Temperature-Dependent SRS Behavior of 316L and Its Constitutive Model

The strain rate sensitivity(SRS) and temperature sensitivity(TS) of 316 L austenitic stainless steel were investigated by constant strain rate test(CSRT) and strain rate jump test(SRJT) under four temperatures(293, 373, 473 and 573 K) and four strain rates(5 9 10-4/s, 1 9 10~(-3)/s, 5 9 10~(-3)/s and 1 9 10~(-2)/s). The results show that temperature sensitivity(TS)indexes at different strain rates are coincidence to be negative, related to temperature softening. On the contrary, SRS indexes change from positive to negative with the increase in temperature associated with dynamic strain aging(DSA).Moreover, based on the comparison between CSRT and SRJT, SRS and TS indexes obtained by two methods agree well. It proves that the SRJT can describe the SRS and TS phenomenon of 316 L efficiently. Furthermore, the effects of temperature and strain rate on fracture mechanism were discussed. At last, an improved Johnson–Cook model was proposed to consider the temperature-dependent SRS behavior of 316 L.     

Layer Thickness-Dependent Hardness and Strain Rate Sensitivity of Cu–Al/Al Nanostructured Multilayers

Cu–Al/Al nanostructured metallic multilayers with Al layer thickness hAlvarying from 5 to 100 nm were prepared, and their mechanical properties and deformation behaviors were studied by nanoindentation testing. The results showed that the hardness increased drastically with decreasing hAldown to about 20 nm, whereafter the hardness reached a plateau that approaches the hardness of the alloyed Cu–Al monolithic thin films. The strain rate sensitivity(SRS, m),however, decreased monotonically with reducing hAl. The layer thickness-dependent strengthening mechanisms were discussed, and it was revealed that the alloyed Cu–Al nanolayers dominated at hAlB 20 nm, while the crystalline Al nanolayers dominated at hAl[ 20 nm. The plastic deformation was mainly related to the ductile Al nanolayers, which was responsible for the monotonic evolution of SRS with hAl. In addition, the hAl-dependent hardness and SRS were quantitatively modeled in light of the strengthening mechanisms at different length scales.     

日本铝材巨头UACJ拟收购美国汽车铝架制造商SRS

正据报道,日本铝生产商UACJ计划收购一家美国的汽车铝架制造商,希望借此开发北美市场。根据一项协议,UACJ将在5月底前以1.55亿美元的价格收购美国铝架制造商SRS Industries。SRS在美国和     

废旧锌锰电池回收利用的研究现状

废锌锰电池中含有汞、镉、锌、铜、锰等重金属，随意丢弃，会对环境造成污染，也导致金属资源浪费。我国每年报废50万吨废锌锰电池，若能全部回收利用，可再生锰11万吨、锌7万吨、铜1.4万吨，是相当可观的资源。     

异质金属界面超声波检测

异质金属熔合和粘合时,若基体表面有锈蚀、油污或其它杂质,会直接影响熔合的效果,可产生气孔、灰渣;若基体和异质金属在浇注过程中温度不够,则结果会造成粘合处脱壳.为了保证熔合的质量,采用超声波方法检测,简单而有效.为避免带有这种缺陷的异质金属,本文介绍发电机组轴瓦(巴氏合金-钢熔合)或电动机车电机的电极(银-铜熔合)等在工业上应用中的检测方法.     

ASTM 4145H钢冲击功偏低的原因分析

ASTM 4145H钢中,若Sn元素含量较高会明显影响钢材的力学性能,造成冲击功严重偏低。     

缓蚀剂化学

1、前言防止金属腐蚀的方法有多种,而使用缓蚀剂即是其中之一.例如过去在内燃机的冷却系统中添加三乙醇胺和2-巯基苯骈噻唑.前者对于铁,后者对于铜系金属有缓蚀效果.若没有使用这类缓蚀剂,铁除了由于溶解的氧及碳酸气造成的腐蚀     

废钢加工处理过程中二次污染的产生及防治途径

随着我国工业化进程的快速发展，越来越多的复合型钢铁制品被报废和淘汰，这些废钢铁经过回收利用可回炉炼钢，循环使用。但在此过程中，若处理不当、控制不严，会造成二次污染。通过改革废钢铁回收加工体系，提高装备水平和对二次污染的控制能力，进而加强对夹杂物资源化转变的研究和开发，实现“零排放”，走科学发展的道路，这是新时期政府部门、相关行业和企业应当关注和研究的新课题。     

Continuously extending extrusion forming of semisolid A2017 alloy by SRS process

A self-made single-roll stirring (SRS) machine was used to manufacture semisolid A2017 alloy, the mechanismof A2017 alloy formation was investigated. It was shown that A2017 dendrites growing on the rough roll surface arecrashed into fragments by the roll, which move and grow freely then contribute the formation of finer spherical microstruc-ture. When casting at 710-750 ℃, fine and homogeneous spherical or elliptical grains of A2017 alloy were obtained. Ex-tending forming mould has been designed and was installed at the exit of roll-shoe gap. A2017 alloy was formed by ex-tending continuously at the semisolid state on SRS machine. Through controlling pouring temperature, semisolid formingand extending extrusion was combined organically. A2017 product with fine surface and rectangular transection of 14mmx25 mm was obtained. By contrast to the national standard, the fracture strength and elongation of A2017 products pro-duced from extending semisolid extrusion have been improved with an increase of 100 MP     

Quantitative analysis of work hardening and dynamic softening behaviors of Cu-6 wt pct Ag binary alloy based on true stress vs strain curves

The work hardening and dynamic softening behaviors of Cu-6 wt pct Ag binary alloy were studied by hot compression tests under temperature range of 700-850℃ at strain rates of 0.01-10s-1.The critical conditions for the onset of dynamic recrystallization (DRX) were determined based on the conventional strain hardening rate curves (dσ/dε versus σ).The progress of DRX was analyzed by constructing a model of volume fraction of DRX based on flow curves.The strain rate sensitivity (SRS) and activation volume V were calculated.The results show that the DRX almost can happen under all deformation conditions even at high Z deformations where dynamic recovery (DRV) is the main softening mechanism.The DRX fraction curves can well predict the DRX behavior.The strain has significant effects on SRS at the strain rates of 0.01s-1 and 10s-1 which are mainly due to off-equilibrium saturation of dislocation storage and annihilation while the effects of the temperature on the SRS are based on the uniformity of microstructure distribution.The formation of "forest" of dislocation is contributed to the low activation volume V*(about 168b3) which is independent of Z values at the initial deformation.The cross-slip due to dislocation piled up beyond the grain boundaries or obstacles is related to the low activation volume under the high Z deformation conditions at high strain (ε=0.6) while the fine DRX grains coarsed is the main reason for the high activation volume at low Z under the same strain conditions.