scholarly journals Effect of Galvannealed Coating Evolution during Press Hardening on RSW Weldability

2020 ◽  
Vol 99 (05) ◽  
pp. 156s-162s
Author(s):  
X. HAN ◽  
◽  
M. H. RAZMPOOSH ◽  
E. BIRO ◽  
Y. ZHOU ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Diffusion Layer ◽  
Treatment Time ◽  
Steel Substrate ◽  
Welding Process ◽  
Heat Treatment Time ◽  
Process Window ◽  
Diffusion Layer Thickness ◽  
Press Hardening ◽  
Shear Performance

Press-hardening steels (PHSs) are used in modern passenger vehicles to increase part strength while reducing vehicle weight to meet both environmental and safety regulations. To prevent oxidization and decarburization during heat treatment, some PHSs are coated with Zn (galvanized or galvannealed). Heating during the press-hardening process drives interdiffusion of Zn from the coating and the Fe from the steel substrate, forming a diffusion layer composed of -Fe phase (a Zn-Fe solid solution). The electrical resistance of the diffusion layer is a function of its thickness and Zn-Fe composition. Both the diffusion layer thickness and the Zn-Fe composition are dependent on the initial coating thickness and heat-treatment time/temperature conditions. Changes to the heat-treatment process shift the resistance spot welding process window by altering the resistance behavior of the material. If the shift in the process window is not accounted for during assembly welding, the welds produced may either be too small or exhibit expulsion, both of which will reduce the strength of the weld. This study showed increasing heat-treatment time shifted the process window toward lower current. A final combined processing window of 1.5 kA, which is suitable for industrial application, was obtained when taking into account the variation in heat-treatment time. The tensile shear performance was not affected by the heat treatment, as increased softening in the heat-affected zone at longer heat-treatment time canceled the strength gain from increasing nugget size.

Experimental Study on Mechanical Properties and Microstructure of 2.25Cr1Mo0.25V Steel by the Influence of Heat Treatment and Welding

2018 ◽  
Author(s):  
Qing Li ◽  
Guangxu Cheng ◽  
Mu Qin ◽  
Zaoxiao Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Base Metal ◽  
Arc Welding ◽  
Treatment Time ◽  
Welding Process ◽  
Heat Treatment Time ◽  
Evolution Of Microstructure ◽  
Welding Metal ◽  
Submerged Arc

In this paper, the mechanical properties and microstructural changes of 2.25Cr1Mo0.25V steel under different heat treatment and welding process were investigated. The heat treatment of steel during practical processing is taken as a reference. Different heat treatment time are used to obtain samples with different condition. Automatic submerged arc welding was used to obtain welding sample. The mechanical properties of different samples are obtained by tensile test; the evolution of microstructure and precipitates of different sample with heat treatment and welding was studied on scanning electron microscopy. The experimental results show that with the increase of heat treatment time, the strength of the samples decreases and the plasticity remains nearly constant. Heat treatment also affects the precipitation of carbides; the longer the heat treatment time is, the more precipitates are. Compared with the base metal, the welding metal sample has higher strength. The amount of precipitates in welding metal is much larger than it in base metal. The research on precipitation shows that there are different kinds of precipitates which have different morphologies in welding metal.

Low-temperature thermal pretreatment process for recycling inner core of spent lithium iron phosphate batteries

2020 ◽  
pp. 0734242X2095740
Author(s):  
Haijun Bi ◽  
Huabing Zhu ◽  
Lei Zu ◽  
Yong Gao ◽  
Song Gao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Heat Treatment Temperature ◽  
Lithium Iron Phosphate ◽  
Inner Core ◽  
Treatment Time ◽  
Iron Phosphate ◽  
Treatment Temperature ◽  
Heat Treatment Time ◽  
Physicochemical Changes

Spent lithium iron phosphate (LFP) batteries contain abundant strategic lithium resources and are thus considered attractive secondary lithium sources. However, these batteries may contaminate the environment because they contain hazardous materials. In this work, a novel process involving low-temperature heat treatment is used as an alternative pretreatment method for recycling spent LFP batteries. When the temperature reaches 300°C, the dissociation effect of the anode material gradually improves with heat treatment time. At the heat treatment time of 120 minutes, an electrode material can be dissociated. The extension of heat treatment time has a minimal effect on quality loss. The physicochemical changes in thermally treated solid cathode and anode materials are examined through scanning electron microscopy with energy-dispersive X-ray spectroscopy. The heat treatment results in the complete separation of the materials from aluminium foil without contamination. The change in heat treatment temperature has a small effect on the quality of LFP material shedding. When the heat treatment temperature reaches 300°C and the time reaches 120 minutes, heat treatment time increases, and the yield of each particle size is stable and basically unchanged. The method can be scaled up and may reduce environmental pollution due to waste LFP batteries.

Effect of Heat Treatment Condition on the Characteristics of MnO2 Added-Fe2TiO5 Ceramics for NTC Thermistors Using Local Iron Oxide

2018 ◽  
Vol 917 ◽  
pp. 64-68
Author(s):  
Wiendartun ◽  
Jaenudin Kamal ◽  
Dadi Rusdiana ◽  
Andhy Setiawan ◽  
Dani Gustaman Syarief
Keyword(s):  
Heat Treatment ◽  
Iron Oxide ◽  
Treatment Condition ◽  
Treatment Time ◽  
Heat Treatment Condition ◽  
Heat Treatment Time ◽  
Second Phase ◽  
Room Temperature Resistivity ◽  
Electrical Characteristics ◽  
Ntc Thermistor

A study on the effect of heat treatment condition on the characteristics of MnO2 added-Fe2TiO5 ceramics for NTC thermistor has been carried out. The ceramics were produced by pressing an homogenous mixture of Fe2O3 (local/ yarosite), TiO2 and MnO2 (2.0 mole %) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1050 °C for 3 hours in oxygen gas. Some sintered pellets were heat treated by heating them at 300 °C for 5, 15 and 25 minutes in Ar + 7% H2 gas. The XRD analyses showed that the Fe2TiO5 ceramics with and without heat treatment time had orthorhombic structure. No peak from second phase was observed from the XRD profiles. From the electrical characteristics data, it was known that the heat treatment could change the electrical characteristics of the Fe2TiO5 based-thermistor. The thermistor constant (B) and room temperature resistivity (ρRT) decreased with the increasing of heat treatment time. All ceramics made had thermistor characteristics namely B = 3459-7596 K and ρRT = 1.056-6936.062 MΩcm. Thermistor constant of the ceramics was relatively big, indicated that ceramics made from local iron oxide in this work fit the market requirement for NTC thermistor.

Effect of Heat Treatment on the Reactivity and Crystallinity of Coal-Char

2005 ◽  
Author(s):  
Shouyu Zhang ◽  
Junfu Lu ◽  
Jianmin Zhang ◽  
Qing Liu ◽  
Guangxi Yue
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Treatment Time ◽  
Treatment Temperature ◽  
Coal Char ◽  
Heat Treatment Time ◽  
Heat Treat ◽  
Heat Treated ◽  
Layer Stacking ◽  
Crystalline Growth

The effect of heat treatment on the reactivity and crystallinity of char prepared from the vitrinite of two coals (YX, JJ) was investigated by using XRD and TGA in this paper. The results from TGA show that the reactivity of the chars from YXV and JJV decreases with the increase of heat treatment temperature. The reactivity of YXV char decreases quickly and significantly as heat treatment time increases. However, after heat treatment time of 60 min, it decreases slowly. The effect of heat treatment time on the reactivity of JJV char is small. The results from XRD show that the crystallinity of coal-char is determined by the intensity of heat treatment. When heat treatment time is more than 60 minutes, the turbostratic crystallite of YXV char prepared under 900°C changes remarkably and becomes more orderly. The aromatic layer stacking heights (Lc) of YXV Char when heat treated above 900°C increased with the increase of heat treatment time. The effect of heat treat time on Lc of JJV char is small, but under heat treatment temperature of 1200°C, the crystalline of JJV char grows distinctly. There is a good parallel relationship between the crystalline growth and deactivation of the chars. It can be concluded that the growth of the crystalline is the main reason for the deactivation of coal-char.

Post heat treatment time induced distinguished superconducting features of JR Nb3Al wires rapidly heated around the Tc peak condition

2019 ◽  
Vol 110 ◽  
pp. 106482 ◽  
Author(s):  
Changkun Yang ◽  
Xiaguang Sun ◽  
Pingyuan Li ◽  
Zhou Yu ◽  
Yongliang Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Heat Treatment Time ◽  
Post Heat Treatment
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