Metallurgy Commons^™

Process-Property-Microstructure Relationships In Laser-Powder Bed Fusion Of 420 Stainless Steel., Subrata Deb Nath

Electronic Theses and Dissertations

Laser-powder bed fusion (L-PBF) is an additive manufacturing technique for fabricating metal components with complex design and customized features. However, only a limited number of materials have been widely studied using L-PBF. AISI 420 stainless steel, an alloy with a useful combination of high strength, hardness, and corrosion resistance, is an example of one such material where few L-PBF investigations have emerged to date. In this dissertation, L-PBF experiments were conducted using 420 stainless steel powders to understand the effects of chemical composition, particle size distribution and processing parameters on ensuing physical, mechanical and corrosion properties and microstructure in comparison …

Optimization Of The Practice Of Slow Cooling Steel Bars: A Redesign And Modernization Of Materials, Eryn Johnston

Mechanical Engineering Undergraduate Honors Theses

Throughout the process of steel making, certain grades of steel are a higher risk for defects caused by the inability to quickly diffuse hydrogen through the steel when cooled to room temperature at a normal rate based on the ambient air temperature. To reduce the hydrogen flaking defects that are caused due to hydrogen entrapment in the steel, the process of slow cooling is utilized. This process reduces the cooling rate of steel bars by keeping them at a higher temperature for extended periods and in turn gives the hydrogen a chance to fully dissipate from the steel. In many …

A Study Of The Diffusion Characteristics Of Tungsten Bar Stock And Tungsten Produced Via Direct Metal Laser Sintering (Dmls), Jonathan Robert Bruss

Master's Theses (2009 -)

Using a vacuum hot extraction method diffusivity and concentration of hydrogen were measured in samples of tungsten bar stock and direct metal laser sintered (DMLS) tungsten. It was found that the tungsten bar stock closely adhered to the model established by Frauenfelder. The DMLS samples approximately follow a downward sloping trend over the 500K-1200K temperature range. The trend is opposite of what is expected suggesting processing has a major effect on diffusion behavior. A CFD model was created using ANSYS Fluent to simulate the diffusion behavior. The model functions by separating out diffusion mechanisms and solving Fick’s law with each …

Comparison Of Salicyl Hydroxamate Adsorption On Rare Earth Phosphates To Oxides And Carbonates, Stephanie Trant

Graduate Theses & Non-Theses

Adsorption behavior of the anionic collector salicyl hydroxamic acid (SHA) on a group of selected rare earth phosphates (REPs) was studied by means of experimental methods and modeling software. These REPs were then compared to rare earth carbonates (RECs) and rare earth oxides (REOs) to develop a trend. A suite of rare earth elements (REE) were studied that included light (LREE) and middle (MREE). Results for heavy (HREE) were inferred. Synthetic phosphate, oxide and carbonate powders of the rare earth elements Lanthanum (La), Cerium (Ce), Europium (Eu) and Dysprosium (Dy) were tested for these studies. Dysprosium phosphate was the only …

Surface Chemistry And Modelling Of Salicyl Hydroxamic Acid Adsorption At The Surface Of Rare Earth Oxides, Carbonates And Phosphates, Marc F. Sime

Graduate Theses & Non-Theses

The adsorption mechanism of salicyl hydroxamic acid (SHA, C7H7O3N) on rare earth minerals was investigated using two complementary methods: precipitation studies and modelling. Precipitation studies showed that SHA adsorption occurs through a displacement of the hydroxide ion at the surface in an ion exchange mechanism, leading to surface precipitation and/or chemisorption. Surface precipitation predominates in the light rare earth oxides (LREOs), while chemisorption predominates in the heavier REOs. Modelling revealed that adsorption of SHA on the REM surface is dependent upon the orientation of SHA on the surface as well as the distance between rare earth elements sites on the …

Microstructure And Mechanical Properties Of Selective Laser Melted Superalloy Inconel 625., Md Ashabul Anam

Electronic Theses and Dissertations

Selective Laser Melting (SLM), a powder based Additive Manufacturing (AM) process, has gained considerable attention in the aerospace, biomedical and automotive industries due to its many potential benefits, such as, capability of fabricating complex three-dimensional components, shortened design to product time, reduction in process steps, component mass reduction and material flexibility. This process uses metallic powder and is capable of fabricating complex structures with excellent microstructure which make SLM not only an improvement over other manufacturing processes but also innovative material processing technology. Inconel 625, a nickel-based super alloy is widely popular in aerospace, chemical and nuclear industries. This alloy …

Modeling And Validations Of Control Parameters For Material Extrusion-Based Additive Manufacturing Of Thixotropic Aluminum Alloys., Lars Herhold

Electronic Theses and Dissertations

Additive Manufacturing (AM) with metals has been accomplished mainly through powder bed fusion processes. Initial experiments and simulations using Material Extrusion Additive Manufacturing (MEAM) have been performed by various researchers especially using low melting alloys. Recently Stratasys Inc. submitted a patent application for the use of their Material Extrusion technology also called Fused Deposition Modeling (FDM) where they describe the process using thixotropic semi-solid alloys. Currently this process using semi-solid, engineering type alloys such as A356 or THIXALLOY 540 aluminum have not been researched to evaluate the control parameters. This research combines the in-depth knowledge of applying thixotropic semi-solid aluminum …

Electrocatalytic Properties Of Ni-Fe Basedalloys Toward Oxygen Evolution Reaction, Xiaodan Cui

LSU Doctoral Dissertations

In this dissertation, laser-based manufacturing was applied to develop NiFe-based alloys, with focus on their electrochemical characteristics toward oxygen evolution reaction during water electrocatalysis. The targeted electrocatalysts were designed by combining catalysis principles of absorption energy, electronic effect and geometry effect. Firstly, a one-step laser-based manufacturing method was applied to prepare a thin layer of NiFe-based electrodes with varied Ni to Fe ratios to replace high-cost noble metals as the electrocatalyst for oxygen evolution reaction (OER). Since each Ni has 0.6 d-vacancy and each Fe atom has 2.2 d-vacancies. The alloying of Ni-Fe allows electrons flowing from Ni to Fe, …

Material Properties Of Laser Powder Bed Fusion Processed 316l Stainless Steel, Steven Keckler

Graduate Theses & Non-Theses

Laser powder bed fusion additive manufactured 316L stainless steel specimens were evaluated to establish a baseline for future research in determining an optimized energy density and build orientation. Test specimens were printed at various energy densities. At each energy density, tensile and fatigue specimens were printed at 0o (longitudinal), 45o, and 90o (transverse) orientation to the build plate. Tensile and high cycle fatigue tests were performed then representative fracture surfaces were analyzed. The apparent melt track and dendrite size were evaluated using grain analysis software. Static loading of the tensile specimens showed a marginal difference in UTS for specimens with …

The Effects Of Varying Composition And Build Direction On Direct Metal Deposition Fabricated Inconel 718, Abigail P. Nilan, Jessica M. Fordham

Materials Engineering

Inconel 718 (IN718) is a popular wrought superalloy, and is currently being investigated for additive manufacturing (AM) applications in the aerospace industry. However, overaging and the presence of microcracks have caused a significant reduction in properties. The purpose of this study is to meet or exceed the mechanical properties of wrought IN718 by varying the composition and build direction of the AM alloy. Alternative compositions were selected with Oerlilon Metco’s Rapid Alloy Development (RAD) software, and differ in niobium content, which increases the fraction of the primary strengthening phase (γʺ). Direct metal deposition (DMD) was used to fabricate the samples, …

Anomalous 304 Stainless Steel Mechanical Properties In Medical Guide Wires, Andrew Joseph Freeman

Materials Engineering

Stainless steel medical guide wire cores, processed by Abbott Vascular, are returning anomalous mechanical properties upon strain hardening and heat treatment. As theory dictates, mechanical strength properties increase with strain hardening, and decrease with an annealing treatment. The opposite response is being observed. This is counter intuitive to fundamental materials knowledge, and a perfect materials engineering paradox. This project was designed to characterize these behaviors, and attempt to determine causation. To accomplish this, tensile testing of all processing steps mapped the mechanical property evolution of the wire. Published literature research revealed the potential of nitrogen and chromium solid state diffusion …

Effects Of Head Formation And Heat Treatment On The Mechanical Properties Of Connecting Rod Bolts, Caleb A. Leavitt, Matthew R. Lauretta

Materials Engineering

Oliver Racing Parts (ORP; Charlevoix, Michigan) is looking to optimize their manufacturing process for high-strength connecting rod bolts. A high yield strength is desired for the bolts because deformation would result in catastrophic engine failure. The bolts were made of H11, a chromium hot-work tool steel; and MLX17, a precipitation hardenable stainless steel. Tensile testing was performed to determine the tensile and yield strengths of the bolts. Fracture surfaces were imaged via scanning electron microscopy to characterize the failure modes. To observe the effects of bolt heading on microstructure and bolt strength, two batches of MLX17 were prepared; one batch …

Investigation Of Narloy-Z Yield Strength In Response To Changes In Ingot Processing And Heat Treatment, Stanley C. Goto, Sarah E. Wattenberg

Materials Engineering

This study investigates the effect of cooling rate on the yield strength of NARloy-Z. NARloy-Z is a copper-based alloy with 3 wt.% silver and 0.5 wt.% zirconium. The types of NARloy-Z were classified by the ingot processing (old or new) and the material lot (old or new). There were three variations of NARloy-Z in this study: old processing and material (Old/Old); old processing and new material (Old/New); and new processing and material (New/New). NARloy-Z undergoes a braze thermal cycle and age (BTCA) heat treatment for its application, and a single cooling rate within the BTCA was manipulated in this study. …

Temper Response Of A Vanadium Microalloy Steel, Bradley W. Hostetler

Materials Engineering

This investigation details the effect of a quench-and-temper processing treatment on the mechanical properties of a microalloy steel being considered for use as a pipeline flange. Microalloy steels are normally processed via Thermo-Mechanically Controlled Processing (TMCP) due to the increased strength from ferrite grain refinement; however, the geometry of a pipeline flange requires post processing beyond TMCP which diminishes the strengthening effect provided by TMCP. The purpose of this research project is to determine the mechanical properties produced when a vanadium microalloy steel is quenched and tempered. The two major considerations are the effect of tempering time on properties and …

In Situ Sem Solidification Study Of Ga And Egain: A Characterization Technique For Monitoring The Microstructural Evolution Of Liquid Metals, Jeremy Geovann Del Aguila

Materials Engineering

Scanning electron microscopy (SEM) video recording is used to characterize the solidification of small volumes of 99.999% pure gallium (Ga) and eutectic gallium-indium (eGaIn) under a high vacuum environment. Specimen are superheated to 55℃ using a hot plate, cast into spherical droplets, and cooled in situ by means of a Peltier cooling stage. Special attention is given to the preparation of the specimen prior to viewing because of gallium and its alloys’ nature to form an oxide layer when melted and air cooled. The oxide acts as a skin that inhibits the observation of microstructural features during solidification. Heated samples …

An Evaluation Of Ultrasonic Shot Peening And Abrasive Flow Machining As Surface Finishing Processes For Selective Laser Melted 316l, Rhys Gilmore

Master's Theses

Additive Manufacturing, and specifically powder bed fusion processes, have advanced rapidly in recent years. Selective Laser Melting in particular has been adopted in a variety of industries from biomedical to aerospace because of its capability to produce complex components with numerous alloys, including stainless steels, nickel superalloys, and titanium alloys. Post-processing is required to treat or solve metallurgical issues such as porosity, residual stresses, and surface roughness. Because of the geometric complexity of SLM produced parts, the reduction of surface roughness with conventional processing has proven especially challenging. In this Thesis, two processes, abrasive flow machining and ultrasonic shot peening, …

The Incorporation Of Graphene To Lithium Cobalt Oxide As A Cathode To Improve The Performance Of Lithium Ion Batteries, Kenan Wang

Graduate Theses and Dissertations

One of the objectives of this thesis work was to investigate the cathode performance of lithium cobalt oxide (LiCoO2) incorporated with graphene powder in lithium ion batteries (LIBs). Graphene powder was incorporated into cathode materials to enhance the performance of LIBs. The other objective was to impede the construction of a solid electrolyte interphase (SEI) sheet using graphene sheet coating on its cathode.

The results of this work show that adding graphene powder improved the performance of LiCoO¬2 as a cathode material. With the incorporation of different weight percentages of graphene powder, the LiBs showed distinct changes in their charging …

Self-Assembled Barium Titanate Nanoscale Films By Molecular Beam Epitaxy, Timothy Allen Morgan

Graduate Theses and Dissertations

One challenge of investigating ferroelectrics at the nanoscale has been controlling the stoichiometry during growth. Historically, the growth of barium titanate (BaTiO3) by molecular beam epitaxy has relied on a growth technique called shuttered RHEED. Shuttered RHEED controls the stoichiometry of barium titanate through the precise deposition of alternating layers of BaO and TiO2. While this approach has achieved 1% control of stoichiometry, finding self-limiting mechanisms to lock-in stoichiometry has been the focus of the growth community. The Goldschmidt tolerance factor predicts an unstable perovskite when barium sits in the titanium lattice site. The BaO-TiO2 phase diagram predicts a low-solubility …

Fabrication And Characterization Of Graphene Based 2d Materials For Supercapacitors, Anishkumar Manoharan

Graduate Theses and Dissertations

Supercapacitors have attracted a lot attention due to their efficient energy storage. In comparison to batteries, supercapacitors have high capacitance, energy, and power densities per unit mass than conventional capacitors. Carbon based materials are most promising in supercapacitor application due to their outstanding physical and electrochemical behavior. In this work, a facile method to synthesize a nanocomposite electrode consisting of annealed carbon from carbon ink and MoS2 was demonstrated. Effects of various aqueous and solid electrolytes were studied. It was found that the nanocomposite electrode with 10% MoS2 and 1M Na2SO4 as the aqueous electrolyte tested using the three electrode …

Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli

Electronic Theses and Dissertations

Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of process-structure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the …

Evolution Of Mg Az31 Twin Activation With Strain: A Machine Learning Study, Andrew D. Orme

Undergraduate Honors Theses

Machine learning is being adopted in various areas of materials science to both create predictive models and to uncover correlations which reveal underlying physics. However, these two aims are often at odds with each other since the resultant predictive models generally become so complex that they can essentially be described as a black box, making them difficult to understand. In this study, complex relationships between microstructure and twin formation in AZ31 magnesium are investigated as a function of increasing strain. Supervised machine learning is employed, in the form of J-48 decision trees. In one approach, strain is incorporated as an …

Evaluation Of Metallurgical And Mechanical Properties Of Alsi10mg Produced By Selective Laser Melting, Luke J. Suttey

Graduate Theses & Non-Theses

Selective laser melting (SLM) additive manufacturing (AM) of metal powders has long been a focus in the study of AM due to the possibility of weight reduction, complex shape formation, and production cost savings. Although applicable to a variety of metals SLM AM of the AlSi10Mg alloy was studied in an attempt to characterize the effect of processing parameter and build angle variation on the final microstructural, fractographic, and mechanical properties of parts produced without any thermal post-processing techniques. Research was conducted on five build angles (0°, 30°, 45°, 60°, and 90°), and three Global Energy Densities (GED) (37.15, 45.39, …

Investigations Of Solid-State Sintering Behavior Of Binary Refractory Metal Oxide Systems, Maureen Chorney

Graduate Theses & Non-Theses

Refractory metals are commonly alloyed for improved corrosion resistance, thermal stability, and strength. In service, these alloys form highly stable oxides under mildly oxidizing conditions at relatively low temperatures. In order to recycle these materials, high temperature electrochemical processing is required to reduce the refractory metal oxides. To abet experimental evaluation of the electrochemical reduction process under development at the Idaho National Laboratory, binary mixtures of selected refractory metal oxide powders were sintered to produce cathode pellets, which could be suspended in the molten salt electrolyte during reduction experiments. Preparatory literature review revealed a paucity of published information relative to …

Characterization Of Process Induced Defects In Laser Powder Bed Fusion Processed Alsi10mg Alloy, Edward Stugelmayer

Graduate Theses & Non-Theses

Additive manufacturing using laser powder bed fusion (AM-LPBF) methods have recently experienced rapid growth and development, having the potential to replace manufacturing by plastic deformation, precision machining, or casting. AM offers advantages such as the freedom to design highly complex geometries, time and cost savings through material usage efficiency and shortened production cycles, and the potential for improved mechanical properties. Process induced defects, however, result in degradation and scattering of mechanical properties and hinder the widespread adoption of AM-LPBF in industry. This investigation focuses on the effects of varying energy density and build orientation on the evolution of process induced …

Study On The Surface Features Of Preg-Robbing Carbonaceous Matter During Oxidation Treatment, Mana Pourdasht

Electronic Thesis and Dissertation Repository

Carbonaceous gold ores have the ability to adsorb gold (I) cyanide from leach solutions during processing. This phenomenon, known as preg-robbing, is responsible for poor recoveries as the carbonaceous materials of the ore compete with activated carbon used during the leaching and adsorption phase of processing. Chemical oxidation of carbonaceous materials by different reagents has been utilized to investigate and compare the mechanism of Au (CN)₂ adsorption onto carbonaceous materials prior to and following the treatment.

The procedure for characterization of the carbonaceous materials (plain and modified) in the sample combines the use of several analytical techniques and test …

Measurement Of Planar Fault Probabilities In Austempered Ductile Iron And 304l Stainless Steel, Nathan Peterson

Dissertations, Master's Theses and Master's Reports

During plastic deformation both stacking and twin faults can be generated in face-centered cubic materials, including iron-based metals that contain thermally stable austenite. These planar faults are a critical component of the austenite to martensite transformation, forming shear bands that can act as nucleation sites. The measurement of these faults via x-ray diffraction has been long established, however it has not been applied widely to austempered ductile irons. The ability to measure these faulting probabilities could give insights into the transformation as a function of deformation. In this work both planar fault densities were measured in austempered ductile iron to …

Synthesis And Characterization Of Magnesium - Titanium Composites By Severe Plastic Deformation, Baleegh Alobaid

Theses and Dissertations--Chemical and Materials Engineering

Magnesium alloys are widely used in engineering applications, including aerospace and automobile industries, due to their desirable properties, such as lower density, high damping capacity, relatively high thermal conductivity, good machinability, and recyclability. Researchers have, therefore, been developing new magnesium materials. However, mechanical and corrosion properties are still limiting many commercial applications of magnesium alloys. In this Ph.D. thesis research, I developed Mg-Ti composite materials to offer some solutions to further improve the mechanical behavior of magnesium, such as titanium-magnesium (Ti-Mg) claddings, Mg-Ti multilayers, and Ti particle enforced Mg alloys. Low cost manufacturing processes, such as hot roll-bonding (RB) and …

Effects And Limitations Of Residual Alloying Elements In Silicon Solid Solution Strengthened Ferritic Ductile Iron, Julia Scruton

Dissertations, Master's Theses and Master's Reports

Transitioning from traditional grades of ductile iron to solution strengthened ferritic ductile iron (SSFDI) grades can be difficult because of the need to reduce the amount of pearlite promoting elements, particularly copper and manganese, which are used in traditional grades. Knowing the acceptable threshold of residual alloying elements will allow for more cost-effective tailoring of the charge stream. Data were generated from a series of casting trials with the target grade of EN-GJS-500-14 where the levels of copper and manganese were varied from 0.05% to 0.3% and 0.15% to 0.4% respectively while maintaining silicon in the 3.8%-4.3% range. The pearlite …

Effect Of Chromium Content On Heat Treatment Behavior And Abrasive Wear Resistance Of Multi-Alloyed White Cast Iron, Jatupon Opapaiboon

Chulalongkorn University Theses and Dissertations (Chula ETD)

The effect of Cr content on heat treatment behavior and abrasive wear resistance of multi-alloyed white cast irons with basic composition was investigated. The cast irons with varying Cr content from 3-9% were prepared. The annealed specimens were hardened from 1323K and 1373K austenitizing and then, tempered at 673K to 873K with 50K intervals. The microstructure of each specimen consisted of primary austenite dendrite (γP) and (γ+MC) and (γ+M2C) eutectics in specimens with 3 and 5%Cr. By contrast, (γ+M7C3) eutectic appeared in specimens with 6%Cr and more. The matrix in as-cast state was mostly retained austenite but that in as-hardened …

การศึกษาสมบัติการหน่วงแรงสั่นสะเทือนด้วยวัสดุเพื่อใช้ในฐานวางชิ้นงานสำหรับกระบวนการขัดสีความเที่ยงตรงสูง, ศิรวิทย์ ดวงทวี

Chulalongkorn University Theses and Dissertations (Chula ETD)

แรงสั่นสะเทือนที่เกิดขึ้นระหว่างกระบวนการขัดสีความเที่ยงตรงสูงเป็นตัวแปรหนึ่งที่ส่งผลให้คุณภาพผิวของชิ้นงานเซรามิคชนิด AlTiC ที่ถูกขัดสีลดลง โดยที่การควบคุมแรงสั่นสะเทือนนั้นอาจหมายถึงการควบคุมคุณภาพผิวชิ้นงานเซรามิคชนิด AlTiC ที่จะได้จากกระบวนการขัดสีนั้นๆ สำหรับงานวิจัยนี้ได้ทำการศึกษาสมบัติการหน่วงแรงสั่นสะเทือนของวัสดุที่ใช้ทำฐานวางชิ้นงานในกระบวนการดังกล่าว ซึ่งจะช่วยให้มีการลดลงหรือยับยั้งแรงสั่นสะเทือนที่เกิดขึ้นระหว่างกระบวนการ ในงานวิจัยนี้ได้มีการเลือกใช้วัสดุโลหะที่มีใช้อย่างแพร่หลายในทางวิศวกรรมและสามารถนำมาใช้เพื่อทำฐานวางชิ้นงานได้ ได้แก่ อะลูมิเนียม ทองแดงอัลลอยด์ และ เหล็กกล้าไร้สนิม โดยที่ทำการทดสอบเพื่อวัดค่า damping ratio ซึ่งเป็นค่าที่ใช้บอกถึงสมบัติการหน่วงแรงสั่นสะเทือน นอกจากนี้ยังได้เลือกวัสดุพอลิเมอร์(Polymer) ทางการค้ามาใช้ร่วมกับวัสดุโลหะ(เหล็กกล้าไร้สนิมเกรด 304) ในรูปแบบของวัสดุผสมโดยคาดว่าจะได้ผลของค่า damping ratio ที่สูงมากขึ้น หรือมีการหน่วงแรงสั่นสะเทือนที่ดีขึ้น สำหรับวัสดุพอลิเมอร์ที่ใช้ในงานวิจัย ได้แก่ ซิลิโคน(silicone rubber), เทอร์โมเซตโพลียูรีเทน(thermosetting polyurethane), เทอร์โมพลาสติกโพลียูรีเทน(thermoplastic polyurethane, TPU) และ ไนลอนโพลีเอไมด์12(Nylon 12) ที่ความแข็งต่างกัน 2 ชนิด ในการทดลองเพื่อหาค่า damping ratio จะใช้ชิ้นงานที่มีขนาด 6 มิลลิเมตร x 20 มิลลิเมตร x 120 มิลลิเมตร ทำการให้แรงกระทำต่อชิ้นงานและตรวจวัดในช่วงของค่าความถี่ตอบสนองของชิ้นงานนั้นๆ แล้วจึงนำค่าแรงสั่นสะเทือนที่ได้มาคำนวณหาค่า damping ratio ต่อไป ซึ่งผลที่ได้จากการวิจัยพบว่าวัสดุโลหะที่ได้ค่า damping ratio สูงที่สุด คือ เหล็กกล้าไร้สนิมเกรด 304 มีค่าเท่ากับ 0.0398 และ วัสดุผสมพอลิเมอร์ชนิด TPU มีค่า damping ratio สูงที่สุดที่ 0.0802 และยังสูงที่สุดจากวัสดุทั้งหมดที่นำมาทดลอง และเมื่อนำไปใช้ในฐานวางชิ้นงานจริงยังพบว่าฐานวางชิ้นงานที่เสริมด้วยพอลิเมอร์ชนิด TPU ให้ผลค่าเฉลี่ยความหยาบผิวที่ต่ำที่สุดหรือมีคุณภาพผิวชิ้นงานที่ดีที่สุด โดยมีค่า 1.28 นาโนเมตร และมีค่าเฉลี่ยกำลังสองของความหยาบผิว เท่ากับ 1.59 นาโนเมตร