Austenitic stainless steel has good comprehensive mechanical properties and excellent corrosion resistance. Usually austenitic stainless steel with lower yield strength, yield ratio, in accordance with the current safety coefficient, the allowable stress of the material yield strength, resulting in pressure vessel design of thick, heavy equipment, serious waste of materials, manufacturing and transportation cost is high.
By using strain hardening technology, it can effectively improve the yield strength of austenitic stainless steel under the premise of ensuring that the original mechanical properties of austenitic stainless steel are not affected greatly. The container can be thinned by 30% to 50%, which can be used to save materials, reduce manufacturing cost and energy consumption in transportation, and the economic benefit is obvious. Therefore, strain hardening technology is a kind of green manufacturing technology.
Strain hardening technology was first proposed in 1950s by the Swedish Avesta company, followed by australia. Because of the lack of sufficient experience in design and use, in the next more than and 20 years, other countries in the world are cautious about this technique, the main reason is that most of the current national standard is the pressure vessel design conservative strain strengthening technology. Therefore, for security reasons, the majority of countries have changed to strengthen the use of restrictive technologies, and the application of the conditions are more stringent. In the past 10 years, with the successful use of the case and the accumulation in the use of engineering experience more and more, the British Standards Institute, the American Society of mechanical engineers and other authoritative institutions have adopted standard strain strengthening technology relates to the manufacture of austenitic stainless steel pressure vessels.
In view of national standards and industry standards in our country there is no strain strengthening technology of austenitic stainless steel, in order to regulate the application of technology in our country, the State Administration of Quality Supervision Inspection and quarantine commissioned by the National Standardization Committee on boilers and pressure vessels to carry out technical review austenitic stainless steel strain strengthening technology of cryogenic pressure vessel manufacturing.
In order to improve the yield strength of austenitic stainless steel, the strain hardening process was adopted to improve the yield strength of austenitic stainless steel. Analysis of strain hardening process in two key process parameters, strain rate and strain dependent on the mechanical behavior of materials, the strain rate should not be too slow, otherwise there will be a serrated yielding behavior, adversely affect the material properties. After the strain hardening, the austenitic stainless steel can improve the toughness remarkably. Through the microstructure analysis, the martensite volume fraction measurement results show that the variables should be controlled below 10%, after strengthening austenite martensite transformation occurs only a 'small, has little effect on the mechanical properties of the material, microstructure and material did not change significantly.
The results show that the strain strengthening technology in increasing the yield strength of austenitic stainless steel and other mechanical properties of the material are not a big impact, so as to provide a strong guarantee for the safe operation of pressure vessel, pressure vessel can realize the lightweight design, significant economic and social benefits, the broad application prospect.
