Nonmetallic Inclusions in Low-Alloy Tube Steel

Study of the nonmetallic phase of unalloyed tube steel 10G2FB has shown that the steel contains four types of nonmetallic inclusions. Relatively fine (no coarser than 12 µm) calcium aluminates of variable composition are the main type of nonmetallic inclusion (NI) in such steel. It was established that a decrease in the point rating for NI contamination of the steel from 3.5 to 1.5 leads to an increase in the steel’s impact toughness from 235 to 318 J/cm².__________Translated from Metallurg, No. 4, pp. 67–72, April, 2005.     

Characterization of Nonmetallic Inclusions in High-Manganese and Aluminum-Alloyed Austenitic Steels

The effects of Al and Mn contents on the size, composition, and three-dimensional morphologies of inclusions formed in Fe-xMn-yAl (x?=?10 and 20?mass?pct, y?=?1, 3, and 6?mass?pct) steels were investigated to enhance our understanding of the inclusion formation behavior in high Mn-Al?Calloyed steels. By assuming that the alumina is a dominant oxide compound, the volume fraction of inclusions estimated from the chemical analysis, i.e., insoluble Al, in the Fe-Mn-3Al steels was larger than the inclusion volume fractions in the Fe-Mn-1Al and Fe-Mn-6Al steels. A similar tendency was found in the analysis of inclusions from a potentiostatic electrolytic extraction method. This finding could be explained from the terminal velocities of the compounds, which was affected by the thermophysical properties of Fe-Mn-Al steels. The inclusions formed in the Fe-Mn-Al?Calloyed steels are classified into seven types according to chemistry and morphology: (1) single Al₂O₃ particle, (2) single AlN or AlON particle, (3) MnAl₂O₄ single galaxite spinel particle, (4) Al₂O₃(-Al(O)N) agglomerate, (5) single Mn(S,Se) particle, (6) oxide core with Mn(S,Se) skin (wrap), and (7) Mn(S,Se) core with Al₂O₃(-Al(O)N) aggregate (or bump). The Mn(S,Se) compounds were formed by the contamination of the steels by Se from the electrolytic Mn. Therefore, the raw materials (Mn) should be used carefully in the melting and casting processes of Fe-Mn-Al?Calloyed steels.     

Role of Nonmetallic Inclusions in Hydrogen Embrittlement of High-Strength Carbon Steels with Different Microalloying

High-strength carbon steels of 1200 MPa strength level with different microalloying were tensile tested at constant extension rate and constant load under continuous electrochemical hydrogen charging. The results show that hydrogen markedly reduces elongation and time to fracture of all the studied steels. Fractography of the steels shows that nonmetallic inclusions (NMIs) play the major role in crack initiation in hydrogen-charged specimens. The role of NMIs in the hydrogen-induced fracture of steels is discussed.     

Corrosive Damage Close to Nonmetallic Inclusions in Bearing Steels

The development of corrosive damage in bearing steels close to nonmetallic inclusions is analyzed. The influence of the chemical and mineralogical composition of the inclusions on their activity in corrosive media is studied.     

Effect of Nonmetallic Inclusions and Impurities on the Properties and Quality Characteristics of Round Rolled Product Made of Special Alloyed Steels

Metallurgist - It is found from results of studying rolled steel from special alloyed steels of industrial grades 30G1R, 40Kh and laboratory grades 12KhN, 38KhGNM, 41Kh1 that a change in the ratio...     

Effect of Heat Treatment on Corrosion Activity of Nonmetallic Inclusions and Steel Corrosion Resistance in Aqueous Media

Metallurgist - Results of the studying the effect of heat treatment on the corrosion activity of non-metallic inclusions in contemporary steels, and correspondingly on corrosion resistance of the...     

Mechanical Properties and Corrosion–Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion–abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion–abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion–abrasion wear conditions.     

Correlation Between Nonmetallic Inclusions and Localized Corrosion of a Low-Nickel Stainless Steel with Cerium Treatment

The localized corrosion induced by different kinds of inclusions in low-nickel stainless steel is studied through immersion tests and first-principles calculations. The galvanic corrosion between the steel matrix and different kinds of inclusions occurs in the corrosive environment due to the difference in the electron work function of the steel matrix and inclusions. The electron work function of MnS, CeS, and Ce-O-S is smaller than that of the steel matrix, thus, these inclusions first dissolve as the anode. However, the electron work function of cerium-containing oxides is bigger than that of the steel matrix, and the steel matrix dissolves prior to cerium-containing oxides. The order of the volume expansion rate of pits induced by inclusions is CeS > Si-Mn(-Al)-O > MnS > Ce-C-O-S > Ce-Si-Mn(-Al)-O > Ce-O-S. For cerium-containing inclusions, the electron work function of inclusions increases with the increase of the O/Ce ratio and the S/Ce ratio of inclusions. The order of the electron work function of cerium-containing inclusions is cerium oxides > cerium sulfides > cerium oxysulfide.     

Latest Progress of Low-Alloy High-Strength Steels in Baosteel

After research and development for decades,low-alloy high-strength steels have been widely used and playing an important role in economy.This article introduces,from the perspective of environmental protection,the Baosteel’s latest progress of low-alloy high-strength steels continuously innovated with the focus of achieving high-strength,high-toughness,long service life and versatile functions,and with the aim of providing energy-saving and pollution-reduction solutions to down-stream sectors.     

Modification of Nonmetallic Inclusions in Steel with Yttrium

The modification affects of yttrium on formation of nonmetallicinclusions in steel has been studied by use of metallographic method. The effect of added quantity of modificater on type and size of inclusions was also studied in this work.     

Hydrogen Diffusion and Trapping in Low-Alloy Tempered Martensitic Steels

Metallurgical and Materials Transactions A - Structural characterization of ten low-alloy tempered martensitic steels of varied composition (C, Cr, Mo, Mn, and V contents) and tempering temperature...     

Effect of the Carbon Content of Low-Alloy Steels on the Surface Quality of Continuous-Cast Semifinished Products and Rolled Plates

An analysis is made of the effect of the carbon content of low-alloy steels on the damage done to slabs and rolled plates of those steels by surface defects. The effect of carbon content on the formation of cracks of different morphology is evaluated for the conditions that exist at the Azovstal' Metallurgical Combine.     

Assimilation of Steel Contemporary Extra-Furnace Treatment Technology with the Aim of Reducing Metal Contamination with Nonmetallic Inclusions

Metallurgist - Contemporary technology of steel extra-furnace treatment that makes it possible to reduce scrap with respect to non-metallic inclusions is considered. Improvement of steel...     

Methods of Evaluating the Corrosion Resistance of Low-Alloy and Carbon Tube Steels under the Service Conditions of Oil and Gas Pipelines

At present, determining the content of corrosion-active nonmetallic inclusions in tube steels is the best way to evaluate these steels' resistance to local corrosion under the service conditions of oil-field tubing in Western Siberia. However, the method needs to be refined or supplemented. Field tests of tube steels are an important means of gauging the corrosion resistance of these materials and pipes when certain conditions are observed. Laboratory corrosion tests should be performed under conditions identical to the corrosion conditions encountered in the field. The rates of the main corrosion processes that take place during the problem-free operation of pipelines may turn out to be significantly higher in the laboratory than in field tests. __________ Translated from Metallurg, No. 5, pp. 44–50, May, 2005.     

低碳钢奥氏体中Ti夹杂溶解度积的分析

对低碳钢(含无间隙原子-IF钢)奥氏体中Ti的各类夹杂物固溶度积进行了计算和定性比较。结果表明,在不考虑其它因素影响的情况下,在950～1 250℃,TiN具有最小的固溶度积,TiC具有最大的固溶度积,而TiS和Ti₄C₂S₂则处其间。表明低碳钢在高温时优先析出的应该是TiN,其次是TiS和Ti₄C₂S₂,而TiC析出则处在最后。     

Origin and Subsequent Behaviour of Inclusions in Water-Atomized Low-Alloy Steel Powder

Abstract

The origin of inclusions in a water-atomized 3·5%Ni steel powder and their subsequent behaviour during sintering have been investigated. Four samples of the powder were produced under different melting and atomizing conditions. For example, both acid SiO₂ and basic MgO linings were used in the melting furnace. The volume fraction of inclusions was measured for the powders in the as-delivered and sintered conditions. Similarly, the chemical composition of individual inclusions was determined using electron microprobe techniques. The analysis showed the inclusions to be mainly complex oxides. Those oxides formed from elements less stable than SiO₂ were reduced by the sintering process. These oxides originated mainly from the alloying elements present in the steel powder. The residual stable complex oxides containing silicon, aluminium, magnesium, calcium, sodium, and sulphur were shown to originate from the refractories and atomizing medium used. A much lower volume fraction of inclusions was measured for the powder produced with fewer silicon-containing refractories in the atomizing system. Other measures to help minimize the inclusion levels in water- atomized low-alloy powders during their manufacture are highlighted. PM/0175