XCQ16-1车桥用钢调质热处理工艺的研究

为了提高整体式车桥用钢的综合力学性能,对XCQ16-1钢进行了调质热处理工艺研究.通过材料单向拉伸、冲击和硬度等试验,研究了不同回火温度、回火保温时间、淬火温度和淬火保温时间对XCQ16-1钢力学性能的影响规律,制定了试验条件下的调质热处理工艺,并分析了不同工艺参数对材料组织的影响规律.试验结果表明:回火工艺对XCQ16-1钢组织和力学性能的影响比较大,随回火温度的升高和回火保温时间的延长,材料的强度性能下降,塑性和韧性指标上升.经860℃保温30min淬火+470℃保温90min回火调质处理后,该材料可获得良好的综合性能.     

连铸10MnNiCrMoV钢中板火工工艺对钢板力学性能及微观组织的影响

连铸10MnNiCrMoV钢中板在不同条件下进行火工工艺处理,通过分析钢板处理后的力学性能和微观结构,深入研究该钢板的火工工艺适应性,结果表明,火工后产生的孪晶马氏体是影响钢板火工工艺适应性的主要原因。     

船用921A钢高温、高应变率下动态本构模型研究EI北大核心CSCD

921A钢是我国重要的舰船结构钢,研究921A钢在高温、高应变率条件下的动态力学性能对舰船结构防护设计和安全评估具有重要意义。采用电子万能试验机和带有同步组装系统的高温Hopkinson压杆试验装置,对921A钢在不同温度(25~500℃)、不同应变率(0.001~4000 s^(-1))下的准静态和动态力学性能进行了研究。结果表明,921A钢具有明显的应变率强化效应和热软化效应,应变率强化效应随温度升高逐渐减弱,热软化效应对应变率变化不敏感。考虑了应变、应变率和温度对力学性能的影响,拟合得到了921A钢的Johnson-Cook本构模型参数。开展了弹体高速撞击双层921A钢板的试验,并采用得到的Johnson-Cook本构模型参数进行了数值仿真,靶板弹孔平均直径和破坏形貌的仿真结果与试验结果吻合较好,验证了该模型能够较好地描述921A钢在高速冲击条件下的动态力学行为。     

10MnNiCrMoV钢宽板拉伸试验研究

本文通过对10MnNiCrMoV钢板宽板拉伸试验,研究了10MnNiCrMoV钢板在低温环境条件的防断及止裂性能。     

舰船模型水下爆炸应力应变试验研究

通过工程试验研究,观测并计算了水下爆炸引起的舰船模型应力应变现象。根据舰船材料强度理论、分析试验结果,总结了舰船模型应力应变受水下爆炸冲击的变化规律,指出舰船模型底板的应力应变与舰船底板的结构尺寸有关。试验给出了水下爆炸时舰船模型的应变数值和应力计算结果,以及舰船模型底板沿短边方向产生最大的应力与应变。     

舰船模型水下爆炸应力应变试验研究

通过工程试验研究,观测并计算了水下爆炸引起的舰船模型应力应变现象。根据舰船材料强度理论、分析试验结果,总结了舰船模型应力应变受水下爆炸冲击的变化规律,指出舰船模型底板的应力应变与舰船底板的结构尺寸有关。试验给出了水下爆炸时舰船模型的应变数值和应力计算结果,以及舰船模型底板沿短边方向产生最大的应力与应变。     

回火温度对1500MPa级Nb-Ti低合金直接淬火钢组织与性能的影响

通过低成本成分设计,在控制轧制的基础上,应用直接淬火+回火工艺制得抗拉强度1 500 MPa级经济型低合金高强高韧钢,测定了该合金成分体系的连续冷却转变曲线,研究了不同回火温度对直接淬火钢组织与力学性能的影响.结果表明:随着回火温度的升高,试验钢抗拉强度逐渐下降,屈服强度先升高后降低,-40℃冲击功则呈现出先升高、后降低、再升高的趋势.回火温度为200℃时,试验钢获得了最优的综合力学性能,抗拉强度达到1 730 MPa,屈服强度为1 400 MPa,-40℃冲击功为43 J.     

电弧增材制造舰船用高强钢10CrNi_3MoV的组织及性能

采用电弧增材制造技术制备了舰船用高强钢10CrNi_3MoV试样。分析和评价了10CrNi_3MoV舰船用高强钢电弧增材制造试样的物相组成、显微组织结构、晶体结构和力学性能。通过对10CrNi_3MoV高强钢电弧增材制造试样的组织及性能研究发现:采用电弧增材制造技术制备的10CrNi_3MoV舰船高强钢试样成形质量良好,未出现较大的缺陷,试样内部冶金结合良好,金相组织主要为针状铁素体、块状铁素体和粒状贝氏体;试样截面显微硬度分布较均匀,平均显微硬度约为217HV_(0.2)。试样的力学性能优良,横向平均屈服强度为498MPa,平均抗拉强度为676MPa,平均伸长率为25.5%,-40℃时夏比冲击值为127J;纵向平均屈服强度为459MPa,平均抗拉强度为648MPa,平均伸长率为23.5%,-40℃夏比冲击值为109J。     

舰船浮筏隔振装置DDAM抗冲击计算

简叙舰船设备抗冲击设计方法,对美国海军动力学分析方法（DDAM）进行详细介绍。应用ANSYS软件对浮筏实验装置建模并进行模态分析,同时通过自编程序计算实验装置的固有频率,有限元的计算结果与由程序计算结果在前12阶模态频率基本一致,可以认为所建有限元模型的总刚度、质量分布与实际模型较为接近。并且根据美国舰船结构设计军规DDS100-7的冲击设计值,按照DDAM方法的要求对所建模型进行冲击设计分析,计算方法可用于海军舰船设备的冲击设计分析。     

单层隔振系统中塑性限位器应用设计

提出舰船单层隔振系统中采用以聚氨酯泡沫为材料的限位器进行设备限位,研究塑性限位器各参数对舰船设备最大加速度和最大相对位移这两个重要指标的影响,提出确定限位器参数理论方法,采用Matlab软件将塑性限位器理论量化方法和设计计算程序用于单层隔振系统模型,并进行冲击实验,证明该理论方法的正确性。     

工程结构用钢温度转变特性的表征及其应用

根据冲击吸收功－温度转变曲线的特点，选定了一种表征该曲线的数学模型，分析了该数学模型的物理意义，验证了用该数学模型描述单组船体钢及桥梁钢韧脆转变过程的可能性。结果表明，该数学模型在拟合系列温度的冲击试验数据时有很好的相关性。在建立指定钢种多批号的冲击吸收功－温度的统计关系时，通过适当的坐标变换进行曲线拟合，该模型也是可行和可靠的。     

10Ni5CrMoV钢低温冲击断裂行为研究

采用示波冲击试验方法，研究了１０Ｎｉ５ＣｒＭｏＶ钢在冲击断裂过程中各部分能量与温度的关系。在２０℃～－１００℃温度范围内，裂纹形成功（Ｅｉ）基本不变，裂纹扩展功（Ｅｐ）显示与总冲击功相一致的转变特征。在上平台，１０Ｎｉ５ＣｒＭｏＶ钢具有高的裂纹扩展功，Ｅｐ＞１００Ｊ；在转折区，钢的韧脆转变平缓。试验结果表明，Ｅｐ＝Ｅｉ对应的温度可作为韧脆转折温度。本试验钢的韧脆转折温度低达－８５℃，具有优良的低温韧性。     

冷处理温度对CF62C低合金高强度钢冲击性能的影响

在-50℃至室温范围的不同温度对CF62C低合金高强度钢进行冷处理,将冷处理试样和室温下的试样进行夏比(V型)冲击试验,并对冲击试样进行冲击吸收能量测试和显微组织、断口形貌的分析。研究结果表明:CF62C钢在室温和0~-40℃的冷处理条件下有良好的低温冲击韧度,在-40℃冲击吸收功大于300J,而冷处理温度下降至-50℃时,冲击吸收功小于135J,且其断口微观特征呈沿晶脆性断口;CF62C钢的脆性转变温度为-50℃。     

10CrNi3MoV钢的韧性研究

采用夏比冲击、裂纹源落锤和动态撕裂试验，研究了１０ＣｒＮｉ３ＭｏＶ钢的低温韧性，对韧性较高的原因也进行了分析讨论。结果表明：冲击曲线的上平台转变温度在－２０℃以下，韧脆转变温度ＥＴＴ５０和ＦＡＴＴ５０在－１１０℃以下；ＴＮＤＴ低于－７０℃，－４０℃的动态撕裂能在１０００Ｊ以上。     

The effect of the grain size of the ferritic-pearlitic steel 45 on the parameters of its fracture under impact loading

The article investigates the influence of the grain size of the ferritic-pearlitic steel 45 with standard composition in the range 2–50 Μm on the parameters of the energy of crack nucleation and propagation in the process of impact loading in the temperature range from ?100 to +150?C. It is shown that reduction of the grain size from 50 to 2 Μm has no effect on the fracture energy and on the “true” specific values of impact toughness at temperatures inducing completely brittle or ductile fracture, and that it increases the fracture energy and KCV_tru solely in the region of temperatures of the viscobrittle transition. Dissipation of the fracture energy expanded on the nucleation of secondary cracks and microcracks has no significant effect on the KCV_tru of the steel in all the examined ranges of grain sizes and temperatures. The article notes the structural insensitivity of the process of crack and microcrack nucleation in steel 45 under dynamic loading.     

440MPa级10MnNiCrMoV钢板裂纹分析

采用金相显微镜、扫描电镜及能谱仪等分析设备,研究了440MPa级10MnNiCrMoV钢板裂纹产生的原因.结果表明,裂纹附近钢板组织、硬度与基体相同,而裂纹表面存在大量氧化物,可断定该缺陷来源于连铸坯端部的某种缺陷,通过轧制经延展形成.     

Effect of pearlite morphology on impact toughness of eutectoid steel containing vanadium

Abstract

The effect of a change in the morphology of the pearlite colonies on the Charpy impact energy of a fully pearlitic steel containing 0·76%C, 1·20%Mn, and 0·085% V was examined over the range of testing temperatures from ?50 to 200°C. The change from a multicolony nodular pearlite structure produced from austenite of grain size 185 μm to a structure composed of individually formed colonies produced from austenite of grain size 25 μm caused a decrease in the transition temperature of 75 K and an almost 100% increase in the Charpy impact energy measured at room temperature. It is proposed that the impact toughness of pearlitic steel can be affected by pearlite morphology, at constant interlamellar spacing, only at temperatures above the ductile–brittle transition temperature of the ferrite, when local plastic deformation in the pearlitic ferrite at high angle boundaries can arrest propagating brittle cracks.

MST/730     

Application of decreased hot-rolling reduction treatments for improved mechanical properties of quenched and highly-tempered low alloy structural steels

Decreased hot-rolling reduction treatments from 98% = × 50 elongation to 80% = × 5 elongation, which modify the sulphide-inclusion shape from a stringer to an ellipse, have been applied to improve the mechanical properties of quenched and highly tempered low alloy structural steels. The decreased hot-rolling reduction treatments significantly increased the transverse fracture ductility at similar strengths and uniform elongation levels independent of the type of steel. The treatments also improved the transverse Charpy U-notch (CUN) impact energy independent of the type of steel. The effect of test temperature on CUN impact energy fell into two categories; (1) the treatments significantly improved transverse CUN impact energy in temperature regions which exhibited a ductile fracture mode, (2) the improvement in the mechanical properties was reduced when the temperature decreased and a brittle fracture mode appeared. The results are briefly discussed in terms of a model involving large voids initiated at sulphide-inclusion sites and local shear bands developed between the large voids.     

Impact behavior of different stainless steel weldments at low temperatures

A comparative study was made of the fracture behavior of austenitic and duplex stainless steel weldments at cryogenic temperatures by impact testing. The investigated materials were two austenitic (304L and 316L) and one duplex (2505) stainless steel weldments. Shielded metal arc welding (SMAW) and tungsten inert gas welding (TIG) were employed as joining techniques. Instrumented impact testing was performed between room and liquid nitrogen (?196 °C) test temperatures. The results showed a slight decrease in the impact energy of the 304L and 316L base metals with decreasing test temperature. However, their corresponding SMAW and TIG weld metals displayed much greater drop in their impact energy values. A remarkable decrease (higher than 95%) was observed for the duplex stainless steel base and weld metals impact energy with apparent ductile to brittle transition behavior. Examination of fracture surface of tested specimens revealed complete ductile fracture morphology for the austenitic base and weld metals characterized by wide and narrow deep and shallow dimples. On the contrary, the duplex stainless steel base and weld metals fracture surface displayed complete brittle fracture morphology with extended large and small stepped cleavage facets. The ductile and brittle fracture behavior of both austenitic and duplex stainless steels was supplemented by the instrumented load–time traces. The distinct variation in the behavior of the two stainless steel categories was discussed in light of the main parameters that control the deformation mechanisms of stainless steels at low temperatures; stacking fault energy, strain induced martensite transformation and delta ferrite phase deformation.