Phase Transformations in D6AC Steel during Continuous Cooling

2017 ◽  
Vol 265 ◽  
pp. 712-716 ◽  
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim Ryzhkov ◽  
Aleksandra A. Kuklina

The CCT diagram of the high strength D6AC steel was plotted using the dilatometer data, microstructure investigation, and hardness measurements. The microstructure of the steel under consideration was estimated after various cooling conditions and quenching and tempering. The heat treatment technology of D6AC steel drill bits was developed to obtain the required mechanical properties.

2018 ◽  
Vol 284 ◽  
pp. 351-356 ◽  
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim A. Ryzhkov

The high strength aerospace steel alloyed with Cr, Mn, Si, Ni, W and Mo was studied. The austenite transformations under continuous cooling conditions were investigated using the dilatometer analysis at the cooling rates 0.1...30 °C/s. The mechanical properties of the studied steel were determined after the conventional quenching and tempering heat treatment. The dependences of the mechanical properties on the tempering temperature were obtained. The novel quenching and partitioning heat treatment was applied to the steel under consideration. The microstructure and the mechanical properties were studied after three different modes of the quenching and partitioning (QP) treatment: single-stage QP, two-stage QP and single-stage QP with subsequent tempering (QPT).


2013 ◽  
Vol 58 (1) ◽  
pp. 25-30 ◽  
Author(s):  
G. Golanski ◽  
J. Słania

The paper presents a research on the influence of multistage heat treatment with the assumed parameters of temperature and time on the microstructure and mechanical properties of high-chromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel. In the as-cast state GP91 cast steel was characterized by a microstructure of lath martensite with numerous precipitations of carbides of the M23C6, M3C and NbC type, with its properties higher than the required minimum. Hardening of the examined cast steel contributes to obtaining a microstructure of partly auto-tempered martensite of very high strength properties and impact strength KV on the level of 9-15 J. Quenching and tempering with subsequent stress relief annealing of GP91 cast steel contributed to obtaining the microstructure of high-tempered lath martensite with numerous precipitations of the M23C6 and MX type of diverse size. The microstructure of GP91 cast steel received after heat treatment was characterized by strength properties (yield strength, tensile strength) higher than the required minimum and a very high impact energy KV. It has been proved that GP91 cast steel subject to heat treatment No. 2 as a result of two-time heating above the Ac3 temperature is characterized by the highest impact energy.


Author(s):  
S. A. Golosienko ◽  
N. A. Minyakin ◽  
V. V. Ryabov ◽  
T. G. Semicheva ◽  
E. I. Khlusova

The work covers the effect of niobium, as well as niobium and vanadium together, on mechanical properties of high-strength chromium-nickel-molybdenum steel after thermal improvement (heat treatment). The mechanical properties of steels are determined after applying various tempering temperatures (from 580 to 660°C), durations of tempering (from 1 to 16 hours), and also after quenching from rolling heat and furnace heat with subsequent tempering. It is shown that after quenching and tempering in the temperature range 580– 660°C, simultaneous microalloying by niobium and vanadium, compared to microalloying by niobium alone, increases the yield strength but in significantly decreases toughness and ductility. Quenching from rolling heat increases strength while maintaining high toughness and the increase in strength is most noticeable for steel microalloyed only by niobium.


2021 ◽  
Vol 410 ◽  
pp. 221-226
Author(s):  
Mikhail V. Maisuradze ◽  
Maxim A. Ryzhkov ◽  
Dmitriy I. Lebedev

The features of microstructure and mechanical properties of the aerospace high strength steel were studied after the implementation of various heat treatment modes: conventional oil quenching and tempering, quenching-partitioning, austempering. The dependence of the mechanical properties on the tempering temperature was determined. The basic patterns of the formation of mechanical properties during the implementation of isothermal heat treatment were considered. The optimal heat treatment conditions for the studied steel were established.


2012 ◽  
Vol 557-559 ◽  
pp. 34-37
Author(s):  
Jing Qiang Zhang ◽  
Jie Min Du ◽  
Ji Wei Guo ◽  
Shou Fan Rong ◽  
Guang Zhou Wang

The influences of Mn and heat-treatment technology on microstructure and mechanical properties of medium-carbon-low-alloy wear-resistant cast steel were investigated. The results show that the hardness first increases and then drops down with the increase of Mn content, and the best hardness is 54HRC with Mn content 1.5%. The impact toughness first increases and then drops down with the increase of Mn content. The hardness and impact toughness first increase and then drop down with the increases of quenching temperature. The optimal impact toughness can be obtaind by quenching at 920°C and tempering at 200°C. Part of lower bainite and residual austenite and mass of tempered martensite are obtaind after tempering.


2011 ◽  
Vol 215 ◽  
pp. 25-28 ◽  
Author(s):  
An Ming Li ◽  
Meng Juan Hu

The effect of quenching temperature on the microstructure and mechanical properties of 40Cr steel by zero time holding quenching were studied. The results showed that the strength and hardness of 40Cr steel increased with the increase of quenching temperature in the range of 860~940°C, the strength and hardness reach the maximum at 920°C and then decrease. The metallographic analysis shows austenite grains of the samples by “Zero Time Holding” Quenching have been refined compared with the traditional heat treatment technology. Fine lath martensite was obtained by the “zero time holding” quenching due to the smaller austenitic crystal grain and the uneven distribution of the carbon concentration in austenitic crystal grain.


2008 ◽  
Vol 575-578 ◽  
pp. 1414-1419 ◽  
Author(s):  
Wen Min Zhao ◽  
Zhen Xu Liu ◽  
Zi Lai Ju ◽  
Bo Liao ◽  
Xue Guang Chen

The type, shape and distribution of carbide take directly effect on the mechanical properties of high chromium castings. Vanadium is able to stabilize the structure of carbide in high chromium cast iron, meanwhile the hardness of carbide containing vanadium can reaches about 2800HV. In some cases, vanadium can also refine the microstructure. Rare-earth is able to change the shape of carbide in cast iron, refine the grain size of ferrite and improve the mechanical properties of castings. In this experiment, intention of adding vanadium and rare-earth is modification of mechanical properties with the proper heat treatment technology. With the help of SEM, the characteristics of carbide, such as shape, distribution and quantity can be observed and mechanical properties have been improved for better wear-resistance.


Author(s):  
M. V. Golubeva ◽  
O. V. Sych ◽  
E. I. Khlusova ◽  
G. D. Motovilina ◽  
E. V. Sviatysheva ◽  
...  

Purpose of the present investigation is to determine the optimal heat treatment parameters that ensure yield strength over 690 MPa in combination with toughness of at least 35 J/cm2at temperature –70°C in new economically alloyed cold-resistant steel. The effect of various quenching and tempering parameters on mechanical properties, structure of steel and fracture mode of samples after impact tests at temperature –70°C has been studied. The relationship between the properties, structure and fracture mode of steel samples is shown. The optimal heat treatment parameters of new economically alloyed cold-resistant steel are determined.


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