CN102888558A

CN102888558A - La-containing high-strength steel plate and heat treatment technology thereof

Info

Publication number: CN102888558A
Application number: CN201110291215XA
Authority: CN
Inventors: 高志国; 冯岩青; 程德富; 李培德; 康利明
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2011-09-30
Filing date: 2011-09-30
Publication date: 2013-01-23

Abstract

The invention discloses a La-containing high-strength steel plate and a heat treatment technology thereof, and belongs to the technical field of heat treatment of steel materials. The La-containing high-strength steel plate comprises the following chemical components in percentage by weight: 0.14 to 0.30 percent of C, 1.5 to 2.0 percent of Mn, 0.6 to 1.0 percent of Si, less than or equal to 0.015 percent of P, less than or equal to 0.002 percent of S, 0.01 to 0.06 percent of Ti, 0.0005 to 0.0040 percent of B, 0.001 to 0.1 percent of La and the balance of Fe and inevitable impurities. According to the heat treatment technology, the austenitizing temperature is between 900 and 950 DEG C, heat preservation is performed for 0.5 to 3 hours and then water quenching is performed, the tempering temperature is between 190 and 250 DEG C, and the heat preservation time is 1 to 30 hours. The steel plate produced by the heat treatment technology has high mechanical properties, the tensile strength of 1,500 to 1,700 MPa, the yield strength of 1,100 to 1,300 MPa and the elongation of 7 to 15 percent; and moreover, the production cost is low, and steel plates with the thickness of 5 to 25mm can be produced in batches.

Description

A kind of rare earth La high tensile steel plate and thermal treatment process thereof of containing

Technical field

The invention discloses a kind of rare earth La high tensile steel plate and thermal treatment process thereof of containing, belong to ferrous materials heat treatment technics field.

Background technology

At present, the rare earth steel kind has broken through kind more than 80, but real suitability for industrialized production is less than 20 kinds.Rare earth element lanthanum activity is only second to alkali and alkaline earth metal ions, and lanthanum adds in the Clean Steel, can change the steel microstructure morphology, and the inclusion and improve inclusion morphology of can going bad has improved the performance of Clean Steel.Adding suitable lanthanum element can make Clean Steel cooling transformation tissue that considerable change occurs, when icy salt solution quenched, La made γ → α polytypism transformation be undertaken by the massive transformation mode, and the ferrite crystal boundary presents irregular pattern, it is block that ferrite crystal grain is, and sometimes is strip of sheet or needle-like.Lanthanum is the major cause that causes carbon manganese series Clean Steel tissue and phase transition process to change in the segregation of crystal boundary." rare earth La is on the impact of 5CrNiMo die steel mechanical property " literary composition (" University of Science ﹠ Technology, Beijing's journal " 2007,29 (12): studied 1209-1211) and add that intensity, hardness, the impelling strength of 5CrNiMo steel changes behind the rare earth La, and under identical heat treatment condition, compare with the 5CrNiMo steel that does not add rare earth La.The result shows: when the rare earth La massfraction was 0.033%, the 5CrNiMo steel can obtain best comprehensive mechanical property, and tensile strength reaches 1580MPa, and yield strength reaches 1280MPa.Rare earth affects the stagnation point of steel, and hardened steel tempering and martensite and residual austenite are decomposed thermodynamics and dynamics etc.In different rare earth steels, all observe the phenomenons such as gathering alligatoring of structure refinement, the content that changes the cable body and size, inhibition Carbide Phases; Research contains the supercooled austenite continuous cooling transformation of the low-carbon (LC) of rare earth, middle carbon, high-carbon Mn-Nb (V) steel, observe the stability that rare earth improves supercooled austenite, make continuous cooling transformation curve (CCT) to the lower right to movement, different transmutation product number change, grain structure refinement.

For significantly improving the mechanical property of high tensile steel plate, optimization of Heat Treatment Process and add such as boron high-hardenability element is absolutely necessary.Boron be in the periodic table of elements second cycle III main group element, China's boron resource distribution is extensive, compares low price with other alloying elements.The major advantage of boron is the hardening capacity that content seldom will change steel significantly in the steel.Stoped the forming core of cenotype in the austenitization by the boron of segregation through diffusion on crystal boundary, crystal boundary boron distribution is different from size, and its influence degree is also different.In order to prevent that boride from separating out and form interrupted net along austenite grain boundary, the best retention amount of boron is 0.001～0.003 in the steel.The present invention combines the advantage of rare earth La and two kinds of elements of B in order to design a kind of rare earth La high tensile steel plate that contains, and obtains the rear-earth steel plate novel material of high strength and ductility by optimizing thermal treatment process.

Summary of the invention

The purpose of this invention is to provide a kind of high-performance, contain rare earth La high tensile steel plate and thermal treatment process thereof cheaply.Realize that technical scheme of the present invention is as described below, the steel plate that will contain following chemical ingredients is put into process furnace and is heat-treated heating, carries out shrend after insulation for some time.

The chemical ingredients of steel plate and content (weight percent) are: C 0.14%-0.30%, Mn 1.5%-2.0%, Si 0.6%-1.0%, P≤0.015%, S≤0.002%, Ti 0.01%-0.06%, B 0.0005%-0.0040%, La0.001%-0.1%, surplus is Fe and inevitable impurity.

System of heat treatment process is: austenitizing temperature 900-950 ℃, and shrend after soaking time 0.5-3 hour; Tempering temperature 190-250 ℃, soaking time 1-30 hour.

The steel plate of thermal treatment process processing has good mechanical property thus, and tensile strength reaches 1500-1700MPa, yield strength 1100-1300MPa, unit elongation 7-15%.The interpolation of rare earth La and utilization not only can improve the performances such as intensity of heat-treated steel plate, all right Substitute For Partial alloying element, and the add-on of minimizing alloying element economizes on resources, and reduces cost.Not only can obtain high-performance, product cheaply according to this thinking, and can bring into play the ERM advantage, realize the saving type development pattern of cost efficiency.

Description of drawings

Fig. 1 is the metallographic structure after the tempering of quenching sample.

Embodiment

Below in conjunction with embodiment the present invention is explained in detail.

(weight percent) chemical composition content of steel plate is: C 0.24%, and Mn 1.72%, and Si 0.73%, P0.0115%, and S 0.002%, and Ti 0.03%, and B 0.0007%, and La 0.09%, and surplus is Fe and inevitable impurity.

Embodiment 1

Steel plate thickness is 8mm, and its system of heat treatment process is: 910 ℃ of austenitizing temperatures, soaking time shrend after 44 minutes.Sampling detects, and its mechanical property detected value sees Table 1:

Table 1 mechanical property detected value

Embodiment 2

Steel plate thickness is 8mm, and its system of heat treatment process is: 920 ℃ of austenitizing temperatures, and soaking time shrend after 44 minutes, 200 ℃ of low-temperaturetemperings are incubated 5 hours, air cooling.Sampling detects, and its mechanical property detected value sees Table 2.Use the metallography microscope sem observation, metallographic structure can be observed a large amount of thin yardstick martensite strengthening phases as shown in Figure 1.Solid solution rare earth La in the steel significantly reduces the lath martensite bundle, improves the hardenability of steel.

Table 2 mechanical property detected value

Claims

1. one kind contains the rare earth La high tensile steel plate, it is characterized in that its chemical ingredients and content are by weight percentage: C 0.14%-0.30%, Mn 1.5%-2.0%, Si 0.6%-1.0%, P≤0.015%, S≤0.002%, Ti 0.01%-0.06%, B 0.0005%-0.0040%, La 0.001%-0.1%, surplus is Fe and inevitable impurity.

2. thermal treatment process that contains the rare earth La high tensile steel plate of feature as claimed in claim 1 is characterized in that the system of heat treatment process of described steel plate is: austenitizing temperature 900-950 ℃, and shrend after soaking time 0.5-3 hour; Tempering temperature 190-250 ℃, soaking time 1-30 hour.

3. a kind of rare earth La high tensile steel plate that contains as claimed in claim 1 is characterized in that steel plate has good mechanical property, tensile strength 1500-1700MPa, yield strength 1100-1300MPa, unit elongation 7-15%.