美国舰船用HY-80／100和HSLA-80／100钢板规范的演变

本文主要从化学成分、力学性能两个方面分析了美国舰船用HY-80／100、HSLA-80／lOO钢板规范演变特点，指出新规范的规定更加科学合理，化学成分的调整及优化能确保钢板性能更加稳定可靠。

Microstructure and Mechanical Properties of Aer Met 100 Ultra-high Strength Steel Joints by Laser Welding

AerMet100 ultra-high strength steel plates with a thickness of 2 mm were welded using a COz laser welding system. The influences of the welding process parameters on the morphology and microstructure of the welding joints were investigated, and the mechanical property of the welding joints was analyzed. The experimental results showed that the fusion zone of welding joint mainly consisted of columnar grains and a fine dendrite substructure grew epitaxially from the matrix. With the other conditions remaining unchanged, a finer weld microstructure was along with the scanning speed increase. The solidification microstructure gradually transformed from cellular crystal into dendrite crystal and the spaces of dendrite secondary arms rose from the fusion line to the center of the fusion zone. In the fusion zone of the weld, the rapid cooling caused the formation of martensite, which led the microhardness of the fusion zone higher than that of the matrix and the heat affected zone. The tensile strength of the welding joints was tested as 1 700 MPa, which was about 87% of the matrix. However, the tensile strength of the welding joints without defects existed was tested as 1832 MPa, which was about 94% of the matrix.

TEM observation of precipitation phase produced during tempering of steel AerMet100 and first principles calculations of phase evolution

The microstructure evolution law and the structure of precipitates produced during the tempering of steel AerMet100 based on TEM observation and the calibration of diffraction spot were revealed.The electronic structure and the stability of the MoxCr2-xC phase were calculated using the plane-wave pseudo-potential method on basis of density functional theory.TEM observations show that the precipitation phases Fe3C and Fe2-xCx(x=0.05～0.14) between martensite lath are produced at 425 and 480 ℃,respectively.The increase of tempering temperature or time can lead to the redissolution of both phases Fe3C and Fe2-xCx,and also lead to the precipitation of the phase Cr2C in martensite lath.The calculation results of formation energies and the density of state(DOS) demonstrate that in point of MoxCr2-xC structures formed during tempering,the early precipitation phase is Cr2C and finally later evolves into Mo2C phase with diffusing of incorporation of Mo atom into the Cr2C crystal cell,lattice,which can results in a energy decreases of the structure MoxCr2-xC phase with the increase of x.

Formation and Control of Sharp {100}<021> Texture in Electrical Steel

The formation and control of sharp{100}〈021〉texture in electrical steels were experimentally investigated and the main influencing factors were discussed.The steels of a base composition of Fe-3.2%Si with a certain amount of carbon and manganese were employed to obtain{100}〈021〉texture through one stage cold rolling and annealing.The results indicated that by careful control of the amount of alloying elements and the annealing temperature,a relatively sharp{100}〈021〉texture in fairly thick sheets is obtained.After primary recrystallization,a weak component of{100}〈021〉and strong component of(447)〈18114〉texture,which constitute∑9 coincidence site lattice boundaries with a common〈011〉axis for 39°difference,are presented.This special grain boundary promotes the growth of{100}〈021〉grains in addition to the lower surface energy of(100)grains during secondary recrystallization.

Research on submerged arc welding wire for X100 pipeline steel

According to the study of the microstructure and properties of X100 pipeline steel, the welding consumable-wire based on Mn-Ni-Mo-B-Ti alloy system was successfully designed and developed. The yield strength of the deposited metal of the developed welding wire was 695 MPa, the tensile strength was 810 MPa, and Charpy impact energy was 92 J at negative 20 ℃ when matching with BSG-SJ101H1 sintered flux. The results of the weldability test for X100 pipeline steel which adopting this developed wire showed that the tensile strength of the weld was 827 MPa, 185 J of Charpy impact energy（ -10 ℃ ） , 97% of section of shear and the weld had good strength and toughness matching when the welding speed got to 1.7 m/min. The microstructure and fracture appearance of the weld were analyzed by using metallographic microscope, scanning electron microscope （SEM） and laser confocal microscope, the results indicated that the microstructure was mainly granular bainite in the weld metal, and the fracture was dimple with 200 - 300 μm depth presenting a typical ductile fracture characteristics. The test of welding wire with different content of Ni and Cr element indicated that Ni was better than Cr in improving the strength and toughness of weld metal.

Characteristics of 100Cr6 bearing steel after thixoforming process performed with prototype device

A device based on a high pressure die-casting(HPDC) machine was constructed,with a capacity to produce thixo-casts from steel.After inductive heating to the required semi-solid temperature range,the samples were transported in a protective argon atmosphere to a cylinder of modified HPDC and injected into a pre-heated die.Bearing steel 100Cr6(after forging) was used as the feedstock material.The metallographic analysis of the steel showed a homogenous structure within a whole volume characterized by a grain size between 2 μm and 8 μm.Differential scanning calorimetry(DSC) analysis allowed to estimate the process temperature for thixoforming at 1 390 ?C which was attributed to about 45% of a liquid phase.With such technological parameters after the semi-solid processing the microstructure consisted of globular grains of size from 15 μm to 40 μm.The microstructure of globules indicated predominant presence of martensite(about 76% volume fraction) with residual austenite between plates.X-ray analysis confirmed that the thixo-cast samples contain mainly martensite and residual austenite.The hardness of the initial forged sample was HRC 27 and after the thixoforming process it was HRC 60,which confirms the presence of martensite and carbides.The thixo-casts were subjected to low tempering,at temperature of 150 °C for a period of 2 h,in order to remove stresses created during the process of thixoforming and to increase plasticity.The hardness after tempering was HRC 62.3.Additionally,in order to identify phases present in the thixo-casts,transmission electron microscopy(TEM) was carried out.

Microstructure and properties of HAZ for X100 pipeline steel

In general, the weld thermal cycle results in significant changes in microstructure and mechanical properties of the weld heat affected zone （ HAZ）. The microstructure, microhardness and low temperature impact toughness of HAZfor X100 pipeline steel were studied by means of welding thermal simulation. Influence of cooling time on the microstructure and properties in coarse-grained heat affected zone （CGHAZ） was investigated. The results illustrated that polygonal ferrite and a small amount of granular bainite were obtained when the cooling time ts/5 is larger than 1 500 s. Mainly granular bainite was formed when the cooling time t8/5 is in the range of 1500 s to 100 s. Bainite ferrite was observed when the cooling time is smaller than 60 s. Martensite appeared in the CGHAZ with the 20 s cooling time. The value of microhardness in the CGHAZ was higher than that of base metal （ BM） when the cooling time ts/s is smaller than 100 s. The CVN absorbed energy in the CGHAZ was higher than the value of BM when the cooling time t8/5 is smaller than 30 s.

Microstructure and Property Analysis of AerMet100 Steel Manufactured by In-situ Rolling Mixed Wire Arc Additive Manufacturing

Aer Met100 steel thick wall is fabricated by in-situ rolling composite wire arc additive manufacturing(WAAM).The microstructure and mechanical properties of Aer Met100 steel after heat treatment are studied.The results show that after the introduction of in-situ rolling force,the grain of Aer Met100 steel is broken,the anisotropy is eliminated,and the microstructure is refined obviously.The microstructure of Aer Met100 steel after heat treatment is mainly lath martensite and reverse austenite.There are 40 nm-68.6 nm alloy carbides precipitated in the martensitic matrix,and the hardening mechanism is mainly Orowan bypass strengthening.The film-like reverse austenite with the thickness ranging from 2 nm to 5 nm exists between the martensitic lath,which improves the toughness of the maraging steel.Good combination of strength and toughness can be achieved through proper heat treatment process.

Influence of the secondary welding thermal cycle on the microstructure and property of coarse grain heat-affected zone in an X100 pipeline steel

The influence of the secondary thermal cycle on the microstructure of coarse grain heat-affected zone in an XIO0 pipeline steel was investigated by means of a thermal simulation technique and microscopic analysis method. The property of coarse grain heat-affected zone was characterized by Charpy V-Notch impact properties testing. The results indicated that the experimental steel exhibited local brittleness of intercritically reheated coarse-grained heat-affected zone when the peak tempera- ture of secondary thermal cycle was in the range of two phases region （ ~ and 3/）. There were two main reasons for the local brittleness. The first was that the microstructures of intercritically reheated coarse-grained heat-affected zone were not fined although partial grain recrystallization occurred. The second was that M-A islands, which had the higher content, larger size and higher hardness, existed in intercritically reheated coarse-grained heat-affected zone.

Plasma Enhanced-Chemical Vapour Deposition of Scuff-Resistant Hydrogenated Amorphous Carbon Coatings on C100 Steel

Hydrogenated amorphous carbon coatings, deposited by low pressure plasma to minimize the wear of C100 steel components, were optimized and characterized. In order to ensure good adhesion of the films to the steel surface, a thin Ti interlayer was deposited, by magnetron sputtering, before the plasma deposition. The chemical characterization of the deposits was performed by means of RAMAN, XPS, RBS and ERDA analysis, while nanoindentation, nanoscratch and nanowear tests allowed to estimating the tribomechanical properties of the deposits, with the aim of evaluating their scuff-resistance. It was found that the optimized plasma deposited hydrogenated amorphous carbon coatings were well adherent to C100 steel and increased more than 70% its surface hardness.

低温风冷微量润滑切削A-100超高强度钢工艺研究

针对难加工材料A-100超高强度钢的加工性能差,刀具磨损严重等问题,进行了传统切削液冷却切削与低温风冷微量润滑切削加工对比试验。通过改变冷却温度,切深和进给量参数,分析了刀具寿命变化规律,利用普赛PV4030-DCC影像仪和蔡司Gemini360分别观察了断屑外观形貌和刀具磨损形貌,通过相关分析法对综合加工效率的影响因素进行探究。结果表明,低温风冷微量润滑加工的刀具寿命,刀具磨损和断屑断裂形态均显著优于切削液冷却加工。当切深和进给量增加时,刀具寿命均下降。低温风冷微量润滑加工均能不同程度提升刀具寿命,并得出了最优的加工参数。影响综合加工效率的主要因素是切深,具有强相关关系。实验结果证明低温风冷微量润滑加工A-100超高强度钢具有实际加工应用前景。

Surface Finish Evaluation of AISI P100 Steel after Grinding with MQL Technique with Different Flow Rates

Grinding operation is a finishing process often employed when high precision and narrow geometric tolerances are required.These requirements can be achieved only if cutting conditions are properly selected,especially the cooling-lubrication technique.In general,grinding is performed in presence of cutting fluid,however,due to the environmental impacts and costs of the conventional coolant delivery technique(flow rates from 4 L/min to 300 L/min),alternative cooling-lubrication techniques have been developed on restriction of the coolants use.Among the several techniques,MQL(minimum quantity of lubricant)technique has received special attention from machining users because of its advantages in terms of surface quality of workpiece and drastic reduction in use of coolant.In this context,this paper evaluated the performance of the MQL technique as compared to the flood coolant in peripheral surface grinding of AISI P100(VP100)steel with conventional aluminum oxide grinding wheel in relation to the surface roughness(Ra and Rz).Input parameters tested were equivalent chip thickness(0.09μm,0.18μm and 0.27μm)and flow rate of the cutting fluid(60 mL/h,150 mL/h and 240 mL/h)of the MQL system.Results showed that the grinding with MQL technique provided lower surface roughness values compared to conventional flood cooling,especially when machining under the intermediary cutting conditions.Also,with exception of heq of 0.09 m,the MQL technique resulted in lower values of Rz parameter as compared to the conventional coolant technique,regardless of the flow rate tested.

A-100钢晶粒显示方法研究

【目的】研究建立一套快速稳定的A-100(23Co14Ni12Cr3MoE)超高强度钢晶粒清晰显示方法。【方法】采用化学浸蚀法、氧化法和电解法腐蚀A-100钢的晶粒,并利用金相显微镜观察该钢种的晶界是否显示清晰,通过改变浸蚀溶液、温度、时间、电解参数等方法调整晶粒显示效果。【结果】化学浸蚀法和电解法每次需要摸索不同的腐蚀条件,晶界显示效果不稳定,A-100钢晶粒显示最有效稳定的方式是氧化法。【结论】结合A-100钢的标准热处理制度选择885℃热氧化可获得准确清晰的晶界。

终冷温度对X100管线钢组织与性能的影响

通过光镜、透射电镜、背散射电子衍射技术(EBSD)、拉伸与(-20℃)冲击试验,研究了不同终冷温度对X100管线钢组织、性能的影响规律。结果表明,随终冷温度降低,针状铁素体(AF)、粒状贝氏体(GB)组织逐渐减少,板条贝氏体含量逐渐增加,钢板强度增高,塑韧性降低,当终冷温度在380℃左右时,少量AF、GB组织分割原奥氏体晶粒,板条贝氏体束的有效晶粒尺寸得到细化,钢板具有最优的综合力学性能,屈服强度为775 MPa,抗拉强度为855 MPa,伸长率为16.6%,-20℃冲击功为218 J,各项性能指标均满足X100管线钢的要求。

AerMet100钢有效晶粒细化与逆转变奥氏体稳定性的提高

对二次硬化超高强度AerMet 100钢,通过引入预时效并优化双时效(即预时效+正常时效)工艺,膜状逆转变奥氏体(AR)中合金元素Ni、Co含量的起伏有利于提高其稳定性并降低Ms温度。高分辨透射电子显微镜(HRTEM)与扫描电子显微镜(SEM)分析表明:膜状AR在原奥氏体晶粒及马氏体铁素体(MF)板条边界形成,其间同时存在的K-S和N-W位向关系使有效晶粒由原奥氏体晶粒减小为MF板条(其厚度约80 nm);试样断面大而深的韧窝及高的撕裂棱反映出裂纹尖端钝化和分岔会吸收大量能量,在抗拉强度(σb)>2000 MPa条件下断裂韧度(KIC=127 MPa.m1/2)提高20%。

钢管焊缝100%检测的X射线工业电视检测方法

分析了X射线工业电视检测及计算机实时成像装置,检测钢管端部焊缝时存在盲区的主要原因;介绍了钢管端部焊缝100%检测的3种方法。实践表明,在3种检测方法中,采用改变图像增强器接收屏几何尺寸的方法较优,可解决采用遮挡板、遮挡器方法时存在的不足,满足了对钢管端部焊缝进行100%检测的要求。

X100管线钢烧结焊剂熔渣结构对焊接脱渣性的影响

通过对焊剂渣系、碱度的研究分析，选用碱度为1．3～1．7的氟碱型渣系，研制了X100管线钢用烧结焊剂，并与H03MnNi3MoTiB焊丝匹配进行高焊速双丝埋弧焊接试验。焊后对其熔渣进行XRD测试分析，并利用模糊性评估计算其线膨胀系数。结果表明：虽然焊剂碱度较高，但均具有良好的脱渣性；碱度为1．62的1#焊剂，由于熔渣中没有体心立方晶格结构的尖晶石物质生成，且与焊缝金属线膨胀系数相差最大，因此脱渣性能最优；碱度为1．39和1．64的2#和3#焊剂，虽然焊后熔渣中均有少量的尖晶石生成，但由于熔渣与焊缝金属的线膨胀系数仍然存在较大的差异，因此也表现出较好的脱渣性。

A-100钢材料起落架关键结构件车铣加工工艺研究

通过对A-100钢材料的某型飞机起落架关键结构件开展车铣工艺研究,成功摸索出了可转位刀具加工A-100钢材料的切削参数,掌握了某型飞机起落架关键结构件的车铣加工技术,显著提高了加工效率,大大降低了生产成本。

-100℃低温无缝钢管的开发

通过对化学成分设计,炼钢、轧制、热处理等工艺控制,保证了-100℃低温无缝钢管的低温冲击韧性以及抗腐蚀性能。重点指出使用无缝钢管加工成的弯头产品要进行匹配的热处理,以保证弯头的质量不低于母材。开发的低温无缝钢管具有尺寸范围广、优良的低温韧性和抗腐蚀性能等优点,保证了其在低温环境下使用的安全性。