Properties Of Pressure Vessel Steel Research Articles

Effect of Initial Microstructure on Mechanical Properties of Pressure Vessel Steel after Intercritical Heat Treatment

Effect of Initial Microstructure on Mechanical Properties of Pressure Vessel Steel after Intercritical Heat Treatment

The action mechanism and application of alloying elements in the pressure vessel steel

The research progress of the influence of alloying elements on the microstructure and mechanical properties of pressure vessel steel was summarized. The effects of different alloying elements on the composite mechanical properties of the pressure vessel, such as the strength and toughness and the low temperature fracture resistance, were analysed. The action mechanism of alloying elements in pressure vessel steel was generalized. Combined with the actual production, the adding alloying elements, the research progress and the development prospect of the nuclear power pressure vessel steel were mainly analysed and discussed. The future research should focus on the mechanism of each component element, clarify the interaction relationship between the alloying elements, and develop a complete set of alloy adding scheme. So that the pressure vessel steel, which not only conforms to the actual situation, but also meet the specific requirements should be produced.

Effect of post weld heat treatment on mechanical properties of pressure vessel steels

Welding process results into residual stresses, distortion, cracking, formation of HAZ, etc. due to uneven heating and cooling during welding. For solving these problems, various heat treatment techniques are available, which need to be implemented effectively. This manuscript provides information regarding the effect of various post weld heat treatment on properties of pressure vessel steels. Various problems encountered during and after welding are covered and information about various heat treatment methodology for solving these problems are also described. It also includes literature review of previous important articles on post weld heat treatment of pressure vessel steels and its effect on mechanical properties of material is also summarized. Critical observations, statistics and overall summary related to various materials and heat treatment methods will be useful to the research community.

Surface Defect Inspection of Pressure Equipment Based on Indentation and Numerical Simulation

Surface defects caused by damage or corrosion are major factor in petrochemical pressure vessels and line pipes failure. The characteristic size of typical surface defect is from micron to submillimeter which belongs to mesoscopic scale, leading to difficulties for inspection and evaluation. The instrumented indentation method has widely used in the characterization of micro-zone mechanical behavior which could be effective in surface defects analysis. This paper aims at investigating the correspondence between indentation experimental results and distribution characteristics of surface defects. Mechanical properties of pressure vessel steel with surface defects are measured by indentation, and corresponding finite element models are established. Finite element simulation results of equivalent mechanical properties under indentation and three dimensional deformations are compared, and the applicability of finite element models for indentation test of steel with surface defects is analyzed. The effect of randomized surface defects on measuring result is studied subsequently using stochastic finite element models. The relation of equivalent mechanical properties and description of surface defects is proposed. The achievement could used to estimate the degree of damage or corrosion by miniature indentation testing techniques for safety assessment.

Effects of prestrain on the fracture properties of pressure vessel steel

In this paper, various methods have been used to measure the effects of prestrain on the fracture toughness of 20 g steel experimentally. Based on elastic-plastic FEM analysis, the relationships between crack tip opening displacement δT and the maximum strain emaxc have been obtained and the effects of prestrain ep on the critical fracture strain emaxc have been examined. At the same time, based on the Rice-Tracey's void growth model [4], the cause of the void formation ahead of the crack tip, the condition of the principal crack propagation and the effects of prestrain ep on the fracture properties of 20 g steel were investigated. For ductile material there was a maximum value of V G ahead of the crack tip that was the cause of the void formation in that place. It is believed that when the maximum value of V G ahead of the crack tip reaches a critical value, it may be the principal crack propagating condition for high ductile material.

Effect of ageing on properties of pressure vessel steels

Manganese-molybdenum-nickel steels are used in the fabrication of nuclear pressure vessels operating at temperatures up to 350°C. In this work the effects of thermal ageing in the temperature range 300–550°C for durations up to 2 × 10 4 h have been studied in conventionally quenched and tempered, and simulated heat-affected-zone (HAZ) microstructural conditions. Quantitative fractography and Auger spectroscopy have been used to relate changes in mechanical properties with associated changes in fracture mode and grain boundary chemistry. The results show that ageing increases the ductile-brittle transition temperature by an amount dependent on material, prior heat treatment, ageing temperature and time. Embrittlement was associated with the segregation of phosphorus to grain boundaries and was successfully modelled using McLean's approach to equilibrium segregation. The embrittling potency of phosphorus was highly dependent on prior heat treatment; largest in the coarse-grained, higher hardness simulated HAZ condition, and least in the conventionally quenched and tempered conditon.

The Influence of Load Ratio and Temperature on the Near-Threshold Fatigue Crack Growth Rate Properties of Pressure Vessel Steels

Near-threshold fatigue crack propagation behavior was examined in four pressure vessel steels (SA508 Cl 2a, SA533 Gr A Cl 2, SA508 Cl 3a, and SA533 Gr B Cl 2) and two submerged arc weldments (SA508 Cl 2a and SA533 Gr A Cl 2). At a given temperature and load ratio, near-threshold crack growth rates in the four base materials and two submerged arc weldments were essentially identical. Increasing the load ratio from 0.20 to 0.50 increased the rate of near-threshold crack propagation at a given temperature. At a fixed load ratio, increasing the temperature from 24 to 288°C (75 to 500°F) increased the rate of near-threshold crack growth. The effects of load ratio and temperature on the near-threshold crack growth behavior of pressure vessel steels can be explained based on a crack closure concept.

Fabrication Technology And Material Property Requirements For Heavy Wall Pressure Vessels

The joining of heavy section steels in the fabrication of large pressure vessels is reviewed. For thicknesses ≥ 100mm, narrow-gap welding processes offer a significant saving in weld metal volume, increased productivity, and acceptable levels of mechanical properties, i.e. notch toughness.The in-service properties of pressure vessel steels are discussed, with particular emphasis on 2.25 Cr–1 Mo base metal and stainless steel weld overlay. The results of a study of the effect of phosphorus and silicon on temper embrittlement of 2.25 Cr–1 Mo steel and the role of rare earth additions in reducing the susceptibility to temper embrittlement are presented. The presence of hydrogen in stainless steel overlay can lead to (1) a loss in ductility depending on the amount of sigma phase, and (2) disbonding at the overlay/base metal interface. Résumé L'assemblage d'aciers prolifés lourds dans la fabrication de gros bacs sous pression est revu. Pour une épaisseur supérieur ou égale à 100mm (≥ 100mm), le soudage avec faible écartement des bords offre une économie importante dans le volume du métal de soudure, une productivité augmentée et des propriétés mécaniques de niveaux acceptables, comme la résistance des encoches.Les propriétés des aciers pour bacs sous pression sont discutés, en mettant un accent particulier sur le métal commun 2.25 Cr–1 Mo et les recouvrements de soudure en acier inoxydable. Les résultats d'une étude de l'effet du phosphore et du silicium sur l'accroissement de la fragilite à revenu du metal 2.25 Cr–1 Mo et le rôle des rares additions de terre dans la réduction de la susceptibilite a l'accroissement de la fragilité a revenusont présentés. La presence d'hydrogene dans le recouvrement des aciers inoxydables selon le nombre de phase sigma, et (2) au relâchement des liens a l'interface du métal commun et du recouvrement.

A comparison of the effects of explosive forming and static deformation on the mechanical properties of pressure vessel steels

The mechanical and impact properties of ASTM A285 Grade C and A515 Grade 70 steels were determined after either explosive forming or statically straining to the same level of effective strain. After explosive forming and a standard stress relief anneal, both steels met boiler code specifications. Statically prestraining reduced the impact strength of the A285 steel, whereas explosively formed A285 steel had impact properties comparable to as-received stock. The impact properties of A515 steel strained to about 4 pct effective strain were comparable regardless of method of strain introduction. At strain levels of 35 pct strain the cold-rolled A515 steel had greater impact resistance and lower DBT values than explosively formed steel.