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1.
近年来,激光增材制造技术(3D打印)成为科学研究及工业应用领域的热点。为了研究激光冲击强化对增材制造TC4钛合金性能的影响,本文采用能量为5 J,波长为1 064 nm,脉宽为10 ns,光斑直径为3 mm的脉冲激光对3D打印TC4钛合金进行激光冲击强化,分析了激光冲击强化前后材料的显微硬度、显微组织、残余应力以及高温氧化性能。结果表明,经过激光冲击强化后,材料的显微硬度比激光冲击强化前提高了8%,影响层深度达到0.4 mm,强化区域的晶粒得到细化,位错增多,并产生形变孪晶;激光冲击强化的残余压应力数值高达472 MPa,材料的高温抗氧化性能也得到改善。  相似文献   

2.
研究了激光喷丸(LP)TC6钛合金的组织演变对表面强度的影响机理。结果表明,LP后材料表面的显微硬度和残余应力均随功率密度的增加而增大,LP引起的硬度影响层和残余应力影响层的深度也随功率密度的增加而增大,且影响层深度为500~600μm。LP对TC6钛合金强度的影响机理包括细晶强化和位错强化,晶粒细化使大角度和小角度晶界增多,而晶界能阻止材料发生屈服;LP产生的高密度位错可使材料的屈服强度提高,阻碍位错的运动,抑制裂纹的萌生,从而使材料的力学性能提高。  相似文献   

3.
通过性能测试分析,研究了激光喷丸(LP)技术对TC4钛合金抗氢脆性能的影响。结果表明,LP试样表面产生了-327 MPa的残余压应力;电化学充氢后,试样表面残余压应力降低了9.17%,喷丸与未喷丸试样的表面显微硬度分别提高了5.07%和7.08%,而延伸率分别降低了2.25%和4.84%。LP处理可提高TC4钛合金的韧性,降低其氢脆敏感性。  相似文献   

4.
为了在不影响柱状晶组织的前提下改善DZ17G定向凝固合金的力学性能,采用微激光冲击强化方法进行表面处理,通过X射线衍射、扫描电子显微镜、透射电子显微镜和显微硬度计,测试分析微激光冲击对DZ17G定向凝固合金表面完整性的影响。试验结果表明:在水下无吸收保护层微激光冲击处理后,合金表面发生了烧蚀、熔融,1次冲击后形成光滑熔融区,但随着冲击次数增加而形成了大量微小烧蚀孔洞和难熔颗粒;表层组织仍由和两相组成,柱状晶内形成了高密度位错和位错缠结,但未发生晶粒细化;硬度在深度上呈梯度分布,冲击1次后硬化层深度仅为100 m,表面硬度值达到503 HV,提高了22.7%,而且硬度值和硬化层深度都随着冲击次数增加而增大。  相似文献   

5.
采用激光冲击强化(LSP)处理方法研究了激光冲击强化对AM50铸造镁合金深度方向的晶粒结构、显微硬度和残余应力的影响。结果表明,经过单次冲击强化后,合金表层的显微硬度值、残余压应力值均有明显改善;在冲击强化层,原始粗晶明显细化,表层显微硬度值提高了19%,残余压应力达到-225 MPa,且显微硬度提高区、晶粒细化层及残余压应力层的深度明显增大;当冲击次数增加到2次时,显微硬度、晶粒尺寸和残余应力得到进一步改善。  相似文献   

6.
强激光冲击铝合金改性处理研究   总被引:13,自引:2,他引:13  
吴边  王声波  郭大浩  吴鸿兴 《光学学报》2005,25(10):352-1356
利用新型聚偏1.1-二氟乙烯(PVDF)压电传感器,实现了对激光引发的冲击波压力的实时测量,得到激光引发的冲击波峰压在铝中成指数型的衰减规律;观测了不同约束层材料在铝靶表面产生的激光冲击波,研究了不同约束层对冲击效果的影响;最后用激光冲击强化装置对7050-T7451航空铝合金结构材料进行了冲击强化处理,对试件激光冲击区存在的残余压应力及位错密度进行了测量。结果显示经激光冲击处理的试件表面具有极高的残余压应力,可达-200MPa以上。激光冲击处理后铝合金的位错密度得到显著的提高,疲劳寿命提高到175%~428%。这些重要结果对激光冲击改性处理技术的实际应用具有指导性作用。  相似文献   

7.
为了揭示激光喷丸(LP)强化IN718合金疲劳寿命增益的机制,研究了合金喷丸前后晶粒重排与疲劳特性的关系。结果表明,LP后试样表层的塑性形变深度最大可达33.7μm,合金的最大疲劳寿命增益可达188%;激光冲击波诱导产生的表层残余压应力随激光功率密度的增大而增大,但增幅逐渐减小;疲劳试验后,表层残余应力出现了52%的释放;LP后试样表层晶粒出现细化现象,细化深度达到175μm;位错滑移和位错攀移以及孪晶等共同作用使原始晶粒内形成了亚晶粒,最终细化了晶粒组织。  相似文献   

8.
利用输出波长为1064 nm、脉冲宽度为20 ns的钕玻璃YAG激光器,对2A02铝合金进行了表面冲击强化试验.测定了激光冲击后材料的表面硬度和残余应力,用快速傅里叶逆变换(IFFT)方法分析了铝合金激光冲击诱导的晶内亚结构及其演变行为.结果表明,激光冲击强化可使2A02铝合金表面硬度提高50%以上,残余压应力达到12...  相似文献   

9.
针对近年来发展的激光冲击强化技术,采用1级谐振8级放大的系统结构和模块化设计方法,研制出了激光冲击强化用短脉宽、大能量的Nd:YAG脉冲激光器,并对激光器技术指标进行了测试分析。在预热20 min后、环境温度变化小于2 ℃的情况下,单脉冲最大输出能量高达25 J,能量不稳定度小于3%,脉宽16~20 ns可调,脉宽不稳定度小于1 ns,光束发散角小于等于2.5 mrad,重复频率达5 Hz。对TC4钛合金进行激光冲击强化实验,大幅度提高了TC4钛合金试件表面的残余压应力。结果表明,研制的激光器各项性能良好。  相似文献   

10.
为研究激光冲击对E690高强钢激光熔覆修复层微观组织的影响,选用专用金属粉末对E690高强钢试样预制凹坑进行激光熔覆修复,并使用脉冲激光对激光熔覆层进行冲击强化处理,同时采用扫描电镜、透射电镜和X射线应力分析仪分别对激光冲击前后激光熔覆层的微观组织和表面残余应力进行检测。结果表明:激光熔覆修复后,激光熔覆层组织为等轴晶,熔覆层与E690高强钢基体之间冶金结合良好,其表面残余应力为均匀分布的压应力。经激光冲击后,激光熔覆层截面晶粒得到细化,并观察到大量的形变孪晶,互相平行的孪晶界分割熔覆层粗大晶粒,在激光熔覆层的晶粒细化过程中发挥着重要作用;试样表层位错在{110}滑移面上发生交滑移,在晶界周围形成了位错缠结。经激光冲击后,激光熔覆层冲击区域表面残余压应力数值相较于冲击前提升了1.1倍。  相似文献   

11.
As 7075 aluminum alloy is widely used in a humid environment, in order to enhance its abrasion resistance and electrochemical corrosion resistance, the paper studied the effect of laser shock peening on abrasion resistance in artificial seawater and corrosion resistance in 3.5% NaCl solution of 7075 aluminum alloy. Result shows that when specimens were treated once and twice with 7.17 GW/cm2 the abrasion loss would be reduced by 43.75% and 46.09% compare to untreated respectively, and the corrosion rate of 7075 aluminum alloy could be reduced as much as 50.32% by LSP treatment with 7.17 GW/cm2. What’s more, the effects on the microhardness, microstructure and residual stress with different LSP impacts and power density were investigated to find out strengthening mechanism of laser shock peening, which were observed and measured by microhardness tester, optical microscope and X-ray diffraction (XRD) residual stress tester. In the entire laboratory tests, it is considered that LSP is a practical option to improve abrasion resistance in seawater and corrosion resistance of 7075 aluminum alloy.  相似文献   

12.
We address the effects of processing parameters on residual stresses and fatigue properties of LY2 Al alloy by laser shock processing (LSP). Results show that compressive residual stresses are generated near the surface of samples due to LSP. The maximum compressive residual stress at the surface by two LSP impacts on one side is higher than that by one LSP impact. The maximum value of tensile residual stress is found at the mid-plane of samples subjected to two-sided LSP. Compared with fatigue lives of samples treated by single-sided LSP, lives of those treated by two-sided LSP are lower. However, these are higher than untreated ones.  相似文献   

13.
采用高功率激光器多次冲击2024铝合金,用X射线衍射技术分析了冲击区域的残余应力,研究了冲击残余应力状态分布规律,并用其评价激光冲击强化效果。研究表明,随着冲击次数增加,塑变量及塑性应变梯度逐渐减小,测点是双向压应力状态,而4次冲击时,塑性应变梯度增大,光斑中心是单向压应力状态,其他点是双向压应力状态。当激光功率密度为2.8 GW/cm2时,3次冲击强化效果最佳,材料是二向压应力状态,残余最大主应力及应力强度的均值最大,方差最小,分布基本均匀,塑性应变梯度较小。  相似文献   

14.
Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field, which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 2.5 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto aluminum samples. Density of 2500 pulses/cm2 with infrared (1064 nm) radiation was used. The effect of an absorbent overlay on the residual stress field using this LSP setup and this energy level is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the overlay makes the compressive residual stress profile move to the surface. This effect is explained on the basis of the vaporization of the coat layer suppressing thermal effects on the metallic substrate. The effect of coating the specimen surface before LSP treatment may have advantages on improving wear and contact fatigue properties of this aluminum alloy.  相似文献   

15.
In order to enhance the thermal fatigue resistance of gray cast iron with non-smooth surface further, the non-smooth units in samples’ surface layer were fabricated by laser cladding with Fe-based, Ni-based and Co-based self-fluxing alloy powders, respectively, instead of laser melting technique. The microstructure, phase structure, microhardness and thermal fatigue behaviors were investigated by means of scanning electron microscope, X-ray diffraction and Vickers microhardness tester, as well as self-restrain thermal fatigue test. The results indicated that laser cladding with self-fluxing alloy powders was beneficial to reinforcing the units so as to enhance the thermal fatigue resistance of non-smooth samples further. Of all samples tested, those treated by laser cladding with Co-based (Co50) alloy had the best thermal fatigue resistance.  相似文献   

16.
Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm2 in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm.Results using pulse densities of 2500 pulses/cm2 in 6061-T6 aluminum samples and 5000 pulses/cm2 in 2024 aluminum samples are presented. High level of compressive residual stresses are produced −1600 MPa for 6061-T6 Al alloy, and −1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products.  相似文献   

17.
 利用高功率钕玻璃激光器对7050铝合金表面进行了冲击处理,保持泵浦功率不变,用压电传感器和示波器测试了激光冲击产生的压力波形,用X射线应力测量仪测量了激光冲击后铝合金表面的残余应力,并用非接触式光学轮廓仪分析了激光冲击后铝合金的表面形貌,研究了放大自发辐射强度对激光冲击处理7050铝合金冲击压力、残余应力和粗糙度影响的微观机理。研究结果表明:在泵浦功率不变前提下,放大自发辐射强度的增大降低了激光冲击波压力,铝合金表面残余压应力也随之降低,同时铝合金表面粗糙度增大。  相似文献   

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