Ultra-high strength attributed to retardation of recrystallization during intercritical annealing in cold-rolled (V,Nb) microalloyed 5Mn steel

2020 ◽  
Vol 794 ◽  
pp. 139789
Author(s):  
Hao Wu ◽  
Hui Guo ◽  
Bin Hu ◽  
Masato Enomoto ◽  
Chengjia Shang
2010 ◽  
Vol 638-642 ◽  
pp. 3331-3336 ◽  
Author(s):  
J.M. Choi ◽  
B.J. Park ◽  
K.S. Lee ◽  
K.J. Lee

It is very important to understand interstitial carbon behaviors in cold rolled steel to get the good formability as well as the high strength. In low carbon steel, most of carbons are consumed by the formation of grain boundary cementite during cooling. During heating and holding between Ae1 and Ae3, cementite is dissolved and consequently carbon enriched austenite is formed. By controlled cooling, retained austenite as well as bainite and martensite are formed. In this study, the effect of silicon, intercritical annealing, isothermal bainite transformation on the formation of ferritic bainite, cementite and retained austenite are modeled by nucleation and growth, diffusion and dissolution. In addition, the formation of retained austenite and their carbon contents are modeled and compared with experimental data.


Alloy Digest ◽  
1977 ◽  
Vol 26 (4) ◽  

Abstract YS-T 50 to YS-T 140 Steels comprise a series of high-strength, cold-rolled steels designed to meet performance and weight-saving objectives. They are an extension of Youngstown's series of hot-rolled high-strength steels (see Youngstown YS-T Steel, Alloy Digest SA-261, March 1971). The YS-T 50 to YS-T 140 steels have minimum yield strengths ranging from 50,000 psi to 140,000 psi. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and bend strength. It also includes information on heat treating, machining, and joining. Filing Code: SA-331. Producer or source: Youngstown Sheet and Tube Company.


2013 ◽  
Vol 313-314 ◽  
pp. 693-696
Author(s):  
Ji Yuan Liu ◽  
Fu Xian Zhu ◽  
Shi Cheng Ma

Cold rolled dual phase steel was developed from Q345 steel by heat treatment procedure for automotive applications. The ultimate tensile strength was improved about 100MPa higher than the traditional cold-rolled Q345 steel in the continuous annealing simulation experiment. The microstructure presented varied characteristics in different intercritical annealing temperatures; mechanical properties were changed correspondingly as well. The chief discussions are focus on the recrystallization, hardenability of austenite and martensite transformation in the experiment.


2004 ◽  
Vol 120 ◽  
pp. 607-614
Author(s):  
V. Hein ◽  
H. Freydank ◽  
U. Michel ◽  
H. Zieger ◽  
G. Zouhar ◽  
...  

The empirical optimization of technologies for continuous annealing of cold rolled strips is very time, material and cost intensive. The properties of cold rolled strips demanded by the customer are adjustable only in relatively closely limited temperature - time regimes. Therefore, it is a complex task to increase the performance of continuous annealing furnaces without disadvantages for the product quality. This problem can be solved by nume-rical modelling the microstructure evolution in the cold rolled strip during continuous annealing combined with experimental simulation of the annealing process. At the Institut für Werkstoffwissenschaft, Technische Universität Dresden, in co-operation with EKO Stahl GmbH, Eisenhüttenstadt, a computer program signed as TFB was deve-loped. It is suited for modelling and simulating the recrystallization kinetics in cold rolled strips during continuous annealing. Furthermore, this program can be used for optimizing the annealing technology. For example, for IF steel the pre-sent paper demonstrates to what extent the performance of a continuous annealing furnace can be increased. Further results concern the improvement of the microstructure of the high strength microalloyed steel ZStE 380 Z by optimizing the annealing technology by means of experimental simulation.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5975
Author(s):  
Jae-Hwan Kim ◽  
Jong-Min Jung ◽  
Hyunbo Shim

The tensile properties and damping capacity of cold-rolled Fe–20Mn–12Cr–3Ni–3Si alloys were investigated. The martensitic transformation was identified, including surface relief with a specific orientation and partial intersection. Besides, as the cold rolling degree increased, the volume fraction of ε-martensite increased, whereas α’-martensite started to form at the cold rolling degree of 15% and slightly increased to 6% at the maximum cold rolling degree. This difference may be caused by high austenite stability by adding alloying elements (Mn and Ni). As the cold rolling degree increased, the tensile strength linearly increased, and the elongation decreased due to the fractional increment in the volume of martensite. However, the damping capacity increased until a 30% cold rolling degree was approached, and then decreased. The irregular tendency of the damping capacity was confirmed, depicting that it increased to a specific degree and then decreased as the tensile strength and elongation increased. Concerning the relationship between the tensile properties and the damping capacity, the damping capacity increased and culminated, and then decreased as the tensile properties and elongation increased. The damping capacity in the high-strength area tended to decrease because it is difficult to dissipate vibration energy into thermal energy in alloys with high strength. In the low-strength area, on the other hand, the damping capacity increased as the strength increased since the increased volume fraction of ε-martensite is attributed to the increase in the damping source.


Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6662
Author(s):  
Emilio Bassini ◽  
Antonio Sivo ◽  
Daniele Ugues

The automotive field is continuously researching safer, high-strength, ductile materials. Nowadays, dual-phase (DP) steels are gaining importance, since they meet all these requirements. Dual-phase steel made of ferrite and bainite is the object of a complete microstructural and mechanical characterization, which includes tensile and bending tests. This specific steel contains ferrite and bainite in equal parts; ferrite is the soft phase while bainite acts as a dispersed reinforcing system. This peculiar microstructure, together with fine dispersed carbides, an extremely low carbon content (0.09 wt %), and a minimal degree of strain hardening (less than 10%) allow this steel to compete with traditional medium-carbon single-phase steels. In this work, a full pearlitic C67 steel containing 0.67% carbon was used as a benchmark to build a comparative study between the DP and SP steels. Moreover, the Crussard–Jaoul (C-J) and Voce analysis were adopted to describe the hardening behavior of the two materials. Using the C-J analysis, it is possible to separately analyze the ferrite and bainite strain hardening and understand which alterations occur to DP steel after being cold rolled. On the other hand, the Voce equation was used to evaluate the dislocation density evolution as a function of the material state.


Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1448 ◽  
Author(s):  
Mattia Franceschi ◽  
Luca Pezzato ◽  
Claudio Gennari ◽  
Alberto Fabrizi ◽  
Marina Polyakova ◽  
...  

High Silicon Austempered steels (AHSS) are materials of great interest due to their excellent combination of high strength, ductility, toughness, and limited costs. These steel grades are characterized by a microstructure consisting of ferrite and bainite, accompanied by a high quantity retained austenite (RA). The aim of this study is to analyze the effect of an innovative heat treatment, consisting of intercritical annealing at 780 °C and austempering at 400 °C for 30 min, on the microstructure and mechanical properties of a novel high silicon steel (0.43C-3.26Si-2.72Mn wt.%). The microstructure was characterized by optical and electron microscopy and XRD analysis. Hardness and tensile tests were performed. A multiphase ferritic-martensitic microstructure was obtained. A hardness of 426 HV and a tensile strength of 1650 MPa were measured, with an elongation of 4.5%. The results were compared with those ones obtained with annealing and Q&T treatments.


2015 ◽  
Vol 22 (4) ◽  
pp. 1203-1211 ◽  
Author(s):  
Sheng-ci Li ◽  
Yong-lin Kang ◽  
Guo-ming Zhu ◽  
Shuang Kuang

Sign in / Sign up

Export Citation Format

Share Document