Large heat input energy welding high-strength EH36 steel plate and making method thereof

A large input energy welding, EH36 technology, applied in the field of metallurgy, can solve the problems of small resistive input energy, low carbon equivalent, strong toughness, poor operability, etc., and achieve the goal of enhancing market competitiveness, uniform structure of steel plate, and excellent comprehensive performance Effect

Active Publication Date: 2019-01-08

JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD

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AI-Extracted Technical Summary

Problems solved by technology

[0007] Patent (CN104404369A) applied for a large heat input welding thick steel plate and its manufacturing method, which improves its resistance to large Line energy welding performance, can resist 200KJ/cm-400KJ/cm super large heat input welding, has excellent strength and toughness, the average Charpy impact energy at -40°C is above 50J, but Mg is an extremely oxidizable element, it is difficult to Industrial production controls the addition of alloys, the size and content of micron-sized inclusions, which brings great difficulty to production and poor operability

[0008] The patent (CN102839320A) applied for a steel plate for high heat input welding produced by TMCP process, the tensile strength is ≥550MPa, and it can resist high heat input welding of 100-200KJ...

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Abstract

The invention relates to a large heat input energy welding high-strength EH36 steel plate which is made of the following components in percentage by weight through smelting: 0.06-0.18% of C, 0.15-0.50% of Si, 1.10-1.60% of Mn, less than or equal to 0.012% of P, less than or equal to 0.003% of S, 0.10-0.40% of Ni, 0.010-0.030% of Nb, less than or equal to 0.010% of Al, 0.010-0.030% of Ti, 0.001-0.010% of Ca and the balance of Fe and inevitable impurities. The maximum thickness of the steel plate is 100mm, the yield strength of the steel plate is greater than or equal to 355MPa, the tension strength of the steel plate is greater than or equal to 510MPa, and the low-temperature impact absorption energy KV2 of the steel plate at minus 40 DEG C is greater than or equal to 150KJ. A production method of the steel plate comprises the following steps: carrying out smelting, LF/RH (Ladle Furnace/Ruhrstahl Heraeus) refining, continuous casting, heating, rolling, and rapid cooling, thereby obtaining a finished product of the steel plate. The steel plate produced by using the method provided by the invention has the characteristics of high purity, high strength, good low-temperature impact resistance, good toughness when the maximum input line energy is 300KJ/CM, and the like, can be widely applied to fields such as shipbuilding, bridges and building structures, and has wide application prospects.

Technology Topic

Steel platesHigh intensity +7

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Examples

Experimental program(3)

Example Embodiment

[0049] Example 1

[0050] The high-strength ship plate EH36 for large heat input welding of this embodiment, with a thickness of 50mm, is smelted with the following mass percentage components: C: 0.08%, Si: 0.35%, Mn: 1.54%, P: 0.008% , S: 0.003%, Al: 0.005%, Nb: 0.016%, Ni: 0.30%, Ti: 0.015%, Ca: 0.003%, the balance is Fe and inevitable impurities.

[0051] The steps of the method for producing high-strength ship plate EH36 for large heat input welding of this embodiment are as follows:

[0052] (1) Smelting: will contain the following mass percentage components C: 0.08%, Si: 0.35%, Mn: 1.54%, P: 0.008%, S: 0.003%, Al: 0.005%, Nb: 0.016%, Ni: 0.30 %, Ti: 0.015%, Ca: 0.003% molten steel is first smelted in an electric furnace and sent to the LF refining furnace for refining. When the oxygen content is 15PPM, Ti is used for deoxidation, and the molten steel temperature reaches 1570℃ and transferred to the RH furnace for vacuum degassing treatment; The temperature is 66.6Pa, the vacuum holding time is 20 minutes, the Fe-Ca wire 450m is added after the vacuum degassing treatment, and the molten steel composition is made uniform by soft blowing for 3 minutes, and then the ladle is poured;

[0053] (2) Continuous casting: 370mm slab continuous casting machine is used, and the casting temperature is 1540℃;

[0054] (3) Heating: The heating temperature of the continuous casting slab is up to 1220℃, the soaking temperature is 1200℃, and the heat preservation is 3.5 hours;

[0055] (4) Rolling: Rolling is carried out with a two-stage rolling process of recrystallization + non-recrystallization, the thickness of the open steel is 110mm, the first stage rolling temperature is 1055℃, the final rolling temperature is 970℃, and the cumulative reduction ratio is 60 %; In the second stage, the start-rolling temperature is 850°C, the final rolling temperature is 820°C, and the cumulative reduction ratio is 55% to obtain a crude steel plate;

[0056] (5) Water cooling after steel plate rolling: After steel plate rolling, fast water cooling is set to DQ mode, cooling rate is 15℃/s, water quantity is automatically controlled, steel plate water temperature is 790℃, steel plate water redness temperature is 580℃.

[0057] The mechanical properties and metallographic structure of the 50mm steel plate of this example:

[0058] (1) Mechanical properties of the board

[0059] The yield strength is 410MPa, the tensile strength is 550MPa, and the transverse impact absorption energy at -40℃ is KV2 with an average of 258J.

[0060] (2) Mechanical properties of the heat affected zone of plate welding

[0061] The yield strength is 405MPa, the tensile strength is 540MPa, and the transverse impact absorption energy at -40℃ is KV2 with an average of 191J.

[0062] (3) Phase organization

[0063] The high-strength ship plate EH36 for large heat input welding has a uniform and fine structure with a grain size of 9.5; the coarsening of the structure of the heat-affected zone of steel welding is controlled within a certain range, and the grain size is 7.5. See you in the metallographic photo figure 1 , figure 2.

Example Embodiment

[0064] Example 2

[0065] The high-strength high-strength ship plate EH36 for large heat input welding of this embodiment has a thickness of 70mm and is smelted with the following mass percentage components: C: 0.10%, Si: 0.30%, Mn: 1.55%, P: 0.007%, S: 0.003%, Al: 0.004%, Nb: 0.020%, Ni: 0.28%, Ti: 0.019%, Ca: 0.003%, the balance is Fe and inevitable impurities.

[0066] The steps of the production method of the high-strength high-strength ship plate EH36 steel plate for large heat input welding of this embodiment are as follows:

[0067] (1) Smelting: will contain the following mass percentage components C: 0.10%, Si: 0.30%, Mn: 1.55%, P: 0.007%, S: 0.003%, Al: 0.004%, Nb: 0.020%, Ni: 0.28 %, Ti: 0.019%, Ca: 0.003% molten steel is first smelted by an electric furnace, and then sent to the LF refining furnace for refining. When the oxygen content reaches 48PPM, Ti is used for deoxidation, and the molten steel temperature reaches 1560℃ and transferred to the RH furnace for vacuum degassing treatment; vacuum The temperature is 66.6Pa, the vacuum holding time is 20 minutes, 400m of pure Ca wire is added after vacuum degassing, soft blowing for 3 minutes to make the molten steel composition uniform, and then ladle pouring.

[0068] (2) Continuous casting: It is produced by a 370mm slab continuous casting machine with a casting temperature of 1542°C.

[0069] (3) Heating: The heating temperature of the continuous casting slab is up to 1240℃, the soaking temperature is 1220℃, and the heat preservation is 4 hours;

[0070] (4) Rolling: Rolling is carried out with a two-stage rolling process of recrystallization + non-recrystallization, the thickness of the open steel is 140mm, the first stage of the rolling temperature is 1050℃, the final rolling temperature is 960℃, and the cumulative reduction ratio is 60 %; In the second stage, the start-rolling temperature is 840°C, the final rolling temperature is 810°C, and the cumulative reduction ratio is 55% to obtain a crude steel plate;

[0071] (5) Water cooling after steel plate rolling: After steel plate rolling, fast water cooling, set to DQ mode, cooling rate 15℃/s, water volume automatic control, steel plate water temperature 800℃, steel plate water redness temperature is 600℃.

[0072] The mechanical properties of the 70mm steel plate of this example:

[0073] (1) Mechanical properties of steel plate

[0074] The yield strength is 455MPa, the tensile strength is 585MPa, and the transverse impact absorption energy at -40℃ is KV2 with an average of 212J.

[0075] (2) Mechanical properties of steel plate welding heat affected zone

[0076] The yield strength is 450MPa, the tensile strength is 570MPa, and the transverse impact absorption energy at -40°C is KV2 with an average of 185J.

[0077] (3) Phase organization

[0078] The high-strength ship plate EH36 for large heat input welding has a uniform and fine structure with a grain size of 9.5; the coarsening of the structure of the heat-affected zone of steel welding is controlled within a certain range, and the grain size is 7.5. See the metallographic photos of the steel plate image 3 , Figure 4.

Example Embodiment

[0079] Example 3

[0080] The high-strength high-strength ship plate EH36 for large heat input welding of this embodiment, with a thickness of 100mm, is smelted with the following mass percentage components: C: 0.10%, Si: 0.30%, Mn: 1.50%, P: 0.004%, S: 0.003%, Al: 0.004%, Nb: 0.020%, Ni: 0.28%, Ti: 0.019%, Ca: 0.003%, the balance is Fe and inevitable impurities.

[0081] The steps of the production method of the high-strength high-strength ship plate EH36 steel plate for large heat input welding of this embodiment are as follows:

[0082] (1) Smelting: will contain the following mass percentage components C: 0.10%, Si: 0.30%, Mn: 1.50%, P: 0.004%, S: 0.003%, Al: 0.004%, Nb: 0.020%, Ni: 0.28 %, Ti: 0.019%, Ca: 0.003% molten steel is first smelted in an electric furnace and then sent to the LF refining furnace for refining. When the oxygen content is 95PPM, Ti is used for deoxidation, and the molten steel temperature reaches 1565°C and transferred to the RH furnace for vacuum degassing treatment; The temperature is 66.6Pa, the vacuum holding time is 20 minutes, 400m of pure Ca wire is added after vacuum degassing, soft blowing for 3 minutes to make the molten steel composition uniform, and then ladle pouring.

[0083] (2) Continuous casting: It is produced by a 450mm slab continuous casting machine with a casting temperature of 1542℃.

[0084] (3) Heating: The heating temperature of the continuous casting slab is up to 1240℃, the soaking temperature is 1220℃, and the heat preservation is 5 hours;

[0085] (4) Rolling: Rolling is carried out with a two-stage rolling process of recrystallization + non-recrystallization, the thickness of the open steel is 180mm, the first-stage rolling temperature is 1050℃, the final rolling temperature is 960℃, and the cumulative reduction ratio is 60 %; In the second stage, the start-rolling temperature is 840°C, the final rolling temperature is 810°C, and the cumulative reduction ratio is 44% to obtain crude steel plate;

[0086] (5) Water cooling after steel plate rolling: After steel plate rolling, fast water cooling, set to DQ mode, cooling rate 15℃/s, water volume automatic control, steel plate water temperature 800℃, steel plate water redness temperature is 600℃.

[0087] The mechanical properties of the 100mm steel plate of this example:

[0088] (1) Mechanical properties of steel plate

[0089] The yield strength is 430MPa, the tensile strength is 575MPa, and the transverse impact absorption energy at -40°C is KV2 with an average of 225J.

[0090] (2) Mechanical properties of steel plate welding heat affected zone

[0091] The yield strength is 415MPa, the tensile strength is 560MPa, and the transverse impact absorption energy at -40℃ is KV2 with an average of 189J.

[0092] (3) Metallographic organization

[0093] The high-strength ship plate EH36 for large heat input welding has a uniform and fine structure with a grain size of 9.5; the coarsening of the structure of the heat-affected zone of steel welding is controlled within a certain range, and the grain size is 7.5. See the metallographic photos of the steel plate Figure 5 , Image 6.

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PUM

Property	Measurement	Unit
Yield strength	410.0	MPa
Tensile strength	550.0	MPa
Yield strength	405.0	MPa
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Large heat input energy welding high-strength EH36 steel plate and making method thereof

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

Example Embodiment

Example Embodiment

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Description & Claims & Application Information

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