Influence of Heat Treatment Process on the Structures and Properties of Grate Bars Used in Sintering Trolley

2014 ◽  
Vol 697 ◽  
pp. 95-101
Author(s):  
An Min Li ◽  
Ding Ma ◽  
Qi Feng Zheng ◽  
Ruo Huai Chen ◽  
Zu Jiang Huang ◽  
...  

The as-cast structure of grate bar used in sintering trolley is primarily comprised of austenite and eutectic (eutectic austenite and eutectic carbide). The austenite is dendrite, while the carbide is reticular and chrysanthemum-like. The grate bars were quenched and tempered under various temperature (one set of samples: quenching (975~1050°C); the other: quenching (1000°C) + tempering (240~600°C)). With rise in quenching temperature, the content of martensite increases and gradually stabilizes, and the hardness increases and then decreases (the maximum is 61.5HRC). For the tempered simple, the strip-like carbides gradually become smaller, shorter and homogenized; the resistance to temper softening is high and the maximum hardness is 58HRC; the wear resistance gradually decreases and is lower than that of as-cast one when the temperature is higher than 480°C. The heat treatment process to improve the service properties of grate bars is: quenching (1000°C, 2.5h, and air-cooling) + tempering (300~420°C, 2.5h, and air-cooling).

Author(s):  
Pengjun Cao ◽  
Yilong Zhang ◽  
Kejian Li ◽  
Jiling Dong ◽  
Wei Wu

Abstract The 25Cr2MoVA steel was subjected to various heat treatments. We found that the hardness increased when the quenching temperature was in the range of 870 – 910 °C, and then it decreased for the temperature of 910 – 990 °C. The maximum hardness was 553 HV after quenching from 910 °C. Following quenching from 910°C, the 25Cr2Mo-VA steel was tempered in the temperature range of 560 to 750 °C. With an increase in the tempering temperature, the hardness and tensile strength of the material decreased, while the impact toughness increased; the corrosion resistance increased initially and then decreased. The best heat treatment process for the 25Cr2MoVA steel involved quenching form 910 °C and tempering at 650°C for 1 h, the hardness was 362 HV, the tensile strength reached 1 310 MPa, the impact energy reached 149 J, and the material exhibited the best corrosion resistance.


2015 ◽  
Vol 1120-1121 ◽  
pp. 1109-1114
Author(s):  
Xin Lei ◽  
Hui Huang ◽  
S.P. Wen

This study investigated the mechanical properties and microstructures of Er-containing Al–Mg alloys. The research found that the H114-T sheet of Er-containing Al–Mg alloys showed a relative good comprehensive performance in mechanical properties. With the special rolling and heat treatment process, this H114-T sheet showed different morphology of microstructures with the other sheets in Er-containing Al–Mg alloys. Grains in H114-T sheet performed irregular shape polygon, a number of subgrains appeared in grains, the amount of dislocations in grains decreased. H114-T sheet possessed a lot of Copper texture, this may be one of important factors influenced the mechanical properties.


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1302
Author(s):  
Zhongnan Xiang ◽  
Zhanjiang Li ◽  
Fa Chang ◽  
Pinqiang Dai

In this paper, the effect of heat treatment on the microstructure and properties of a 0.8 μm WC–10%Co ultrafine cemented carbide was studied. The results show that the microstructural differences in ultrafine WC–Co cemented carbides without and with heat treatment are mainly reflected in the Co phase. For conventional cemented carbides, the hardness and wear resistance can be increased only at the expense of the toughness and strength. An ultrafine-grained WC–Co cemented carbide with good hardness and toughness can be obtained by strengthening the Co phase through an appropriate heat treatment process, and the service life of the ultrafine-grained WC–Co cemented carbide can be improved under actual cutting conditions.


2011 ◽  
Vol 284-286 ◽  
pp. 273-276
Author(s):  
Li Sheng Zhong ◽  
Yun Hua Xu ◽  
Xin Cheng Liu ◽  
Fang Xia Ye ◽  
Jing Lai Tian ◽  
...  

The method of infiltration casting plus heat treatment process employing chromium wires and cast iron applied to in-situ synthesized (Fe,Cr)7C3 particulates bundle reinforced iron matrix composites. The phase analysis, microstructure, microhardness and wear-resistance of composite were observed and measured. The results show that it is possible to fabricate (Fe,Cr)7C3 particulates bundle reinforced iron matrix composite produced by this technology, and a special structure which called particulates bundle was fabricated. (Fe,Cr)7C3 particulates bundle were distributed in the forms of granular, lath-shaped and hexagon-shaped in the particulates bundle. The macrohardness of particulates bundle was 52 HRC, and the relative wear resistance of the composites is 2.3—23 times higher than that of the cast iron.


2015 ◽  
Vol 727-728 ◽  
pp. 322-326 ◽  
Author(s):  
Shi Lu Zhao ◽  
Zhen Zhang ◽  
Lian Chong Qu ◽  
Jun Zhang ◽  
Jian Ming Wang ◽  
...  

Effects of heat treatment process of quenching and tempering under different temperature conditions on mechanical properties of X70 grade pipeline steel bends were studied. Brinell hardness, yield strength, tensile strength, elongation and impact absorbing energy of the bends were tested by using hardness tester, cupping machine and impact testing machine, respectively. It shows that the best heat treatment process of the X70 grade pipeline steel bends is quenching at 890 °Cand thermal insulation for 26 min then water cooling followed by tempering at 590 °C and thermal insulation for 60 min then air cooling. Furthermore, the resulting hardness, yield strength, tensile strength, yield ratio, elongation and impact absorbing energy reach HB230, 595 MPa, 725 MPa, 0.82, 28% and 300 J respectively, which has excellent comprehensive mechanical properties.


Author(s):  
Nelu CAZACU ◽  
◽  
◽  

The paper is based on laboratory experiments of heat treatments applied to samples of A537/A537M steel. The work continues other previous works aimed at modifying structures and properties of this steel, including through surface treatments. The experiments were performed using Taguchi methods from Quality Engineering. A number of four factors were selected as influencing the structure after heat treatment: heating temperature for hardening, cooling rate on hardening, time and tempering temperature. A number of nine experiments were performed using an L9 orthogonal matrix. Objective function was changed to maximum hardness after the heat treatment regime. The results show that the tempering temperature has the greatest influence on the final hardness of the A537 steel samples.


2012 ◽  
Vol 706-709 ◽  
pp. 1580-1585
Author(s):  
Hai Liang Yu ◽  
Jin Wu Kang ◽  
Tian You Huang

Blades are key part of hydro turbines, which often distorts during heat treatment process for their special structures. In this paper, thermal fluid finite element simulation of the forced air cooling process of a blade casting was carried out under a variety of distances between fans and blades, air speeds, groups of fans and circumstance temperatures. The temperature fields of blade castings were obtained. A novel parameter, temperature difference between surfaces of castings along thickness direction, was proposed to analyze the distortion of blade castings. The distortion behavior of blade castings with martensitic stainless steel were discussed, which is in good agreement with distortion regularity of the experimental ones. The temperature differences between blade casting surfaces are always greater than zero, resulting in distortion which could be divided into three stages. Finally, we focused on discussing the control methods of distortion behavior of blade castings which could be operated in actual production.


2007 ◽  
Vol 561-565 ◽  
pp. 2283-2286 ◽  
Author(s):  
T.Y. Hsu ◽  
Zu Yao Xu

For steel with combination of high strength (~2000MPa) and toughness, along with low cost, the designed structure should be low-temperature tempered, fine lath martensite with high density of dislocation, coated by film of austenite with considerable thickness and distributed with fine ε (η) or (and) complex carbide. Correspondently, the steel should contain less than 0.5 (wt%) of carbon, certain amount of alloying elements for lowering Ms, such as Ni, Mo and (or) Mn, carbide forming element, e.g. Nb, as well as Si or (and) Al, the element depressing the formation of cementite, the brittle phase in high strength steel. The heat treatment process is suggested as: austenitizing at a temperature slightly above Ac3, followed by quenching at Ms-Mf, partitioning either at quenching temperature or at slightly above Ms for a few minutes, cooling down to room temperature and tempering at low temperature about half an hour.


2013 ◽  
Vol 648 ◽  
pp. 50-54
Author(s):  
Chun Yan Wang ◽  
Hong Sheng Ding ◽  
Zhi Fang Cheng ◽  
Li Geng Zhao

Cutting steel is required to have high wear resistance with certain hardness and deformation resistance. The commonly used machinery material for meat processing in china is 4Cr13, which is far inferior to the imported German steel X80CrVMo13-2. After studying the influence of different heat treatment process on its wear resistance, we have come to the following conclusion: X80CrVMo13-2 steel, after quenched at 1050°C and tempered at 500°C, has an excellent wear resistance and 4Cr13 steel, after normalized at 1010°C and tempered at 500°C has a fairly good wear resistance.


2013 ◽  
Vol 820 ◽  
pp. 15-19
Author(s):  
Xiao Dong Du ◽  
Zi Li Song ◽  
Yi Qing Chen ◽  
Jia Qing Wang ◽  
Guang Fu Liu ◽  
...  

This paper describes the influence of heat treatment process on the microstructure and properties of a new martensitic stainless steel, which contains 0.7% carbon, 17% chromium and 1% molybdenum and can be used as kitchen knives and scissors. The microstructure and properties of the tested alloys after quenching at 980 - 1100 °C and low tempering were investigated by means of optical microscope (OM), scanning electron microscope (SEM), Rockwell hardness tester and impact tester. The results show that the microstructure consists of acicular martensite, carbides and a litter retained austenite after quenching and tempering. The carbides are mainly (Fe,Cr)23C6. The content of retained austenite increases with the increase of the quenching temperature. The solubility of carbon in martensite changes similarly. The martensite gets coarser as the quenching temperature increasing. The maximum value of hardness is 59 HRC, when the quenching temperature is 1060 °C. The impact toughness increases when the quenching temperature increases from 980 °C to 1080 °C and then decreases. The suitable heat treatment process for this alloy is quenching at 1060 °C~1080 °C for 30 min and then tempering at 200°C.


Sign in / Sign up

Export Citation Format

Share Document