Effects of Cold Work on Abnormal Grain Growth During Simulated Carburizing of 4121 Steel Containing Nb

Abstract Precision cold-forging processes are used to produce near-netshape parts that may then be carburized. During carburization thermal cycles, abnormal grain growth (AGG) after cold forging is known to develop microstructures which limit fatigue strength. In the present study, a small 0.04 wt.% Nb addition was made to a low-alloyed AISI 4121 steel containing 0.3 wt.% Mo. Subcritically annealed specimens were cold rolled (to simulate cold forging) at selected reduction ratios up to 50%, heated according to a simulated gas carburizing cycle at 930 °C, and water quenched to produce a final martensitic microstructure. The number density of abnormally grown grains increased rapidly as the cold rolling reduction ratio increased from 0 to 10%. With a further increase in reduction ratio, the extent of AGG decreased and was absent in samples subjected to the maximum reduction ratio of 50%. The evolution of fine (Nb, Mo)(C,N) precipitates at various stages of processing was characterized by thermodynamic calculations and electron microscopy and compared to the occurrence of abnormal austenite grain growth. The significance of these results for controlling AGG and thus optimizing fatigue performance in commercially-produced cold-forged and carburized components is discussed.

Download Full-text

Effects of Cold-Rolling Reduction on Microstructure and Mechanical Properties of Ti50Zr30Nb10Ta10 Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.849.376 ◽

2016 ◽

Vol 849 ◽

pp. 376-381

Author(s):

Ming Long Li ◽

Yu Jie Geng ◽

Chen Chen ◽

Shu Jie Pang ◽

Tao Zhang

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Plastic Strain ◽

Cold Rolling ◽

Reduction Ratio ◽

High Fracture ◽

Dendrite Structure ◽

Microstructure And Mechanical Properties ◽

Cold Rolling Reduction ◽

Cold Rolled

The effects of cold-rolling with different reduction ratios of 70%-90% on the microstructure and mechanical properties of Ti50Zr30Nb10Ta10 alloy were investigated. It was found that the β-Ti phase in this alloy was stable under cold-rolling. With the increase in reduction ratio from 70% to 90%, the microstructure of the alloys evolved from deformed dendrite structure to fiber-like structure. The alloy cold-rolled with the reduction ratio of 70% exhibited optimum mechanical properties of combined high fracture strength of 1012 MPa and plastic strain of 10.1%, which are closely correlated with the dendrite structure of the alloy. It is indicated that the proper cold-rolling is an effective way to improve the mechanical properties of the titanium alloy.

Download Full-text

The influence of Mg and Mn content on abnormal grain growth in AA5182 type alloys

Metallurgical and Materials Engineering ◽

10.30544/463 ◽

2020 ◽

Vol 25 (04) ◽

pp. 315-323

Author(s):

Tamara Radetić ◽

Miljana Popović ◽

Bojan Gligorijević ◽

Ana Alil ◽

Endre Romhanji

Keyword(s):

Cold Rolling ◽

Grain Growth ◽

Processing Parameters ◽

Abnormal Grain Growth ◽

Strong Anisotropy ◽

Grain Boundary Mobility ◽

Zener Pinning ◽

Cold Rolling Reduction ◽

Mn Content ◽

Aa5182 Alloy

The occurrence of abnormal grain growth (AGG) in AA5182 alloy during annealing imposes severe restrictions on processing parameters and deteriorates mechanical properties. In this work, we investigated the effect of chemical composition on the appearance of abnormal grain growth by varying Mg and Mn content in the range of composition limits for standard AA5182 alloy, 4.0-5.0% Mg, and 0.2-0.5% Mn, respectively. Thermo-mechanical processing of alloys included cold rolling with reductions ranging from 40 to 85%, followed by annealing in the temperature range from 350 to 520 °C. The results showed that the rise in alloying elements content drives the onset of abnormal grain growth toward higher temperatures. The increase in the cold rolling reduction degree promotes abnormal grain growth and lowers its onset temperature. Abnormal grain growth and grain boundary mobility showed strong anisotropy related to rod-like shape and alignment of Al6Mn(Fe) dispersoids through Zener pinning.

Download Full-text

Abnormal Grain Growth on the Surface of Cold-Rolled AA1235 Aluminum Plate during the Annealing Process

Materials Science Forum ◽

10.4028/www.scientific.net/msf.898.1123 ◽

2017 ◽

Vol 898 ◽

pp. 1123-1133

Author(s):

Y.Z. Zhu ◽

Xiao Hui Li ◽

J.C. Li ◽

Wei Long Fan ◽

Cheng Wei Xia ◽

...

Keyword(s):

Grain Growth ◽

Orientation Angle ◽

Abnormal Grain Growth ◽

Bottom Surface ◽

X Ray Diffraction ◽

X Ray ◽

Abnormal Growth ◽

Cold Rolled ◽

Twin Roll Cast ◽

Twin Roll

AA1235 aluminum alloys were twin roll cast into a 7.0 mm-thick billet and further rolled into a plate with 70% reduction, followed by annealing at 500 C for 8 h. Abnormal grains were found to be formed on the plate bottom surface. SEM, EBSD, and micro X-ray diffraction were used to analyze the mechanism underlying the abnormal growth of these grains. Results showed that the {100} <001> texture was formed in the surrounding normal grains adjacent to the abnormal grain. The orientation angle between the abnormal grain and its adjacent normal grains was 45°. The {100} <001> texture formed during rolling and annealing accelerated abnormal grain growth. The partially dissolved Fe precipitates were heterogeneously distributed in the plate bottom heterogeneously, which also mainly explained abnormal grain growth.

Download Full-text

Texture Change during Grain Growth in Non-Oriented Electrical Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.753.329 ◽

2013 ◽

Vol 753 ◽

pp. 329-332

Author(s):

Yoshihiro Arita ◽

Yoshiyuki Ushigami ◽

Kenichi Murakami ◽

Kohsaku Ushioda

Keyword(s):

Grain Growth ◽

Electrical Steel ◽

Abnormal Grain Growth ◽

Initial Structure ◽

Rolled Steel ◽

Ebsd Data ◽

Texture Change ◽

Average Grain Size ◽

Cold Rolled ◽

Initial Texture

Texture change during grain growth in Fe-3%Si non-oriented electrical steel was investigated. Cold rolled steel, 0.35mm in thickness, was annealed and recrystallized as an initial structure. Normal grain growth and abnormal grain growth occurred by additional annealing. {111} was dominant in the initial texture. However {100} component, which was not in majority in the initial structure, became stronger after normal grain growth. It was revealed that an average grain size of {100} in the initial structure was bigger than those of other components by analysis of the EBSD data,. Therefore, it is concluded that {100} strengthened after normal grain growth due to its size advantage. On the other hand, {111} components became more stronger after abnormal grain growth. It is inferred that another mechanism of the texture change worked in abnormal grain growth.

Download Full-text

Magnetically Affected Texture and Microstructure Evolution during Grain Growth in Zirconium

Materials Science Forum ◽

10.4028/www.scientific.net/msf.715-716.946 ◽

2012 ◽

Vol 715-716 ◽

pp. 946-951 ◽

Cited By ~ 4

Author(s):

Dmitri A. Molodov ◽

Nathalie Bozzolo

Keyword(s):

Magnetic Field ◽

Grain Growth ◽

Abnormal Grain Growth ◽

X Ray Diffraction ◽

Magnetic Annealing ◽

Mean Grain Size ◽

Pure Zirconium ◽

Cold Rolled ◽

Faster Development ◽

The Magnetic Field

The effect of a magnetic field on texture and microstructure development in cold rolled (80%) commercially pure zirconium (Zr701) was investigated. X-ray diffraction and EBSD measurements were utilized for the texture and microstructure characterization. The results revealed that a magnetic field promotes grain growth in the investigated material. During annealings at 550°C this is particularly apparent from the faster development of specific (0/180, 35, 30) texture components and the bigger mean grain size after magnetic annealing. The magnetic annealing at 700°C resulted in an asymmetry of the two major texture components. This is due to a magnetic driving force for grain growth arising from the anisotropic magnetic susceptibility of zirconium. During annealing at 700°C the abnormal grain growth occurred. This behavior is attributed to the higher mobility of grain boundaries between grains misoriented by 30° around [000. The magnetic field essentially enhanced the observed abnormal grain growth.

Download Full-text

Development of Abnormal Grain Growth in Cold Rolled and Recrystallized AA 5182 Sheet

Solid State Phenomena - Semi-Solid Processing of Alloys and Composites ◽

10.4028/3-908451-26-4.316 ◽

2006 ◽

pp. 316-319

Author(s):

Han Gil Suk ◽

E.J. Shin ◽

Moo Young Huh

Keyword(s):

Grain Growth ◽

Abnormal Grain Growth ◽

Cold Rolled

Download Full-text

Development of Abnormal Grain Growth in Cold Rolled and Recrystallized AA 5182 Sheet

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.116-117.316 ◽

2006 ◽

Vol 116-117 ◽

pp. 316-319 ◽

Cited By ~ 3

Author(s):

Han Gil Suk ◽

E.J. Shin ◽

Moo Young Huh

Keyword(s):

Grain Boundaries ◽

Grain Growth ◽

Growth Behavior ◽

Abnormal Grain Growth ◽

Annealing Temperatures ◽

Cold Rolled ◽

Grain Growth Behavior

Grain growth in the cold rolled and subsequently recrystallized AA 5182 sheets was investigated by means of microstructure observations and texture measurements. Grain growth behavior strongly depends on the annealing temperatures. Grain growth hardly took place at temperatures lower than 470°C, which is attributed to a low mobility of grain boundaries. Abnormal grain growth occurred at temperatures ranging from 480 to 530°C. Annealing above 560°C gave rise to the dissolution of inhibitor precipitates, which led to normal grain growth.

Download Full-text