The Cracking Mechanism of Ferritic-Austenitic Cast Steel

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.

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Fracture Mechanisms in Steel Castings

Archives of Foundry Engineering ◽

10.2478/afe-2013-0066 ◽

2013 ◽

Vol 13 (3) ◽

pp. 88-91 ◽

Cited By ~ 2

Author(s):

Z. Stradomski ◽

S. Stachura ◽

G. Stradomski

Keyword(s):

Cast Steel ◽

Hot Cracking ◽

Hadfield Steel ◽

Fracture Mechanisms ◽

Structural Factors ◽

Low Carbon ◽

High Carbon ◽

Cast Steels ◽

Steel Castings ◽

Low Alloyed Steel

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.

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The Althoff-Radtke Test Adapted for High Chromium Cast Iron

Archives of Foundry Engineering ◽

10.1515/afe-2016-0084 ◽

2016 ◽

Vol 16 (4) ◽

pp. 61-64

Author(s):

D. Kopyciński ◽

D. Siekaniec ◽

A. Szczęsny ◽

M. Sokolnicki ◽

A. Nowak

Keyword(s):

Cast Iron ◽

White Cast Iron ◽

Cast Steel ◽

Hot Cracking ◽

Kinetics Parameters ◽

High Tendency ◽

High Chromium ◽

High Chromium Cast Iron ◽

Initial Chemical Composition ◽

Chromium Cast Iron

Abstract The paper presents results of the possibility of adapting the Althoff-Radtke test for High Chromium Cast Iron. The Althoff-Radtke test is a clump attempt used for steel. The Althoff-Radtke test has four different lengths of clamp which qualifies it as a test to quantitatively take into account different kinds of shrinkage ΔL. The length of the slot of the cracked corner and the length of each staple (50 - 350 mm) are the parameters tendency to cast cracks. Castings of white cast iron have a high tendency to hot cracking due to the large range of solidification temperatures, unfavorable kinetics parameters of shrinkage, and especially a lack of expansion before shrinkage. Shrinkage of high chromium white cast iron is similar to the shrinkage of cast steel, and is approximately 2%. Therefore it is important to test susceptibility to hot cracks. Research was carried out under industrial conditions. Four melts were performed, one of the initial chemical composition and the other three modified by different amounts of Fe-Ti, respectively, 0.25%, 0.5% and 0.75% Fe-Ti. The propensity for hot cracking was based on the observation of the dark surface in the corner of the sample. The study shows that the Althoff-Radtke test can be adapted to determine the tendency for hot cracking of high chromium cast iron. It should however be noted that the test results cannot be compared with those for other alloys.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098083 ◽

1981 ◽

Vol 39 ◽

pp. 314-315 ◽

Cited By ~ 1

Author(s):

M.T. Jahn ◽

J.C. Yang ◽

C.M. Wan

Keyword(s):

Mechanical Property ◽

Chemical Composition ◽

Alloy Steel ◽

Thermomechanical Treatment ◽

Room Temperature ◽

Good Combination ◽

Thermal Treatments ◽

Low Carbon ◽

4340 Steel ◽

Good Improvement

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.

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ALLOY STEEL 1.8 Cu-1.0 Mn-1.2 Si

Alloy Digest ◽

10.31399/asm.ad.sa0325 ◽

1976 ◽

Vol 25 (10) ◽

Keyword(s):

Tensile Strength ◽

Corrosion Resistance ◽

Yield Strength ◽

Physical Properties ◽

Tensile Properties ◽

Alloy Steel ◽

Cast Steel ◽

Heat Treating ◽

Low Carbon ◽

Steel Mills

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.

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Structural Factors Inducing Cracking of Brass Fittings

Materials ◽

10.3390/ma14123255 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3255

Author(s):

Lenka Kunčická ◽

Michal Jambor ◽

Adam Weiser ◽

Jiří Dvořák

Keyword(s):

Chemical Composition ◽

Plastic Flow ◽

Beta Phase ◽

Alpha Phase ◽

Structural Factors ◽

Transmission Electron ◽

Medical Gas ◽

Hot Die Forging ◽

Multiple Step

Cu–Zn–Pb brasses are popular materials, from which numerous industrially and commercially used components are fabricated. These alloys are typically subjected to multiple-step processing—involving casting, extrusion, hot forming, and machining—which can introduce various defects to the final product. The present study focuses on the detailed characterization of the structure of a brass fitting—i.e., a pre-shaped medical gas valve, produced by hot die forging—and attempts to assess the factors beyond local cracking occurring during processing. The analyses involved characterization of plastic flow via optical microscopy, and investigations of the phenomena in the vicinity of the crack, for which we used scanning and transmission electron microscopy. Numerical simulation was implemented not only to characterize the plastic flow more in detail, but primarily to investigate the probability of the occurrence of cracking based on the presence of stress. Last, but not least, microhardness in specific locations of the fitting were examined. The results reveal that the cracking occurring in the location with the highest probability of the occurrence of defects was most likely induced by differences in the chemical composition; the location the crack in which developed exhibited local changes not only in chemical composition—which manifested as the presence of brittle precipitates—but also in beta phase depletion. Moreover, as a result of the presence of oxidic precipitates and the hard and brittle alpha phase, the vicinity of the crack exhibited an increase in microhardness, which contributed to local brittleness.

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Corrosion of low-carbon cast steel in concentrated synthetic groundwater at 80 to 150°C

Waste Management ◽

10.1016/0956-053x(96)00001-3 ◽

1995 ◽

Vol 15 (7) ◽

pp. 471-476 ◽

Cited By ~ 8

Author(s):

Tae M. Ahn ◽

Peter Soo

Keyword(s):

Cast Steel ◽

Low Carbon ◽

Synthetic Groundwater

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Alternative method for vegetables cultivation in Benin

Journal of Agricultural Engineering ◽

10.4081/jae.2013.407 ◽

2013 ◽

Vol 44 (2s) ◽

Author(s):

Lucia Recchia ◽

Paolo Boncinelli ◽

Enrico Cini

Keyword(s):

Agricultural Sector ◽

Poultry Manure ◽

Structural Factors ◽

Low Carbon ◽

Technical Problems ◽

Active Population ◽

Price Increases ◽

High Level ◽

Poor Management ◽

Agricultural Machines

In the developing countries populations, which are already vulnerable and food insecure, are likely to be the most seriously affected by the effects of climate change, e.g. yield decreases and price increases for the most important agricultural crops. The IPCC’s Fourth Assessment Report for Africa describes a trend of warming at a rate faster than the global average and increasing aridity: in many parts of Africa, it seems that warmer climates and changes in precipitation will destabilise agricultural production and aggravates food security. The present work concerns the vegetables cultivation in the Parakou region in Benin, where agriculture employs approximately 70% of the active population and contributes to 36% of the Gross Domestic Product and 88% of export earnings. However, the agricultural sector has been regarded as unproductive with low adaptation capacities because of structural factors (e.g. high level of poverty among rural populations, weak mechanization and intensification of production modes), but also because of natural constraints (e.g. poor management of water and soils, leading to soil degradation). Considering the aridity, the low carbon content and the reduced level of nutrients available in the soil, the use of an hydroponic module has been hypothesised. In this way sufficient yields of the crops may be assured and no agricultural machines will be needed for the tillage operations. In addition, the nutrients can be added to the growing solution using residual materials as poultry manure, ashes and green wastes. In order to verify if some construction or maintenance problems can occur and if a growing solution can be easily obtained using agricultural wastes, some tests have been carried out. Moreover laboratory analyses have been done for different solutions that may be adopted with different shares of water, poultry manure, ashes and green wastes. The tests have indicated that the hydroponic module could be used in Benin without incurring in technical problems and that a growing solution containing poultry manure, ashes and green wastes can supply to the crops a significant amount of nutrients.

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