scholarly journals Evidence of Martensitic Transformation in Fe-Mn-Al Steel Similar to Maraging Steel

2020 ◽  
Vol 52 (1) ◽  
pp. 26-33
Author(s):  
Gurumayum Robert Kenedy ◽  
Yi-Jyun Lin ◽  
Wei-Chun Cheng
Keyword(s):  
Martensitic Transformation ◽  
Maraging Steel ◽  
Trip Steel ◽  
Single Phase ◽  
Lath Martensite ◽  
Al Alloy ◽  
Air Cooling ◽  
Small Temperature Gradient ◽  
Austenite Grains ◽  
Equilibrium Phases

AbstractThe Fe-Mn-Al steels claim a low density, and some fall into the category of transformation-induced plasticity (TRIP) steel. In Fe-Mn-Al TRIP steel development, phase transformations play an important role. Herein, the martensitic transformation of an Fe-16.7 Mn-3.4 Al ternary alloy (wt pct) was experimentally discovered, whose equilibrium phases are a single phase of austenite at 1373 K and dual phases of ferrite and austenite at low temperature. Ferritic lath martensite forms in the prior austenite grains after cooling from 1373 K under various cooling rates via quenching, air cooling, and furnace cooling. The formation mechanism of the ferritic lath martensite is different from that of traditional ferritic lath martensite in steel and quite similar to that in maraging steel. A slight strain energy coupled with a small temperature gradient can lead to the formation of ferritic lath martensite in the Fe-Mn-Al alloy after cooling from high temperature. It is also found that micro-twins exist in the ferritic lath martensite.

The Observation of Austenite to Ferrite Martensitic Transformation in an Fe-Mn-Al Austenitic Steel after Cooling from High Temperature

2016 ◽  
Vol 879 ◽  
pp. 335-338 ◽  
Author(s):  
Wei Chun Cheng ◽  
Kun Hsien Lee ◽  
Shu Mao Lin ◽  
Shao Yu Chien
Keyword(s):  
Martensitic Transformation ◽  
Phase Transformations ◽  
Austenitic Steel ◽  
Lath Martensite ◽  
Equilibrium Phase ◽  
Stable Phase ◽  
Air Cooling ◽  
Trip Steels ◽  
Heating And Cooling ◽  
Austenite Grains

Fe-Mn-Al steels with low density have the potential to substitute for TRIP (transformation induced plasticity) steels. For the development of Fe-Mn-Al TRIP steels, phase transformations play an important role. Our methods of studying the phase transformations of the Fe-16.7 Mn-3.4 Al (wt%) austenitic steel include heating and cooling. We have studied the martensitic transformation of the ternary Fe-Mn-Al steel. Single austenite phase is the equilibrium phase at 1373 K, and dual phases of ferrite and austenite are stable at low temperatures. It is noteworthy that lath martensite forms in the prior austenite grains after cooling from 1373 K via quenching, air-cooling, and/or furnace-cooling. The crystal structure of the martensite belongs to body-centered cubic. The formation mechanism of the ferritic martensite is different from the traditional martensite in steels. Ferrite is the stable phase at low temperature.

Three-Dimensional Approach to Observing Growth of Blocks and Packets in Fe-18Ni Maraging Steel

2014 ◽  
Vol 783-786 ◽  
pp. 916-919 ◽  
Author(s):  
Shigekazu Morito ◽  
Show Yoshida ◽  
Rei Hayamizu ◽  
Taisuke Hayashi ◽  
Takuya Ohba ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundaries ◽  
Maraging Steel ◽  
Prior Austenite ◽  
Early Stage ◽  
Lath Martensite ◽  
Three Dimensional ◽  
Boundary Edge ◽  
Austenite Grain ◽  
Prior Austenite Grain

The present study aims to clarify the development of blocks and packets in lath martensite in Fe–18Ni maraging steel using three-dimensional observations. The specimens were step-quenched in order to clarify the sequential development of the three-dimensional morphology in a prior austenite grain. In a prior austenite grain, we found that five independent packets formed during the early stage of martensitic transformation. Four of the packets exist along the prior austenite grain boundaries and one packet grows from the boundary edge into the prior austenite grain. Each packet consists of a single block, although the fraction of martensitic transformation is 50.6%. The observed rules of the block-selection are as follows: (1) the blocks have near Kurdjumov–Sachs orientation relationship with adjacent austenite grains and elongated directions of the laths are parallel to adjacent grain boundaries and (2) transformation shear directions of the laths are parallel to adjacent grain boundaries.

Effect of Austenization Temperature on the Martensitic Transformation in a Low-Alloy Ultra-High-Strength Steel

2011 ◽  
Vol 66-68 ◽  
pp. 1797-1801
Author(s):  
Zhi Xia Qiao ◽  
Dan Tian Zhang ◽  
Yong Chang Liu ◽  
Ze Sheng Yan
Keyword(s):  
Martensitic Transformation ◽  
High Strength Steel ◽  
Heating Temperature ◽  
Lath Martensite ◽  
High Strength ◽  
Treatment Temperature ◽  
Austenite Grain ◽  
Ultra High Strength Steel ◽  
Austenite Grains ◽  
Vanadium Carbides

The effect of austenization treatment temperature on the martensitic transformation in the 30CrNi3MoV ultra-high-strength steel was investigated by means of dilatometric measurements and microstructural observations. The results showed that the coarsening temperature of austenite grains in the 30CrNi3MoV steel is raised to about 1000°C due to the inhibition to the migration of austenite grain boundaries, not only by the fine and disperse vanadium carbides, but also by the solute atoms adsorbed near the boundaries. The martensite obtained in 30CrNi3MoV samples with different austenization temperatures varied in the structural constituent, as well as in the size. The martensite microstructures obtained in the samples austenized at relatively low temperatures were composed of both lath martensite and acicular martensite and they are small in size. Yet the microstructures in the 30CrNi3MoV samples with relatively high austenization temperatures were occupied mostly by coarse lath martensite. For the 30CrNi3MoV steel, the austenization heating temperature should be kept below 1000°C in order to achieve the optimum mechanical property.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Microstructure of resistance spot welding of maraging steels

1990 ◽  
Vol 48 (4) ◽  
pp. 900-901
Author(s):  
I. Neuman ◽  
S.F. Dirnfeld ◽  
I. Minkoff
Keyword(s):  
Maraging Steel ◽  
Spot Welding ◽  
Lath Martensite ◽  
Base Material ◽  
Aging Treatment ◽  
High Strength ◽  
Maraging Steels ◽  
Heat Treated ◽  
Current Cycle ◽  
Welding Processes

Experimental work on the spot welding of Maraging Steels revealed a surprisingly low level of strength - both in the as welded and in aged conditions. This appeared unusual since in the welding of these materials by other welding processes (TIG,MIG) the strength level is almost that of the base material. The maraging steel C250 investigated had the composition: 18wt%Ni, 8wt%Co, 5wt%Mo and additions of Al and Ti. It has a nominal tensile strength of 250 KSI. The heat treated structure of maraging steel is lath martensite the final high strength is reached by aging treatment at 485°C for 3-4 hours. During the aging process precipitation takes place of Ni3Mo and Ni3Ti and an ordered solid solution containing Co is formed.Three types of spot welding cycles were investigated: multi-pulse current cycle, bi-pulse cycle and single pulsle cycle. TIG welded samples were also tested for comparison.The microstructure investigations were carried out by SEM and EDS as well as by fractography. For multicycle spot welded maraging C250 (without aging), the dendrites start from the fusion line towards the nugget centre with an epitaxial growth region of various widths, as seen in Figure 1.

scholarly journals Precipitation during Quenching in 2A97 Aluminum Alloy and the Influences from Grain Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2802
Author(s):  
Xiaoya Wang ◽  
Jiantang Jiang ◽  
Guoai Li ◽  
Wenzhu Shao ◽  
Liang Zhen
Keyword(s):  
Aluminum Alloy ◽  
Grain Structure ◽  
Water Quenching ◽  
Al Alloy ◽  
Air Cooling ◽  
Quenching Rate ◽  
Subsequent Aging ◽  
Nucleation Sites ◽  
Aging Response ◽  
Δ Phase

The quench-induced precipitation and subsequent aging response in 2A97 aluminum alloy was investigated based on the systematic microstructure characterization. Specifically, the influence on precipitation from grain structure was examined. The results indicated the evident influence from the cooling rate of the quenching process. Precipitation of T1 and δ′ phase can hardly occur in the specimen exposed to water quenching while become noticeable in the case of air cooling. The yield strength of 2A97-T6 alloy de-graded by 234 MPa along with a comparable elongation when water quenching was replaced by air cooling. Sub-grains exhibited a much higher sensitivity to the precipitation during quenching. The presence of dislocations in sub-grains promoted the quench-induced precipitation by acting as nucleation sites and enhancing the diffusion of the solute. A quenching rate of 3 °C/s is tolerable for recrystallized grains in 2A97 Al alloy but is inadequate for sub-grains to inhibit precipitation. The study fosters the feasibility of alleviating quench-induced precipitation through cultivating the recrystallization structure in highly alloyed Al–Cu–Li alloys.

Microstructure of ausformed lath martensite in 18%Ni maraging steel

2003 ◽  
Vol 112 ◽  
pp. 453-456 ◽  
Author(s):  
S. Morito ◽  
I. Kishida ◽  
T. Maki
Keyword(s):  
Maraging Steel ◽  
Lath Martensite

scholarly journals Appraisal of linear load effect on non-linear distortion coefficient from rectifier

2021 ◽  
Vol 3 (397) ◽  
pp. 92-96
Author(s):  
G. Tsitsikyan ◽  
◽  
S. Kunaev ◽  
Keyword(s):  
Harmonic Analysis ◽  
Direct Current ◽  
Single Phase ◽  
Harmonic Coefficient ◽  
Air Cooling ◽  
Load Effect ◽  
Distortion Coefficient ◽  
Linear Load ◽  
Non Linear ◽  
Numerical Estimations

Object and purpose of research. The object of research is the rectifier (transducer) OPED-12,5-115 (О – single phase; P – direct current; Е – natural air cooling; D – on diodes with an example of document record; 12.5 – current rating; 115 – voltage rating). Materials and methods. Methods of power electronics and harmonic analysis are applied. Main results. Ways of appraisal and restriction for the harmonic coefficient (non-linear distortion coefficient from transducer) are worked out taking account of an active load of higher frequencies generator (400 Hz). Conclusion. Numerical estimations for the attenuation coefficient of harmonics 3, 5 and 7 are obtained using basic values Xd and Xq of generator АТО-20.

Sign in / Sign up

Export Citation Format

Share Document