Effect of prestrain on the mechanical properties of eutectoid steel

This investigation was designed to study the effect of prior compressive deformation and temperature on the subsequent dynamic fracture toughness, K,_Id, of fully pearlitic 1080 rail steel. Charpy instrumented impact tests on precracked specimens were performed at room temperature at a variety of prior strain levels from 0 to 20 pct. In addition, transition temperature tests were performed on specimens of zero, low (5 to 10 pct), and high (15 to 20 pct) prior strains. Dynamic fracture toughness (K,_Id) and energy absorbed per fractured area (W/A) were obtained from instrumented impact data. It was found that, at room temperature, compressive strain had no effect on either K_Id or W/A. In the transition temperature range, W/A decreased with increasing prior strain, while there was no effect on K_Id. At temperatures in the upper shelf region, prior strain decreased both K,_Id and W/A. There was no effect on the transition temperature as the amount of prior strain was increased. Thus, while both dynamic fracture toughness and impact properties can be significantly changed by varying temperature, cold working the material has at best a modest effect on impact energy and then primarily only in the upper shelf region.     

钢材力学性能不确定度的评定

通过对上海申力公司1000kN拉力试验机测定钢筋力学性能的不确定度的来源进行分析,并对测定结果的不确定度进行评定。     

Regulating the mechanical properties of IF titanium steel

The influence of technological processes (smelting, hot and cold rolling, and recrystallizational annealing) on the mechanical properties of steel (yield point) is considered. A mathematical approach is outlined to the influence of the C, S, N, and Ti content in the steel, the hot-rolling conditions (T _ro, T _f , T _co, D), the cold-rolling conditions (relative reduction), and the recrystallizational-annealing conditions (grain size d) on the mechanical properties. Applications of this mathematical framework to regulation of steel quality are explored.     

含铝TRIP钢组织和性能的研究

根据镀锌工艺要求设计ω(Al)为1.2%的TRIP钢进行实验研究,使用光学显微镜、SEM、XRD以及拉伸试验对TRIP钢的微观组织和性能进行检测和分析.结果表明,ω(Al)为1.2%的TRIP钢的Ac1达到747℃、Ac3达到930℃,在贝氏体区等温30 s即可得到最大强塑积.实验TRIP钢退火组织中残留奥氏体体积分数...     

Effect of silicon additions on the mechanical properties of eutectoid steel

Tensile, impact and fatigue strengths of 0%, 2% and 4% silicon steels of eutectoid compositions have been determined using standard testing methods. Tensile and impact strengths tests show an increase in brittleness (loss in elongation) and an increase in yield point, tensile strength and fatigue strength due to Si additions.     

Influence of scale removal on the mechanical properties of low-carbon steel

The influence of heat treatment and of the acidic and mechanical removal of rolling scale on the variation in mechanical properties of 1kp low-carbon steel wire rod is investigated.     

304H钢高温力学性能试验研究

采用不同温度的高温拉伸、冲击试验,对比经历3种不同热状态的304H钢的高温力学性能,并通过固溶处理前后的微观组织的对比,对其高温力学性能进行了分析。     

高碳钢高温力学性能研究

在Gleeble-2000动态热模拟试验机上采用凝固法研究了高碳钢的高温力学性能.测定了tZD(零塑性温度)、tZS(零强度温度).在4×10-4/s应变速率条件下,所测钢种在熔点到750 ℃范围存在两个脆性温度区域,即熔点到1 300 ℃的第Ⅰ脆性温度区域和750～925 ℃的第Ⅲ脆性温度区域.在第Ⅲ脆性温度区域,γ单相AIN、NbN等氮化物在γ晶界的析出和在γ α两相区先共析α相呈网膜状,在γ晶界的析出是造成钢脆化的主要原因.通过控制钢中氮、铝含量,以及采用合理的冷却方式可以提高钢种的内在质量.     

热处理对TRIP 590钢微观组织及力学性能的影响

采用Gleeble3800热模拟机对TRIP钢拉伸试样进行不同工艺条件的快速热处理模拟实验,并采用金相分析、显微硬度测试等方法对试样进行组织观察和性能测试,目的是通过适宜的热处理工艺促使材料微观组织中出现适量的残余奥氏体组织,增强该材料在变形过程的相变诱导塑性(TRIP)效应,强化材料结果表明:在两相区内,TRIP钢中的残余奥氏体含量随着退火温度和退火时间的增加而增大,以25℃/s缓慢加热到700℃,再以150℃/s的速率快速加热到820℃保温120s后淬火处理,处理后的试样,残余奥氏体体积分数达到13％,显微硬度最高,达到262HV.     

Variation of mechanical properties in large steel forgings

In a continuing effort to reduce mechanical property variation in large, low alloy, steel forgings, the effects of forging reduction on mechanical and metallurgical properties were examined. This included tensile strength, ductility, impact energy and fracture toughness. Also examined were nonmetallic inclusion content and microstructure. In addition, the consequences of ingot solidification could not be ignored, therefore, the aspect of chemical homogeneity was considered. For these ingots and the range of forging reductions investigated (1.5:1 to 10:1), a reduction of approximately 3:1 produced optimum values in pct reduction of area, Charpy impact energy, and plane strain fracture toughness. The significant variations statistically determined in these parameters were accompanied by real variation in carbon concentration. Therefore, segregation of carbon on a macro scale was shown to be a major contributor to mechanical property variation in large steel forgings produced from statically cast ingots. Indeed, mechanical working alters segregation patterns but will not eliminate them.     

Recrystallization and mechanical properties of microalloyed cold-rolled steel

Cold-rolled microalloyed steels have proven themselves in many applications. Here microalloying fulfills different metallurgical functions that can be used to produce high-strength or very mild deep-drawing steels. This article studies the recrystallization behaviour of microalloyed steels during anneals performed in the laboratory and in the production shop. The delay in recrystallization compared with unalloyed steels can be explained by the amount and distribution of precipitated carbonitrides and also by dissolved microalloying elements. The mechanical properties of the cold-rolled, high-strength steels are determined mainly by grain refinement and, depending upon the annealing process, to a smaller extent by precipitation hardening. With complete fixation of all the interstitial atoms and, at the same time, minimization of the amount of precipitates very mild special deep-drawing steels can be made.     

Study on the mechanical properties and service life of H13 mandrels

The microstructures and mechanical properties of H13 mandrels made by Baosteel and foreign companies were investigated in this study.Based on the comparison research,the processes were optimized,such as steelmaking,heat treatment and multiple forging processes.The quality of Baosteel mandrels was greatly improved by increasing the homogenizing of an annealing temperature and refining processes.The results of the pilot trial showed that the average number of piercing steel tubes for Baosteel mandrels was over 3000,which reached the level of imported mandrels.     

合金元素对马氏体时效强化不锈钢力学性能的影响

探讨了合金元素对马氏体时效不锈钢各项力学性能的影响规律,结果表明：影响强度和硬度的最主要合金元素是Ti,Cu是最有效的改善马氏体时效强化不锈钢的断裂韧性的合金元素,合金元素Ni和Mo对强度、硬度以及韧性的影响不是很大。并在此基础上进一步优化了马氏体时效不锈钢的合金成分,该成分的合金钢具有超高强度（Rm=1610MPa）的同时保持了高韧性（KIC=94MPa·m1／2）,达到了超高强度高韧性合金钢的标准。     

热处理工艺对建筑用PC钢棒强韧性的影响

对PC钢棒淬火、回火的热处理工艺、强韧性及其组织和性能的关系进行了系统研究,发现屈强比主要受到淬火温度的影响,当回火温度控制在440－460℃时,能使强度和塑性达到最佳值。尽管在960－1000℃的温度区间淬火屈强比较低,但可以获得较细的显微组织。     

Influence of pipe processing on the mechanical properties of K60 steel sheet

The mechanical properties of thick steel sheet (13?C27 mm) produced at PAO MK Azovstal?? and the basic metal in K60 pipe (diameter 1220 mm) for the VSTO pipeline manufactured at PAO Khartsyzskii Trubnyi Zavod are subjected to statistical analysis, so as to establish the variation in the mechanical properties of the steel as a function of the sheet thickness and the wall thickness of the pipe and also under the influence of pipe processing.     

Effect of thermal cycling on the mechanical properties of 350-grade maraging steel

The effects of retained austenite produced by thermal cycling on the mechanical properties of a precipitation-hardened 350-grade commercial maraging steel were examined. The presence of retained austenite caused decreases in the yield strength (YS) and ultimate tensile strength (UTS) and effected a significant increase in the tensile ductility. Increased impact toughness was also produced by this treatment. The mechanical stability of retained austenite was evaluated by tension and impact tests at subambient temperatures. A deformation-induced transformation of the austenite was manifested as load drops on the load-elongation plots at subzero temperatures. This transformation imparts excellent low-temperature ductility to the material. A wide range of strength, ductility, and toughness can be obtained by subjecting the steel to thermal cycling before the precipitation-hardening treatment.