两种船体钢耐海水腐蚀性能对比

针对10MnNiCr钢、新型440 MPa船体钢,开展了钢的自然腐蚀电位测试、室内加速腐蚀试验,1年期北海海域裸钢海港挂片试验。试验结果表明,由于钢的合金成分不同,10MnNiCr钢表现出较好的耐海水腐蚀性能。     

一种低合金高强度船体钢模拟粗晶区组织及相变研究

通过对一种低合金高强度船体钢热模拟试验,研究了不同的焊接热循环对其组织及相变的影响,综合相转变分析、金相组织观察及显微硬度测试,建立了试验钢的焊接CCT曲线。结果表明,在常规焊接热输入条件下,试验钢焊接热影响区粗晶区组织主要为马氏体和贝氏体,试验钢对焊接热输入不敏感。随焊接热输入的增大,试验钢相变温度、热影响区组织及硬度不发生明显的变化。     

Ce含量对X100管线钢显微组织和耐腐蚀性能的影响

为了研究稀土元素Ce对X100管线钢显微组织和耐腐蚀性能的影响,利用蔡司显微镜、场发射电子显微镜及其配套的能谱仪和电化学工作站对不同Ce含量的4种试验钢0,1,2,3号(Ce质量分数分别为0,0.001 7%,0.002 8%,0.004 9%)进行测试。结果表明：随着Ce含量的增多,试验钢表面的晶粒尺寸减小,Al₂O₃夹杂被改性为CeAlO₃夹杂和Ce₂O₃夹杂。浸泡7 d后,4种试验钢的腐蚀电位均比较接近;浸泡30 d后3号试验钢的腐蚀电位较之前提高了8.94%,2号和1号试验钢的腐蚀电位分别较之前提高了6.34%和6.06%;浸泡45 d后,1号试验钢的腐蚀电位较7 d时降低了10.38%,其他3种试验钢的腐蚀电位变化不大。0号试验钢的容抗弧半径随浸泡时间的延长而逐渐减小,3号试验钢的容抗弧半径增大得最为明显。测试结果均表明,Ce含量的增加会提高试验钢的耐腐蚀性能。     

外加微米ZrC颗粒对低碳微合金钢组织及性能的影响

本文研究了ZrC颗粒加入量对低碳微合金钢组织和力学性能的影响。对试验钢进行了各种力学性能的测试,并用金相显微镜和TEM观察了试验钢的微观组织,用SEM观察了ZrC颗粒的分布状态及拉伸断口形貌。结果表明,加入ZrC颗粒后,试验钢的晶粒都得到了一定程度的细化,当加入ZrC颗粒体积含量为1.1%时,晶粒被细化到5.5μm,此时试验钢的抗拉强度、屈服强度、伸长率、冲击韧性和维氏硬度分别达到635MPa、517.5MPa、20.66%、215.0J/cm2和214 Hv5,获得了最佳综合力学性能;添加ZrC颗粒后,试验钢的组织仍为铁素体,拉伸断口仍为韧窝状;轧制态试验钢中ZrC颗粒分布较为均匀。     

S-07钢在高压充气阀芯中的替代应用研究

目的解决高压充气阀S-03钢渗氮阀芯生产过程中周期长、合格率低、渗氮层开裂和贮存过程中锈蚀及方向漏率超标等问题。方法结合S-03钢渗氮阀芯工艺流程,分析其生产及贮存过程中存在的问题,并提出由S-07钢替代S-03钢渗氮工艺,从防锈、硬度和强度3个方面进行两种材料特性理论分析,同时进行耐蚀性试验、功能性试验、力学环境试验和寿命试验考核。结果 S-03钢渗氮阀芯经历湿热试验20 d后,出现轻微锈蚀,盐雾试验96 h后,锈蚀严重,而同条件下的S-07钢阀芯无锈蚀。S-07钢阀芯经过了功能性试验,x,y,z这3个方向的力学环境试验,动作200次的寿命考核试验后,动作灵活,功能测试合格。结论充气阀阀芯完成了S-07钢替代工艺研究,成功解决了影响充气阀功能的阀芯锈蚀问题和渗氮层开裂问题,同时使生产效率提高了约70%,生产成本降低了约50%。     

合金元素Mo对材料超高周疲劳性能的影响

采用超声疲劳试验技术对42CrMo钢超高周疲劳性能进行了研究。将42CrMo钢超高周疲劳S-N曲线与已有文献中40Cr钢在相同试验方法和试验条件下得到的超高周疲劳S-N曲线进行比较,结果显示42CrMo钢超高周疲劳性能优于40Cr钢。通过分析推测,合金元素Mo增加了疲劳裂纹内部萌生的时间,进而提高了材料超高周疲劳的寿命。     

1200 MPa级冷轧双相钢组织性能及其热塑性

在实验室分别采用C-Si-Mn-Cr-Nb系及C-Si-Mn-Nb系成分设计试制了1 200MPa级冷轧双相钢,并对其热塑性进行了研究。结果表明,试验钢冷轧后连退板的抗拉强度分别达到了1 205 MPa、1 235 MPa,屈服强度分别为545 MPa、530 MPa,屈强比分别为0.45、0.43,伸长率分别为11.5%、10.5%,C-Si-Mn-Cr-Nb系成分设计的试验钢各项力学性能明显优于C-Si-Mn-Nb系试验钢。采用热模拟仪对试验钢的热塑性进行研究,发现1 200 MPa级冷轧双相钢在实验条件下,C-Si-Mn-Nb系试验钢出现第Ⅰ脆性区和第Ⅲ脆性区,而C-Si-Mn-Cr-Nb系试验钢仅出现第Ⅲ脆性区;C-Si-Mn-Nb系和C-Si-Mn-Cr-Nb系两种试验钢在600~1 100℃均出现热塑性降低,在750℃时降到这一区间的最低点,原因在于Nb(C,N)和AlN发生了沿奥氏体晶界析出。     

热轧C-Si-Mn系TRIP钢的组织与力学性能

为了探讨热轧TRIP钢的制备工艺与其组织及力学性能的关系,采用热轧控冷工艺在实验室制备了C-Si-Mn系TRIP钢,利用光学显微镜、扫描电镜及透射电镜对试验钢的组织进行了观察,利用能谱仪对试验钢中的夹杂进行了观察.研究得到试验钢的力学性能为:σb=605 Pa,σs=440 Pa,δ=28.4%,σs/σb=0.73.定量金相检测结果表明,试验钢中三相含量分别为:残余奥氏体5.6%,铁素体67.6%,贝氏体26.8%.     

基于加工硬化率的新型轻质钢动态再结晶临界条件及变形机制研究

采用Gleeble3500热模拟实验机,在850～1 050℃温度范围内和0.01～5 s^-1应变速率范围内,对试验钢进行了等温压缩变形处理,得到试验钢的应力-应变曲线。通过数据处理进一步得到试验钢加工硬化率-应变关系曲线、动态再结晶临界应力和临界应变,并借助OM、TEM及EBSD表征技术,分析了试验钢的组织演化规律和变形机制。结果表明：在相对低温和低应变速率下,随着应变量的增加,由于加工硬化再次占据主导地位,试验钢出现了明显的流动应力“二次增大”现象;随着热变形温度的降低和应变速率的增大,试验钢的峰值应力和临界应力、峰值应变和临界应变都呈现出增大趋势,并得出其相互之间新的关系模型;在变形条件下,试验钢再结晶晶粒尺寸随着温度的升高和应变速率的降低而增大,层错能(SFE)值随着变形温度的升高而增大,范围为181.1～237.4 mJ/m²,试验钢热变形后组织中有孪晶存在,说明SFE并非是影响高锰奥氏体钢变形机制的唯一因素,试验钢的主要变形机制为位错滑移。     

稀土处理对Mn-V-Ti钢点蚀性能影响的研究

实验室冶炼了5炉稀土处理及未处理的锰系低合金船体钢,并收集了一种工业生产的同种钢。通过冶金分析、极化试验、闭塞电池试验及挂片试验,研究了夹杂物变性对钢材点蚀诱发及扩展的影响;结果表明:钢中夹杂物是点蚀的诱发源,硫化物夹杂物的数量对钢材的点蚀性能有显著影响。稀土硫化物夹杂数量少,体积小,能显著降低钢的点蚀诱发敏感性,降低钢的蚀坑扩展速度,提高钢的耐蚀性。     

中锰奥氏体基耐磨钢的热处理工艺及性能研究

合理设计了中锰奥氏体基耐磨钢的成分,并选择合适的水韧处理３工艺来获得一种介稳的单相奥氏体组织,在此组织基础上进行了不同的等温热处理工艺,获得一定量的马氏体,以提高基体的初始硬度,又不恶化其冲击韧性,再通过与高锰钢（Ｍｎ１３）在同等式况条件下进行耐磨性模拟对比实验,来选择适合中锰钢在中、低冲击磨料磨损条件下使用的热处理工艺和组织。同时对试样进行了金相组织观察及力学性能测试。     

The effect of tempering temperature,machining operations,and applied stress on the susceptibility of high-quality 1Cr12Ni2WMoV steel to stress corrosion

The effect of mechanical and heat treatment conditions and applied stresses on the stress-corrosion susceptibility of a high-quality 1Cr12Ni2WMoV-type chromium stainless steel widely used in power generating plants was studied. The effectiveness of the reagent used and its equivalent in relation to the actual working conditions of the steel studied were determined.     

Influence of hot rolling and heat treatment on structure and properties of HSLA steel explosively clad with austenitic stainless steel

Abstract

The present work aims at studying structure–property correlations in an explosively clad HSLA steel with austenitic stainless steel of AISI 304L grade. The clad plate was subjected to hot rolling followed by a quenching and tempering treatment to achieve better mechanical properties in the base plate. Optical microscopy studies revealed that the interface between the two steels was wavy in the as clad plate and the waviness decreased substantially due to hot rolling. Subsequent heat treatment has not shown any significant effect either. The base plate had tempered martensite/bainite structure in as clad or heat treated conditions and ferrite-pearlite-bainite structure in hot rolled condition. The grains were finer and elongated near the interface. The stainless steel exhibited equiaxed grain structure in as clad, hot rolled or heat treated plates. Tensile properties and charpy impact energy of the base plate were lowered due to hot rolling and then increased substantially due to heat treatment. The microhardness was observed to be a maximum at the bond interface for all three conditions studied. The shear bond strength was the highest in the as clad condition and decreased for the rolled as well as heat treated conditions. Scanning electron microscopy fractography on shear bond specimens revealed the presence of predominantly equiaxed dimples with few regions of rubbed fracture. Quantitative electron probe microanalysis across the bond interface indicated linear change in concentrations of nickel, chromium and manganese between the levels appropriate to the clad layer and base metal.     

Microstructure and mechanical properties of as-deposited and heat-treated additive manufactured 9Cr steel

Wire arc additive manufacturing technology has been applied to fabricate 9Cr ferritic/martensitic steel. The steel is widely used in the power industries because of good performances. The effects of different heat treatment conditions on microstructure, hardness, tensile properties, and Charpy impact toughness were investigated. The results show that the microstructure of the as-deposited condition consists of untempered lath martensitic with high strength and low toughness. It was found that heat treatment can change the microstructure characteristics. Moreover, samples after heat treatment have been observed with high elongation and impact toughness but relatively low hardness and tensile strength. The better combination of strength, ductility and microstructure were obtained for the normalising temperature of 1323?K and tempering temperature of 1033?K.     

Structure and properties of friction welds between high-speed steel and medium-carbon steel for bimetal tools

Abstract

Bimetal joints between high-speed steel and medium-carbon steel are often required in the tool industry. Friction welds were made between this dissimilar combination of materials and the joint behaviour was evaluated under conditions appropriate to the intended service applications. The welding was carried out under optimized conditions, the joints were subjected to a heat treatment schedule that is usual in service, and the joint performance was estimated in dynamic torsion. The structural changes occurring during welding and during the subsequent heat treatments were followed by optical metallography and hardness testing. The results show that, although decarburization occurs during post-weld annealing in the medium-carbon steel adjacent to the weld, the joint properties are adequate for moderately severe drilling conditions. Friction welding may thus prove to be an acceptable process for producing such joints.

MST/393     

The corrosive wear of nickel coating on mild steel

The abrasive wear of nickel coatings on steel substrates, under corrosive conditions was studied. For specimens with and without heat treatment, the wear rate was observed to depend upon the nature of the corrosive solution. The composition of the wear debris was noted to be a function of the corrosive wear conditions. The wear rate of the heat treated specimens was observed to be lower than that of the non-heat treated nickel-coated steel specimens.     

热处理工艺对22MnCrNiMo系泊链钢组织与耐蚀性能的影响

本文比较系统地研究了新型22MnCrNiMo系泊链钢经不同的工艺热处理后的组织和耐蚀性,从而得到该系泊链钢不同的热处理工艺、组织与耐蚀性能的变化规律。研究结果表明:新型22MnCrNiMo系泊链钢在930℃二次高温快速加热淬火+620℃×30min回火能获得较好的综合力学性能和耐蚀性能。对R4S级高级系泊链的研发与产业化生产具有较好的工程应用意义。     

A study of fatigue failure initiation in high cycle high-pressure automotive applications and conventional rotating bending fatigue testing

The search for greater power and efficiency from automotive engines places components under ever increasing stress. This study compares results obtained from testing of engine components under extreme operating conditions with those obtained from laboratory-based tests. Conventional rotating bending fatigue testing has been applied to high strength alloy steel samples processed and heat treated under the same conditions as engine test components. The results are compared with those obtained from engine components tested under high-pressure cyclic loading using specially designed engine test rigs. Failure initiation sites in the high strength alloy steel samples have been identified and categorised using scanning electron microscopy with X-ray mapping. The influence of inclusion content, heat treatment process and surface finish have been determined and used to inform design considerations, heat treatment processing conditions and material selection.     

工艺参数对热冲压成型钢组织性能及硼偏聚的影响

通过Gleeble1500热/力模拟实验机对轧后含硼钢板进行了热冲压过程模拟,分析了各种热处理条件对含硼钢组织性能的影响,并采用X射线衍射技术和径迹照相技术分析了硼的偏聚和硼相析出情况。研究结果表明:提高加热温度或延长保温时间,可促进钢的奥氏体化和硼的偏聚。通过偏聚合适含量的硼,能够很好地起到提高淬透性作用,使材料得到全部马氏体组织。热冲压成型过程中的变形破碎了奥氏体组织,促进相变,更易获得细小的马氏体组织。当冷却速度不高时,钢中"硼相"会沿晶界连续析出,从而降低了硼钢的淬透性。     

Abrasive Wear Characteristics of Carbon and Low Alloy Steels for Better Performance of Farm Implements

The low stress abrasion behaviours of heat treated mild, medium carbon and high C - low Cr steels, which are generally used in making farm implements, have been investigated. The simple heat treatment greatly improves the hardness, tensile strength and abrasion resistance of medium carbon and high C - low Cr steels. The results indicate that the material removal during abrasion is controlled by a number of factors, such as hardness, chemical composition, microstructure and heat treatment conditions. The conclusion is that the heat treated high C - low Cr steel and mild steel carburized by using coaltar pitch provide the best hardness and abrasion resistance and thus appear to be the most suitable materials for making agricultural tools.