Microstructure and Mechanical Properties of G17CrMoV5-10 Cast Steel After Regenerative Heat Treatment

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Grzegorz Golański
Keyword(s):  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Strength Properties ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Energy Increase ◽  
Regenerative Heat ◽  
Term Operation

This paper presents the results of a research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long-term operation at the elevated temperature. The material under investigation was G17CrMoV5-10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250,000 h. Performed research has proven that through the microstructure degradation long-term service contributes to an embrittlement and decrease in yield strength and tensile strength. The heat treatment, however, contributes to an impact energy increase regardless of the applied parameters (cooling rate). It has also been established that the optimum combination of strength properties and impact energy is ensured by the microstructure of high tempered bainite, whereas low strength properties and impact energy were obtained for the microstructure, which was slowly cooled from the austenitizing temperature, i.e., the ferritic-bainitic-ferritic microstructure.

Microstructure and Mechanical Properties of G17CrMoV5 – 10 Cast Steel After Regenerative Heat Treatment

2009 ◽  
Author(s):  
Grzegorz Golan´ski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Optimum Combination ◽  
Austenitizing Temperature ◽  
Regenerative Heat ◽  
Term Operation ◽  
Structure Degradation

The paper presents results of research on the influence of regenerative heat treatment on microstructure and properties of a cast steel after long term operation at the elevated temperature. The material under investigation was G17CrMoV5 – 10 cast steel taken out (in the form of a section) from an internal frame of steam turbine serviced for about 250 000 hours. Performed research has proved that, through the structure degradation, long-term service contributes to an increase of brittleness and decrease of mechanical properties — higher in the case of yield strength than tensile strength. The heat treatment, however, contributes to an increase of impact energy, regardless of the applied parameters. Is has also been proved that the optimum combination of mechanical properties and impact energy is ensured by the structure of high tempered bainite. Low mechanical properties and impact energy, however, were obtained for the structure which was slowly cooled from the austenitizing temperature, i.e. the ferritic – bainitic – ferritic structure.

Mechanical Properties of G17CrMoV5 – 10 Cast Steel after Regenerative Heat Treatment

2009 ◽  
Vol 147-149 ◽  
pp. 732-737 ◽  
Author(s):  
Grzegorz Golański
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Negative Influence ◽  
Optimum Combination ◽  
Structure And Properties ◽  
Tempering Temperature ◽  
Regenerative Heat ◽  
Bainitic Structure

The paper presents results of research on the influence of regenerative heat treatment on structure and properties of G17CrMoV5 – 10 cast steel. Investigated material was taken out from a turbine frame serviced for over 250 000 hours (total service time) at the temperature of 535 oC. The cast steel after service revealed degraded bainitic-ferritic structure and was characterized by mechanical properties ranging below norm requirements. It has been proved that high tempering temperature in the case of cast steel with bainitic structure ensures optimum combination of mechanical properties and impact energy. It has also been shown that ferrite has a negative influence on impact energy of the cast steel with bainitic-ferritic structure.

Effect of Different Heat Treatments on Microstructure and Mechanical Properties of the Martensitic Gx12CrMoVNbN9-1 Cast Steel / Wpływ Parametrów Obróbki Cieplnej Na Mikrostrukture I Własciwosci Mechaniczne Martenzytycznego Staliwa Gx12CrMoVNbn9-1

2013 ◽  
Vol 58 (1) ◽  
pp. 25-30 ◽  
Author(s):  
G. Golanski ◽  
J. Słania
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Energy ◽  
Cast Steel ◽  
Lath Martensite ◽  
High Strength ◽  
Strength Properties ◽  
Microstructure And Mechanical Properties ◽  
Quenching And Tempering ◽  
Very High

The paper presents a research on the influence of multistage heat treatment with the assumed parameters of temperature and time on the microstructure and mechanical properties of high-chromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel. In the as-cast state GP91 cast steel was characterized by a microstructure of lath martensite with numerous precipitations of carbides of the M23C6, M3C and NbC type, with its properties higher than the required minimum. Hardening of the examined cast steel contributes to obtaining a microstructure of partly auto-tempered martensite of very high strength properties and impact strength KV on the level of 9-15 J. Quenching and tempering with subsequent stress relief annealing of GP91 cast steel contributed to obtaining the microstructure of high-tempered lath martensite with numerous precipitations of the M23C6 and MX type of diverse size. The microstructure of GP91 cast steel received after heat treatment was characterized by strength properties (yield strength, tensile strength) higher than the required minimum and a very high impact energy KV. It has been proved that GP91 cast steel subject to heat treatment No. 2 as a result of two-time heating above the Ac3 temperature is characterized by the highest impact energy.

scholarly journals Effect of Long Term Service at Elevated Temperatures on Mechanical Properties of Manaurite XM Reformer Tubes

2016 ◽  
Vol 16 (4) ◽  
pp. 38-44
Author(s):  
J. Łabanowski ◽  
M. Jurkowski ◽  
M. Landowski
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Cast Steel ◽  
Internal Diameter ◽  
Term Operation ◽  
Static Tensile ◽  
Different Shapes ◽  
Reformer Tubes ◽  
The Relationship

Abstract Microstructure transformations occur in the Manaurite XM cast steel tubes during long-term operation in the reformer furnace were revealed and described. The relationship between mechanical properties, an increase of internal diameter of the tube and microstructure degradation is discussed. Static tensile test was performed on two types of samples with different shapes. It has been shown differences in the results of tests and an explanation of this phenomenon.

Effect of Initial Bainite Microstructure on Tensile Properties After Long-Term Exposure at Elevated Temperature

2018 ◽  
Author(s):  
Junji Shimamura ◽  
Shusaku Ota ◽  
Tomoyuki Yokota ◽  
Ryuji Muraoka
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
The Other ◽  
Accelerated Cooling ◽  
Oil Sand ◽  
Initial Strength ◽  
Term Operation ◽  
Steel Pipes ◽  
Bainite Microstructure

In the oil sand production field in Canada, steel pipes are used for injecting steam into the sands. Pipes for steam distribution are subjected to high operating temperature such as 350 degrees C for a long time. In this study, in order to insure the reliability of high strength pipe for steam distribution, long-term heating tests were conducted for X80 grade UOE pipe. To simulate the long-term operation at 350 degrees C for 40 years, accelerated tests were conducted at 400 degrees C for up to 4400 hours. The effect of initial bainite microstructure on tensile properties after long-term heat treatment was investigated by using two kinds of steel pipes with different bainite microstructure. One is accelerated cooling (ACC) type, and the other is heating on-line process (HOP) type just after accelerated cooling in plate manufacturing process. It was revealed that strength decrease in ACC type steels produced by only accelerated cooling was mainly governed by decomposition of hard phase MA (Martensite-Austenite constituent) and recovery of dislocations. On the other hand, HOP type steels had small amount of MA and nanometer-sized carbides by applying HOP after accelerated cooling. The HOP type steels had almost the same initial strength in spite of small amount of MA. Fine niobium carbides gave enough precipitation strengthening. Formation of fine niobium carbides was promoted by the addition of niobium. The precipitates were stable after long-term heat treatment at 400 degrees C. It is confirmed that the fine niobium carbides in HOP type steels remained even after long-term heat treatment. The suppression of initial MA also lead to minimize the strength decrease by MA decomposition. Therefore, HOP type steels tend to have higher resistance to the strength decrease after long-term heat treatment.

scholarly journals Effect of Quenching Media Variations on the Mechanical Behavior of Martensitic Stainless Steel

2019 ◽  
Vol 15 (2) ◽  
pp. 1-12 ◽  
Author(s):  
Abbas Kh. Hussein ◽  
Laith K. Abbas ◽  
Wisam N. Hasan
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Wear Rate ◽  
Process Parameters ◽  
Impact Energy ◽  
Salt Solution ◽  
Martensitic Stainless Steel ◽  
Austenitizing Temperature ◽  
Soaking Time ◽  
Α Al2o3

The purpose of this study is designate quenching and tempering heat treatment by using Taguchi technique to determine optimal factors of heat treatment (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time) for increasing hardness, wear rate and impact energy properties of 420 martensitic stainless steel. An (L18) orthogonal array was chosen for the design of experiment. The optimum process parameters were determined by using signal-to-noise ratio (larger is better) criterion for hardness and impact energy while (Smaller is better) criterion was for the wear rate. The importance levels of process parameters that effect on hardness, wear rate and impact energy properties were obtained by using analysis of variance which applied with the help of (Minitab18) software. The variables of quenching heat treatment were austenitizing temperature (985 C˚,1060 C˚),a soaking times (50,70 and 90 minutes) respectively, Percentage of volumetric fractions of nanoparticles with three different levels(0.01, 0.03 and 0.08 %) were prepared by dispersing nanoparticles that are  (α-Al2O3,TiO2 and CuO) with base fluids (De-ionized water, salt solution and engine oil).The specimens were tempered at 700°C after quenching of nanofluids for  (2 hours).The results for ( S/N) ratios showed the order of the factors in terms of the proportion of their effect on hardness, and wear rate  properties as follow: Austenitizing temperature ( 1060 C˚),Type of base media (salt solution), Nanoparticles type (CuO), Percentage of nanoparticles (0.08%) and Soaking time(90min) was the least influence while for the impact energy were as follows: Type of base media (oil), Austenitizing temperature (985C˚), Percentage of nanoparticles (0.01%), Nanoparticles type (α-Al2O3) and last soaking time (50min).

scholarly journals The Process of Regenerative Heat Treatment of the Valve Chamber of the Steam Turbine

2019 ◽  
Vol 26 (3) ◽  
pp. 243-248
Author(s):  
Agata Wieczorska
Keyword(s):  
Steam Turbine ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Cast Steel ◽  
Degradation Process ◽  
Steam Turbines ◽  
Regenerative Heat ◽  
Plastic Properties ◽  
Term Operation ◽  
Dynamic Damage

Abstract Steel castings are often used in the construction of valve chambers of steam turbines. Stringent requirements are set due to the continuous operation of the material at elevated temperatures, in the order of 300°C to 600°C. The material of the valve chamber must be resistant to fatigue-creep changes as well as corrosion. This material must be also resistant to dynamic damage which occures when the turbine is starting and stopping. Dynamic damage is induced by a short-lasting but intense accumulation of localized stresses. The castings of the valve chambers of the steam turbine are usually made from the “three-component” type CrMoV-cast steel. Mentioned castings of the valve chamber are continuously subjected to high temperatures, either constant and periodically variable stresses. Due to this, the degradation process of material of the castings is taking place. It is caused by physicochemical processes such as: creep, relaxation, thermal fatigue, corrosion, erosion and changes in material properties, e.g. displacement of the critical point of brittleness. Finally, first cracks and deformations can be observed in the material during the operation. The art presents the process of revitalization technology of the steam turbine valve chamber which was subjected to long-term operation at high temperatures. The revitalization process is aimed at improving the plastic properties of the material and, as the result, extending its service life. The research presented in the article show that impact strength of the chamber material after revitalization is very high. Also the strength properties of the valve chamber, after revitalization, are high and in line with the requirements. The study show that the revitalization of the valve chamber was carried out correctly and restored the material to plastic deformation.

Effects of Heat Treatment Process on Microstructure and Mechanical Properties of 31Mn2SiREB Cast Steel

2013 ◽  
Vol 762 ◽  
pp. 418-423
Author(s):  
Feng Zhang Ren ◽  
Feng Jun Li ◽  
Ling Bai ◽  
Yun Fei Wang
Keyword(s):  
Heat Treatment ◽  
Impact Energy ◽  
Treatment Process ◽  
Cast Steel ◽  
Diffusion Annealing ◽  
Heat Treatment Process ◽  
Micro Hardness ◽  
Quenching Temperature ◽  
Pre Treatment ◽  
The Impact

The heat treatment process of 31Mn2SiREB cast steel used in crawler shoes is directly lifted from the heat treatment process of Mn13 high-manganese cast steel, i. e., quenching at 1050 oC after casting. The reasonableness of the process needs to be surveyed. In this paper, the effects of quenching temperature and diffusion annealing pre-treatment on mechanical properties, micro-area composition uniformity and micro-hardness uniformity were investigated. For quenching after casting, the tensile strength and impact energy increase observably with the elevation of quenching temperature, but the impact energy at higher quenching temperature is still very small. The fluctuation of micro-hardness and chemical composition at different micro-areas becomes obviously small with the increase of quenching temperature. For quenching after a diffusion annealing pre-treatment, the impact energy is very high and up to 36.3 J.

The effect of heat treatment on the mechanical properties of a low carbon steel (0.1%) for offshore structural application

2012 ◽  
Vol 226 (3) ◽  
pp. 242-251 ◽  
Author(s):  
Sung S Kang ◽  
Amir Bolouri ◽  
Chung-Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Cooling Rate ◽  
Impact Energy ◽  
Cast Steel ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Tempering Temperature ◽  
Austenite Grain

In this study, a low carbon cast steel (0.1% C) alloy designed for offshore structures, and the mechanical properties of the alloy under different heat treatment cycles have been evaluated. The effect of austenitizing time on the austenite grain size was studied. Subsequently, the quenched samples with minimum austenite grain size subjected to tempering experiments at different tempering temperatures (450 °C, 550 °C, and 650 °C) and cooling rates (0.23, 36, and 50 °C/s) from the temperature. The results showed that by increasing the austenitizing time, the austenite grain size initially decreased and reached the minimum value with ASTM number of 6.35 and then followed by an increase. When the tempering temperature increased, yield and tensile strengths decreased, whereas the ductility properties improved. In addition, yield and tensile strengths were not affected by cooling rate from tempering temperature, whereas the ductility properties were slightly affected. The increase in tempering temperature significantly led to improvement in the toughness to fracture of the alloy. The effect of cooling rate on impact energy for the samples tempered at 450 °C and 550 °C was negligible. By the contrast, impact energy for the samples tempered at 650 °C was markedly affected by cooling rate, in which the highest value was achieved for a cooling rate of 50 °C/s.

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