CN102146549A - Method for producing steel for LQ380G wheels - Google Patents

Abstract

The invention provides a method for producing steel for LQ380G wheels. Through the measures of reasonably controlling the chemical components of the steel, adjusting the proportion of C, Si and Mn, adding trace Ti alloy element, adjusting the temperature schedule, reducing the heating temperature of billets, improving the finish rolling temperature and the coiling temperature and the like, the target of improving the elongation of the steel for the LQ380G wheels is fulfilled, so that the breakage elongation of the LQ380G is higher than 38 percent and reaches 80 percent of the total amount, and other various performance indexes totally meet the requirements of the steel for the wheels. The rejection rate caused by ''cracking'' defects fed back by automobile production users is reduced to 0.4 percent from 3 percent, and the yield of the wheels and the economic benefit of an enterprise are greatly improved. The method is simple, feasible and convenient for operation, and can have immediate effect without special investment.

Description

A kind of production method of LQ380G wheel-use steel material

Technical field

The invention belongs to the ferrous metallurgy technical field, relate in particular to the production method that a kind of trade mark is the wheel-use steel material of LQ380G.

Background technology

LQ380G is a kind of automobile spoke steel that is widely used in the automobile manufacture industry, because this automobile spoke stamping forming characteristics of steel repeated multiple times in the course of processing, and use is in the singularity of product space, requiring the LQ380G wheel-use steel material should any surface finish to be beneficial to sprays paint, but have good intensity and deep draw performance again, thereby how the LQ380G wheel-use steel material is guaranteed that in process of production its intensity and unit elongation have higher requirement.

Yet, LQ380G wheel-use steel material after rolling often finds that but the roughen of steel matrix texture appears in wheel surface through after the punching press repeatedly in the downstream automobile making user course of processing, crooked serious place even " be full of cracks " defective occurs, form is similar to the staff dry and cracked peeling shape of enduring cold.This defective has a strong impact on the quality of spraying paint of wheel surface, forms a large amount of waste products.According to the information of user feedback, the condemnation factor that its LQ380G wheel-use steel material " be full of cracks " defective causes is seriously restricting the product percent of pass of automobile factory up to more than 3%.

Discover, the major cause that causes " be full of cracks " defective be since the unit elongation of LQ380G wheel-use steel material not enough due to.Though the macroscopical presentation that shows is " be full of cracks ", essence is that steel plate is in the course of processing, because local punching press distortion place unit surface is stressed big, exceeded the tension limit of steel and occur that smooth fracture causes, so radical solving method is to improve the toughness and the extension property of steel plate.

Summary of the invention

Purpose of the present invention is exactly at above-mentioned defective, provides a kind of simple, is convenient to operation, can effectively improve the unit elongation of LQ380G wheel-use steel material, thereby reduces the production method of automobile making user loss due to spoiled work.

For this reason, the solution that the present invention taked is:

A kind of production method of LQ380G wheel-use steel material, chemical ingredients by reasonable control steel, adjust the ratio of C, Si, Mn, add the trace Ti alloying element, adjust temperature schedule, reduce billet heating temperature, improve measures such as finish rolling finishing temperature and coiling temperature, realize improving the target of LQ380G wheel-use steel material unit elongation.Concrete grammar is:

1, chemical Composition Control: in the smelting process, carry out the Composition Control of steel according to table 1 " LQ380G wheel-use steel material chemical Composition Control table ".

Table 1 LQ380G wheel-use steel material chemical Composition Control table

Element

C

Si

Mn

P

S

Ais

Ti

Content (%)

0.06-0.08

≤0.05

0.65-0.75

≤0.018

≤0.01

0.01-0.05

0.005-0.015

Constituent content is a weight percentage in the table;

2, temperature schedule control: the actual temp system is pressed table 2 and is carried out.

The control table of table 2 LQ380G wheel-use steel material temperature schedule

Finished product thickness (mm)	Heating temperature (℃)	The roughing finishing temperature (℃)	The finish rolling finishing temperature (℃)	Coiling temperature (℃)
					＜4.0	1210±30	1050±30	870±20	630±20
4.0-7.0	1210±30	1040±30	860±20	620±20

In temperature schedule control, mainly be that Heating temperature, finish rolling finishing temperature and coiling temperature are adjusted, the weight percent target content of each element is in the chemical ingredients of recommendation steel:

C?0.07％、Si≤0.05％、Mn?0.7％、P≤0.018％、S≤0.01％、Ais?0.03％、Ti?0.01％。

Beneficial effect of the present invention is:

Adopt automobile spoke of the present invention to be higher than 38% ratio with the elongation after fracture of steel LQ380G and 10% risen to and account for 80% of total amount by what account for total amount, other various performance index also satisfy the requirement of wheel-use steel material fully.The condemnation factor that " be full of cracks " defective of automobile production user feedback causes drops to 0.4% by 3%, has greatly improved the lumber recovery and the economic benefit of enterprises of wheel.The inventive method is simple, is convenient to grasp and operation, need not special investment and just can produce immediate results.

Embodiment

Below, the invention will be further described in conjunction with the embodiments.

Embodiment 1:

Steelworks carries out the ratio adjustment according to the composition design in the quality planning, and in steelmaking process, the chemical ingredients of strict control steel guarantees that the weight percent content of each element is:

C?0.07％、Si?0.025％、Mn?0.7％、P≤0.018％、S≤0.01％、Ais?0.03％、Ti0.01％。

Hot rolling mill is produced according to the process system in the quality planning, and the process condition during according to actual production, according to the temperature schedule target value in the table 2,, guarantee that the finished product reach the quality planning requirement by adjusting technology points such as cooling water inflow, roll speed and rolling rhythm.

According to rolling the back finished product thickness is the specified conditions of 3.5mm, and the chosen temperature system is:

Heating temperature: compare with the steel grade of other purposes, LQ380G wheel-use steel material Heating temperature suitably is adjusted downward to 1200 ℃, and is less to guarantee original grain, for the grain refining in the follow-up operation of rolling provides the basis, and guarantees to roll the back armor plate strength more than standard-required.

Roughing finishing temperature: select normal roughing finishing temperature to get final product, so be chosen to be 1050 ℃.

The finish rolling finishing temperature: the finish rolling finishing temperature is 880 ℃, and the purpose that improves the finish rolling final rolling temperature is to guarantee in the steel plate rolling deformation process, the crystal grain of its metallographic structure distortion uniform and delicate.

Coiling temperature: be increased to 640 ℃, be beneficial to improve the toughness of steel, improve the extension performance of steel.

Surplus technology is all routinely carried out.

Embodiment 2:

In the steelmaking process, the weight percent content of each element is in the control steel:

C?0.06％、Si?0.04％、Mn?0.66％、P≤0.018％、S≤0.01％、Ais?0.015％、Ti?0.015％。

Rolling the back finished product thickness is 4.5mm, and hot rolling mill chosen temperature system is:

1190 ℃ of Heating temperatures, less to guarantee original grain;

1040 ℃ of roughing finishing temperatures;

The finish rolling finishing temperature is controlled at 870 ℃;

Coiling temperature is controlled at 630 ℃, is beneficial to improve the unit elongation of steel.

Surplus technology is all routinely carried out.

Claims (2)

1. the production method of a LQ380G wheel-use steel material is characterized in that, rationally controls the chemical ingredients of steel, adjusts the ratio of C, Si, Mn, adds the trace Ti alloying element; Adjust temperature schedule, reduce billet heating temperature, improve finish rolling finishing temperature and coiling temperature, realize improving LQ380G wheel-use steel material unit elongation; Concrete grammar is:

1), chemical Composition Control:

Element C Si Mn P S Ais Ti Content (%) 0.06-0.08 ≤0.05 0.65-0.75 ≤0.018 ≤0.01 0.01-0.05 0.005-0.015

Constituent content is a weight percentage in the table;

2), temperature schedule control:

Finished product thickness (mm) Tapping temperature (℃) Heating temperature (℃) Finishing temperature (℃) Coiling temperature (℃) ＜4.0 1210±30 1050±30 870±20 630±20 4.0-7.0 1210±30 1040±30 860±20 620±20

2. the production method of LQ380G wheel-use steel material according to claim 1 is characterized in that, the weight percent target content of each element is in the chemical ingredients of steel:

C?0.07％、Si≤0.05％、Mn?0.7％、P≤0.018％、S≤0.01％、Ais?0.03％、Ti?0.01％。