Self-organized Formation of Multilayer Structure in a High Nitrogen Stainless Steel during Solution Treatment

MRS Advances ◽  
2019 ◽  
Vol 4 (5-6) ◽  
pp. 271-276 ◽  
Author(s):  
Rui Zhou ◽  
Xuan Wang ◽  
Cheng Liu ◽  
Derek O. Northwood
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Multilayer Structure ◽  
Low Cost ◽  
Subsurface Layer ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Partial Replacement ◽  
High Nitrogen ◽  
Outward Diffusion

ABSTRACTCompared with traditional stainless steels, high nitrogen stainless steels (HNSS), have been widely used due to their high strength, toughness along with excellent corrosion resistance and low cost, formed by partial replacement of Ni (austenite-forming element) by N. The evolution of the microstructure of a Cr19Mn19Mo2N0.7 stainless steel is investigated after solution treatment at 1010, 1060, 1200 or 1250°C for 30min. A complex multilayer structure has been found under a negative pressure vacuum. A white ferritic layer at the surface is formed, and a subsurface layer with full austenitic structure and a bulk microstructure comprising of austenite and ferrite are detected. With increasing solution temperature, the surface layer thickness increases. The formation of the multilayer structure is attributed to an outward diffusion, a diffusive retardation and an abnormal accumulation of nitrogen during solution treatment.

scholarly journals The Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Novel Low-Cost Ti-3Al-5Mo-4Cr-2Zr-1Fe Alloy

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3798
Author(s):  
Meng Sun ◽  
Dong Li ◽  
Yanhua Guo ◽  
Ying Wang ◽  
Yuecheng Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aging Time ◽  
Volume Fraction ◽  
Low Cost ◽  
Solution Treatment ◽  
Solution Temperature ◽  
The Novel ◽  
Α Phase ◽  
The Cost

In order to reduce the cost of titanium alloys, a novel low-cost Ti-3Al-5Mo-4Cr-2Zr-1Fe (Ti-35421) titanium alloy was developed. The influence of heat treatment on the microstructure characteristics and mechanical properties of the new alloy was investigated. The results showed that the microstructure of Ti-35421 alloy consists of a lamina primary α phase and a β phase after the solution treatment at the α + β region. After aging treatment, the secondary α phase precipitates in the β matrix. The precipitation of the secondary α phase is closely related to heat treatment parameters—the volume fraction and size of the secondary α phase increase when increasing the solution temperature or aging time. At the same solution temperature and aging time, the secondary α phase became coarser, and the fraction decreased with increasing aging temperature. When Ti-35421 alloy was solution-treated at the α + β region for 1 h with aging surpassing 8 h, the tensile strength, yield strength, elongation and reduction of the area were achieved in a range of 1172.7–1459.0 MPa, 1135.1–1355.5 MPa, 5.2–11.8%, and 7.5–32.5%, respectively. The novel low-cost Ti-35421 alloy maintains mechanical properties and reduces the cost of materials compared with Ti-3Al-5Mo-5V-4Cr-2Zr (Ti-B19) alloy.

scholarly journals A Review on Diffusion Bonding between Titanium Alloys and Stainless Steels

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
De-feng Mo ◽  
Ting-feng Song ◽  
Yong-jian Fang ◽  
Xiao-song Jiang ◽  
Charles Q. Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Titanium Alloy ◽  
Titanium Alloys ◽  
Stainless Steels ◽  
Diffusion Bonding ◽  
Low Cost ◽  
Phase Interface ◽  
Intermetallic Phases ◽  
Voids Growth

High-quality joints between titanium alloys and stainless steels have found applications for nuclear, petrochemical, cryogenic, and aerospace industries due to their relatively low cost, lightweight, high corrosion resistance, and appreciable mechanical properties. This article reviews diffusion bonding between titanium alloys and stainless steels with or without interlayers. For diffusion bonding of a titanium alloy and a stainless steel without an interlayer, the optimized temperature is in the range of 800–950°C for a period of 60–120 min. Sound joint can be obtained, but brittle FeTi and Fe-Cr-Ti phases are formed at the interface. The development process of a joint mainly includes three steps: matching surface closure, growth of brittle intermetallic compounds, and formation of the Kirkendall voids. Growth kinetics of interfacial phases needs further clarification in terms of growth velocity of the reacting layer, moving speed of the phase interface, and the order for a new phase appears. The influence of Cu, Ni (or nickel alloy), and Ag interlayers on the microstructures and mechanical properties of the joints is systematically summarized. The content of FeTi and Fe-Cr-Ti phases at the interface can be declined significantly by the addition of an interlayer. Application of multi-interlayer well prevents the formation of intermetallic phases by forming solid solution at the interface, and parameters can be predicted by using a parabolic diffusion law. The selection of multi-interlayer was done based on two principles: no formation of brittle intermetallic phases and transitional physical properties between titanium alloy and stainless steel.

Influence of Nitrogen on Oxidation Resistance of Automotive Steel Grades

2020 ◽  
Vol 835 ◽  
pp. 83-92
Author(s):  
Saeed Ghali ◽  
Mamdouh Eissa ◽  
Hoda El-Faramawy ◽  
Azza Ahmed ◽  
Fathy Baiomy ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Stainless Steels ◽  
Oxidation Process ◽  
Diffusion Mechanism ◽  
Solution Treatment ◽  
Mass Gain ◽  
Optical Microscope ◽  
Partial Replacement ◽  
Steel Grades ◽  
Automotive Steel

With the objective of partial and total replacement of nickel by nitrogen in austenitic exhausted valve steel X45CrNiW18-9, a program of work with series of experimental heats was designed. Experimental heats were carried out in 10 Kg. induction furnace under nitrogen pressure. The chemical composition of produced stainless steels was determined. The produced automotive steel grades were forged. The nitrogen contents were determined. The produced forged stainless steels were subjected to solution treatment at 1050 °C for 1 hour, followed by water cooling. Isothermal oxidation test is used to detect the behavior of new grades at different temperatures in air for solution treated stainless steels. The mass gain was measured for samples exposed to air at temperatures (500 °C, 600 °C, 700 °C, 800°C) for different time intervals, up to 1000 hrs. The oxide layer thickness for two selected steels was investigated by using optical microscope. XRD was used to detect types of oxides which are formed during oxidation process at 800 °C for 1000 hrs for represented investigated exhausted valve steels. Scanning Electron Microscope was used to make scan steels surface, after heating at 500 °C and 800 °C for l000hr. The mechanism of the oxidation of developed steels was investigated. It was found controlled by diffusion mechanism and the kinetic of oxidation process is parabolic. Oxidation rate of the investigated stainless steels for times, up to 8 h and between 200 andl000 h, at all investigated temperatures (500 °C - 800 °C), is parabolic and the oxidation is diffusion controlled. While in the time region 10 to 200 h, it obeys combined mechanisms. Partial replacement of nickel, by nitrogen, improves the oxidation resistance in air at temperature range 500°C - 800°C.

Effect of Solution Temperature on the Microstructure and Mechanical Properties of Wrought 316LN Stainless Steel

2014 ◽  
Vol 915-916 ◽  
pp. 576-582 ◽  
Author(s):  
H. C. Wu ◽  
B. Yang ◽  
Ming Xian Zhang ◽  
Sheng Long Wang ◽  
Y. Z. Shi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Tensile Fracture ◽  
316Ln Stainless Steel ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
Fracture Morphologies

The effect of forging and solution temperature on the microstructure and mechanical properties of 316LN stainless steel has been investigated by optical microscope, tensile testing machine and scanning electron microscope (SEM). The results show that the average grain size of the steel was refined from 150μm to 70μm after forging and solution treatment. With increasing solution temperature, the tensile strength and yield strength decreased. On the contrary, the elongation of the steel increased with increasing solution temperature except at 1200°C. The tensile strength of the samples forged at 1100°C is better than those of the samples forged at 1000 and 1200°Cafter solution treatment. Tensile fracture morphologies observation showed that all the specimens have ductile fracture morphologies. With increasing solution temperature, the toughness of the steel becomes better and better except at 1200°C. Both the microstructure and mechanical properties of the 316LN stainless steel have been improved after forging at 1100°C and following by solution treatment at 1150°C.

Research on Mechanical Properties of High Boron Alloyed Stainless Steel Composite Plate Containing Titanium

2013 ◽  
Vol 401-403 ◽  
pp. 804-808
Author(s):  
Lin Lin Yuan ◽  
Jing Tao Han ◽  
Jing Liu ◽  
Yan Long Liu
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Composite Plate ◽  
Solution Treatment ◽  
Composite Plates ◽  
Solution Temperature ◽  
Forming Process ◽  
High Boron ◽  
Steel Composite ◽  
Ti Content

High boron alloyed stainless steel composite plates with different Ti content by cladding casting and hot forming process were fabricated. The mechanical properties of composite plates were analyzed after solution treatment. The results show that the composite plate has optimal microstructure and properties at 1100°C solution temperature, holding for 4h.The comprehensive properties of the composite plates are improved with the increase of Ti content, but excess Ti content can lower the plasticity. The elongation and the tensile strength of composite plate reaches 29% and 527MPa respectively, the mechanical properties can meet and exceed the supply standard requirements in ASTM A887-89 of U.S. when the reasonable content of Titanium is about 5%.

Effect of Solid Solution Treatment on Corrosive Action of 00Cr26Ni5Mo2Cu3Re Duplex Stainless Steel in Acid Stage

2011 ◽  
Vol 335-336 ◽  
pp. 566-570
Author(s):  
Hong Pu Zhao ◽  
Shun Xing Wang
Keyword(s):  
Solid Solution ◽  
Stainless Steel ◽  
High Temperature ◽  
Low Temperature ◽  
Acid Solution ◽  
Duplex Stainless Steel ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Solid Solution Treatment ◽  
Corrosive Resistance

Effect of solid solution treatment on corrosive behavior of 00Cr26Ni5Mo2Cu3Re Duplex Stainless Steel in static stage of HNO3+HF acid solution is studied in the paper.The results show that the corrosion between phases and pitting corrosion on ferrite are serious at low temperature ,the phenomenon gradually disappear with the solid solution temperature rising ; the corrosive resistance of 00Cr26Ni5Mo2Cu3Re is getting better first and then decrease with solution temperature at high temperature, the best corrosive resistance temperature is at 1050°C.

Effect of Solution Annealing on Microstructure and Mechanical Properties of MIM Fe-Cr-Mn-Mo-N Stainless Steels

2010 ◽  
Vol 129-131 ◽  
pp. 886-890
Author(s):  
Da Wei Cui
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Stainless Steels ◽  
Solution Treatment ◽  
Austenitic Stainless Steels ◽  
Solution Annealing ◽  
High Nitrogen ◽  
Solid Solution Treatment ◽  
Microstructure And Mechanical Properties ◽  
Dimple Fracture

The influence of solution annealing on the microstructure and mechanical properties of high nitrogen Fe-Cr-Mn-Mo-N austenitic stainless steels prepared by MIM was investigated. The results show that the solution treatment can improve the microstructure and properties of the stainless steels significantly. The sintered specimens before solution annealing consist of γ-austenite and embrittling intergranular Cr2N precipitates, showing a low mechanical property. After solid solution annealing, the specimens reveal a fully austenitic structure without any intergranular nitrides, whose tensile properties are much higher than those without solution annealing, which is attributed to the elimination of the nitride precipitation along the grain boundaries and the greater amount of nitrogen retained in solid solution. A mixed mode of intergranular and dimple fracture happen to the specimens before solid solution treatment, while a completely tough fracture of dimple happen to those after solid solution treatment.

Experimental Study on Heat Yreatment Processing of a New Low Cost Titanium Alloy Used in Aviation Field

2013 ◽  
Vol 747-748 ◽  
pp. 919-925 ◽  
Author(s):  
Guo Qiang Shang ◽  
Xin Nan Wang ◽  
Yue Fei ◽  
Jun Li ◽  
Zhi Shou Zhu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Low Cost ◽  
Solution Treatment ◽  
Heat Treating ◽  
Optical Microscope ◽  
Phase Region ◽  
Solution Temperature ◽  
Two Phase ◽  
Common Solution ◽  
Strength And Plasticity

The effect of common solution treatment, two-step solution treatment and aging, solution treatment and aging (STA) on the microstructure and mechanical properties of a new low cost titanium alloy used in aviation field were investigated by optical microscope (OM), scanning electron microscopy (SEM) and tensile test. The results show that a typical equiaxed structure can be obtained by common solution treatment leading to a good combination of strength and plasticity. Besides, solution heat treating in the β region and subsequently ageing at a low temperature results in a significant increase in mechanical strength and a little decrease in plasticity. When the solution temperature is at α+β two-phase region (895), the low cost titanium alloy acquires the best combination of strength and ductility.

Effect of Solution Temperature on Microstructure of 2205 Duplex Stainless Steel Welded Joints

2010 ◽  
Vol 658 ◽  
pp. 432-435
Author(s):  
Yuan Yuan Qiao ◽  
De Ning Zou ◽  
Jiao Li ◽  
Ying Han
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Arc Welding ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Solution Temperature ◽  
2205 Duplex Stainless Steel ◽  
Manual Arc Welding ◽  
Temperature Solution ◽  
Steel Joints

The various temperature solution experiments were carried out in this paper, which for 2205 duplex stainless steel joints welded by manual arc welding. The evolutions of microstructure in pre/post solution treatment and the contents of ferrite phase were conducted by using optical microscope and ferrite scope detector. The analysis results in the welded, the heat affected and the base metal regions show that suitable solution treatment is effective to adjust the welded microstructure condition. The austenite in each region transformed into ferrite when the temperature enhanced from 1050 to 1200°C. This resulted in increasing the volume of ferrite and coarsening the grain. All microstructure characteristics of the three regions were taken into account, it deduced that the feasible solution temperature range was 1050~1100°C for 2205 duplex stainless steel welded joint.

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