Microstructure and Properties of Ultrafine-Grained Steel Produced by Warm Compression of Martensite

2011 ◽  
Vol 682 ◽  
pp. 205-209
Author(s):  
Xin Zhao ◽  
Xiao Ling Yang ◽  
Tian Fu Jing

Specimens of medium carbon steel were quenched and warm-compressed on a Gleeble 3500 Machine. The microstructure of the specimens was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that the starting microstructure is lath martensite with a small amount of flake martensite. After 50% compression at 550-650°C, ultrafine grains can be observed in the specimens. The microstructure of the specimens compressed at 600°C is equiaxed ultrafine ferrite grains + nano-carbides and a good combination of strength and ductility is obtained. The tensile strength and total elongation are 861MPa and 19.1%, respectively. The hardness is 233.81Hv.

2010 ◽  
Vol 667-669 ◽  
pp. 863-866
Author(s):  
Xin Zhao ◽  
Xiao Ling Yang

Steel plates with lath martensite microstructure were rolled up to 68% reduction at 673 K and then annealed at 473-973 K. The microstructure evolution was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that ultrafine grains + nano-carbides are obtained in the steel plates. The specimen annealed at 823 K has a good combination of strength and ductility. The tensile strength and total elongation are 1028 MPa and 7.2%, respectively. And the hardness is 338 Hv.


2008 ◽  
Vol 47-50 ◽  
pp. 853-856 ◽  
Author(s):  
Xin Zhao

In order to produce nano-structured carbon steel, a 0.45%C steel was quenched and warm-compressed on a Gleeble 3500 Machine. The microstructural evolution during the process was studied by using an optical microscope and a transmission electron microscopy. The starting microstructure was lath martensite with a small amount of flake martensite. A lot of high-angle boundaries between martensite laths were induced after 50% reduction compression at 350°C. The microstructure of the specimen compressed at 600-650°C was nano-carbides + equiaxed ultrafine ferrite grains. The mechanism for grain refinement is incomplete dynamic recrystallization.


2014 ◽  
Vol 528 ◽  
pp. 149-152
Author(s):  
Hua Zheng ◽  
Kai Ming Wu ◽  
S.F. Sun ◽  
G.W. Hu

Given the strong recent interest in quenching-partitioning-tempering processed steels, the Niobium-alloyed medium carbon steel was investigated here. The microstructural observations and hardness were analyzed by optical microscope, transmission electron microscope, X-ray diffraction and hardness test. Results show that when quenched at 210°C and partitioned at 450°C, the quenching partitioning-tempering process leads to ultra fine-grained microstructures of martensite, retained austenite and carbides. And the microstructure and hardness changed differently with the increase of partitioned time.


2014 ◽  
Vol 1063 ◽  
pp. 69-72
Author(s):  
Cai Nian Jing ◽  
Ji Chao Fan ◽  
Shu Bo Xu ◽  
Yi Sheng Zhang

In this paper, the microstructure and mechanical properties of 0.15C-1.5Mn-0.3Si steels after quenching and partitioning (Q&P) process was studied. The microstructure of experimental steels was characterized by optical microscope (OM), scan electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), and mechanical properties were performed through uni-axial tensile tests. The microstructure evolution during Q&P process was also discussed together with mechanical properties. The investigated steels show excellent strength and ductility product of 10.76GPa% with retained austenite content of 11.08%. The microstructure mainly consists of lath martensite and retained austenite at room temperature, which promotes persistent work hardening during deformation.


2011 ◽  
Vol 682 ◽  
pp. 109-113
Author(s):  
Hai Yan Zhu ◽  
Long Fei Li ◽  
Wang Yue Yang ◽  
Zu Qing Sun

Mechanical properties of a medium-carbon steel with the ultrafine (α+θ) microstructures obtained by hot deformation of undercooled austenite and annealing were investigated by tensile tests, in comparison with that of a eutectoid steel. The results indicated that in the case of hot deformation of undercooled austenite to strain of 1.61 at 650°C at 0.01s-1 and annealing at 650°C for 30min, the ultrafine (α+θ) microstructures consisting of ultrafine ferrite grains and dispersed cementite particles were similar in the medium-carbon steel and the eutectoid steel, but the mechanical properties of the eutectoid steel were better that maybe be attributed to the relatively coarser size and the higher amount of cementite particles. With the increase of temperature for hot deformation of undercooled austenite to 700°C, the ultrafine (α+θ) microstructure of the medium-carbon steel changed obviously with the presence of some spheroidized pearlite colonies, and demonstrated the best balance of strength and elongation, the yield strength of about 545MPa, the tensile strength of about 635MPa, and the total elongation of about 35%.


2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.


2021 ◽  
Vol 118 (6) ◽  
pp. 601
Author(s):  
Chunhui Jin ◽  
Honglin Zhou ◽  
Yuan Lai ◽  
Bei Li ◽  
Kewei Zhang ◽  
...  

The influence of aging temperature on microstructure and mechanical properties of Cr15Ni5 precipitation hardening stainless steel (15-5 PH stainless steel) were investigated at aging temperature range of 440–610 °C. The tensile properties at ambient temperature of the 15-5 PH stainless steel processed by different aging temperatures were tested, and the microstructural features were further analyzed utilizing optical microscope (OM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD) as well as X-ray diffraction (XRD), respectively. Results indicated the strength of the 15-5 PH stainless steel was firstly decreased with increment of aging temperature from 440 to 540 °C, and then increased with the increment of aging temperature from 540 to 610 °C. The strength and ductility were well matched at aging temperature 470 °C, and the yield strength, tensile strength as well as elongation were determined to be 1170 MPa, 1240 MPa and 24%, respectively. The microstructures concerning to different aging temperatures were overall confirmed to be lath martensite. The strengthening mechanisms induced by dislocation density and the second phase precipitation of Cu-enriched metallic compound under different aging temperatures were determined to be the predominant strengthening mechanisms controlling the variation trend of mechanical properties corresponding to different aging temperatures with respect to 15-5 PH stainless steel.


2018 ◽  
Vol 119 (10) ◽  
pp. 1004-1012 ◽  
Author(s):  
G. V. Klevtsov ◽  
R. Z. Valiev ◽  
N. A. Klevtsova ◽  
I. N. Pigaleva ◽  
E. D. Merson ◽  
...  

2021 ◽  
Vol 1 (1) ◽  
pp. 51
Author(s):  
Alfan Ekajati Latief ◽  
Syahril Sayuti ◽  
Rakean Wide Windujati

 ABSTRAKTanto merupakan senjata tajam yang berasal dari Jepang dan merupakan senjata kedua bagi para Samurai di Jepang. Tanto biasa terbuat dari baja karbon menengah hingga baja karbon tinggi yang. Material baja yang digunakan untuk pembuatan Tanto dalam penelitian ini adalah baja AISI seri O1 karena memiliki karakteristik sifat mampu bentuk yang baik serat dapat dikuatkan melalui proses heat treatment. Material baja ini dibuat dengan proses tempa lipat  dengan variasi tempa empat lipatan dan satu lipatan. Pembuatan Tanto dan spesimen uji dilakukan dengan proses tempa lipat secara konvensional menggunakan tungku arang, dengan temperatur tempa rata-rata yaitu ±1200oC, kemudian dilanjutkan dengan quenching pada temperatur ± 850oC, serta tempering pada temperatur ±250oC. Penelitian ditujukan untuk mengetahui pengaruh dari proses tempa empat lipatan dan tempa satu lipatan terhadap sifat mekanik, yaitu kekerasan dan kekuatan impak serta untuk melihat perubahan pada struktur mikro. Hasil pengujian menunjukkan bahwa nilai kekerasan paling tinggi sebesar41HRC yang dimiliki oleh pada raw material, ,sedangkan nilai impak paling tinggi sebesar 224,02 Joule/cm² ayng dicapai oleh material dengan proses tempa empat lipatan, Fasa akhir yang ditemukan pada baja tempa empat lipatan adalah  bainit dan martensit, sementara  perlit dan ferit ditemukan  pada baja satu lipatan, dan lath martensit ditemukan pada pada raw material  Kata kunci: Pisau Tanto, Tempa lipat ,Quenching, Tempering, Uji Impak  ABSTRACT Tanto is a sharp weapon originating  from Japan and is the second weapon for Samurai in Japan. Tanto is usually made of medium carbon steel to high carbon steel. The material which is used in this research is AISI O1 series steel because of its high ability to be formed and also can be made tough through a heat treatment process. This steel is made by folding forge process, with variation in number of folding, which is 4 folds and 1 fold. The making of Tanto and test specimens was carried out by conventional fold forging processes by using a charcoal furnace, with an average forging temperature at ± 1200oC, continue with quenching at ± 850oC, and tempering at ± 250oC. The research is carried out in order to determine the effect of the four-folds forging and one-fold forging to the mechanical behavior, which are hardness and impact strength,  and also to see change in its micro structure. The test that have been carried out shows that the highest hardness value of 41 HRC owned by raw material, while the highest impact value of 224.02 Joules / cm² obtained by material with four layer forging process. Final phases that found in the four-fold forged steel are bainite and martensite, pearlite and ferrite found in one-fold forged steel. and lath martensite in found in the raw material. Keywords: Tanto Knife, Folding Forging, Quenching, Tempering, Testing, Impact Tests


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