Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel

Author(s):  
M.T. Jahn ◽  
J.C. Yang ◽  
C.M. Wan

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.

2015 ◽  
Vol 116 (2) ◽  
pp. 189-199 ◽  
Author(s):  
V. M. Schastlivtsev ◽  
T. I. Tabatchikova ◽  
I. L. Yakovleva ◽  
S. Yu. Del’gado Reina ◽  
S. A. Golosienko ◽  
...  

2018 ◽  
Vol 61 (6) ◽  
pp. 447-453
Author(s):  
T. A. Nechaikina ◽  
S. A. Nikulin ◽  
S. O. Rogachev ◽  
V. Yu. Turilina ◽  
A. P. Baranova

The creation of new structural materials for cladding tubes  of fast neutron reactors is an urgent task of modern nuclear power  engineering. A three-layer radiation-resistant and corrosion-resistant material based on vanadium alloy and stainless steel, intended  for work under extreme conditions (high temperatures, radiation  and aggressive environment) of operation of fast neutron reactor  cladding tubes has been developed in recent years. The most important aspect determining the operability of this material during  operation is the quality of the joining of different materials layers  among themselves, determined by the modes of thermomechanical treatment. The effect of the annealing on the chemical composition, structure, and fracture resistance of the “steel/vanadium  alloy” interface in the steel/vanadium alloy/steel three-layer tube,  obtained by hot co-extrusion of three-layer tube billet at 1100  °C  was studied. The 20Kh13 (AISI 420 type) steel for the outer layers and V – 4Ti – 4Cr vanadium alloy for the core were used as the  components of the tube. The structure and chemical composition  in the layer joining zone were studied using the optical microscopy and electron microscopy with X-ray microspectral analysis.  The fracture resistance of the “steel/vanadium alloy” interface was  evaluated by a compression test of a three-layer ring sample with  notch using an acoustic emission (AE) measurement. It is shown  that after co-extrusion a “transition” area of diffusion interaction  having a variable chemical composition with a width of 10–15 μm  is formed between vanadium alloy and steel, which represents the  continuous series of solid solutions, without precipitation of brittle  phases, providing a strong bonding between vanadium alloy and  steel in the three-layer material. No voids, delaminations or defects were detected at the “steel/vanadium alloy” interface. However, a  crack is formed in the steel layer during the compression tests of  the notched semi-ring three-layer samples after hot co-extrusion.  Annealing favorably influences the formation of the “transition”  area due to the increase in the width of the diffusion interaction  area. No cracks or delaminations at the boundary between steel and  vanadium layers were observed in the three-layer tube samples after annealing, and the three-layer material behaves like a monolith  material during testing.


Author(s):  
D.S. Kotenko

Introduction. The use of different mathematical approaches to assessing and forecasting the quality characteristics of materials for different purposes is always relevant. The urgency of solving problems and problems of modern materials science with the use of methods of mathematical modeling allows to optimize technological processes of production, to determine in a short period of time the set parameters with minimal time and material costs. In the work using the method of regression analysis, the strength criteria of low-carbon low-alloy steel depending on the characteristics of the structure were evaluated. Materials and methods. Samples of Ст3пс steel grade made of a circle with a diameter of 24 mm were selected as the material for the study. The structure and mechanical properties were investigated at three reference points: at a distance of 0 mm from the center of the sample, 6 mm from the center of the sample and 12 mm from the center of the sample. The steel was investigated in the state of factory delivery, and after two modes of heat treatment to obtain ferritic-perlite and bainite structure. The following properties were determined: microhardness, tensile strength and yield strength, hardness and toughness at room temperature. The results of the experiment. Models for estimating mechanical properties were obtained using regression analysis. Models describing the relationship between the microhardness of pearlite and its area (R2 = 0.8366) in the state of factory delivery have a relatively high correlation coefficient; the score and the ultimate strength (R2 = 1.0) and yield strength (R2 = 0.8669) of steel after cooling in an oil medium; hardness and area of pearlite after hardening steel in the pearlite region (R2 = 0.7215). Conclusions. The practical significance of the work performed is the ability to perform a rapid analysis of the properties of rolled metal from steel Ст3пс based on determining the area of the structural elements and their scoring. However, it should be noted that the existing discrepancy between the results of the experiment and the forecast using the obtained models may be due to the influence of other factors. Such factors include the influence of chemical composition, incompleteness of formal axiomatics, which occurs when estimating the geometry of complex structural elements. Keywords: low-alloy steel; structure; chemical composition; mechanical properties; regression model; properties forecast


Author(s):  
S. A. Nikulin ◽  
◽  
S. O Rogachev ◽  
V. A. Belov ◽  
V. Yu. Turilina ◽  
...  

The mechanical properties of the seam metal of a low-carbon low-alloy steel welded joint of the 22K type (Russian standard) have been investigated when testing for uniaxial tension in the temperature range from room temperature to 1200 °C. A comparative analysis of the changes in the structure, the strength and plastic properties of base metal and weld seam metal in the selected temperature range was carried out.


Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.


Alloy Digest ◽  
1985 ◽  
Vol 34 (12) ◽  

Abstract ALUMINUM 713.0 is an aluminum-base casting alloy that ages at room temperature to provide high-strength sand and permanent-mold castings. It has a good combination of mechanical properties and its corrosion resistance is equivalent to that of the aluminum-silicon alloys. It is dimensionally stable. Among its many uses are housings, machinery parts, fittings, lever arms and brackets. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive and shear strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-263. Producer or source: Various aluminum companies.


Alloy Digest ◽  
1965 ◽  
Vol 14 (7) ◽  

Abstract AISI 8615 is a low-carbon, nickel-chromium-molybdenum alloy steel capable of producing high core strength and toughness. It is a case hardening steel recommended for heavy duty gears, cams, shafts, chains, fasteners, piston pins, etc. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-180. Producer or source: Alloy steel mills and foundries.


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