Influence of Cooling Rate and Chemical Composition on Phase Transformation and Hardness of C70S6 Steel

2017 ◽  
Vol 898 ◽  
pp. 1202-1207 ◽  
Author(s):  
Yan Ji ◽  
Ning Bo Zhou ◽  
Xiao Hang Sun ◽  
Bo Jiang ◽  
Lei Lei Xiao ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Transformation Temperature ◽  
Testing Machine ◽  
Transformation Products ◽  
Carbon Equivalent ◽  
Phase Transformation Temperature ◽  
Pearlite Content ◽  
Simulation Testing

The influence of cooling rate and chemical composition on phase transformation and hardness of C70S6 steel were studied by Gleeble-3800 thermal simulation testing machine and box type electric furnace. The results showed that when the cooling rate was between 0.3 and 5 °C/s, the transformation products of two experimental steels were mainly composed of ferrites, pearlite and sorbite. The pearlite content gradually decreased with the cooling rate increasing, while the sorbite content increased and the ferrite content changed little. Both the ferrite and pearlite transformation starting temperature and ending temperature decreased with the cooling rate increasing. Besides, the hardness increased with the cooling rate. At the same cooling rate, the phase transformation temperature increased slightly with the carbon equivalent decreasing, and the pearlite content increased, while the hardness decreased. The hardness of C70S6 steel was reduced by cooling rate decreasing. However, it was difficult to realize the method of decreasing the hardness by adjusting the cooling rate in the case of higher carbon equivalent. Therefore, in order to obtain an appropriate hardness, the Ceq must be controlled. And a Ceq=0.83% was recommended.

Continuous Cooling Phase Transformation Rules of High Nb X80 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 916-921
Author(s):  
Pei Pei Xia ◽  
Liu Qing Yang ◽  
Xiao Jiang Guo ◽  
Ye Zheng Li
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Thermal Deformation ◽  
Pipeline Steel ◽  
Phase Transformation Temperature ◽  
X80 Pipeline Steel ◽  
Continuous Cooling ◽  
Simulation Testing ◽  
Cooling Phase

The microstructural evolution of the high Nb X80 pipeline steel in Continuous Cooling Transformation (CCT) by Gleeble-3500HS thermal mechanical simulation testing system was studied, the corresponding CCT curves were drawn and the influence of some parameters such as deformation and cooling rate on microstructure of high Nb X80 pipeline steel was analyzed. The results show that as cooling rate increased, the phase transformation temperature of high Nb X80 steel decreased, with the microstructure transformation from ferrite-pearlite to acicular ferrite and bainite-ferrite. When cooling rate was between 20°C/s and 30°C/s, the microstructure was comparatively ideal acicular ferrite, thermal deformation accelerates phase transformation notably and made the dynamic CCT curves move upward and the initial temperature of phase transformation increase obviously. Meanwhile the thermal deformation refined acicular ferrite and extended the range of cooling rate accessible to acicular ferrite.

Effects of Different Alloy Composition on Phase Transformation of Non-Oriented Electrical Steel

2013 ◽  
Vol 423-426 ◽  
pp. 290-293
Author(s):  
Chang Gui Pei ◽  
Pei Kang Bai ◽  
Zhang Xia Guo
Keyword(s):  
Phase Transformation ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Heating Rate ◽  
Electrical Steel ◽  
Alloy Composition ◽  
Phase Transformation Temperature ◽  
Deformation Degree ◽  
Thermal Analyzer ◽  
Phase Chemical

Many factors affect the phase, chemical composition, heating rate, cooling rate, microstructure, deformation will affect the phase transformation. Laboratory testing of finished the test used with different chemical composition, but the heating rate, cooling rate, microstructure and deformation degree are the same. Through differential thermal analyzer (DTA) measurement of phase transformation temperature of the samples, explain the effect of different alloy composition of non-oriented electrical steel phase transformation.

Capability of martensitic low transformation temperature welding consumables for increasing the fatigue strength of high strength steel joints

2020 ◽  
Vol 62 (9) ◽  
pp. 891-900
Author(s):  
Jonas Hensel ◽  
Arne Kromm ◽  
Thomas Nitschke-Pagel ◽  
Jonny Dixneit ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Fatigue Strength ◽  
High Strength Steel ◽  
Transformation Temperature ◽  
Fatigue Cracks ◽  
High Strength ◽  
Filler Material ◽  
Phase Transformation Temperature ◽  
Filler Materials

Abstract The use of low transformation temperature (LTT) filler materials represents a smart approach for increasing the fatigue strength of welded high strength steel structures apart from the usual procedures of post weld treatment. The main mechanism is based on the effect of the low start temperature of martensite formation on the stress already present during welding. Thus, compressive residual stress formed due to constrained volume expansion in connection with phase transformation become highly effective. Furthermore, the weld metal has a high hardness that can delay the formation of fatigue cracks but also leads to low toughness. Fundamental investigations on the weldability of an LTT filler material are presented in this work, including the characterization of the weld microstructure, its hardness, phase transformation temperature and mechanical properties. Special attention was applied to avoid imperfections in order to ensure a high weld quality for subsequent fatigue testing. Fatigue tests were conducted on the welded joints of the base materials S355J2 and S960QL using conventional filler materials as a comparison to the LTT filler. Butt joints were used with a variation in the weld type (DY-weld and V-weld). In addition, a component-like specimen (longitudinal stiffener) was investigated where the LTT filler material was applied as an additional layer. The joints were characterized with respect to residual stress, its stability during cyclic loading and microstructure. The results show that the application of LTT consumables leads to a significant increase in fatigue strength when basic design guidelines are followed. This enables a benefit from the lightweight design potential of high-strength steel grades.

Phase Transformation Temperature of NiTi Alloy Sheet Examined by Lamb Wave

2011 ◽  
Vol 320 ◽  
pp. 359-362
Author(s):  
Kai Sheng Wang ◽  
Ru Hui He ◽  
Zhi Min Zhao
Keyword(s):  
Phase Transformation ◽  
Lamb Wave ◽  
Transformation Temperature ◽  
Lamb Waves ◽  
Niti Alloy ◽  
Alloy Sheet ◽  
Phase Transformation Temperature ◽  
Wave Method

In this study, the ultrasonic PZT transducers were used for exciting and receiving Lamb waves on NiTi alloy sheet. Lamb waves were measured when the temperature of the NiTi alloy changed. Analysis on frequency spectrums of the Lamb waves was also done. Some marked changes were observed in the dependence of the waveforms and the frequency spectrums of the Lamb waves versus temperature during phase transformation of NiTi alloy. The results show that phase transformation temperature of NiTi alloy sheet may be examined by Lamb wave method.

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