LC4高强铝合金的慢应变速率拉伸试验

采用慢应变速率拉伸 (SSRT)技术测试了LC4铝合金在空气和质量分数为 3.5 %的NaCl溶液中的应力腐蚀断裂 (SCC)行为 .研究了应变速率对铝合金SCC行为的影响和氢在LC4高强铝合金应力腐蚀断裂过程中的作用 .试验结果表明 ,LC4合金具有SCC敏感性 ,在潮湿空气中发生应力腐蚀断裂 ,而在干燥空气中不发生应力腐蚀断裂 .对于长横取向的LC4铝合金试样 ,在应变速率为 1.331× 10 6s 1时 ,其SCC敏感性比应变速率为 6 .6 5 5× 10 6s 1时的敏感性大 .在潮湿空气和阳极极化条件下 ,铝合金的应力腐蚀断裂机理是以阳极溶解为主 ,氢几乎不起作用 .在预渗氢或阴极极化条件下 ,氢脆起主要作用 ,预渗氢时间延长可加速LC4合金的应力腐蚀断裂 .     

45钢电镀锌-镍合金过程中的渗氢行为及其氢脆敏感性

目前,有关锌-镍合金电镀过程中氢脆问题的研究较少。采用双电解池测氢法研究了45钢在不同温度、电流密度、pH值下电镀锌-镍合金过程中的渗氢变化规律。通过慢应变速率拉伸试验法评价镀层氢脆性能,并用扫描电子显微镜(SEM)观察断口的微观形貌。结果表明:镀液温度对渗氢电流的影响最大,镀液温度越高,镀样断裂时间越短,氢脆敏感性越强;镀样的断裂时间小于空白样,说明镀样有不同程度的氢脆敏感性;镀样的断口呈解理断裂特征,空白样呈韧性断裂特征;用渗氢电流曲线可间接评价镀样的氢脆敏感性。     

不同环境下TiAl基金属间化合物的力学行为

研究了室温、473K和573K充氢前后Ti-49Al合金在不同应变速率下在真空、空气以及流动的氢气中的拉伸行为.结果表明,在5.6×10-6～2×10-4s-1应变速率范围内,Ti-49Al合金的力学行为没有明显的变化,但温度的影响很大.充氢样品中的内氢通过降低原子键合力来引起氢脆,而未充氢样品在流动的氢气中拉伸时,主要是由于氢引起了局部塑性变形而导致样品的脆性断裂.     

铁素体-粒状贝氏体型双相钢冷变形后的氢脆断裂行为

本实验采用阴极电解预充氢、慢应变速率拉伸的方法,研究了_(05)Si_2铁素体-粒状贝氏体双相钢经70%冷拔形变后的氢脆敏感性及断裂行为,并与_(05)Si_2铁素体-马氏体型。70%冷拔形变双相钢进行比较。发现冷拔铁素体-粒状贝氏体型双相钢的氢脆敏感性高于冷拔相同程度的铁素体-马氏体型双相钢,但由于原来的塑性较好,在充氢条件下仍有较好的塑性。铁素体-粒状贝氏体型冷拔双相钢在预充氢条件下拉伸时,微孔或裂纹在铁素体-粒状贝氏体相界面上形核,并沿着与外力约呈45°方向优先向粒状贝氏体-侧扩展。     

HYDROGEN EMBRITLEMENT OF COLD DRAWN FERRITE-GRANULAR BAINITE DUAL-PHASE STEEL

本实验采用阴极电解预充氢、慢应变速率拉伸的方法,研究了_(05)Si_2铁素体-粒状贝氏体双相钢经70%冷拔形变后的氢脆敏感性及断裂行为,并与_(05)Si_2铁素体-马氏体型。70%冷拔形变双相钢进行比较。发现冷拔铁素体-粒状贝氏体型双相钢的氢脆敏感性高于冷拔相同程度的铁素体-马氏体型双相钢,但由于原来的塑性较好,在充氢条件下仍有较好的塑性。铁素体-粒状贝氏体型冷拔双相钢在预充氢条件下拉伸时,微孔或裂纹在铁素体-粒状贝氏体相界面上形核,并沿着与外力约呈45°方向优先向粒状贝氏体-侧扩展。     

钛合金慢应变速率拉伸应力腐蚀行为研究

对TA31和TC4ELI两合金分别在干燥空气、3.5% NaCl环境下进行慢应变速率拉伸试验。结合应力-应变曲线以及断口宏观、微观组织分析两种材料的应力腐蚀敏感性。结果表明:在35℃、3.5%(w,下同) NaCl溶液、应变速率为10-6/s条件下,TC4ELI合金应力腐蚀敏感性较高,在5×10-7/s和5×10-6/s的应变速率下应力腐蚀敏感性较低;TA31合金在上述3种应变速率下应力腐蚀敏感性均较低;在3.5% NaCl环境中,TA31合金断口形貌较空气中试验的断口形貌无明显的变化,TC4ELI则出现较明显的解理面。      

不同热处理状态40Cr钢的氢脆敏感性判据

本文在选定的应变速率下．用ＳＳＲＴ法研究了不同热处理状态下４０Ｃｒ钢的氢脆（ＨＥ）敏感性，通过对渗氢试样在介质中与未渗氢的原始状态试样在空气中机械性能的比较，以及用扫描电镜分析断口，得到一些结论。     

16Mn钢在H2S溶液中的脆断敏感性

采用慢性变速率拉伸实验（ＳＳＲＴ）、扫描电镜及电化学渗氢技术研究了Ｈ２Ｓ浓度、电位对１６Ｍｎ钢在Ｈ２Ｓ溶液中脆断敏感性的影响，结果表明：１６Ｍｎ钢在Ｈ２Ｓ溶液中的断裂是一种氢脆控制的断裂，随Ｈ２Ｓ浓度（Ｎ）增大，应力腐蚀断裂的机理从韧性转变的脆性；１６Ｍｎ钢片在Ｈ２Ｓ溶液中的稳态渗氢电流值ＩＨ和Ｈ２Ｓ浓度（Ｎ）满足ＩＨ＝８．５２５×Ｎ＾０．７２４９；ＩＨ受温度的影响主要表现在氢在１６Ｎｎ钢中的扩散     

氢对低合金钢上不锈钢堆焊层性能的影响(英文)

本工作研究了高温高压氢 (35 0℃ ,2 5 MPa H2 ) ,对国产氢反应器壁 30 9L 和 34 7L 不锈钢堆焊层性能的影响 .结果表明 :未经热渗氢的原始试样 ,无论是光滑试样还是缺口试样 (除缺口开在 30 9L 区域试样外 ) ,均断裂在 34 7L 区域内 .而经热渗氢后 ,无论起裂于 2 (1/4 ) Cr- 1Mo和 30 9L 熔合线 ,还是 30 9L 和34 7L的熔合线处 ,最后都断在 30 9L区域内 .这是因为热渗氢使 30 9L和 34 7L的断裂应力 ,分别从 885 MPa降至 478MPa和从 799.9MPa降至 5 6 4MPa,它们的氢脆系数分别为 86 .8%和 80 .9% .SEM断口分析结果与上述结论一致     

海水中极化电位对X70钢氢脆敏感性的影响

为探索X70钢最大阴极保护电位,采用电化学测试和慢应变速率实验（SSRT）并结合断口扫描电镜观察,研究了低温低溶解氧和常温海水中阴极极化电位对X70钢氢脆敏感性的影响.结果表明：相对常温海水,X70钢在低温低溶解氧海水中的析氢电位正移;随阴极极化电位的负移,X70钢的最大抗拉强度、屈服强度增加且氢脆敏感性增加;在低温低...     

On the embrittlement of fracture toughness specimens of two high strength steels

Hydrogen embrittlement of two commercial materials, a 1$\text{1}\text{2}$ Ni-Cr-Mo steel and a 5 Cr-V-Mo steel both quenched and tempered to a nominal ilrength of 1.60 × 10³MN/m² has been studied. Frecture toughness testing was carried out on each steel in three conditions, (a) heat-treated and tested in air, (b) thermally charged with hydrogen and tested in air, and (c) uncharged and tested a an atmosphere of dry hydrogen. The effects of hydrogen pressure and loading rate on embrittlement were examined. The experimental results show that thermal charging had a greater embrittling effect on the 1$\text{1}\text{2}$ Ni-Cr-Mo steel than on the 5 Cr-V-Mo steel although the latter had a higher hydrogen concentration. In a hydrogen environment the 1$\text{1}\text{2}$ Ni-Cr-Mo steel was much more sensitive to embrittlement than the 5 Cr-V-Mo steel.     

Tensile behaviour of type 304 austenitic stainless steels in hydrogen atmosphere at low temperatures

Abstract

The tensile behaviour of solution annealed type 304L, solution annealed type 304, and solution annealed and sensitised type 304 stainless steels was investigated in hydrogen and helium under a pressure of 1·1 MPa over the temperature range 300–80 K at strain rates ranging from 4·2×10^-5 to 4·2×10^-2 s^-1. For 304L steel, hydrogen environment embrittlement (HEE) increased with decreasing strain rate. For 304L and 304 steels, HEE increased with decreasing temperature, reached a maximum, and then decreased with further decrease in temperature: the decrease was particularly rapid near the minimum temperature for HEE. Sensitisation enhanced the HEE of 304 steel. Above the maximum HEE temperature, the HEE behaviour was similar to the hydrogen embrittlement behaviour of materials in previous studies, but near the minimum temperature for HEE it was different. Three types of hydrogen induced brittle fracture were observed as a result of HEE: transgranular fracture along strain induced martensite laths and twin boundary fracture on the fracture surfaces of solution annealed 304L and 304 steels, and grain boundary fracture on the sensitised 304 steel. It was found that from room temperature to the maximum HEE temperature, the HEE of the materials depended on the transformation of strain induced martensite and below the maximum HEE temperature it depended on the diffusion of hydrogen.     

Effects of hydrogen on the mechanical response of X80 pipeline steel subject to high strain rate tensile tests

Hydrogen‐induced degradation of X80 pipeline steel was investigated through a high strain rate tensile test (2 × 10^?4/s) with interposed unloading, reloading, aging at 30°C, or annealing at 200°C with or without hydrogen charging. The results indicated that plasticity degradation does not occur in the hydrogen‐precharged specimens; however, hydrogen embrittlement occurs in the reloading stage when the specimens are charged with hydrogen in the unloading stage after applying a prestrain. Interposed aging at 30°C or annealing at 200°C can also increase the degradation. It indicates that the hydrogen traps caused by the strain along with hydrogen charging are the major source of dislocations. The formation of a hydrogen atmosphere around mobile dislocations, which is related to the rates of hydrogen diffusion and dislocation movement, plays an important role in the degradation process. Both pinning and depinning of dislocations affect plasticity degradation.     

Atom probe tomographic observation of hydrogen trapping at carbides/ferrite interfaces for a high strength steel

A three-dimensional atom probe (3DAP) technique has been used to characterize the hydrogen distribution on carbides for a high strength AISI 4140 steel. Direct evidence of H atoms trapped at the carbide/ferrite interfaces has been revealed by 3DAP mapping. Hydrogen is mainly trapped on carbide/ferrite interfaces along the grain boundaries. Slow strain rate tensile (SSRT) testing shows that the AISI 4140 steel is highly sensitive to hydrogen embrittlement. The corresponding fractographic morphologies of hydrogen charged specimen exhibit brittle fracture feature. Combined with these results, it is proposed that the hydrogen trapping sites present in the grain boundaries are responsible for the hydrogen-induced intergranular fracture of AISI 4140. The direct observation of hydrogen distribution contributes to a better understanding of the mechanism of hydrogen embrittlement.     

镀锌层上有机物无铬钝化涂层的耐蚀性

选择了一种无毒的水溶性丙烯酸树脂（AC）加入至钼酸盐、磷酸盐中（M）得到一种钝化液（ACM），对镀锌层进行钝化处理以代替有毒的铬酸盐钝化。通过盐雾试验、扫描电镜、电化学测试等手段，研究了该纯化膜的耐蚀性及耐蚀机理。结果表明，热浸镀锌层采用该无毒钝化液进行钝化，可以推迟镀锌层出现白锈的时间，其抗蚀性已接近铬酸盐钝化水平；ACM钝化膜耐蚀性的提高是由于钝化膜中的钼酸盐与丙烯酸树脂产生交联作用，抑制钝化膜裂纹的扩展，同时由于膜层中钼酸盐的缓蚀作用，提高了镀锌层的抗蚀性。     

Effect of gaseous hydrogen charging on the tensile properties of standard and medium Mn X70 pipeline steels

The tensile properties of two X70 steels with high (1.14 wt-%) and medium (0.5 wt-%) Mn contents have been investigated by testing at 25°C of tubular specimens charged with an internal gas pressure of 10?MPa of hydrogen or argon. The hydrogen-charged samples were additionally tested at 50 and 100°C. Tensile testing showed that the equiaxed ferrite–pearlite microstructure of higher Mn steel was most sensitive to hydrogen embrittlement and that the banded ferrite–pearlite microstructure of the higher Mn strip was more susceptible to hydrogen embrittlement than the medium Mn strip. The more highly banded ferrite–pearlite microstructure in the higher Mn steel provided numerous sites for concentration of hydrogen to levels that promoted crack initiation and growth. Test temperatures up to 100°C reduced the yield and tensile strengths, increased the total elongation and decreased the extent of hydrogen embrittlement because of enhanced dislocation mobility and less effective hydrogen trapping.     

应变速率与40Cr钢氢脆特性关系的研究

本文通过考察不同应变速率下渗氢试样机械性能的变化情况，用扫描电镜（ＳＥＭ）分析断口的宏观微观形貌，研究了４０Ｃｒ钢的应变速率与氢脆敏感性的关系、     

Effects of prestrain and strain rate on dynamic deformation characteristics of 304L stainless steel: Part 1—Mechanical behaviour

Abstract

A split Hopkinson bar is used to investigate the effects of prestrain and strain rate on the dynamic mechanical behaviour of 304L stainless steel, and these results are correlated with microstructure and fracture characteristics. Annealed 304L stainless steel is prestrained to strains of 0·15, 0·3, and 0·5, then machined as cylindrical compression specimens. Dynamic mechanical tests are performed at strain rates ranging from 10² to 5 × 10³ s^-1 at room temperature, with true stains varying from 0·1 to 0·3. It was found that 304L stainless steel is sensitive to applied prestrain and strain rate, with flow stress increasing with increasing prestrain and strain rate. Work hardening rate, strain rate sensitivity, and activation volume depend strongly on the variation of prestrain, strain, and strain rate. At larger prestrain and higher strain rate, work hardening rate decreases rapidly owing to greater heat deformation enhancement of plastic flow instability at dynamic loading. Strain rate sensitivity increases with increasing prestrain and work hardening stress (σ-σ_y). However, activation volume exhibits the reverse tendency. Catastrophic fracture is found only for 0·5 prestrain, 0·3 strain, and strain rate of 4·8 × 10³ s^-1. Large prestrain increases the resistance to plastic flow but decreases fracture elongation. Optical microscopy and SEM fracture feature observations reveal adiabatic shear band formation is the dominant fracture mechanism. Adiabatic shear band void and crack formation is along the direction of maximum shear stress and induces specimen fracture.     

Effect of Strain Rate on Hydrogen Embrittlement Behaviour of Amorphous NiCrFeSiB Alloy

The effect of strain rate on hydrogen embrittlement behaviour of amorphous Ni-6.6Cr-2.6Fe-7.8Si-14.5B (at pct) alloy in 0.1 mol/L H2SO4 solution was studied by the methods of slow Strain rate testond electrochemical charging. The results show that fracture Stress of the alloy decreases with the decrease of Strain rate within a certain range. As a tentative explanation, the effect of strain rate on hydrogen embrittlement fracture stress was attributed to the interaction between hydrogen and the excess volume in amorphous alloys