(中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要: 采用選區(qū)激光熔化技術(shù)，結(jié)合旋轉(zhuǎn)+填充掃描策略制備Rene104鎳基高溫合金，研究了成形參數(shù)對(duì)顯微組織和開(kāi)裂行為的影響。結(jié)果表明：線(xiàn)能量密度和掃描間距是影響Rene104鎳基高溫合金致密度及開(kāi)裂的主要參數(shù)。當(dāng)線(xiàn)能量密度為250 J/m，掃描間距為0.08mm時(shí)，Rene104鎳基高溫合金成形件的致密度達(dá)98.37%。選區(qū)激光熔化成形Rene104合金主要由橫截面尺寸為0.5 μm、軸向尺寸為3~5 μm或30 μm的柱狀晶組織組成，晶粒沿建造方向的(200)晶面擇優(yōu)取向生長(zhǎng)，同時(shí)，在晶界存在碳化物和Laves相，出現(xiàn)了裂紋、孔洞及殘留粉末顆粒等缺陷。高線(xiàn)能量密度產(chǎn)生的大溫度梯度導(dǎo)致殘余應(yīng)力，從而在晶界析出相周?chē)纬蓱?yīng)力集中，在熔池和層間搭接處的熔池尖端萌生裂紋，且沿建造方向擴(kuò)展。殘留孔洞主要來(lái)自粉末空心缺陷，殘留粉末顆粒則由粉末飛濺產(chǎn)生。
關(guān)鍵字: Rene104合金；選區(qū)激光熔化；致密度；顯微組織；裂紋；碳化物
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The Rene104 nickel-based superalloy was fabricated by selective laser melting technology with the scan strategy of rotation plus filling, and the impacts of process parameters on the microstructure and cracking behavior were investigated. The results show the linear energy density and hatch spacing are the main parameters that affect the density and cracking behavior of Rene104 nickel-based superalloy. When the energy density is 250 J/m, and the hatch spacing is 0.08 mm, the relative density of Rene104 nickel-based superalloy samples reaches 98.37%. The Rene104 alloy is mainly composed of columnar grains with the cross-sectional dimension of 0.5 μm and the axial dimension of 3-5 μm or 30 μm. The grain grows along the build direction with the strong (200) texture, while the carbides and Laves phases exist along the grain boundaries. The defects, including cracks, pores and remained powders, are also be found. The high linear energy density can cause the large temperature gradient and residual stress, which results in the stress concentration around precipitates. Therefore, the cracks initiate at the pool tip and interlayer junctions, then extend along the build direction. The remained pores are mainly caused by the powder hollow, and the remained powders are generated by the powder splash phenomenon.
Key words: Rene104 superalloy; selective laser melting; relative density; microstructure; crack; carbide
