HQ590DB超低碳贝氏体钢中厚板的研制

采用 18 0t转炉 RH LF(Ca处理 ) 连铸坯 (mm) :2 30 (30 0 )× 16 5 0× 6 0 0 0 4 30 0轧机控轧控冷工艺试制了HQ5 90DB超低碳贝氏体钢 (% ) :0 0 5C ,1 5Mn ,0 0 4Nb ,0 0 2Ti,≤ 0 0 0 0 2B的 30～ 4 0mm中板。连铸坯的 [H]1 7× 10 - 6 ,[O]2 1× 10 - 6 ,[N]2 9× 10 - 6 。终轧温度 80 0～ 85 0℃ ,控制终冷温度 5 90～ 6 30℃ ,获得铁素体 板条状贝氏体组织 ,钢板抗拉强度σb6 5 0～ 6 90MPa ,屈服强度σ0 .2 4 90～ 5 90MPa ,延伸率δ52 0 % ,并具有良好的成形性能。     

新型高强度弹簧钢40Si2CrNi2MoV的研制

研制的高强韧性新型弹簧钢 4 0Si2CrNi2MoV(4 0T)的σb≥ 195 0MPa ,σ0 .2 ≥ 175 0MPa ,δ5≥ 9% ,ψ≥30 % ,AK～ 30J。该钢的抗弹减性均优于弹簧钢 6 0Si2CrVA。该钢适于制造高应力、大截面弹簧 ,用于制造铁路货车转向架弹簧时 ,设计应力 116 0MPa ,在弹簧疲劳试验中 ,平均应力为 6 4 7MPa ,应力幅值为平均应力的 0 4倍 ,最大应力 90 6MPa ,最小应力 388MPa ,循环周次达 2× 10 6次未发生断裂。     

2195铝锂合金热处理工艺与性能(续)

图 5　转移时间对组织影响　× 2 0 0表 2　冷却水温对性能影响5 0 0℃× 2 5 min+ 1 60℃× 32 h冷却水温 /℃ σb/ MPaσ0 .2 / MPaδ/ %空冷 4 0 82 70 12 .7885 384 5 0 5 .55 35 5 0 4 6 5 5 .815 5 32 4 5 7 6 .5 715 4 3472 6 .3淬火转移时间变化对性能组织影响 ,实际也可归结为冷却速度的影响。淬火转移时间长短对性能影响结果见表 3:表 3　淬火转移时间对性能影响转移时间 Sσb/ MPaσ0 .2 / MPaδ/ %2 5 30 4 738.75 5 4 5 4 87 7.815 5 2 346 5 6 .830 5 2 2 4 5 37.06 0 4 30 312 13.3　　由表 3可知 ,转移停留时间在 5 s内…     

本钢铁道车辆用LZ50钢车轴坯的研制

本钢采用铁水预处理、12 0t顶底复吹转炉冶炼、LF +RH TB二次精炼、4 8t钢锭 80 0轧机成坯工艺试生产了铁道车辆用LZ5 0钢 (% :0 4 7～ 0 5 5C ,0 17～ 0 4 0Si,0 6 0～ 0 90Mn) 2 30mm× 2 30mm车轴坯。LZ5 0钢材中氢含量为 (0 5～ 0 7)× 10 -6,氧 (9～ 10 )× 10 -6,氮 (5 5～ 70 )× 10 -6。A +C类非金属夹杂级别为1 0～ 2 5。LZ5 0钢 84 0℃正火处理后的机械性能为σs370～ 385MPa ,σb710～ 735MPa ,δ52 1%～ 2 3%。     

Nb-Ti微合金钢力学性能的预报模型

根据Nb Ti高强度低合金钢 (0 0 8%～ 0 11%C ,0 0 1%～ 0 0 4 %Nb ,0 0 1%～ 0 2 3%Ti)板材实际生产数据 ,采用多元逐步线性回归 ,得出钢板屈服强度σs(MPa)和抗拉强度σb(MPa)的数学模型 :σs=2 94 0 1Wc+74 7 89WNb+10 2 1 0 9WTi- 0 17Tc+5 95 99;σb=135 6 73WNb+136 1 39WTi- 0 0 1b - 1 6 9h +44 2 4 3(Wc,WNb,WTi为成分质量分数 / % ;Tc 为卷取温度 ;b为成品板宽 ;h为成品板厚 )。同时建立了BP神经网络预报模型 ,两种模型均具有较好的预报精度 ,神经网络预测值与实测值之间的相对误差小于± 10 %。     

氮对含钒20MnSi钢筋强化的影响

实验结果表明 ,在相同钒含量的情况下 ,0 .1 2 %V钢中增加约 1 0 0× 1 0 -6 的氮使钢的屈服强度 (σS)和抗张强度 (σb)分别提高 1 1 7.5MPa和 1 35MPa。钢中增氮后 ,改变了钒在钢中的分布 ,促进了细小V(C ,N)的析出 ,显著提高了钢的强度。因利用了廉价的氮元素 ,对σS 为 40 0MPa的Ⅲ级钢筋可节约钒 33.3%以上。     

Nb、Ti对高强度耐候钢组织和性能的影响

为模拟CSP(紧凑式带材生产)工艺，由实验室10kg真空感应炉冶炼后轧成6mm钢板，试验研究了Nb、Ti对成分(％)为0．060～0．076C，0．25～0．31Cu，0．45～0．56Cr，0．29～0．30Ni的400MPa和460MPa级高强度耐候钢组织和性能的影响。结果表明，含0．03％Ti钢σa和σb分别为450MPa和545MPa，含0．03％Nb、0．02％Ti钢σa和σb分别为550MPa和615MPa，不含Nb、Ti钢σa和σb仅为375MPa和480MPa。400MPa级耐候钢的组织为铁索体 少量珠光体，含Ti钢的主要析出物为CuS2(20～25nm)和TiN(80nm)，含Nb、Ti460MPa级钢的组织主要为粒状贝氏体，析出物CuS2和(NbTi)CN(30～60nm)，从而提高了钢的强度。     

执行GB/T1591-94生产中微合金化元素对力学性能的影响

研究了微合金化元素Nb、Ti对控轧低合金高强度结构钢力学性能的影响，建立了Nb(0．015％～0．070％)和Nb Ti(小于0．030％)微合金化低合金高强度结构钢σs、σb、δ5和如与屈服点碳当量之间的线性回归方程。结果表明，在执行GB／T1591-94生产中，σs提高47～74MPa，σb提高15-75MPa。但如δ5降低2．2％～5．8％。     

JT345耐大气腐蚀塔桅高强度结构钢的耐腐蚀性能

对JT345耐大气腐蚀塔桅结构钢(最大值％：0．16C，0．45Si，1．40Mn，0．035P，0．030S，0．4Cu，0．8Cr，0．02Nb)进行室内快速腐蚀、电化学腐蚀和室外大气曝晒腐蚀试验以及钢表面锈层分析。试验结果表明，JT345钢盐雾(0．5％NaCl，35℃)和干湿交替(0．3％NaCl 0．1g／LNa2SO4 0．1g／L Na2SO3，室温)年腐蚀速率均小于0．6mm，室外大气曝晒腐蚀速率为0．025～0．046mm/a，达到Corten A钢(％：0．10C，0．40Si，0．48Mn，0．094P，0．019S，0．52Cr，0．34Ni，0．32Cu)的实物水平。JT345钢的强度σb 630MPa，σa 465MPa，高于Corten A钢的强度(σb 495MPa，σa 345MPa，δ5 31％)，并具有良好的塑性(δ5 21％)。     

ZJ510L-B汽车用高强度热轧板的试制

珠钢150t电弧炉-LF(VD)-CSP(紧凑式带材生产)流程试生产的5～8mm ZJ510L-B(0．16C--1．22Mn)汽车用高强度热轧板的铁素体晶粒尺寸为6．0～9．2μm，带状组织为1．5～2．5级，强度极限σb562～610MPa，延伸率δ5 32．0％～38．6％。文中还分析和提出了带状组织的形成原因和改进措施。     

含锶钪2099型铝锂合金的晶间腐蚀和剥落腐蚀性能

采用维氏硬度计(HV)、金相显微镜(OM)和扫描电镜(SEM)显微分析技术,研究了一种锶钪复合微合金化2099型铝锂合金(其化学成分为:Al-2.57Cu-1.86Li-1.31Zn-0.420Mg-0.321Mn-0.0735Zr-0.0943Sr-0.0433Sc)的晶间腐蚀性能和剥落腐蚀性能。结果表明,该合金经均匀化退火处理(475℃×24 h)、热锻压变形加工处理(三次变形量均约为100%)、固溶处理(540℃×2 h)、冷水淬火(水温大约5℃)、T8时效处理(121℃×14 h+151℃×48 h)后,合金显微硬度值达到174.6 HV,比2024-T6合金(固溶处理500℃×2 h+时效处理191℃×12 h)高23.1%。合金具有良好的抗晶间腐蚀性能和抗剥落腐蚀性能,其抗腐蚀性能明显优于2024-T6合金。该合金Sr,Zr,Sc的复合微合金化作用(细化粗大第二相、抑制再结晶和晶粒长大),第二相分散、分布不连续,以及Zn的含量高,是合金抗腐蚀性能高的主要原因。研究结果还说明了微量复合添加对铝锂合金具有奇效微合金化作用的过渡族金属元素Sr,Sc,是得到抗腐蚀性能良好的铝锂合金的一种有效途径。     

Microstructures and Properties of Al-Zn-Mg-Cu-Zr Alloys with Minor Scandium

The microstructures of Al-Zn-Mg-Cu-Zr al- loys with minor Sc were studied by using optical microscope（OM）, scanning electron microscope （SEM） and transmission electron microscope（TEM）. The tensile mechanical properties and electric conductivity of the studied alloys under different treatment conditions were tested. The results show that adding minor Sc can greatly fines the grain size of the Al-Zn-Mg-Cu-Zr alloy ingots and obviously improves the tensile properties and electric conductivity of the alloys. The strengthening mechanism is considered as fine grain strengthening, sub-structure strengthening and dispersion strengthening by Al3 （Sc, Zr）.     

Corrosion Behavior of Welded Joints of Al-6Mg Alloy with Trace Scandium Addition

Al-6Mg alloy with trace Sc addition was prepared by means of melting-casting.The samples of the welded joints of Al-6Mg alloy with trace Sc addition were made by method of manual argon-arc welding.Neutral salt spray test was carried out by referring to GB/T10125-1997 and GB6384-1986 practice.Exfoliation testing was carried out in accordance with the method of Al-Mg alloy exfoliation corrosion test.The corrosion behaviors of the welded joints of AlMg alloy with high level of Mg and trace Sc addition were studied.The microstructures of the welded joints were observed by using optical microscope and transmission electron microscope.The corrosion resistance mechanism of the alloy was also involved.This work intended to determine if the welded joints of Al-6Mgalloy with trace Sc addition can have excellent corrosion resistance, when their strength are clearly improved.The results show that trace content of Sc refines the grains of alloys effectively, raises remarkably the corrosion resistance of the welded joints of Al-6Mg alloy with trace Sc addition.The corrosion resistance mechanisms are that there is free of continuous grain boundary precipitation or network which could be susceptible to corrosion in the microstructure of welded joints.     

Age Hardening Behavior and Corresponding Microstructure of Dilute Al-Er-Zr Alloys

The age hardening and the microstructure of dilute Al-Er-Zr alloys were investigated by microhardness tests and TEM. The Al-0.04Er alloy shows a conventional age hardening behavior and obtains a maximum hardness of 410 MPa after aging for 2 h at 523 K (250 °C) due to precipitation of Al₃Er. The addition of Zr to Al-Er alloy can slow down the growth of the precipitates and make the age hardening effect remain for a long time in Al-0.04Er-0.04Zr alloy. Addition of Zr retards the decomposition of Al-Er and the Al-0.04Er-0.08Zr alloy can reach higher peak hardness than that of Al-0.04Er after aging for long time at elevated temperature. The precipitation behavior of Al-Er-Zr system is likely to be a new commercial way to developing creep-resistant aluminum alloy.     

时效对超高强含钪铝合金组织和性能的影响

采用维氏硬度测量、室温拉伸性能测试和显微组织结构分析,研究了不同时效制度下Al-Zn-Cu-Mg-Sc-Zr合金的力学性能、腐蚀性能和显微组织。结果表明,合金具有显著的时效硬化效应,随时效温度的升高,合金达到时效硬度峰值的时间缩短。合金适宜的时效制度为120℃/24 h。此时,合金的抗拉强度、屈服强度、伸长率和维氏硬度分别为696 MPa、654 MPa、11.1%和211.2 HV。合金中主要强化相为GP区和η′相,主要强化作用为沉淀强化及弥散强化。时效过程中Al3Sc和Al3(Sc,Zr)质点表现出较强的热稳定性;合金抗晶间腐蚀能力随时效时间的延长而增强。     

Al-Sc-Zr master alloy and estimation of its modifying capacity

An Al-1.1 Sc-1.1 Zr (wt %) master alloy with a uniform distribution of micron and submicron particles of aluminide phase Al₃(Sc_{1 − x} Zr _x ) has been obtained by exposing of equal amounts of commercial Al-Sc and Al-Zr master alloys to short-time actions of low-frequency vibrations transferred to the alloy via an irradiating plunger. Zirconium substitutes up to 50% Sc in aluminides and retains its L1₂ lattice. The modifying capacity of the experimental master alloy is tested on cast alloy (wt %) Al-8Zn-2.4Cu-3Mg. Intense grain refinement of this alloy is achieved by its modification with a certain amount of the master alloy. At a certain Sc + Zr content, a grain dendrite structure completely disappears in the alloy.     

Sc对7056铝合金组织和性能的影响

对铸态合金进行了均匀化处理、挤压、固溶处理和时效处理，通过分析合金的化学成分，观察合金在不同状态的显微组织及析出相透射电镜(TEM)形貌，测试合金在热处理后的硬度和拉伸性能，研究了向7056铝合金中加入质量分数0.2%的Sc对合金组织和性能的影响.实验结果表明，Sc元素的加入可以明显细化组织晶粒，铸态晶粒由100~500 μm下降到50 μm左右；Sc元素的加入对合金的塑性有大幅度提高，时效处理后，合金的断后伸长率从10.82%增加到了13.60%；但屈服强度却由668 MPa下降到657 MPa.通过综合计算晶粒大小、析出相强化等因素，详细分析了Sc元素加入引起7056铝合金峰时效态屈服强度下降的原因.理论计算显示，向合金中加入质量分数0.2%的Sc元素时，峰时效处理后，合金的强度值会下降12.005 MPa，与试验值11 MPa接近.研究得到7056铝合金最佳的单级时效制度为120℃+16 h，峰值硬度和强度为195.2 HV和714 MPa，此时合金中主要强化相为圆盘状和短棒状的MgZn₂相，大小约为4~6 nm，同时存在球状的Al₃Zr相，大小约为20 nm.      

Mg-xZn-1Mn镁合金均匀化热处理及扩散动力学研究

采用光学显微镜、扫描电镜、能谱分析、X射线衍射、布氏硬度测试等材料方法,研究了新型变形镁合金Mg-xZn-1Mn(x=4%,5%,6%,质量分数)的铸态合金以及均匀化热处理T4和时效处理T6后合金的显微组织、成分以及硬度的演变规律,建立ZM合金的热处理制度。并以空位扩散机制为基础,研究均匀化扩散动力学过程,建立ZM合金的均匀化扩散方程。结果表明:在ZM系列合金中,铸态组织枝晶偏析严重,晶界上有许多粗大的Mg-Zn共晶组织,Mn主要以单质形式存在于合金中。随着Zn含量的增加,合金的化合物体积分数增加,枝晶明显细化。得出3种合金合理的均匀化处理工艺分别是:ZM41为370℃×12 h;ZM51为390℃×12 h;ZM61为390℃×20 h。随着Zn含量的增加,热处理的温度和时间增加。在均匀化过程中,随均匀化处理温度提高,均匀化程度越高,时效硬化效果越好。经均匀化热处理后,大部分的Mg7Zn3相溶入基体。通过扩散动力学计算得到ZM41合金的均匀化处理温度与时间的关系为0.0008/t=exp(- 1160T9.5/T),570 K相似文献   

Effect of alloying by transitional refractory metals on the microstructure and thermal stability of Al–5Zn–3Mg alloys

Abstract

The effect of additions of transitional refractory metals on the structure and properties of Al–Zn–Mg alloys, made by ingot and PM routes, was investigated. The strength of the ingot alloys especially is increased by scandium and zirconium. The modifying action of scandium inhibits recrystallisation and precipitation of the fine-grained coherent Al₃(Sc_1–xZr_x) phase. The effect is weaker in PM alloys where the ultra-high cooling rate during high pressure water atomisation produces the fine-grained structure. PM semi-products of the base composition Al–5Zn–3Mg and alloys without scandium are not recrystallised during heating to 500°C, whereas cast alloys of similar composition recrystallised on the hot extrusion stage at 400–450°C. Of the Sc alloys, Al–5Zn–3Mg–0·5Mn–0·7Zr–0·3Sc showed the highest strength (UTS?=?651 MPa, YS?=?596 MPa), whereas of the PM alloys without scandium Al–5Zn–3Mg–0·85Zr–0·22Cr–0·17Ni–0·15Ti alloy showed UTS?=?618 MPa and YS?=?553 MPa. At melt cooling rates of 10⁵–10⁶ K s^–1 the total content of transitional refractory metals must not exceed 1·5–1·7 wt-% and total content (Zn+Mg) should be <8 wt-% at a Zn/Mg ratio of 5:3.     

Effect of squeeze casting process on microstructures and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy

The effects of squeeze casting process on microstructure and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy were investigated and the hot-compression tests of gravity casting and squeeze casting alloy were carried out at 350-500°C and 0.001-5s-1.The results show that microstructures of Al-17.5Si-4Cu-0.5Mg alloys were obviously improved by squeeze casting.Due to the decrease of coarse primary Si particles,softα-Al dendrite as well as the fine microstructures appeared,and the mechanical properties of squeeze casting alloys were improved.However,when the strain rate rises or the deformation temperature decreases,the flow stress increases and it was proved that the alloy is a positive strain rate sensitive material.It was deduced that compared with the gravity casting alloy,squeeze casting alloy(solidified at 632 MPa)is more difficult to deform since the flow stress of squeeze casting alloy is higher than that of gravity casting alloy when the deformation temperature exceeds 400°C.Flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy can be described by a hyperbolic sine form with Zener-Hollomon parameter,and the average hot deformation activation energy Q of gravity casting alloy and squeeze casting alloy is 278.97 and 308.77kJ/mol,respectively.