶间腐蚀性能。敏化状态下再活化率Rn在氮的质量分数为0．16％时最低；当氮的质量分数大于0．16％时，贫铬区最低铬含量随氮含量的增加而降低；贫铬区宽度在氮的质量分数为0．16％时最窄，氮含量继续提高则贫铬区宽度扩大。     

Principle and Practice on High Nitrogen Steel Melting by Blowing Ammonia Gas

 Abstract: During the HNS melting process, the absorption reaction of Nitrogen in the liquid steel by blowing NH3 and N2 was investigated respectively. In order to obtain higher content of nitrogen in steel, the liquid steel should be deoxidized and desulfurized because the [O] and [S] as surface activity element is not favorable to absorb nitrogen in melting process. Based on the metallurgical thermodynamics, the coupling reaction of NH3 with [O] can improve the generation of activity nitrogen atom in liquid steel. Nitrogen atom is easier to be absorbed than nitrogen molecule. At the same time, blowing ammonia gas can remove the oxygen from liquid steel and decreased the inclusion in the steel. Experiments of HNS melting in ten-kilogram inductive furnace indicated that, for liquid steel with same content of alloys and blowing the same mole of nitrogen , the absorption effect of nitrogen by blowing NH3 increase 18~75% than that of blowing N2.The technical process of melting HNS by blowing NH3 under normal pressure is feasible in industry production.h     

合金元素对高氮不锈轴承钢组织与性能的影响

摘要：采用金相、扫描、X射线衍射和电化学等方法研究了合金元素对高氮不锈轴承钢组织性能的影响。结果表明: 钢中加氮细化组织与碳化物,析出相尺寸随着氮含量的增加而降低。高氮不锈轴承钢1030、1050℃淬火后残余奥氏体体积分数达到20%~35%,而且碳氮含量越高,残余奥氏体越多。经冷处理及回火后残余奥氏体体积分数降至7%~103%,由于残余奥氏体的相变强化与碳氮化物析出强化,低温回火硬度约为59HRC,500℃高温回火硬度可达到58HRC~59HRC。高氮不锈轴承钢中析出相细化、基体贫铬区减少及氮 钼协同作用,使其耐蚀性能明显优于440C钢,而且钢中氮含量越高,耐蚀性能越好。因此,较高合金含量(C+N)的高氮不锈轴承钢兼具高硬度和优异的耐蚀性能。     

Microstructure and Mechanical Properties of a Nitride-Strengthened Reduced Activation Ferritic/Martensitic Steel

Nitride-strengthened reduced activation ferritic/martensitic (RAFM) steels are developed taking advantage of the high thermal stability of nitrides. In the current study, the microstructure and mechanical properties of a nitride-strengthened RAFM steel with improved composition were investigated. Fully martensitic microstructure with fine nitrides dispersion was achieved in the steel. In all, 1.4?pct Mn is sufficient to suppress delta ferrite and assure the steel of the full martensitic microstructure. Compared to Eurofer97, the steel showed similar strength at room temperature but higher strength at 873?K (600?°C). The steel exhibited very high impact toughness and a low ductile-to-brittle transition temperature (DBTT) of 243?K (?C30?°C), which could be further reduced by purification.     

Principle and Practice of High Nitrogen Steel Melting by Blowing Ammonia Gas

During the high nitrogen steel (HNS) melting process, the absorption reaction of nitrogen in the liquid steel by blowing NH_3 and N_2 was investigated respectively. In order to obtain higher content of nitrogen in steel, the liquid steel should be deoxidized and desulfurized because the oxygen and sulfur as surface activity element are not fa-vorable to the absorption of nitrogen in melting process. Based on the metallurgical thermodynamics, the coupling re-action of NH_3 with oxygen can improve the generation of activity nitrogen atom in liquid steel. Nitrogen atom is easi-er to be absorbed than nitrogen molecule. At the same time, blowing ammonia gas can remove the oxygen from liquid steel and decrease the inclusion in the steel. Experiments of HNS melting were carried out in a 10 kg induction fur-nace, and the results indicated that for liquid steel containing the same content of alloys and blowing the same mole of nitrogen, the absorption effect of nitrogen by blowing NH_3 is obviously higher than that of blowing N_2. The techni-cal process of melting HNS by blowing NH_3 under normal pressure is feasible in industrial production.     

双相沉淀硬化粉冶不锈钢的开发

不锈钢可通过压制与烧结水雾化粉末来制取.粉冶品级的不锈钢有铁素体、奥氏体、马氏体、两相(铁素体+奥氏体)、双相(铁素体+马氏体)以及沉淀硬化(马氏体)等不锈钢.开发双相粉冶不锈钢反映了对较高强度、较高延性与韧性的需求在增长.在本研究中,开发出一种新的低成本粉冶不锈钢,它将双相(铁素体+马氏体)显微结构与沉淀硬化的优点结合在一起.它与其他沉淀硬化合金不同,尽管这种不锈钢在时效后强度与韧性有所提高,但延性与冲击韧度的提高更大.借助组成与显微结构评估了新合金的力学性能.     

吹氨冶炼高氮钢的原理与实验

根据冶金热力学的计算结果,提出了钢液-气相界面可能发生的NH3和[O]、[S]耦合反应.该界面反应过程促使NH3在钢液界面生成易被钢液吸收的活性氮原子,同时,脱除了钢液中的氧、硫杂质元素,与常压下钢液吹氮增氮的工艺比较,可以取消为增氮而采用的钢液预脱氧、脱硫工艺环节,减少钢中非金属夹杂物的生成.10 kg中频感应炉的冶炼实验结果表明,合金成分相同的钢液供给等摩尔氮含量的氮化介质,NH3比N2的增氮效果提高了18%～75%.吹NH3条件下,钢液中保持一定量的氧、硫表面活性元素,有利于氮的吸收.     

Effect of Adding Nitrogen on Microstructure and Property of Vanadium Microalloyed Reinforcing Bar Steel

Worldwideattentionhasbeenpaidtomicroal loyedsteelwhichhasbeendevelopedrapidly .Manyadvantagesofmicroalloyedsteelhavebeenrecog nizeddeeply .Firstly ,themicroalloyedsteelhashighstrengthand goodcomprehensiveproperties .Sec ondly ,highprofitscanbegainedduetolowerpro ductionandapplicationcost .Themicroalloyingele mentsareaddedtomicroalloysteelsforgrainrefin ingandprecipitationstrengthening[1] .　　Theabilityofsecondphaseparticlestomaintainfinegrainsizesathightemperaturebypinningmi gratingboundarie…     

超纯铁素体不锈钢品种和精炼技术的进展

超纯铁素体不锈钢中(C+N)含量≤150×10- °,其耐蚀性、焊接性能、韧性等显著高于普通铁素  体不锈钢。介绍了新开发的409改进型、429及改进型、444及改进型超纯铁素体不锈钢的钢种、成分和性能; 采用三步法工艺冶炼18Cr超纯铁素体不锈钢,用SS-VOD 精炼时,钢中[C+N]≤70×10-⁶ ;VOD-PB 精炼时, [C+N] 为80×10-⁶ ;VCR 精炼时,[C+N] 为(80~100)×10-⁶。     

Effect of Heat Treatment on Microstructure of Modified Cast AISI D3 Cold Work Tool Steel

 High chromium high carbon AISI D3 steel is used as cold-work tools and dies in industry. Microstructure of this wrought steel usually consists of chromium carbides homogenously dispersed in a ferritic or martensitic matrix. On the other hand, a eutectic network consisting of chromium carbide and austenite forms in a cast D3 steel, at the end of solidification due to the segregation of carbon and chromium. This heterogeneous microstructure gives rise to the reduced mechanical properties such as toughness, impact strength, and tensile strength. In this research, modified AISI D3 steel was developed by replacing part of Cr with Nb and Ti, in which chromium carbide was partially replaced with MC carbides. The cast samples produced by investment casting were heat treated at different conditions. The microstructures of the samples were studied by light and scanning electron microscope attached with EDS analyzer. To determine the optimized homogenizing process, the effects of homogenizing treatment on the microstructure and the morphology of carbides were also studied.     

430铁素体不锈钢脱氮工艺

430铁素体不锈钢中的氮能恶化晶间腐蚀、低温冲击韧性、缺口敏感性以及焊接等性能。在热力学分析的基础上,研究了430铁素体不锈钢冶炼过程中初始碳质量分数、温度、氩氧比以及冶炼时间等工艺参数与对终点氮质量分数的影响。研究表明,在一定范围内,初始碳质量分数越高,氩氧比越大,脱氮效果越好;吹氩20min左右时脱氮效果最好,脱氮率可达到60%左右,继续延长冶炼时间会有回氮现象发生。