Analysis of Cold Rolled Plate Requirements for Manufacturing Yellow Phosphorus Tanks

1 Introduction

Yellow phosphorus is an important basic industrial raw material. Its melting point is 44.1°C. It can spontaneously ignite in air at room temperature. Yellow phosphorus is a flammable dangerous goods. It is suitable for long-distance transportation. Barrel inspection methods have strict requirements. However, there are no specific requirements for the performance of cold-rolled steel sheet, which is a raw material for the manufacture of yellow phosphorus drums. This article combines the yellow-phosphorous drum packaging technology of Kunming Iron and Steel Co., Ltd. to analyze the manufacture and properties of cold-rolled steel sheets, and provide yellow-phosphorous drums for drums. reference.

2. Yellow phosphorus barrel manufacturing process and requirements

Yellow phosphorus drums currently use cold-rolled sheet as a raw material, and their manufacturing processes consist of barrel body processing, barrel bottom processing, dome top processing and assembly processes. The assembly process refers to the process of assembling the barrel, the bottom of the barrel, and the top of the barrel by using a seven-layer triple-circle crimping process, filling the sealant with a sealant, and processing it into a finished product barrel.

2.1 Process of Yellow Phosphorus Packaging

(1) Barrel's processing process: blanking → roller roll pressing into a round barrel shape → tap joint spot welding → welding over the whole body → welding trimming → flange forming → barrel body tendons → barrels Body weld quality inspection → pickling → cleaning → electro-galvanizing → passivation → natural drying

(2) Bottom processing process:

Blanking → Stamping → Flanging → Pickling → Cleaning → Galvanizing → Passivation → Natural Drying

(3) The processing process of the lid:

Blanking → Punching → Flanging Forming → Punching Inlet and Breathable Port → Inlet and Venting Thread Machining → Pickling → Cleaning → Electro-Zinc Plating → Passivation → Natural Drying

(4) Assembly and inspection of barrels:

The barrel body and the lid and the bottom of the barrel are assembled with seven layers of triple round crimps → air tightness test → hydrostatic test → drop test → barrel spray marking → acceptance

From the manufacturing process, it can be seen that during the production of yellow phosphorus drums, the welding, flanging, ribbing, and punching processes are included. After the barrels are processed, they must also undergo airtightness tests, hydrostatic tests, and drop tests. The test that simulates the conditions of use shall be carried out as qualified yellow phosphorus drums after inspection. 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 domestic technical requirements for yellow phosphorus packaging drums: the national standard GB16473-1996 "Yellow Phosphorus Packaging" and the Ministry of Chemical Industry Industry Standard HG2035-1991 yellow phosphorus packaging steel drum technical conditions, in which The relevant requirements for materials (steel plates) are shown in Table 1.

Table 1 Technical Requirements for Copper Plates for Yellow Phosphorus Packaging

Claim

GB16473-1996 "Yellow Phosphorus Packaging"

HG2035-1991

"Yellow phosphorus packaging steel barrel technical conditions"

Instructions

Steel plate thickness

1.2mm

1.2mm~1.5mm

In order to ensure the safety of exported products, the Yunnan Provincial Commodity Inspection Bureau stipulates that the packaging 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 material thickness of barrel body, barrel top and bottom material is more than 1.25mm, the hot-rolled steel sheet with performance equal to or better than that of GB-912 is used; when the thickness is not more than 1.25mm, the performance is equal to or better than the cold of GB/T11253 Rolled steel sheet.

Drum material should be made of GB/T912, GB/T11253, GB/T2518, GB/3276, the performance of materials not less than Q215 (wall thickness of 1.2mm steel drum, cold rolled steel plate), And have a quality certificate of the material manufacturer.

Requires a certain degree of strength and plasticity. Steel plates must have product standards and quality certificates.

Assembly of barrel, top and bottom

The use of seven triple-folding edges. The barrel, top of the barrel and bottom of the barrel are made of thin steel sheets, respectively.

Triple trapped curls are used. The barrel, top of the barrel and bottom of the barrel are made of thin steel sheets, respectively.

Requires good plasticity and certain deformation properties.

Appearance requirements

The barrel is round and smooth, with no obvious loss of roundness, convexity, concavity; no burr and mechanical damage. Barrel plating is smooth and compact.

Steel drums should be smooth and round, with no obvious round-off, skew, burrs, and mechanical damage. Barrel plating complete, dense organization.

It is required that the steel plate has a good plate shape and a high surface quality, and scratches are not allowed.

test

Tightness test, hydraulic test, stacking test and drop test.

Tightness test, hydrostatic test, stacking test and drop test

According to GB325 regulations, test GB3538, GB4857

3. Yellow phosphorus drum processing requirements on the characteristics of the material analysis

(1) Welding performance:

The weldability of steel is a very complex process performance because it is both related to the sensitivity of weld cracks and to the toughness required for service conditions and test temperatures. The International Welding Association uses carbon equivalent to calculate and evaluate the welding performance 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 welding performance. Therefore, the lower the carbon and manganese content of the material, the better. Generally speaking, after the carbon equivalent is less than 35%, the welding performance can be guaranteed. Because the production of yellow phosphorus drums is made of low-carbon, low-manganese cold-rolled sheet, the carbon equivalent is less than 25%, and the welding performance can be guaranteed completely.

(2) Stamping type: The stamping process of yellow phosphorus drums consists of ribbing, flanging, punching and crimping. The molding process involves deep drawing, extension and bending. The performance of the stamping process involves the composition, structure and cold deformation process parameters of the deformed material (mold shape, deformation amount, deformation speed, lubrication conditions, etc.). Material stamping formability is mainly related to the composition of the material, 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 bodies are related.

(3) Grades, chemical composition, organization and performance requirements of raw materials for yellow phosphorus drum production At present, domestic production of yellow phosphorus drums adopts cold-rolled sheet, the main brands 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

Grade

Deoxygenation

chemical composition%

C

Si

Mn

S

P

Als

St12

Deoxidation of aluminum

≤0.10

≤ 0.05

≤ 0.50

≤0.025

≤0.025

--

SPCC

Deoxidation of aluminum

≤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

Grade

Yield Strength

ReL(MPa)

tensile strength

Rm(MPa)

Elongation A80mm

(Bo=20mm)%

Cupping

(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

In view of chemical composition and performance, St12 and SPCC are the same type of steel for use. The steelmaking process uses aluminum for deoxidation. It is an aluminum killed steel and strictly controls the content of C, Si, Mn, S, and P that affect stamping performance. Rolling uses the "three high and one low" process principle (higher heating temperature, higher open-rolling temperature, higher finish rolling temperature, lower coiling temperature). Cold rolling adopts appropriate pressing process and appropriate annealing system to make AIN evenly precipitated, making the grain size 6 ~ 8 grades, the organization is ferrite + free cementite see Figure 1, free cementite is granular, dispersed distributed. The deep drawing performance of St12 and SPCC cold-rolled steel 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. Relative to St12 and SPCC steels, the contents of C, Si, Mn, S, and P are high. There is no dissolution and precipitation of AIN, and the strength is high. The stamping pressure is not as good as St12 and SPCC steel, and the plastic strain ratio r value. Generally less than 1.1. Therefore, the use of St12 and SPCC cold-rolled plates for production of yellow phosphorus drums is higher than that of Q195.

Fig.1 Grain size of cold rolled sheet of St12: II 7, 400X

(4) Other quality requirements:

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

2) Surface Inclusions: Refers to slag inclusions on the steel surface and residual iron oxide skin on the surface. After yellow phosphorus is packaged, it can easily cause holes in the steel drum due to shipping and corrosion conditions, resulting in fire. The airtightness test and hydrostatic test of yellow phosphorus drums are not easy to check the slag inclusions and residual iron oxide skin on the surface. The drop test can test that the slag on the surface of the drum and the surface residual iron oxide skin cannot be repaired and can only be scrapped.

3) Scratching: The causes of scratches include rolling process, leveling, rewinding process, slitting process and user's barrel making process. Light scratches affect the appearance of the surface of the barrel, but it will not affect the use. Severe scratches not only affect the appearance of the surface, but also directly affect the strength of the yellow phosphorus drum, affecting the air tightness test, hydrostatic test and drop test test results of the yellow phosphorus drum.

4) Residue on the surface: Mainly refers to residual oil (oiled) and other substances adsorbed on the surface of the steel plate. Excessive amounts of slag may cause imaginary welding and affect the welding quality of the bucket. It can use cotton yarn or waste cloth to dip the light lubricant and then weld it. Longitudinal welding can eliminate the influence of residual oil (oil coating) and other adsorbents on welding.

(5) Surface quality requirements of cold-rolled strip products for manufacturing of yellow phosphorus packaging drums of Kunming Steel:

Kunming Steel requires that the surface of the cold-rolled steel strip for yellow phosphorus drums be free from defects that are harmful to use such as delamination, cracks, bubbles, crusting, cracking, and inclusions. Steel strips are allowed to have slight pits or local deep pits, small bubbles, small cracks, scratches, and rolling defects that do not exceed the thickness tolerance range: local oxidation and pickling are allowed. film.

4 Conclusion