EOS公司推出可以用于增材制造工艺的钛合金与不锈钢材料

正EOS公司是一个提供增材制造系统的德国企业,近期该公司新开发了可用于增材制造工艺的2种材料,分别是Ti64ELI和316L不锈钢,增加了EOS公司可用于直接激光金属烧结的材料种类。EOS公司的产品营销经理Christiane Krempl说:"我们推出更多的钛和不锈钢材料,开辟了一些新的应用领域,这是我们客户不断变化的需求的反映。"EOS公司有关方面表示:使用Ti64材料以增材制造方法生产的零件的化学成分和力学性能与ASTM F136相当;可以用Ti64材料制作出精美的钛合金制品,其具有优异的耐腐蚀性能、生物相容性和高纯度,特别适合用增材制造方法生产医疗用移植物。EOS公司开发的应用于增材制造的316L不锈钢合金具有很好的耐腐蚀性能和延展性,其制造的零件的化学成分与ASTM F138相当。在医疗行业,316L     

激光增材制造技术制备高熵合金研究进展

介绍了激光增材制造高熵合金的工艺方法,从成形工艺、合金元素含量（摩尔分数）、热处理工艺和增强相添加等几个方面综述了国内外激光增材制造高熵合金的研究进展,分析了激光熔化沉积和选区激光熔化成形两种主要激光增材制造技术,以及两种技术制备高熵合金的微观结构和力学性能,指出了高熵合金激光增材制造技术的发展趋势及存在的主要问题,并提出了改进措施。     

增材制造17-4PH马氏体不锈钢研究进展

17-4PH马氏体不锈钢具有高强高韧以及耐腐蚀等优异性能,在航空航天、核能和民用工业等领域得到广泛的应用。增材制造技术通过离散堆积的制备方法,能够实现复杂异形零部件的成形,满足装备迭代的需求。综述了国内外增材制造17-4PH的研究成果,针对增材制造微小熔池、快速熔凝、复杂热历史冶金特点,介绍影响增材制造17-4PH试样致密度的因素,阐述其相构成、微观组织和力学性能,简述后处理对17-4PH力学性能的影响规律,最后对增材制造17-4PH的发展进行展望。     

Cr_2N对粉末注射成形316L不锈钢组织与性能的影响

在316L不锈钢粉末中添加Cr_2N粉末,采用粉末注射成形工艺制备Cr_2N增强奥氏体不锈钢,利用扫描电镜观察与能谱分析以及洛氏硬度测定,研究Cr_2N对MIM 316L不锈钢组织、成分与硬度的影响,并通过中性盐雾试验研究Cr_2N对MIM316L不锈钢抗腐蚀性能的影响。结果表明,316L不锈钢中添加Cr_2N后,显微组织仍为典型的奥氏体组织,材料的密度与硬度都有所提高。Cr_2N添加量为3%时,不锈钢硬度由64.5 HRB提升至78HRB,并且不会导致抗腐蚀性能下降。     

316L奥氏体不锈钢的氮合金化

采用金相显微镜、XRD、拉伸试验机及高低温冲击试验机等,并结合Thermo-calc软件计算研究了氮对316L奥氏体不锈钢微观组织、析出相、力学性能和耐点蚀性能的影响.结果表明:氮合金化能够抑制316L不锈钢中σ相和Chi相的析出,增加Cr2N的析出倾向,对奥氏体晶粒细化不明显;氮的添加能够提高316L不锈钢的室温强度和-100℃以上温度的夏比冲击功,降低-100℃以下的夏比冲击功,但对室温拉伸塑性影响不明显.此外,氮能够改善316L不锈钢的耐点蚀能力.     

基于增材制造双金属比例交织结构的性能研究

确保奥氏体高氮钢的强度前提下,为了增加其韧性,采用奥氏体高氮钢和奥氏体不锈钢308L丝材,通过仿照贝壳等生物材料珍珠母层,使用等离子弧作为热源的增材制造方法,设计并制备初级仿生双金属交织结构。分析了该初级仿生结构的双金属不同成分比例对交织结构的强度和韧性的影响规律。结果表明:当高氮钢与不锈钢体积比为3∶1时,等离子弧增材制造技术制备的双金属交织初级仿生结构的抗拉强度与高氮钢相当,冲击吸收功提高了2.3倍。通过等离子弧的双金属交织结构增材制造技术研究,可证明仿生结构硬质材料和软质材料的体积比在3∶1时,获得的交织结构能够确保材料强度甚至提高材料强度,同时增加材料的冲击韧性,为今后仿生结构的研究提供一定的参考。     

金属材料电弧增材制造技术研究现状

电弧增材制造（WAAM）技术将电弧作为热源，具备熔敷效率高、设备简单、成本较低的特点，在制备大型零件时具有更大的优势。基于3种典型电弧热源的电弧增材制造方法包括熔化极电弧（GMA）增材制造、非熔化极电弧（GTA）增材制造与等离子弧（PA）增材制造。GMA增材制造技术拥有熔敷效率高、易于实现等特点，特别是基于冷金属过渡（CMT）的增材制造技术取得了重要进展，主要缺点在于熔滴过渡对熔池的显著冲击易影响成形精度和质量。GTA增材制造技术具有最为稳定的电弧燃烧过程，具有无飞溅、成形精度与质量高等显著优势，特别适合于铝合金、镍基合金、钛合金等材料的增材制造。PA增材制造与GMA增材制造与GTA增材制造相比，存在能量密度高、集束性好等优点。但是PA合理参数区间较窄、参数匹配复杂、热输入大等缺点也限制了其在该领域的应用。由于增材制造过程使得后堆积层存在反复加热与冷却，增材制造成形件组织存在上中下区域的差异以及熔敷方向及垂直于熔敷方向性能的各向异性。增材制造金属材料的热循环过程对于晶粒尺寸、熔覆层性能以及成形精度非常关键，分别可以通过改变成形件冷却条件、改变熔池凝固条件对组织性能进行改善。新型电弧热源...     

316L/碳化钒复合材料SLM成形性能强化研究

基于316L不锈钢粉末的选择性激光熔化(SLM)技术已经取得了较好的进展,对于成形件性能的改进多针对于SLM工艺参数的优化。为了进一步提升316L不锈钢成形件的机械性能,在原始316L不锈钢粉末中加入平均粒度为800 nm的碳化钒(VC)陶瓷颗粒,SLM成形后检测其机械性能。结果表明,添加了VC的316L/VC混合粉末成形后,VC固溶于基体中,成形件硬度提升约22.8%,屈服强度提升约33.8%,抗拉强度提升约45.3%,弹性模量提升约67.0%。由于孔隙率略有增加,伸长率降低约15.7%。     

难熔高熵合金激光增材制造：研究进展与展望

难熔高熵合金（RHEAs）是一类以Nb, Mo, W, Ta等难熔元素为主元的高熵合金（HEAs），具有简单的相结构和优异的高温综合力学性能，在航空航天、核能和石油等领域具有广阔的应用前景。由于RHEAs室温脆性难加工的特点，传统的工艺方法在制备RHEAs时存在制造过程复杂、周期长、材料利用率低、成本高等诸多问题，极大地限制了RHEAs的发展和应用。激光增材制造（LAM）技术因其能实现复杂零件的直接自由成形，而逐渐成为制备RHEAs的一条重要途径，为RHEAs的研发和应用带来了新的契机。对近年来激光增材制造RHEAs的研究现状进行了综述，介绍了激光增材制造RHEAs的成形特性，分析了RHEAs打印件的相组成和显微组织特征，总结了打印件的显微硬度、压缩强度以及耐磨、耐腐蚀和抗高温氧化性能。最后归纳出目前激光增材制造RHEAs的现存问题，并对其未来的发展趋势进行了展望。     

激光粉床增材制造不锈钢中氧化物夹杂调控的研究进展

激光粉床增材制造技术是一个涉及熔池移动、快速非平衡凝固、固态相变的复杂冶金过程，该过程的非均匀快速热-力耦合易导致金属制件出现翘曲变形、裂纹及孔洞、夹杂物、晶粒异常形核与长大等缺陷，这些缺陷会对金属制件的尺寸精度、致密度及力学性能等产生不利影响。激光粉床增材制造金属制件中非金属氧化物夹杂大多为内生夹杂物，产生于金属液脱氧以及极速熔化和凝固过程中的二次氧化，其种类、尺寸、形貌以及分布等物化特性直接影响或决定了金属产品的质量与性能，也是导致金属中产生各类缺陷的重要原因之一。分析了不锈钢材料激光粉床增材制造及后续热处理过程金属中氧化物夹杂的形成和演化及其对金属零件性能的影响性，并对不锈钢金属制件中氧化物夹杂特性的调控研究进展进行了总结，为激光粉床增材制造企业生产工艺优化提供了科学指导和理论依据。     

Research progress of austenitic stainless steel made by metal additive manufacturing

Compared with the parts prepared by conventional methods, the parts formed by metal additive manufacturing (MAM) technology are prone to have non equilibrium and sub micro cellular structures, which show more excellent performance. Especially, the 316L stainless steel formed by laser powder bed melting technology has high yield strength, good elongation, and excellent corrosion resistance. Aiming at the superfast thermal cycle, complex metallurgical reactions, intense non equilibrium solidification, and particular thermal history of MAM technologies, the current advances in the related fields of laser powder bed fusion 316L (L PBF 316L) austenitic stainless steel were systematically reviewed. The mechanical properties and corrosion mechanism of L PBF 316L and its influencing factors including microstructural features evolution and corresponding regulation were discussed. All importantly, the strengthening and toughening mechanisms of 316L deformation were thoroughly revealed. Finally, a brief prospect on the future research direction of additive manufacturing austenitic stainless steel was provided.     

选区激光熔化工艺参数对气雾化 316L不锈钢粉末成形制品性能的影响

本研究系统考察了激光功率和扫描速度对316L不锈钢粉末选区激光熔化工艺成形熔道、制品微观组织及力学性能的影响,并分析了各类缺陷的形成原因。研究结果表明:在低激光功率和高扫描速度条件下,熔道中出现了大量球状颗粒,这些颗粒之间的空隙恶化了下一层粉末的熔化条件,这正是成形制品中熔道分布混乱以及孔洞、裂纹产生的根本原因,进而导致成形制品力学性能降低;在高激光功率和低扫描速度条件下,熔池快速升温/冷却的热应力作用增强,使得成形制品的熔道交界处也存在孔洞和裂纹等缺陷。在本研究实验条件下,激光功率为350 W,扫描速度为1750 mm/s时,SLM成形制品的力学性能最为优异,其中抗拉强度为731 MPa、屈服强度为638 MPa、断后伸长率为40.0%,致密度为96.27%。     

445J2超纯铁素体不锈钢和316L超低碳奥氏体不锈钢在溴化锂溶液的点蚀分析

445J2铁素体不锈钢由于高的导热率、低的热膨胀系数以及良好的耐蚀性能使得其作为溴冷机中一些部件的良好候选材料,本文采用电化学测试方法对比研究了445J2超纯铁素体不锈钢(/%:0.01C,22.5Cr, 1.9Mo, 0.27Nb, 0.20Ti, 0.09Al, 0.36Cu, 0.015P,0.001S,0.015N)和316L奥氏体不锈钢(/%:0.002C,16.8Cr, 10.19Ni, 2.02Mo, 0.025P,0.0008S)在20～60℃0.1～1M的溴化锂溶液中的点蚀行为,并采用扫描电镜(SEM)和能谱分析仪(EDS)对电化学结果进行表征。结果表明,随着LiBr温度和浓度的升高,两种钢腐蚀电流密度增大,点蚀电位降低,耐点蚀性变差;氧化物和硫化物夹杂会引起两种钢的点蚀;高含量的Cr以及Mo、Ti、Nb、Al等合金元素使445J2钢具有优异的耐点蚀性能。     

高分子复合波纹膨胀节在高炉煤气系统上的研发与应用

介绍了高分子复合波纹膨胀节的耐煤气腐蚀机理、优异性能,从根本上解决了目前316L、800镍基合金、超级奥氏体不锈钢等金属补偿器无法解决的晶界腐蚀问题。     

Towards the Optimization of Post-Laser Powder Bed Fusion Stress-Relieve Treatments of Stainless Steel 316L

The use of post-processing heat treatments is often considered a necessary approach to relax high-magnitude residual stresses (RS) formed during the layerwise additive manufacturing laser powder bed fusion (LPBF). In this work, three heat treatment strategies using temperatures of 450 °C, 800 °C, and 900 °C are applied to austenitic stainless steel 316L samples manufactured by LPBF. These temperatures encompass the suggested lower and upper bounds of heat treatment temperatures of conventionally processed 316L. The relaxation of the RS is characterized by neutron diffraction (ND), and the associated changes of the microstructure are analyzed using electron backscattered diffraction (EBSD) and scanning electron microscopy (SEM). The lower bound heat treatment variant of 450 °C for 4 hours exhibited high tensile and compressive RS. When applying subsequent heat treatments, we show that stress gradients are still observed after applying 800 °C for 1 hour but almost completely vanish when applying 900 °C for 1 hour. The observed near complete relaxation of the RS appears to be closely related to the evolution of the characteristic subgrain solidification cellular microstructure.

     

Heterogeneity and Solidification Pathways in Additively Manufactured 316L Stainless Steels

Metallurgical and Materials Transactions A - A unique microstructural feature often referred to as “fish-scale” has been reported in 316L austenitic stainless steel parts made by laser...     

High performance ferritic stainless steel B445R for architectural applications

Traditionally,austenitic stainless steels 304 and 316 have been employed in coastal regions as roofing materials unfortunately,they are expensive and not fully resistant to pitting corrosion under severe coastal corrosive environment.A ferritic stainless steel B445R was developed.Compared with austenitic 316L,B445R is①less costly;②uperior corrosion resistant with minor maintenance for long-term service;③insusceptible to thermal distortion in the welding seam. B445R sheet shows a higher yield strength and lower tensile strength,lower elongation and lower work-hardening than austenitic 316L.It can be easily fabricated and deformed just like plain carbon steel.After bending 180o,there is no occurrence of "cracking" or noticeable "orange peel".The formability of the welding seam is also satisfactory.The pitting potential of B445R is 650 mV,larger than that of 304 and 316L,as shown in Fig.1. The corrosion rate of B445R submerged in 6%FeCl,solution is 0.3 -0.56 g/(m² ? h^-1),much lower than that of 316L,as shown in Fig.2.The superior pitting corrosion resistance of B445R can be ascribed to synergetic effect of higher Cr and Mo. Dull-finished B445R sheets have been employed as the roofing materials for Guangzhou Asian Games Arena,as shown in Fig.3.About 380 t of 1.0 mm B445R with dull finish was used for roofing panels.About 100 t of 0.8 mm B445R with hairline or fluororesin paint finish was used for side wall panels.The composite roof build-up （from up to bottom） includes:①shingles of ferritic stainless steel B445R;②Kalzip-type standing seam of austenitic 304;③water-proof DFM;④structural steel;⑤75 mm thick insulation;⑥secondary purlin of 150 mm×100 mm×4.5 mm of galvanizied Q235;⑦0.8 mm thick profile deck of galvanizied Q235;⑧acoustic insulation.The roofing shingles or panels with the same width but different length were formed by bending four sides and fixed to a "L" shape reinforcing frames of stainless steel by fasteners.The "L" frames was connected to ribs of the standing seam by a clamping fixture made of aluminum.     

Microstructure of 316L stainless steel components produced by direct laser deposition

The prospects for direct laser deposition in the manufacture of 316L austenitic stainless steel parts are assessed. The influence of the power of the laser beam and the state of the initial material on the structure and properties of the product is considered.     

Development of ferritic stainless steel B445R with superior corrosion resistance for architectural applications

The dull-finish ferritic stainless steel(FSS) sheet B445R for architectural roofing has been developed by Baosteel.This steel product exhibits excellent corrosion resistance superior to that of SUS 316L with a lower cost.It can be easily formed into roofing panels by ordinary processes.Moreover,the thermal strain of it is less than SUS 316L because of its lower thermal expansion coefficient,and its reflectivity is lower due to the dull-finish treatment.All of these features make it capable of being used as architectural roofing materials in coastal regions.