Microstructures and mechanical properties of surface and center of carburizing 23Cr2Ni2Si1Mo steel subjected to low-temperature austempering

2016 ◽  
Vol 670 ◽  
pp. 166-177 ◽  
Author(s):  
Yanhui Wang ◽  
Zhinan Yang ◽  
Fucheng Zhang ◽  
Dongdong Wu
2017 ◽  
Vol 898 ◽  
pp. 104-110 ◽  
Author(s):  
Peng Qi ◽  
Bo Long Li ◽  
Wen Jian Lv ◽  
Tong Bo Wang ◽  
Zuo Ren Nie

The effect of the different electromagnetic stirring frequency after low temperature pouring on microstructures and mechanical properties of Al-7Si-0.42 Mg-0.1Cu alloys was studied. It was found that the primary α-Al becomes smaller and tended to be spherical morphology, and the particles were uniformly distributed after electromagnetic stirring. The tensile strength of alloys improved gradually from 193.02 MPa to 212.54 MPa, and the elongation increased from 3.73% to 6.67% when the stirring frequency was 10 Hz. From the fracture morphology, the fracture for alloy stirred at frequency of 10 Hz showed more dimples than that without stirring. When the stirring frequency increased to 15 Hz, the microstructures of primary α-Al appeared to be dendritic structures, and the grains became coarse. As a result, the 10 Hz was the best electromagnetic stirring frequency.


2011 ◽  
Vol 194-196 ◽  
pp. 165-168
Author(s):  
Wang Xiao ◽  
Zuo Cheng Wang ◽  
Xie Bin Wang ◽  
Xian Da Li ◽  
Jun Qing Gao ◽  
...  

To lower the fracture appearance transition temperature (FATT) of Nb-treated HSLA H-beams further, boron-nickel-added Nb-treated HSLA H-beams were tempered after they were quenched at 870, 910 and 950°C respectively. Microstructures and mechanical properties, especially low temperature toughness of the experimental steels were investigated by scanning electron microscopy (SEM), uniaxial tensile test and Charpy impact test (V-notch). The results indicate that the FATTs of quenched & tempered specimens are all below -70С and that of some specimens is even below -90°С . Tensile strength of all quenched & tempered steels and their total elongation value are above 570 MPa and 21 % respectively. It can be seen that dual-phase microstructure of ferrite and tempered martensite in steels leads to the best low temperature toughness, and carbides along grain boundaries are beneficial to low temperature toughness.


Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4186 ◽  
Author(s):  
Haeju Jo ◽  
Moonseok Kang ◽  
Geon-Woo Park ◽  
Byung-Jun Kim ◽  
Chang Yong Choi ◽  
...  

This study investigated the mechanical properties of steel in flanges, with the goal of obtaining high strength and high toughness. Quenching was applied alone or in combination with tempering at one of nine combinations of three temperatures TTEM and durations tTEM. Cooling rates at various flange locations during quenching were first estimated using finite element method simulation, and the three locations were selected for mechanical testing in terms of cooling rate. Microstructures of specimens were observed at each condition. Tensile test and hardness test were performed at room temperature, and a Charpy impact test was performed at −46 °C. All specimens had a multiphase microstructure composed of matrix and secondary phases, which decomposed under the various tempering conditions. Decrease in cooling rate (CR) during quenching caused reduction in hardness and strength but did not affect low-temperature toughness significantly. After tempering, hardness and strength were reduced and low-temperature toughness was increased. Microstructures and mechanical properties under the various tempering conditions and CRs during quenching were discussed. This work was based on the properties directly obtained from flanges under industrial processes and is thus expected to be useful for practical applications.


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