【摘要】：選區(qū)激光熔化技術(shù)(Selective Laser Melting, SLM)是一種應(yīng)用較廣泛的增材制造技術(shù),憑借其制造精度高、制造結(jié)構(gòu)復(fù)雜和個(gè)性化等優(yōu)勢(shì),越來(lái)越受到社會(huì)的關(guān)注。316L不銹鋼和Ti-6Al-4V合金因其優(yōu)良的性能在醫(yī)療與航空航天領(lǐng)域有著較大的應(yīng)用空間。但是上述兩合金SLM成形過(guò)程的組織與性能研究還不完善,其缺陷的控制技術(shù)還沒(méi)成熟。為此,本課題對(duì)SLM成形316L不銹鋼和Ti-6Al-4V合金的組織與性能進(jìn)行了詳細(xì)的研究。首先,考察了離焦打印與焦點(diǎn)打印對(duì)316L不銹鋼組織與性能的影響;接著,考察了不同SLM工藝參數(shù)和熱處理工藝對(duì)316L不銹鋼和Ti-6Al-4V合金的缺陷、組織、拉伸力學(xué)性能、硬度和壓縮性能的影響,從而確定較佳的SLM工藝參數(shù)和熱處理工藝,從而為316L不銹鋼和Ti-6Al-4V合金的3D打印應(yīng)用提供技術(shù)支撐。本課題得出的主要結(jié)論如下:(1)焦點(diǎn)打印優(yōu)于離焦打印,采用不同工藝參數(shù)正交試驗(yàn),得出的316L不銹鋼較優(yōu)工藝參數(shù)組合為掃描間距S=0.05mm,掃描速度V=1500 mm/s,掃描功率P=450W,在此工藝下樣品的致密度達(dá)到95.9%; Ti-6Vl-4V合金較優(yōu)工藝參數(shù)組合為掃描間距S=0.07 mm,掃描速度V=2500mm/s,掃描功率P=450W,此工藝下的致密度為98.1%。(2) SLM成形的316L不銹鋼組織主要由細(xì)小的柱狀組織以及蜂窩狀組織組成。其室溫拉伸抗拉強(qiáng)度為645 MPa,屈服強(qiáng)度為560 MPa,伸長(zhǎng)率達(dá)45%。其拉伸斷口出現(xiàn)韌窩,表現(xiàn)為典型的韌性斷裂。(3) 316L不銹鋼在熱處理后組織呈現(xiàn)出單一奧氏體組織,并且隨熱處理溫度升高,晶粒發(fā)生長(zhǎng)大,從而使熔合線(xiàn)搭接消失;通過(guò)熱處理可以調(diào)節(jié)制件的力學(xué)性能,在750℃保溫2h并隨爐冷卻的熱處理工藝下,其表現(xiàn)出了較好的拉伸性能,其中抗拉強(qiáng)度為680MPa,屈服強(qiáng)度為480MPa;在1000℃保溫lh并隨爐冷的熱處理工藝下,其延伸率最好,高達(dá)56%。(4) SLM成形的Ti-6All4V合金組織主要為細(xì)小針狀的α'馬氏體組織,其室溫拉伸抗拉強(qiáng)度為1250MPa,屈服強(qiáng)度為1160MPa,延伸率僅8.0%,斷口有撕裂棱,呈現(xiàn)出準(zhǔn)解理斷裂;抗壓強(qiáng)度高于其抗拉強(qiáng)度,為1755Mpa;經(jīng)850℃真空熱處理后,組織發(fā)生了明顯的粗化,且較均勻,此時(shí)的室溫拉伸抗拉強(qiáng)度為1010 MPa,屈服強(qiáng)度為950 MPa,延伸率為9.00%。拉伸斷口有大小不一的韌窩出現(xiàn),塑性有所增強(qiáng)。
[Abstract]:Selective laser melting technology (Selective Laser Melting, SLM) is a widely used material increasing manufacturing technology, which has the advantages of high manufacturing precision, complex manufacturing structure and individuation. 316L stainless steel and Ti-6Al-4V alloys have great application space in medical and aerospace fields because of their excellent properties. However, the microstructure and properties of the two alloys in SLM forming process are not perfect, and the defect control technology is not mature. Therefore, the microstructure and properties of 316L stainless steel and Ti-6Al-4V alloy formed by SLM were studied in detail. Firstly, the effects of defocus printing and focus printing on the microstructure and properties of 316L stainless steel were investigated. Then, the effects of different SLM process parameters and heat treatment on the defects, microstructure, tensile mechanical properties, hardness and compression properties of 316L stainless steel and Ti-6Al-4V alloy were investigated, and the better SLM process parameters and heat treatment process were determined. It provides technical support for the application of 316L stainless steel and Ti-6Al-4V alloy in 3D printing. The main conclusions of this paper are as follows: (1) focus printing is superior to defocus printing. By orthogonal test of different process parameters, the optimum process parameters of 316L stainless steel are as follows: scanning distance S0. 05 mm, scanning speed V1 500 mm/s,. The scanning power is 450W, and the density of the sample reaches 95.9 under this process. The optimum process parameters of Ti-6Vl-4V alloy are as follows: scanning interval S0. 07 mm, scanning speed VN 2 500 mm / s, scanning power PX 450 W, (2) the microstructure of 316L stainless steel formed by SLM is mainly composed of fine columnar structure and honeycomb structure. The tensile strength at room temperature is 645 MPa, and the yield strength is 560 MPa,. (3) the microstructure of 316L stainless steel shows a single austenitic structure after heat treatment, and the grain grows up with the increase of heat treatment temperature, which makes the fusion line lap disappear; (3) the tensile fracture of stainless steel is characterized by ductile fracture. (3) the microstructure of 316L stainless steel shows a single austenitic structure after heat treatment. The mechanical properties of the parts can be adjusted by heat treatment. The tensile strength and yield strength are 680MPa and 480MPa respectively, and the tensile strength is 680MPa and the yield strength is 480MPa under the heat treatment process of 750 鈩，

本文編號(hào)：2304339