CN103276301B

CN103276301B - Low-temperature engineering steel with yield strength not lower than 550MPa and production method of engineering steel

Info

Publication number: CN103276301B
Application number: CN201310183626.6A
Authority: CN
Inventors: 李德发; 王世森; 董汉雄; 熊玉彰; 熊涛; 陆在学; 陈勇; 易勋; 洪君; 余宏伟
Original assignee: Wuhan Iron and Steel Group Corp
Current assignee: Baowu Group Echeng Iron and Steel Co Ltd
Priority date: 2013-05-17
Filing date: 2013-05-17
Publication date: 2015-07-08
Anticipated expiration: 2033-05-17
Also published as: CN103276301A

Abstract

The invention discloses low-temperature engineering steel with yield strength not lower than 550MPa. The low-temperature engineering steel with yield strength not lower than 550MPa comprises the following components in percentage by weight: 0.04%-0.18% of C, 0.15%-0.50% of Si, 1.63%-2.00% of Mn, not more than 0..015% of P, not more than 0.008% of S, 0.05%-0.12% of Nb+Ti, 0.20%-0.4% of Mo+Cr, and 0.015%-0.05% of Als; the production steps are as follows: smelting and continuously casting to form blank, heating up the casting blank; rolling in a segmented manner by adopting a TMCP (Thermo-Mechanical Control Process); cooling; and straightening for the future use. The low-temperature engineering steel with yield strength not lower than 550MPa disclosed by the invention is not only capable of producing a steel plate with the thickness bigger than 80mm; the steel plate is uniform in tissue performance in the thickness direction, better in low-temperature impact toughness, i.e., impact power being not less than 100J at (-)60 DEG C, suitable for manufacturing engineering machinery that works in an extremely cold environment. The casting blank has center segregation C lower than 1.5 level and center porosity lower than 0.5 level; the low-temperature engineering steel is free of Ni and relatively low in content of Cr, Mo and other micro alloys, so that the cost is greatly lowered; the TMCP is adopted for producing without the processes including thermal treatment, PRC (Pre-stressed Reinforced Concrete), stacking slow-cooling and the like, and any other equipment is not needed to be added, so that the production process is simple and the production efficiency is high.

Description

The cryogenic engineering steel of a kind of yield strength >=550MPa and production method thereof

Technical field

The present invention relates to steel for engineering machinery and production method thereof, belong to cryogenic engineering steel and the production method thereof of yield strength >=550MPa particularly.

Background technology

High-strength engineering machinery steel is mainly for the manufacture of Constructional Machinery, by the restriction of service condition and weldprocedure, the steel plate of this kind of purposes not only needs material to have enough intensity, plasticity and welding property, but also require to possess excellent low-temperature impact toughness, to adapt to field work under extreme environment.Along with engineering machinery is to maximization and lightness future development, high-strength engineering machinery super-thick steel plate market demand is in rising trend.

Tradition high-intensity high-tenacity super-thick steel plate mainly adopts hardening and tempering process to produce, to obtain the excellent martenaging martempering tissue of obdurability, weak point is that energy consumption is large, manufacturing cost is high, the production cycle is long, and easily occurs crackle and surface imperfection in quenching engineering, reduces lumber recovery.In recent years, various countries develop a series of physical construction high-strength steel not needing Tempering and Quenching in succession, but thickness specification is limited, major cause is that special heavy plate thickness direction structure and properties homogeneity is difficult to control, over-all properties level is also not ideal enough, be mainly manifested in intensity and toughness can not meet steel for engineering machinery demand, or cause production cost high owing to increasing precious alloy, the drawbacks such as low-temperature performance and welding property deterioration.Therefore, current Micro Alloying super-thick steel plate still with ferrite/perlite for master control is organized, and generally need through normalizing or tempering heat treatment, intensity and toughness all can not meet application demand, and economic and social benefit is not obvious.For accelerating restructuring, promote industrial upgrading, in the urgent need to strengthening the innovation of super-thick steel plate, break traditions Composition Design and process exploitation limitation.

CN102041438 provides low-alloy high-tensile structural steel Q460C super-thick steel plate and production method thereof, its chemical composition: C :≤0.20%, Si :≤0.60%, Mn:1.40 ~ 1.60%, P :≤0.020%, S :≤0.005%, microalloy element (Nb+Ti+V+Ni) :≤0.25%, Als: >=0.015%, all the other are Fe and micro impurity element.The optimum proportioning compound of reasonable selection micro alloying element Nb, Ti, V, Ni adds, give full play to precipitation strength and refined crystalline strengthening double effects, under the prerequisite not reducing plasticity and toughness, guarantee to make the property indices of pressurized vessel plate reach the requirement of international 120mm.It is advantageous that alloying element addition is lower and proportioning free, thickness reaches more than 120mm, and its weak point is: adopt die casting cast to reduce production efficiency relative to continuous casting process; Adopt normalizing heat treatment technique, add the production cycle; Aspect of performance, intensity and low-temperature impact toughness are not enough to meet large-scale engineering machinery life-time service at low ambient temperatures, and machine life and construction ability do not have and significantly improve.

The reduce production method of a CN101597673 low-alloy high-strength thick steel plate, the processing parameter controlled is: rolling technology: Heating temperature 1150 ~ 1180 DEG C, tapping temperature is set in 1080 ~ 1130 DEG C, rate of heating is 08 ~ 0.9mm/min, rolling technology adopts the rolling of austenite recrystallization district, finishing temperature 950 ~ 1050 DEG C; Roller repairing technique: adopt section cooling, final cooling temperature 650 ~ 750 DEG C, rate of cooling 3 ~ 10 DEG C/s.Advantage is: special heavy plate adds appropriate Mn, does not add other alloying element, greatly reduces production cost; Rolling must not adopt controlled rolling, and save energy accelerates rhythm of production, does not also need thermal treatment.But intensity and low-temperature impact toughness are too low, inapplicable with manufacture the large-scale engineering machinery used under low temperature environment.

Therefore, the object of the present invention is to provide a kind of thickness at more than 80mm, Composition Design cost is lower, simplified manufacturing process, the high-strength engineering machinery super-thick steel plate used under being applicable to low temperature environment.

Summary of the invention

The invention reside in and provide a kind of thickness at more than 80mm, do not need the operations such as thermal treatment, RPC, stacking slow cooling ,-60 DEG C of ballistic works are not less than 100J, the cryogenic engineering steel of the uniform yield strength >=550MPa of thickness direction structure property and production method thereof.

Realize the measure of above-mentioned purpose:

The cryogenic engineering steel of a kind of yield strength >=550MPa, its component and weight percent content are: C:0.04 ~ 0.18 %, Si:0.15 ~ 0.50%, Mn:1.63 ~ 2.00%, P≤0.015%, S≤0.008%, Nb+Ti:0.05 ~ 0.12%, Mo+Cr:0.20 ~ 0.4%, Als:0.015 ~ 0.05%, and all the other are Fe and micro impurity element.

Produce the cryogenic engineering steel of a kind of yield strength >=550MPa, the steps include:

1) smelt also continuous casting and become base;

2) to strand heating, Heating temperature is controlled at 1150 ~ 1200 DEG C;

3) TMCP segmentation rolling is adopted: control first stage start rolling temperature at 1050 ~ 1120 DEG C. accumulative draft is 40 ~ 50%; Control subordinate phase start rolling temperature at 820 ~ 860 DEG C, finishing temperature is not less than 760 DEG C, and every time draft is not less than 10%, and accumulative draft is not less than 33%;

4) cool, speed of cooling controls at 10 ~ 20 DEG C/S, and final cooling temperature is 400 ~ 450 DEG C;

5) align, aligning front spring swings 80 ~ 120S on roller-way;

6) stand-by.

The present invention compared with prior art, can not only produce the steel plate that thickness is greater than 80mm, and the structure property in steel plate thickness direction is even, and there is more excellent low-temperature impact toughness, i.e.-60 DEG C of ballistic work >=100J, are applicable to be manufactured on the engineering machinery worked in extreme cold environment; Center segregation of casting blank C class less than 1.5 grades, center porosity less than 0.5 grade; Due to not containing Ni and Cr, Mo and other microalloy content relatively low, cost significantly reduces; Adopt TMCP explained hereafter, do not need other complicated processing techniques such as thermal treatment, RPC, stacking slow cooling, without the need to adding any miscellaneous equipment, production technique is simple, and production efficiency is high.

Accompanying drawing explanation

Accompanying drawing is metallographic structure figure of the present invention.

Embodiment

Below the present invention is described in detail:

The present invention tests and adopts 130t converter smelting, and pours into the continuously cast bloom of 250 ~ 300mm × 1600 ~ 2000mm × L, adopts TMCP technique rolling test.

Table 1 is the value list of various embodiments of the present invention and comparative example;

Table 2 is the main technologic parameters list of various embodiments of the present invention and comparative example;

Table 3 is various embodiments of the present invention and the list of comparative example performance monitoring situation.

Various embodiments of the present invention are produced according to following steps:

1) smelt also continuous casting and become base;

2) to strand heating, Heating temperature is controlled at 1150 ~ 1200 DEG C;

3) TMCP segmentation rolling is adopted: control first stage start rolling temperature at 1050 ~ 1120 DEG C. accumulative draft is 40 ~ 50%; Control subordinate phase start rolling temperature at 820 ~ 860 DEG C, finishing temperature is not less than 760 DEG C, and every time draft is not less than 10%, and accumulative draft is not less than 35%;

5) align, aligning front spring swings 80 ~ 120S on roller-way;

6) stand-by.

The chemical composition of table 1 various embodiments of the present invention and comparative example

Note: Mo and Cr, Nb and Ti be any value in limited range all, but does not comprise 0.

Table 2 various embodiments of the present invention and comparative example rolling technology significant parameter control (one)

Various embodiments of the present invention all adopt the rolling of TMCP technique.

Table 2 various embodiments of the present invention and comparative example rolling technology significant parameter control (two)

Table 3 various embodiments of the present invention and comparative example mechanical properties test result

Can analyze from the result of table 3, the steel plate of 80 ~ 100mm thickness of the employing continuous casting+TMCP manufacture technics that the present invention relates to, yield strength is all more than or equal to 550MPa, and has excellent low-temperature impact toughness, and-60 DEG C of ballistic works are greater than 100J.

Above-described embodiment is only the best and exemplifies, and is not the restriction to embodiments of the present invention.

Claims

1. produce the method for the cryogenic engineering steel of a kind of yield strength >=550MPa, the steps include:

1) smelt also continuous casting and become base; Its component and weight percent content are: C:0.09 ~ 0.18 %, Si:0.15 ~ 0.19 or 0.35 ~ 0.50%, Mn:1.63 ~ 1.95%, P≤0.015%, S≤0.008%, Nb+Ti:0.075 ~ 0.12%, Mo+Cr:0.25 ~ 0.4%, Als:0.015 ~ 0.05%, all the other are Fe and micro impurity element;

2) to strand heating, Heating temperature is controlled at 1150 ~ 1200 DEG C;

3) TMCP segmentation rolling is adopted: control first stage start rolling temperature at 1050 ~ 1120 DEG C. accumulative draft is 40 ~ 50%; Control subordinate phase start rolling temperature at 820 ~ 840 DEG C, finishing temperature is not less than 760 DEG C, and every time draft is not less than 10%, and accumulative draft is not less than 35%;

4) cool, speed of cooling controls at 10 ~ 20 DEG C/S, and final cooling temperature is 400 ~ 440 DEG C;

5) align, aligning front spring swings 80 ~ 120S on roller-way;

6) stand-by.