CN101358319A - Low carbonaceous steel plate for 610MPa grade high strength pressure vessels and production method thereof - Google Patents

Abstract

The invention relates to a steel sheet used for low-carbon Grade 610MPa high-strength pressure containers, and a production method thereof. The invention belongs to the technical field of low-alloy wide heavy plates. Chemical components in the mass percent are as follows: 0.05 percent to 0.09 percent of C, 0.25 percent to 0.45 percent of Si, 1.20 percent to 1.40 percent of Mn, 0.035 percent to 0.045 percent of Nb, 0.010 percent to 0.020 percent of Ti, 0.20 percent to 0.30 percent of Cu, 0.25 percent to 0.55 percent of Cr, 0.25 percent to 0.30 percent of Ni, and the rest is Fe; the thickness of the steel sheet is 10mm to 50mm; the micro tissue of the steel sheet is ferrite + bainite tissue, and the grain size is 9.5 to 11. The steel sheet is prepared through controlled rolling and cooling. The production method has the advantages that the produced steel produced steel sheet has greatly improved integrated performance than conventional steel sheets with the same strength grade: the yield stress can be stabilized to be above 460MPa, the tensile strength is stabilized to be above 570MPs, and toughness of the steel sheet at 40 DEG C below zero of low temperature reaches above 100J, and the welding adaptability of the steel sheet is excellent.

Description

A kind of low-carbon (LC) 610MPa grade high strength pressure vessels steel plate and production method thereof

Technical field

The invention belongs to the steel plate of pressure vessel production technical field, a kind of low-carbon (LC) 610MPa grade high strength pressure vessels steel plate and production method thereof particularly are provided.Mainly utilize the TMCP+ tempering process to make 610MPa grade pressure vessels steel, to replace traditional 610MPa grade pressure vessels steel that back off-line quenching+temper is produced that rolls.

Background technology

Home-made 610MPa grade high strength pressure vessels plate is to adopt traditional quenching-and-tempering process, and the technological process of production is long, energy consumption is big, the high theory that does not meet modern energy conservation and emission reduction of production cost.Prior heat treatment process steel plate microtexture is based on tempered sorbite, and utilizes steel plate that deformation effect produces based on middle temperature transformation product bainite, after the tempering still based on bainite.

Along with society and expanding economy, the pressure of the saving resource that Iron And Steel Industry faced, save energy, protection environment is increasing.So, traditional ferrous materials is adopted special complete processing, increase substantially its performance, increase the service life, improve the utilization ratio and the rate of recovery of resource effectively, become the focus of ferrous materials research field.Adopt TMCP technology to make the 610MPa grade pressure vessels and can save traditional postheat treatment technology of rolling, shortened process, reduced energy consumption and saved production cost with steel, significant for the Sustainable development of China's economy.

Summary of the invention

The object of the present invention is to provide a kind of low-carbon (LC) 610MPa grade high strength pressure vessels steel plate and production method thereof, has good tough coupling by the processing parameter production that changes in the thermal deformation process, make yield strength greater than 490MPa, tensile strength is more than 610MPa, unit elongation has the High Strength Steel Plate of good low temperature impact property and welding property simultaneously more than 17%.The tissue of its product contains a spot of ferrite and martensite simultaneously based on bainite.

Low-carbon (LC) 610MPa grade high strength pressure vessels of the present invention with the chemical ingredients (weight %) of steel plate is: C0.08-0.15%, Si 0.15-0.40%, Mn 1.20-1.60%, P＜0.01%,, S＜0.01%, Ni0.15-0.40%, Mo 0.1-0.30%, V 0.02-0.06%, microalloy element Ti 0.01-0.03%, Nb0.01-0.06%, surplus is Fe; The metallographic structure of steel plate is the mixed structure of tempering bainite and tempered sorbite.

Production technique of the present invention is as follows:

(1) rolling technology: heat 1150-1250 ℃; In the austenite recrystallization district, non-recrystallization district and the controlled rolling of deformation induced phase change zone, 1000-1150 ℃ of roughing open rolling, 950-1050 ℃ of roughing finish to gauge; Intermediate blank thickness is 2-2.5 times of finished product thickness, 850-900 ℃ of finish rolling open rolling, 780-820 ℃ of finish rolling finish to gauge;

(2) roll postcooling technology: speed of cooling 15-25 ℃/s, final cooling temperature is at 600-650 ℃;

(3) carry out 600-700 ℃ of tempering after rolling, obtain the mixed structure of tempering bainite and tempered sorbite.

It is in proof strength that the C content of steel of the present invention is controlled at 0.09-0.10%, avoids the infringement of C content raising to plasticity, toughness and weldability.Adding Nb is in order suitably to enlarge the scope in austenite non-recrystallization district, to make full use of the controlled rolling of austenite non-recrystallization and to roll the back controlled chilling.

Adopt the foundation of this TMCP (hot mechanical controlled rolling) technology to be: by the austenite recrystallization controlled rolling of high-temperature zone, abundant refine austenite crystal grain; Control finish rolling start rolling temperature makes it in the distortion of austenite non-recrystallization district, increases the distortion in austenite non-recrystallization district, and the finish rolling finishing temperature is controlled at 780-820 ℃, makes and produces a small amount of deformation induced ferrite in the operation of rolling; Obtain bainite and a spot of martensitic stucture by rolling the quick cooling in back.

Utilize deformation effect explained hereafter 610MPa grade pressure vessels as follows with the steel plate characteristics:

1, armor plate strength satisfies the requirement of 610MPa intensity rank;

2, through after SR (eliminating stress) processing, because the precipitation strength effect of Nb, Ti, V carbide, the mechanical property of steel changes very little;

3, steel grade newly developed has good welding property, because carbon equivalent and Pcm value are low, can weld without preheating, is applicable to that the pressurized vessel that low temperature is on active service uses.

The invention has the advantages that, controlled deformation amount, texturing temperature and cooling temperature in the whole thermo-mechanical deformation of steel plate, control the structural transformation and the transmutation product of steel plate with this, the solid solution of microalloy element in steel in addition, separate out in the thermodynamic process also inequalityly, its corresponding strengthening and toughening mechanism of also changes.The tank plate that the deformation effect technology use to be produced has good comprehensive mechanical properties can save traditional back quenching heat treatment technology of rolling, and has shortened technical process, has reduced energy consumption and saved production cost.

Description of drawings

Accompanying drawing 1 is the metallographic structure of embodiment.

Embodiment

Embodiment

The chemical ingredients scope of 610MPa steel is smelted on the 150kg vacuum induction furnace according to the present invention, and is swaged into the steel billet of 100mm * 120mm * 150mm, and is rolling on 450 milling trains, after 620 ℃ of temper.Chemical ingredients is as shown in table 1, and TMCP technology is as shown in table 2, and mechanical property is as shown in table 3, and metallographic structure as shown in Figure 1.

The chemical ingredients of the ultra-fine crystal zone of table 1 embodiment steel (weight, %)

Table 2 TMCP process system

Table 3 mechanical properties test result

Claims (2)

1, a kind of low-carbon (LC) 610MPa grade high strength pressure vessels steel plate is characterized in that the chemical ingredients of steel is: C 0.08-0.15%, Si 0.15-0.40%,, Mn 1.20-1.60%, P＜0.01%,, S＜0.01%, Ni 0.15-0.40%, Mo 0.1-0.30%, V 0.02-0.06%, microalloy element Ti 0.01-0.03%, Nb 0.01-0.06%, surplus is Fe; All be weight percentage; The metallographic structure of steel plate is the mixed structure of tempering bainite and tempered sorbite.

2, the described low-carbon (LC) 610MPa of a kind of production claim 1 grade high strength pressure vessels method of steel plate is characterized in that production technique is:

(1) rolling technology: heat 1150-1250 ℃; In the austenite recrystallization district, non-recrystallization district and the controlled rolling of deformation induced phase change zone, 1000-1150 ℃ of roughing open rolling, 950-1050 ℃ of roughing finish to gauge; Intermediate blank thickness is 2-2.5 times of finished product thickness, 850-900 ℃ of finish rolling open rolling, 780-820 ℃ of finish rolling finish to gauge;

(2) roll postcooling technology: speed of cooling 15-25 ℃/s, cold 600～650 ℃ eventually;

(3) carry out 600-700 ℃ of tempering after rolling, obtain the mixed structure of tempering bainite and tempered sorbite.

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