JPH04350122A - Production of high strength and lightweight vessel for lp gas - Google Patents

Abstract

PURPOSE:To produce a high strength and lightweight vessel for LP gas having the desired strength and capable of thinning and lightening weight. CONSTITUTION:A slab of a steel having a composition consisting of, by weight, 0.05-0.15% C, <=0.04% Si, 0.30-1.00% Mn, 0.010-0.100% Al, 0.10-2.0% Cu, 0.10-2.0% Ni, and the balance Fe with inevitable impurities is heated up to 1100-1200 deg.C. After the completion of hot rolling, the resulting hot rolled steel plate is coiled at 400-500 deg.C, subjected to cold working where a working strain of >=10% is applied, and then subjected to heating at 600-700 deg.C for 10min-2hr. Accordingly, by simultaneously incorporating Cu and Ni in combination, the hot rolled steel plate excellent in formability can be formed into a final product having >=50kgf/ mm<2> tensile strength by means of cold working and thinning can be attained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a high-strength, lightweight LP gas container, and more specifically, in the cold working process of press forming, a hot rolled plate with excellent cold workability is used, The present invention relates to a method for manufacturing an LP gas container with high tensile strength of 50 kgf/mm2 or more and excellent pressure resistance by annealing to remove processing strain after processing.

0002

[Prior Art] Generally, gas containers have a strength level of 41K class.
Manufactured by press forming and welding from 45K class hot rolled steel plate with a thickness of approximately 3.2mm, and weighs 20kg.
The main products are 50kg and 50kg.

[0003] By reducing the weight of the container by reducing the thickness of the steel plate used, favorable results can be obtained in that the burden of transportation work can be reduced and the steel plate used as a raw material can be saved. However, gas containers are important and strict safety components, and therefore, a decrease in the strength of the container due to thinning is not acceptable.

[0004] As a countermeasure against this problem, conventional efforts have been made to incorporate Nb into hot rolled steel sheets in order to improve the strength of the steel sheets through precipitation strengthening and grain refinement.

[0005] In addition, in the manufacturing process of gas containers, improving the strength of steel sheets means that (1) the press pressure increases on the press processing surface, making it necessary to increase the size of the press machine, and causing damage to the mold. It's cheap. (2) On the product side, springback after press working is large and wrinkles occur. (3) Earrings occur due to the anisotropy due to Nb content, and vertical cracks occur due to the earrings. (4) In strain relief annealing, the annealing temperature becomes high, so the capacity of the furnace must be increased. There are other problems.

[0006]

[Problems to be Solved by the Invention] The present invention has been made in view of the various problems that occur during the production of conventional LP gas containers as described above, and as a result of intensive research by the present inventor, By using strain relief annealing during the LP gas container manufacturing process, it is possible to maintain the desired strength, make the wall thinner, and reduce the weight without requiring modification of equipment or reducing yield. We have developed a method for manufacturing high-strength, lightweight LP gas containers.

[0007]

[Means for Solving the Problems] The method for manufacturing a high-strength, lightweight LP gas container according to the present invention is characterized by:
0.05-0.15wt%, Si 0.04wt% or less, Mn 0.30-1.00wt%, Al0.01
0-0.100wt%, Cu 0.10-2.0wt
%, Ni 0.10 to 2.0 wt%, the balance F
A steel piece consisting of e and inevitable impurities was heated to 1100 to 12
Heated to a temperature of 00℃ and 400 to 500℃ after hot rolling.
The hot-rolled steel sheet is rolled up at a temperature of
It consists in heating at a temperature of 0° C. for 10 minutes to 2 hours.

The method for manufacturing a high-strength, lightweight LP gas container according to the present invention will be explained in detail below.

First, the components and component ratios of the steel used in the method for manufacturing a high-strength, lightweight LP gas container according to the present invention will be explained.

[0010] C is an element that increases the strength of steel sheets; if the content is less than 0.05 wt%, the desired strength cannot be secured, and if the content exceeds 0.15 wt%, the ductility decreases. This results in impairing press formability and inhibiting weldability. Therefore, in terms of press formability, weldability, and rigidity, the C content is 0.05 to 0.15 wt%.
shall be.

[0011] Si tends to generate Si red scale during hot rolling, which deteriorates the surface quality of the steel sheet. Therefore, the Si content is set to 0.04 wt% or less.

Mn is an element that improves hardenability, increases strength, and at the same time prevents hot embrittlement caused by S during hot rolling. If the content is less than 0.30 wt%, the above effects cannot be expected. Moreover, if the content exceeds 1.00 wt%, the strength will become too high, and furthermore, cold workability will decrease due to increased segregation of Mn during manufacturing. Therefore, the Mn content is set to 0.30 to 1.00 wt%.

[0013] Al is a deoxidizing element, and the content is 0.01
This effect is small below 0 wt%, and 0.100 wt%
If the content exceeds wt%, inclusions will increase. Therefore, the Al content is set to 0.010 to 0.100 wt%.

[0014]Cu is a basic element that increases age hardenability, and in combination with hot rolling conditions, it is relatively soft at the stage of hot rolled steel sheets and has high strength after cold working and strain annealing. It is an essential element, and the content is 0.10wt.
If the content is less than 2.0 wt%, the desired strength will not be obtained in the final product, and if the content exceeds 2.0 wt%, the strength will be too high. Therefore, the Cu content is 0.10 to 2.0wt
%.

[0015] Ni is an element that increases strength and prevents hot embrittlement of Cu. If the content is less than 0.10 wt%, hot embrittlement cannot be prevented, and if the content exceeds 2.0 wt%, the hot embrittlement cannot be prevented. If it is contained, the strength of the steel plate becomes too high. Therefore, the Ni content is set to 0.10 to 2.0 wt%.

[0016] In the method for manufacturing a high-strength, lightweight LP gas container according to the present invention, the steel used has the above-mentioned essential components and basic Fe and inevitable impurities,
In order to maintain excellent cold workability, P, S
Since elements such as , O, and N are harmful to cold workability, the lower the content, the more desirable.

Next, heat treatment in the method for manufacturing a high-strength, lightweight LP gas container according to the present invention will be explained.

[0018] As in the case of ordinary rolling of steel having the above-described components and component ratios, the heating temperature is 1100-1100°C.
The range is preferably 1200°C; at temperatures below 1100°C, it is difficult to roll with a normal continuous hot rolling mill, and at heating temperatures above 1200°C, despite the Ni content. , hot embrittlement peculiar to steel occurs due to Cu content.

Hot rolling is carried out at this heating temperature, but the conditions for hot rolling are not particularly limited, and the coiling temperature of the hot rolled steel sheet after hot rolling is 400°C.
It is wound up at ~500°C.

[0020] Winding temperature is less than 400°C and 500°C
If the temperature exceeds , the tensile strength becomes high, and in this heating temperature range, the tensile strength is 45 kgf/mm2 or less,
In the subsequent cold working, the rolling load may be relatively small.

[0021] Next, this hot-rolled steel plate is subjected to cold working to which a working strain of 10% or more is applied, so that the tensile strength becomes 50 kgf/mm2 or more.

[0022] Also, at a cold working rate of 20%, the tensile strength is 60 kgf/mm2 or more, and in this case, the aging treatment temperature is 600 to 750°C, and the aging treatment time is 10 minutes to 2 hours. It is better.

[0023]

[Example] Examples of the method for manufacturing a high-strength, lightweight LP gas container according to the present invention will be described.

[0024]

[Example] After melting steel with the ingredients and proportions shown in Table 1 using the normal melting method, it is made into ingots to a plate thickness of 3.2 mm.
mm.

[0025] A hot-rolled steel sheet with excellent formability can be cold-worked to have a tensile strength of 50 kgf/mm2 or more.

[0026]

[Table 1]

[0024]

[Effects of the Invention] As explained above, since the method for manufacturing a high-strength, lightweight LP gas container according to the present invention has the above-mentioned structure, it has excellent moldability, especially by simultaneously containing Cu and Ni in a composite manner. Using hot-rolled steel plates, the tensile strength of the final product can be made 50 kgf/mm2 by cold working, which makes it possible to manufacture lightweight LP gas containers because the walls can be made thinner. It is effective.

Claims (1)

[Claims] Claim 1: C 0.05-0.15wt%, Si0
．． 04wt% or less, Mn 0.30-1.00wt%
, Al0.010~0.100wt%, Cu0.10~
2.0 wt%, Ni 0.10 to 2.0 wt%,
A steel billet consisting of the balance Fe and unavoidable impurities was heated to 1100
Heated to a temperature of ~1200℃, and heated to a temperature of 400℃ after hot rolling.
The hot-rolled steel sheet is rolled up at a temperature of 500°C, cold-worked to apply a working strain of 10% or more, and then rolled at a temperature of 600°C.
A method for manufacturing a high-strength, lightweight LP gas container, which comprises heating at a temperature of ~700°C for 10 minutes to 2 hours.