scholarly journals Fracture Mechanisms in Steel Castings

2013 ◽  
Vol 13 (3) ◽  
pp. 88-91 ◽  
Author(s):  
Z. Stradomski ◽  
S. Stachura ◽  
G. Stradomski

Abstract The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

2016 ◽  
Vol 16 (4) ◽  
pp. 153-156 ◽  
Author(s):  
G. Stradomski

Abstract In the high-alloy, ferritic - austenitic (duplex) stainless steels high tendency to cracking, mainly hot-is induced by micro segregation processes and change of crystallization mechanism in its final stage. The article is a continuation of the problems presented in earlier papers [1 - 4]. In the range of high temperature cracking appear one mechanism a decohesion - intergranular however, depending on the chemical composition of the steel, various structural factors decide of the occurrence of hot cracking. The low-carbon and low-alloy cast steel casting hot cracking cause are type II sulphide, in high carbon tool cast steel secondary cementite mesh and / or ledeburite segregated at the grain solidified grains boundaries, in the case of Hadfield steel phosphorus - carbide eutectic, which carrier is iron-manganese and low solubility of phosphorus in high manganese matrix. In duplex cast steel the additional factor increasing the risk of cracking it is very “rich” chemical composition and related with it processes of precipitation of many secondary phases.


2014 ◽  
Vol 698 ◽  
pp. 378-381 ◽  
Author(s):  
Alexandra Chevakinskaya ◽  
Aelita Nikulina ◽  
Natalia Plotnikova

In this paper combined Hadfield steel - stainless steel - rail steel compounds are considered. Structural studies and estimation of mechanical properties showed that using an intermediate layer of low-carbon steel with 0.2 C wt. % and 5-20 mm thick between high-carbon steel and chromium-nickel steel in the formation of welded joints increases the reliability of connections by reducing the amount of high-strength zones as compared to compounds without a barrier layer.


Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 612 ◽  
Author(s):  
Andrés Felipe Santacruz-Londoño ◽  
Oscar Rios-Diez ◽  
José A. Jiménez ◽  
Carlos Garcia-Mateo ◽  
Ricardo Aristizábal-Sierra

Nanoscale bainite is a remarkable microstructure that exhibits a very promising combination of high strength with good ductility and toughness. The development of these types of microstructures has been focused on wrought materials, and very little information is available for steel castings. In this work, a specially designed cast steel with 0.76 wt % C was fabricated, and the heat treatment cycles to develop bainitic nanostructures were determined by studying the kinetics of the bainitic transformation using high-resolution dilatometry. The effects of isothermal holding temperature and time on the final microstructure and mechanical properties were thoroughly characterized in order to evaluate a future industrial implementation of the process in an effort to contribute to enhance and widen the potential applications for cast steels.


2010 ◽  
Vol 654-656 ◽  
pp. 1327-1330 ◽  
Author(s):  
Yasunori Harada

The cold joining of dissimilar metal sheets using a shot peening process was investigated. In shot peening the substrate undergoes large plastic deformation near the surface due to the hit with shots. Consequently, plastic flow areas formed by cold working may form the surface layer. The dissimilar sheets with the concavo-convex edge are connected, and then the contact area is shot-peened. In this joining, the convex edges of the sheet are laid on the other sheet. Namely, in the joining area, the two sheets are superimposed. In the experiment, the shot peening treatment was performed by using an air-type peening machine. The shots used were made of high carbon cast steel. Air pressure was 0.6MPa and peening time was in the range of 30-150s. The peening conditions were controlled in the experiment. The sheets were commercial low-carbon steel, stainless steel, pure aluminum, pure titanium, pure copper, and magnesium alloy. The effects of processing conditions on the joinability were mainly examined. The joint strength increased with the kinetic energy of shots. It was found that the present method was effective for cold joining of dissimilar metal sheets.


2013 ◽  
Vol 58 (3) ◽  
pp. 769-773 ◽  
Author(s):  
E. Olejnik ◽  
S. Sobula ◽  
T. Tokarski ◽  
G. Sikora

Abstract Application of in-situ technique allows for fabrication of composite zone in the casting with a matrix of cast steel with low carbon content. The reinforcing phase in the composite zone is titanium carbide, produced by the synthesis of substrates introduced into the mould in the form of pressed compacts. Metallographic studies were performed in order to determine of homogeneity of composite zones and characteristic features existed in transition area between the composite zone and core of the casting. The transition areas of composites zone were blurred and there were no discontinuities caused by poor bonding between the composite zone and the core of the casting. To confirm the correct run of the TiC synthesis, phase analysis was performed of the base alloy as well as composite zone. The results of this examination indicated that there were two phases in composite zone, i.e. α Fe and TiC and only α Fe was observed in base alloy. Changes of mechanical properties in the composite zone were examined, measuring its hardness HV. The average hardness values of the base alloy and composite zone were 175 ±4 and 696 ±201 HV, respectively.


2014 ◽  
Vol 14 (3) ◽  
pp. 83-86
Author(s):  
G. Stradomski

Abstract The paper presents the results of research on the microstructure of GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoCuN25-6-3 cast steels with a varying carbon content. The cause for undertaking the research were technological problems with hot cracking in bulk castings of duplex cast steel with a carbon content of approx. 0.06% and with 23% Cr, 8.5% Ni, 3% Mo and 2.4% Cu. The research has shown a significant effect of increased carbon content on the ferrite and austenite microstructure morphology, while exceeding the carbon content of 0.06% results in a change of the shape of primary grains from equiaxial to columnar.


Author(s):  
F. A. Khalid ◽  
D. V. Edmonds

The austenite/pearlite growth interface in a model alloy steel (Fe-1lMn-0.8C-0.5V nominal wt%) is being studied in an attempt to characterise the morphology and mechanism of VC precipitation at the growth interface. In this alloy pearlite nodules can be grown isothermally in austenite that remains stable at room temperature thus facilitating examination of the transformation interfaces. This study presents preliminary results of thin foil TEM of the precipitation of VC at the austenite/ferrite interface, which reaction, termed interphase precipitation, occurs in a number of low- carbon HSLA and microalloyed medium- and high- carbon steels. Some observations of interphase precipitation in microalloyed low- and medium- carbon commercial steels are also reported for comparison as this reaction can be responsible for a significant increase in strength in a wide range of commercial steels.The experimental alloy was made as 50 g argon arc melts using high purity materials and homogenised. Samples were solution treated at 1300 °C for 1 hr and WQ. Specimens were then solutionised at 1300 °C for 15 min. and isothermally transformed at 620 °C for 10-18hrs. and WQ. Specimens of microalloyed commercial steels were studied in either as-rolled or as- forged conditions. Detailed procedures of thin foil preparation for TEM are given elsewhere.


Alloy Digest ◽  
1976 ◽  
Vol 25 (10) ◽  

Abstract Alloy Steel 1.8 Cu-1.0 Mn-1.2 Si is a low-carbon (0.20% max.) cast steel designed to provide intermediate tensile and yield strength. Copper lowers the ductility and toughness of cast steel but, for a given increase in tensile strength, the loss of ductility and toughness is less if copper is added than if carbon is increased. This steel has many uses such as booms, long shafting and gears. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: SA-325. Producer or source: Alloy steel mills and foundries.


Alloy Digest ◽  
1973 ◽  
Vol 22 (7) ◽  

Abstract CANNON-MUSKEGON D-2 is a high-carbon high-chromium air-hardening cast tool steel with excellent resistance to abrasion. It is moderately machinable with excellent non-deforming characteristics. A higher silicon content is permissible in this cast steel than in AISI D2 (wrought) tool steel. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: TS-259. Producer or source: Cannon-Muskegon Corporation.


Author(s):  
Yong Wang ◽  
Andrey Karasev ◽  
Joo Hyun Park ◽  
Wangzhong Mu ◽  
Pär G. Jönsson

AbstractChromium is normally added to liquid alloy in the form of different grades of ferrochromium (FeCr) alloys for the requirement of different alloy grades, such as stainless steels, high Cr cast iron, etc.. In this work, inclusions in two commercially produced alloys, i.e., high-carbon ferrochromium (HCFeCr) and low-carbon ferrochromium (LCFeCr) alloys, were investigated. The FeCr alloy/liquid iron interactions at an early stage were investigated by inserting solid alloy piece into contact with the liquid iron for a predetermined time using the liquid-metal-suction method. After quenching these samples, a diffusion zone between the alloys and the liquid Fe was studied based on the microstructural characterizations. It was observed that Cr-O-(Fe) inclusions were formed in the diffusion zone, FeOx inclusions were formed in the bulk Fe, and an “inclusion-free” zone was detected between them. Moreover, it was found that the HCFeCr was slowly dissolved, but LCFeCr alloy was rapidly melted during the experiment. The dissolution and melting behaviors of these two FeCr alloys were compared and the mechanism of the early-stage dissolution process of FeCr alloys in the liquid Fe was proposed.


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