Analysis on the requirements of cold rolled sheet for the manufacture of yellow phosphorus packaging drum

Analysis on the requirements of cold rolled sheet for the manufacture of yellow phosphorus packaging drum

1 Introduction

Yellow phosphorus is an important basic industrial raw material with a melting point of 44.1 ° C. It can spontaneously ignite in air at room temperature. Yellow phosphorus is a flammable dangerous product. It is suitable for long-distance transportation. The country processes the size and finished product of yellow phosphorus packaging drum. Barrel inspection methods have strict requirements. However, there is no specific requirement for the performance of the raw material for the production of yellow phosphorus packaging barrels. The paper combines the process of making barrels and barrels of Kunming Steel's yellow phosphorus packaging barrels to analyze the manufacturing and performance of cold-rolled sheets for the supply of yellow phosphorus packaging barrels. reference.

2. Yellow phosphorus barrel manufacturing process and requirements

The yellow phosphorus packaging barrel currently uses cold-rolled sheets as raw materials for production, and its manufacturing process consists of barrel processing, barrel bottom processing, dome processing and assembly processes. The assembly process refers to the process of assembling the barrel body with the bottom of the bucket and the top of the bucket by using a seven-layer triple round crimping, filling the sealant with the sealant, and processing into a finished bucket.

2.1 Processing process of yellow phosphorus packaging drum

(1) Processing process of the barrel body: blanking → rolling up the roll into a round barrel shape → spot welding of the joints → welding on the side seams → grinding of the welds → forming of the flanges → barrels of the barrels → barrels Body weld quality inspection → pickling → cleaning → electro-galvanizing → passivation → natural drying

(2) Processing process of the bottom of the barrel:

Cutting → stamping → flanging forming → pickling → cleaning → electroplating → passivation → natural drying

(3) Processing process of the lid:

Cutting → stamping → flanging forming → stamping injection port and venting port → injection port and vent thread processing → pickling → cleaning → electroplating → passivation → natural drying

(4) Assembly and inspection of barrels:

The barrel body and the lid of the barrel and the bottom of the barrel are assembled with seven layers of triple round crimping → air tightness test → hydraulic pressure test → drop test → barrel body spray mark → acceptance

It can be seen from the manufacturing process that the processing process of welding, flanging, ribbing and punching is included in the production process of yellow phosphorus packaging drum, and it must pass the air tightness test, hydraulic pressure test and drop test after processing into barrels. The test shall be carried out under the conditions of simulated use, and the test shall be carried out before being shipped as a qualified yellow phosphorus packaging drum. The entire processing and inspection process has certain requirements on the welding performance, strength, stamping deformation performance and surface quality of the material.

2.2 Yellow phosphorus packaging technical requirements

At present, there are two technical requirements for barrels of yellow phosphorus packaging in China: and the national standard GB16473-1996 "Yellow Phosphorus Packaging" and the technical standard of the Ministry of Chemical Industry HG2035-1991 yellow phosphorus packaging steel drum technical conditions, of which, for yellow phosphorus packaging See Table 1 for the relevant requirements for materials (steel plates).

Table 1 Technical requirements for copper plate for yellow phosphorus packaging

Claim

GB16473-1996 "Yellow Phosphorus Packaging"

HG2035-1991

"Technical Conditions for Yellow Phosphorus Packaging Steel Barrels"

Description

Steel plate thickness

1.2mm

1.2mm~1.5mm

In order to ensure the safety of export products, the Yunnan Provincial Commodity Inspection Bureau stipulates that the drums for exporting yellow phosphorus must be made of steel plates with a nominal thickness of not less than 1.4 mm.

material

When the thickness of the barrel body, the top of the barrel and the bottom of the barrel is greater than 1.25mm, the performance is in accordance with or better than the hot-rolled steel sheet specified in GB Hall 912; when the thickness is not more than 1.25mm, the performance is consistent with or better than the cold specified in GB/T11253. Rolled steel sheet.

Steel drum materials shall be made of materials with the performance and quality not lower than Q215 as specified in GB/T912, GB/T11253, GB/T2518 and GB/3276 (steel drums with a wall thickness of 1.2 mm, the materials of which are selected from cold-rolled steel sheets). And has a quality certificate of the material manufacturer.

A certain strength and plasticity are required. Steel plates must have product standards and quality certificates.

Assembly of the barrel, the top of the bucket and the bottom of the bucket

It adopts seven layers of triple sleepy curling. The barrel body, the top of the bucket and the bottom of the bucket are made of the entire thin steel plate, and the splicing is not allowed.

The triple sleepy side is used. The barrel body, the top of the bucket and the bottom of the bucket are made of the entire thin steel plate, and the splicing is not allowed.

Good plasticity and certain deformation properties are required.

Appearance requirements

The barrel is round and smooth, with no obvious rounding, unevenness, and skew; no burrs and mechanical damage. The outside of the barrel is smooth and smooth, and the structure is fine.

The steel drum should be smooth and round, with no obvious rounding, skewing, burrs and mechanical damage. The barrel is completely plated and densely organized.

The steel plate is required to have a good shape and a high surface quality, and no scratches are allowed.

test

Air tightness test, hydraulic test, stacking test and drop test.

Air tightness test, hydrostatic test, stacking test and drop test

According to GB325 regulations, test GB3538, GB4857

3. Analysis of material properties requirements for yellow phosphorus packaging barrel processing

(1) Welding performance:

The weldability of steel is a very complex process performance because it is closely related to the sensitivity of the weld crack and to the toughness required for service conditions and test temperatures. The International Welding Association uses carbon equivalents to calculate and evaluate the weldability of steel. The approximate formula is as follows:

= C+Mn/6+(Ni+Cu)/15+(Cr+Mo+ V)/5

Where: the element symbol represents the weight percentage of the element.

For steel materials, the lower the carbon equivalent, the better the weldability. Therefore, the lower the carbon and manganese content of the material, the better. It is generally believed that the welding performance can be guaranteed after the carbon equivalent is less than 35%. Since the yellow phosphorus packaging drum is made of low-carbon and low-manganese cold-rolled sheets, the carbon equivalent is less than 25%, and the welding performance can be completely guaranteed.

(2) Stamping city type: The stamping and forming of the yellow phosphorus packaging barrel is composed of the rib, the flanging, the punching and the curling. The forming process involves deep forming, stretching and bending. The performance of the stamping process involves the composition, structure and cold deformation process parameters (mold shape, deformation, deformation speed, lubrication conditions, etc.) of the material being deformed. Material stamping formability is mainly related to material composition, yield strength, elongation, elongation, work hardening index (n value), plastic strain ratio (r value), grain size, shape and distribution of inclusions, free carburizing The number and distribution of the bodies are related.

(3) Grade, chemical composition, organization and performance requirements of yellow phosphorus packaging barrels. At present, domestic yellow phosphorus packaging barrels are made of cold-rolled sheets. The main grades are Q195, St12 and SPCC. The composition requirements are shown in Table 2. Performance requirements See Table 3.

Table 2 Cold plate grades and chemical composition requirements for yellow phosphorus packaging barrels

Brand

Deoxidation mode

chemical composition%

C

Si

Mn

S

P

Als

St12

Aluminum deoxidation

≤0.10

≤0.05

≤0.50

≤0.025

≤0.025

--

SPCC

Aluminum deoxidation

≤0.10

≤0.05

≤0.50

≤0.025

≤0.025

--

Q195

Silicon manganese deoxidation

0.06~0.12

≤0.30

0.2~0.5

≤0.050

≤0.045

no

There is no requirement for A ls in St12 and SPCC, generally it is controlled at 0.010~0.070%.

Table 4 Mechanical properties

Brand

Yield Strength

ReL (MPa)

tensile strength

Rm(MPa)

Elongation A80mm

(Bo=20mm)%

Cup burst

(thickness 1.2mm)

n value

r value

St12

≤280

270~410

≥28

9.8

≥0.2

1.2~1.4

SPCC

≤280

≥270

≥28

9.6

≥0.2

1.2~1.4

Q195

≥195

315~430

≥24

--

<0.2

<1.1

From the chemical composition and properties, St12 and SPCC are the same type of steel. The steelmaking process uses aluminum deoxidation and is aluminum killed steel. The C, Si, Mn, S and P contents which affect the stamping performance are strictly controlled. The rolling adopts the "three high and one low" process principle (higher heating temperature, higher rolling temperature, higher finishing temperature, lower coiling temperature). Cold rolling adopts a suitable pressing process and a suitable annealing system to uniformly precipitate AIN, so that the grain size is 6-8, the structure is ferrite + free cementite as shown in Fig. 1, and the free cementite is granular, diffused. distributed. The deep drawing performance of St12 and SPCC cold-rolled sheets is improved, so that the strain hardening index n value reaches 0.2 or more, and the plastic strain ratio r value reaches 1.2 or more. Q195 is a silicon hammer deoxidized steel. Compared with St12 and SPCC steel, C, Si, Mn, S and P contents are high, no AIN is dissolved and precipitated, and the strength is high. The stamping is not as good as St12 and SPCC steel, and the plastic strain ratio is r value. Generally less than 1.1. Therefore, the production of yellow phosphorus packaging drums using St12 and SPCC cold-rolled sheets is higher than that of Q195.

Figure 1 St12 cold rolled sheet microstructure grade: II 7, 400X

(4) Other quality requirements:

1) Plate shape: The plate shape is the basic condition for ensuring the packaging of yellow phosphorus, which affects the welding quality of the barrel and affects the processing of the barrel. The shape of the raw material of the barrel is not good, which is easy to cause the welding process to be weakly welded, and the weld seam is easy to leak.

2) Surface inclusions: refers to the slag inclusion on the surface of the steel and the surface residual iron oxide scale. After packaging yellow phosphorus, it is easy to cause holes in the steel barrel under transportation and corrosion conditions, resulting in fire. The airtightness test and hydraulic pressure test of the yellow phosphorus packaging drum are not easy to check the slag inclusions and the surface residual iron oxide scale. The drop test can be found that the surface of the packaging drum has slag inclusions and the surface residual iron oxide scale cannot be repaired, and can only be scrapped.

3) Scratch: The causes of scratching are rolling process, leveling, rewinding process, slitting process and user barreling process. Light scratches affect the appearance of the barrel, but it will not affect the use. Severe scratching not only affects the appearance of the surface, but also directly affects the strength of the yellow phosphorus packaging barrel, affecting the air tightness test, hydraulic pressure test and drop test results of the yellow phosphorus packaging drum.

4) Surface residue: mainly refers to residual oil (oiling) and other substances adsorbed on the surface of the steel plate. Excessively, it is easy to cause virtual welding and affect the welding quality of the barrel. It can be cleaned with cotton yarn or waste cloth and light lubricating oil, and then spot welding can eliminate the influence of residual oil (oiling) and other adsorbents on welding.

(5) Surface quality requirements for cold rolled strip products for the manufacture of yellow phosphorus packaging drums in Kunming Steel:

Kunming Steel requires that the surface of the cold-rolled steel strip for yellow phosphorus packaging barrels should be free of defects such as delamination, cracks, air bubbles, crusting, cracking and inclusions. The steel strip allows for slight pitting or local deep pitting, depth, small cracking, scratching, rolling indentation with depth not exceeding the thickness tolerance range: partial oxidation and partial coloring after pickling are allowed film.

4 Conclusion