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The corrosion resistance of laser surface alloyed stainless steels

Brytan Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 91, nr 2

49--59

EN

Purpose: of this paper was to examine the corrosion resistance of laser surface alloyed (LSA) stainless steels using electrochemical methods in 1M NaCl solution and 1M H2SO4 solution. The LSA conditions and alloying powder placement strategies on the material's corrosion resistance were evaluated. Design/methodology/approach: In the present work the sintered stainless steels of different microstructures (austenitic, ferritic and duplex) where laser surface alloyed (LSA) with elemental alloying powders (Cr, FeCr, Ni, FeNi) and hard powders (SiC, Si3N4) to obtain a complex steel microstructure of improved properties. Findings: The corrosion resistance of LSA stainless steels is related to process parameters, powder placing strategy, that determines dilution rate of alloying powders and resulting steel microstructure. The duplex stainless steel microstructure formed on the surface layer of austenitic stainless steel during LSA with Cr and FeCr reveal high corrosion resistance in 1M NaCl solution. The beneficial effect on corrosion resistance was also revealed for LSA with Si3N4 for studied steels in both NaCl and H2SO4 solutions. Ferritic stainless steel alloyed with Ni, FeNi result in a complex microstructure, composed of austenite, ferrite, martensite depending on the powder dilution rate, also can improve the corrosion resistance of the LSA layer. Research limitations/implications: The LSA process can be applied for single phase stainless steels as an easy method to improve surface properties, elimination of porosity and densification and corrosion resistance enhancement regarding as sintered material. Practical implications: The LSA of single phase austenitic stainless steel in order to form a duplex microstructure on the surface layers result in reasonably improved corrosion performance. Originality/value: The original LSA process of stainless steels (austenitic, ferritic and duplex) was studied regarding corrosion resistance of the alloyed layer in chloride and sulphate solutions.

2

Sintered stainless steel surface alloyed with Si3N4 powder

Brytan Z., Dobrzański L., Pakieła W.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 1

43-55

EN

Purpose: The goal of this study was to investigate effects of laser surface alloying with Si3N4 powder on the microstructural changes and properties of vacuum sintered stainless steels, both austenitic X2CrNi17-12-2, ferritic X6Cr13 and duplex X2CrNiMo22-8-2. Design/methodology/approach: High power diode laser (HPDL) was applied to surface modification of sintered stainless steels with Si3N4 powder. The influence of laser alloying conditions on the width, penetration depth of alloyed surface layer were studied and analysed via FEM simulation. The microstructure of alloyed layers was examined using light and scanning electron microscopy as well as X-ray diffraction. The microhardness and wear resistance of studied surface layers were also evaluated. Findings: The hardness increased with addition of Si3N4 due to strong solution hardening effect of nitrogen and silicon that dissolved in the steel matrix during laser alloying. The strong austenite stabilizer effect of nitrogen was observed in ferritic stainless steel that revealed duplex microstructure. The hardness increased with addition of Si3N4 due to strong solution hardening effect of nitrogen and silicon dissolved in the steel matrix during laser alloying. The hardening effect of Si3N4 was strongest in case of ferritic stainless steel where microhardness increased to 450 HV0.1 for 2.1 kW of laser beam power. The duplex stainless steel shows the regular microhardness on the whole penetration depth. Laser surface alloying with Si3N4 improved wear resistance of sintered stainless steels compared to not processed stainless steel as well as comparing layers prepared as machined grooves and surface with pre-coated paste. Practical implications: Laser surface alloying with Si3N4 powder can be an efficient method of surface layer hardening of sintered stainless steels and produce improvement of surface layer properties in terms of hardness and wear resistance. Moreover, application of high power diode laser HPDL and surface prepared as machined grooves can guarantee uniform heating of treated surface, thus uniform thermal cycle across processed area and uniform penetration depth of alloyed surface layer. Originality/value: Application of high power diode laser can guarantee uniform heating of treated surface, thus uniform thermal cycle across processed area and uniform penetration depth of alloyed surface layer.

3

Wybrane właściwości spiekanych ferrytycznych stali nierdzewnych

Kazior J., Pieczonka T., Nykiel M.

Rudy i Metale Nieżelazne

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2000

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R. 45, nr 12

623-629

PL

Przedstawiono właściwości proszków stali nierdzewnych ferrytycznych oraz przeprowadzono badania spiekania proszków stali nierdzewnej AISI 434L, jak również określono wybrane ich właściwości, które porównano z odpowiednimi właściwościami spiekanej stali austenitycznej AISI 316L.

EN

In this paper, the properties of ferritic stainless steel-powders are reviewed and the study of sintering of the stainless steel-powders AISI 434L is described, with particular reference to metallurgical features of the process. The dimensional change, mechanical properties and corrosion resistance of sintered ferritic stainless steels are detailed. These properties are then compared with those of sintered austenitic stainless steel AISI 316L.

4

Właściwości i zastosowanie spiekanych stali nierdzewnych.

Biało D., Kulesza T., Ludyński Z., Proć T., Kulszewicz I.

Mechanik

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1998

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R. LXXI, nr 1

31-34

PL

Charakterystyka typowych proszków stali nierdzewnych stosowanych do wytwarzania elementów maszyn oraz najczęściej stosowane metody formowania: prasowanie matrycowe, formowanie wtryskowe, prasowanie na gorąco i prasowanie izostatyczne na gorąco. Specyfika spiekania wyrobów ze stali nierdzewnych, właściwości tych stali oraz obszerne zestawienie ich zastosowań w różnych dziedzinach techniki.

EN

Characteristic of typical powders of rustless steel intended for making machine elements and commonest forming methods: die pressing, injection moulding, hot pressing. Specificity of the sintering of rustless steel products, properties of such steels and a comprehensive list of their applications in different fields of technology.