scholarly journals Establishment of a Rotary Print Head to Effect Residual Stresses and Interlayer Bonding in an FLM-Process

2021 ◽  
Vol 5 (3) ◽  
pp. 82
Author(s):  
Philipp Bengfort ◽  
Dennis Stracke ◽  
Bernd Künne
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
High Strength ◽  
Manufacturing Technology ◽  
Air Cooling ◽  
Crystalline Materials ◽  
Print Head ◽  
Forced Air ◽  
Interlayer Bonding ◽  
Research Show

In fused layer modeling (FLM) manufacturing technology, there is an increased demand for semi-crystalline materials due to their favorable mechanical properties, such as high strength and toughness. The reasons for their limited use are process-related residual stresses and reduced interlayer bonding, resulting in component distortion, warping and poor strength. Addressing these problems, this paper presents the development and implementation of a rotary print head that enables local laser pre-deposition heating and forced air cooling in the 2.5-dimensional FLM process. Samples of polypropylene are fabricated to investigate the effects of the modified process on residual stresses and interlayer bonding. The investigations show that local laser pre-deposition heating can positively influence the interlayer bonding. In combination with a reduction of the extrusion temperature and additional cooling, it is possible to considerably reduce the residual stresses. The results of this research show that pre-deposition heating and forced air cooling significantly improve the processability of semi-crystalline thermoplastics in the FLM process.

Deterioration of Mechanical Properties of High-Strength Pumpcrete after Exposure to High Temperatures

2010 ◽  
Vol 168-170 ◽  
pp. 564-569
Author(s):  
Guang Lin Yuan ◽  
Jing Wei Zhang ◽  
Jian Wen Chen ◽  
Dan Yu Zhu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
High Strength Concrete ◽  
Heating Temperature ◽  
High Strength ◽  
Air Cooling ◽  
Test Results ◽  
Strength Deterioration ◽  
Residual Compressive Strength

This paper makes an experimental study of mechanical properties of high-strength pumpcrete under fire, and the effects of heating rate, heating temperature and cooling mode on the residual compressive strength(RCS) of high-strength pumpcrete are investigated. The results show that under air cooling, the strength deterioration speed of high-strength concrete after high temperature increases with the increase of concrete strength grade. Also, the higher heating temperature is, the lower residual compressive strength value is. At the same heating rate (10°C/min), the residual compressive strength of C45 concrete after water cooling is a little higher than that after air cooling; but the test results are just the opposite for C55 and C65 concrete. The strength deterioration speed of high-strength concrete after high temperature increases with the increase of heating rate, but not in proportion. And when the heating temperature rises up between 200°C and 500°C, heating rate has the most remarkable effect on the residual compressive strength of concrete. These test results provide scientific proofs for further evaluation and analysis of mechanical properties of reinforced-concrete after exposure to high temperatures.

Study on Metallography Test of the Steel SPV490 for Atmospheric Storage Tank After Fire

2016 ◽  
Author(s):  
Zhou Fang ◽  
Weiwei Hu ◽  
Deyu Liu ◽  
Guanghai Li ◽  
Zhe Wang
Keyword(s):  
Mechanical Properties ◽  
Working Conditions ◽  
Storage Tank ◽  
High Strength ◽  
Air Cooling ◽  
Microscopic Structure ◽  
Water Cooling ◽  
Storage Tanks ◽  
Fire Temperature ◽  
Optical Microstructure

The fire process was simulated by the heat treatment to the Steel SPV490 of atmospheric storage tank, thereby obtaining the metal specimens in different fire temperature, holding time, and cooling modes. And as the temperature increases, the microscopic structure of Steel SPV490 changes under different working conditions, which could be shown in optical microstructure pictures after doing the interception, inlay, polishing, finishing to the specimens. The result shows that, the mechanical properties of the Steel SPV490 for storage tank changes as the temperature rising from the microscopic view. Nodulizing of the cementite in pearlite occurs, and the strength decreases when the high strength steel SPV490 of large atmospheric storage tanks under air cooling condition below 700 °C, however, it equivalents to the normalizing process, as the sorbite occurs in the steel, and the strength increases a bit when the temperature is above 900 °C. The water-cooling of steel SPV490 above 900 °C equivalents to the process of quenching. The occurrence of martensitic substantially increases the strength and the brittleness, and the elongation decreases rapidly.

Study on the Cooling Process of Low Yield Ratio 590-780MPa Grade Steel Plates for High-Rise Buildings

2011 ◽  
Vol 194-196 ◽  
pp. 292-295 ◽  
Author(s):  
Jian Kang ◽  
Zhao Dong Wang ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Structural Steel ◽  
High Strength ◽  
Ferrite Matrix ◽  
Yield Ratio ◽  
Steel Plates ◽  
Air Cooling ◽  
Soft Phase ◽  
Cooling Temperature ◽  
Ultra Fast Cooling

To develop 590/780MPa grade low yield ratio structural steel, the effects of ultra fast cooling (UFC) new process on microstructure and mechanical properties were investigated. The results showed that the low yield ratio and high strength can be obtained by proper phase compositions including relative soft phase and hard phase. For the process of UFC + air cooling, when UFC final cooling temperature was 521°C, 22.5% M-A second hard phases were distributed on bainite ferrite matrix in steel No.A2. The mechanical properties can meet requirement of 590MPa grade low yield ratio structural steel. For the process of air cooling + UFC, when UFC initial cooling temperature was 781°C, the multiphase composed of 28.3% ferrite and other bainite / martensite lath structure can ensure the high strength and low yield ratio of steel No.B1. And performance indexes can meet the requirement of 780MPa grade low yield ratio structural steel.

Air-Cooled Mn-Series Bainitic Steel as 5Mn2SiNbTi of Grade YS 415 to 550MPa for Seamless Steel Pipe

2011 ◽  
Vol 120 ◽  
pp. 471-474
Author(s):  
Chun Feng ◽  
Zhao Xi Shen ◽  
Yan Kang Zheng
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
High Strength ◽  
Control Rolling ◽  
Air Cooling ◽  
Bainitic Steel ◽  
Medium Temperature ◽  
Final Rolling ◽  
And Control ◽  
Seamless Steel

The mechanical properties and microstructure of Mn-series bainitic steel as 5Mn2SiNbTi after air cooling and tempering have been investigated in this paper. The results show that the investigated steel show high strength (tensile strength up to 671MPa), low toughness (20J at -30°C) after hot rolling (final rolling at 1050°C) and air cooling. Medium temperature tempering can improve the toughness, without sacrificing strength of the steel. After tempering at 450°C for 1h, the steel obtained 632MPa tensile strength, 467MPa yield strength, 140J impact energy at -30°C, remaining 25.0% elongation. It is indicated that the tested steel can gain excellent combination of strength and toughness without precious alloy adding, control rolling and control cooling.

Influence of Deformation and Coiling Temperature on Mechanical Properties of a High Strength Pipeline Steel

2005 ◽  
Vol 500-501 ◽  
pp. 597-604 ◽  
Author(s):  
A.M. Elwazri ◽  
D.Q. Bai ◽  
Fulvio Siciliano ◽  
Steve Yue
Keyword(s):  
Mechanical Properties ◽  
Low Voltage ◽  
Pipeline Steel ◽  
High Strength ◽  
Precipitation Strengthening ◽  
Air Cooling ◽  
Coiling Temperature ◽  
Voltage Imaging ◽  
Additional Control ◽  
Scanning Electron

One of the components required to successfully produce high strength pipeline steel is to optimize precipitation strengthening. Some high strength pipeline grades rely on increased levels of Nb; in these grades, it is important to ensure that all the Nb is effectively employed. It is generally accepted that choice of coiling temperature is critical in maximizing the Nb precipitation in ferrite. Additional control of this precipitation may be attained by deformation at these coiling temperatures, an approach termed ‘cool deformation’. In this work, steel specimens were heated to temperature of 1200°C and held at temperature for 20 minutes to ensure significant dissolution of Nb precipitates. Some specimens were aged at 400°C for times ranging from 10 minutes to 10 hours followed by air-cooling. Others were subjected to deformation at 400°C (‘cool deformation’) prior to aging. It was found that the cool deformation improves the mechanical properties by microstructure; both yield and tensile strengths are significantly higher than that of the aged only specimens. By using low voltage imaging on a field emission gun scanning electron microscopy (FE-SEM), precipitates were observed and identified. The effects of the thermal and cool deformation schedules on the precipitate characteristics are described in this paper.

Sign in / Sign up

Export Citation Format

Share Document