Connect with us

Material

Constitutive relationships of 21-4 N heat-resistant steel for the hot forging process

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Xiaomin Huang, Baoyu Wang, Yong Zang, Hongchao Ji, Ben Guan, Yiming Li, Xuefeng Tang

Republished by Plato

Published

on

open access

Abstract

The Gleeble-1500D thermal simulator was used for the isothermal compression test of 21-4N heat-resistant steel under the T range of 1273–1453 K and

ε˙

of 0.01–10s−1. Using the obtained stress – strain data, various parameters of the Fields–Backofen (F-B), the modified F–B (m–F–B) equations and the modified Zerilli–Armstrong (m–Z–A) equations were calculated respectively. The constitutive equations of 21-4N heat-resistant steel based on the F–B, the m–F–B and the m–Z–A were established. Second, the predictive ability of the three constitutive equations were evaluated using the correlation coefficient (R), average absolute relative error (AARE) and the relative error (r). Third, the established model was imported into Deform-3D to simulate the valve forging process of 21-4N heat-resistant steel, and the distribution rules of the effective stress, effective strain, temperature and damage condition of the forging were analyzed. Finally, a hot forging experiment was performed on a 160t hot die forging press. Results show that the flow stress of 21-4N heat resistant steel is affected by temperature, strain rate and strain. The m–F–B and m–Z–A models can describe the rheological behavior of 21-4N heat-resistant steel, while the original F–B model has a high predictive ability, but only under low temperature, low strain rate and small deformation. The simulation process can be completed successfully, indicating that the established models can be used for the simulation study of the thermal deformation of 21-4N heat-resistant steel and all models are correct. The results can provide some important basic data for the simulation of 21-4N heat resistant steel in the plastic deformation process.

Keywords

Fields–Backofen model

Zerilli–Armstrong model

21-4N

Hot deformation behavior

Constitutive model

Finite element simulation

© 2020 The Authors. Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318317?dgcid=rss_sd_all

Material

Evaluation of microstructural effects on corrosion behavior of AZ31B magnesium alloy with a MAO coating and electroless Ni-P plating

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Chi-An Chen, Shun-Yi Jian, Chia-Hsin Lu, Chia-Yu Lee, Salim Levent Aktuğ, Ming-Der Ger

Republished by Plato

Published

on

open access

Abstract

A bi-layer coating is deposited on the surface of the AZ31B Mg alloy for corrosion protection of the Mg alloy. The bi-layer coating is composed of a micro-arc oxidation coating (MAO), and an electroless plated Ni-P coating. The micro-arc oxidation (MAO) treatment in the electrolyte with or without the addition of phosphate ions is carried out under unipolar power mode. The microstructure and composition of the MAO coatings are analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The roughness of the MAO coatings is obtained by using 3D white light interferometry. The corrosion resistances are evaluated by potentiodynamic polarization test as well as electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution and salt spray test. The adhesion test results of the MAO/Ni-P composite coatings by drawing test machine. The results showed that the micro-pores size of the MAO coating treated in the phosphate-free bath is uniform and smaller than the phosphate-containing solution, which could decrease the roughness and enhance the corrosion resistance. The corrosion resistance of MAO coating with the phosphate-free solution for 2.8 times was better than that of phosphate-containing solution. Moreover, phosphate-free MAO/Ni-P composite coating showed the corrosion rate is more than 4 times lower than the phosphate-containing MAO/Ni-P composite coating. Furthermore, the MAO/Ni-P composite coatings prepared by the MAO coating treated in the phosphate-free bath could suppress the erosion of aggressive media during exposure after 120 h salt spray test (corrosion area is approximately 5%) and present excellent adhesion.

Keywords

AZ31B magnesium alloy

MAO

Electroless Ni-P plating

Adhesion

Corrosion resistance

© 2020 The Authors. Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S223878542031824X?dgcid=rss_sd_all

Continue Reading

Material

Influences of impact energy on the densification and mechanical properties of powder metallurgical Fe–C–Cu preforms during a powder-forged process

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Biao Guo, Qiang Li, Hui Wu, Jinqing Ao, Qifeng Tang, Yu Zhang, Xiao Li, Yun Lu

Republished by Plato

Published

on

open access

Abstract

Accurate impact energy control is important for the success of the powder-forged (P/F) technique. This paper address how impact energy influences the densification and mechanical properties of powder metallurgical (P/M) preforms during a P/F process by combining finite element simulations and experiments. The simulated results coincide well with the experimental results. Results reveal that impact energy strongly influences the P/M preform densification by controlling their stress states and strain rate. The densification continuously proceeds throughout the P/F processing by the three steps of micro-pore compression, segmentation, and closure, while the densification uniformity gradually deteriorates in the earlier free upsetting step and then significantly improves in the later closed compressing step. The increased impact energy within the range below 56.3 J/cm3 induces a higher strain rate, and thus facilitates the P/M preform densification notably. Inversely, the excessive impact energy not only has less influence on the densification but also creates exceptionally high forging pressure. The notably increased density improves the mechanical properties of the P/F forgings significantly; meanwhile, the concomitant work hardening changes their tensile fracture modes and slows down their ductility rising. In this study, the P/F Fe–C–Cu forgings prepared at the optimized impact energy of 56.3 J/cm3 have a high and uniform density and good mechanical properties. This study can provide theoretical guidance for the rational process design of powder forging.

Keywords

Powder-forged

Impact energy

Finite element simulation

Densification

Mechanical properties

© 2020 The Authors. Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318081?dgcid=rss_sd_all

Continue Reading

Material

Cattaneo-Christov double diffusions (CCDD) in entropy optimized magnetized second grade nanofluid with variable thermal conductivity and mass diffusivity

Publication date: November–December 2020

Source: Journal of Materials Research and Technology, Volume 9, Issue 6

Author(s): Yu-Ming Chu, Faisal Shah, M. Ijaz Khan, Seifedine Kadry, Zahra Abdelmalek, Waqar A. Khan

Republished by Plato

Published

on

open access

Abstract

In this research communication, mathematical model is developed to scrutinize the two-dimensional magnetohydrodynamic boundary layer flow of non-Newtonian nanofluid (second grade) toward a permeable and stretchable Riga plate surface. To examined the thermal and solutal relaxation characteristics the proposed model of Cattaneo-Christov double diffusions (CCDD) model is supposed. Furthermore, variable thermal conductivity and variable mass diffusivity are accounted. In addition, the convective condition of heat transfer is involved. The concept of entropy generation is also highlighted. Formulation also consists of thermal radiation, mixed convection and thermophoresis. The resulting problems are computed by modern approach known as optimal homotopy analysis method (OHAM). OHAM is a powerful method to used for the series solution of highly non-linear equations in comparison to other analytical and numerical methods. Total square residual error is computed. Velocity distribution enhances for second grade fluid parameter but reverse trend is seen for larger estimation of inverse Darcy number. Temperature profile increases for larger estimation of thermal relaxation parameter and characterize temperature (

ɛ1

). Nanoparticles concentration decays for boost values of solutal relaxation parameter and characterize concentration (

ɛ2

). Physical arguments for important parameters of interest are organized.

Keywords

Non-Newtonian (second grade) fluid model

Cattaneo-Christov double diffusions (CCDD)

Nanofluid

Stretched Riga plate

Temperature dependent thermal conductivity and mass diffusivity

Entropy generation rate

© 2020 The Author(s). Published by Elsevier B.V.

Source: https://www.sciencedirect.com/science/article/pii/S2238785420318263?dgcid=rss_sd_all

Continue Reading
Heartland4 days ago

Web site credit card processing

Manufacturing3 days ago

New and Noteworthy Categories on Thomasnet.com for October 2020

Heartland4 days ago

CBG Study Shows Antimicrobial Properties of Cannabis

Heartland3 days ago

Medical Marijuana: 7 Incredible Health Benefits for Women

Heartland3 days ago

German Cannabis Flower Market is Ready to Explode

Heartland5 days ago

CBG tinctures

Heartland3 days ago

Thanks to these CBD “cigarettes” I am a full week tobacco/nicotine free 🎉

Heartland1 day ago

Medical Experts Discuss Uses of CBD (via JAMA — Top Medical Journal)

Heartland4 days ago

Find your perfect sleep system

Heartland3 days ago

Cybin Raises C$45 Million: The Largest Go Public Capital Raise in the Canadian Psychedelic Sector

Manufacturing4 days ago

Look ! so lovely and warm smile@v@

Heartland3 days ago

Will I get high from a gummy with 4.5 mg cbd and .5 mg thc? I have no tolerance.

Heartland3 days ago

Question on CBD vs CBG

Heartland2 days ago

Dosage for CBG/CBD tincture from LN?

Material4 days ago

Tribological characteristics of graphite epoxy composites using adhesive wear experiments

Heartland2 days ago

Indus Holdings, Inc. Welcomes Bruce Gates to Board of Directors; Announces Results of Annual Shareholder Meeting

Heartland3 days ago

National Cannabis Lobbying Falls, Again

Heartland3 days ago

Anyone begin CBD as a skeptic?

CBD1 day ago

CBD News Roundup: NFLPA Warns Players Not to Endorse CBD

Heartland1 day ago

CBD is a life-saver for me.

Heartland14 hours ago

Is There An Age Limit For CBD? [Is It 18 or 21?]

Heartland4 days ago

First Ever Harvest 🎃😈 15 Autos hanging to dry!

Heartland4 days ago

In need of some honest advice/opinions concerning the use of thc as a maladaptive coping mechanism and the use of cbd to combat it

Heartland3 days ago

Any success stories with smoking cessation?

Heartland3 days ago

BZA denies permit for hemp facility on Poplar

Material4 days ago

The inhibitive action of Calendula officinalis flower heads extract for mild steel corrosion in 1 M HCl solution

News3 days ago

The First Medical Cannabis Dispensary in Virginia has Opened its Doors

Heartland3 days ago

CBD Storefront 'The Green Room' Comes To Red Bank

Heartland3 days ago

How To Make CBD-Infused Face Masks At Home

Heartland3 days ago

Europe CBD Oil Market 2020 | Covid19 Impact Analysis | Business Outlook, Growth, Revenue …

Trending

A Cloud Nine Capital Entity Copyright © 2020 – All Rights Reserved Proudly Made in America