What is Steel?

Steel is a collective name for iron-carbon alloys with a carbon content of between 0.02% and 2.11%. The chemical composition of steel can vary greatly. Steels containing only carbon elements are called carbon steel (carbon steel) or ordinary steel; in actual production, steel often contains different alloying elements, such as manganese, Nickel, vanadium, etc. Humans have a long history of application and research of steel, but until the invention of the Belleville steelmaking method in the 19th century, the production of steel was a high cost and inefficient work. Today, with its low price and reliable performance, steel has become one of the most used materials in the world. It is an indispensable component in construction, manufacturing and people's daily life. It can be said that steel is the material foundation of modern society.

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1. Yield point (s)

When the steel or specimen is stretched, when the stress exceeds the elastic limit, even if the stress no longer increases, the steel or specimen continues to undergo significant plastic deformation. This phenomenon is called yielding, and the minimum stress value when yielding occurs is For the yield point.

Let Ps be the external force at the yield point s, and Fo be the cross-sectional area of the sample, then the yield point s = Ps / Fo (MPa), MPa is called megapascal equal to N (Newton) / mm2, (MPa = 10 ^ 6Pa, Pa : Pascal = N / m2)

2. Yield strength (0.2)

Some metal materials have extremely insignificant yield points and are difficult to measure. Therefore, in order to measure the yield characteristics of materials, it is stipulated that the stress at which a permanent residual plastic deformation equals a certain value (generally 0.2% of the original length) is called a condition Yield strength or yield strength 0.2 for short.

3. Tensile strength (b)

The maximum stress value reached during the stretching of the material from the beginning to the time of fracture. It indicates the capacity of the steel to resist fracture. Corresponding to tensile strength are compressive strength and flexural strength.

Let Pb be the maximum tensile force achieved before the material is broken, and Fo be the cross-sectional area of the sample, then the tensile strength b = Pb / Fo (MPa).

4. Elongation (s)

After the material is broken, the percentage of its plastic elongation to the original sample length is called elongation or elongation.

5. Yield ratio (s / b)

The ratio of the yield point (yield strength) of a steel to the tensile strength is called the yield ratio. The larger the yield strength ratio, the higher the reliability of the structural parts. Generally, the yield strength ratio of carbon steel is 0.6-0.65, and the low-alloy structural steel is 0.65-0.75.

6. Hardness

Hardness refers to the ability of a material to resist the pressing of a hard object into its surface. It is one of the important performance indicators of metal materials. Generally, the higher the hardness, the better the abrasion resistance. Common hardness indicators are

Alloy structural steel

20-50Mn2, 15-40Cr, 12-42CrMo, 12Cr1MoV, 38CrMoAl, etc.

Spring steel

65Mn, 55Si2Mn, 60Si2Mn (A), 30W4Cr2VA, etc.

Cold heading steel

ML08-45, ML40Cr, ML35CrMo, etc.

Tool steel

Carbon tool steel

T7, T8, T9, T10, T11, T12, T13, T8Mn, etc.

Alloy tool steel

9SiCr, 8MnSi, Cr12MoV, CrWMn, 5CrMnMo, 3Cr2W8V, etc.

High speed tool steel

W18Cr4V, W6Mo5Cr4V2, etc.

Bearing steel

High carbon chromium bearing steel

GCr6, GCr9, GCr9SiMn, GCr15, GCr15SiMn, etc.

High carbon chromium stainless bearing steel

9Cr18, 9Cr18Mo, etc.

Permeable bearing steel

G20CrMo, G20CrNiMo, G10CrNi3Mo, etc.

Special Steel

Hot rolled steel

Converter steel

stainless steel

0 (1) Cr18Ni9, 00Cr18Ni10, 0 (1) 18Ni12Mo2Ti, 0Cr18Ni10Ti, 00Cr17Ni14Mo2, etc.

Heat-resistant steel

0Cr25Ni20, 5Cr21Mn9Ni4N, 1Cr25Ni20Si2, 1Cr17, 1 (2) Cr13, 4Cr10Si2Mo, etc.

High temperature alloy steel

GH2036, GH4033, Incoloy800, Inconel600, etc.

Professional steel

Steel for turbine blades

1Cr12, 1Cr13, 1Cr11MoV, 0Cr17Ni14Cu4Nb, etc.

Internal combustion engine steam valve steel

5Cr21Mn9Ni4N, 4Cr14NiW2Mo, 4Cr9Si2, 8Cr20Si2Ni, etc.

High temperature bolt steel

20Cr1Mo1VnbTiB, etc.

Mold steel

Cr12, Cr12MoV1, Cr12MoV, 4Cr5MoSiV1, etc.

The carbon content of pig iron is higher than that of steel (carbon content of pig iron is 2% -4.3%). After the pig iron is calcined at high temperature, the carbon and oxygen in it react to form carbon dioxide, thereby reducing the carbon content in iron and becoming steel. Repeated smelting accuracy is higher. Its chemical equation is as follows:

Steel demand and supply

The typical characteristics of the stalemate in supply and demand in the domestic steel market in 2012 have shown that the average price fluctuation per ton of steel in June was less than 50 yuan. Merchants call it an embarrassing market that cannot go up and down; the construction steel market is difficult to achieve an effective rebound, and the downstream demand has shrunk as a whole ^[4] .

According to monitoring, the performance of the construction steel market in June was weak in both ups and downs, and some people said vividly that it was neither a "rising market" nor a "falling market". The terminal procurement volume of construction steel is still at a low level, and the seasonal characteristics of previous years have basically not been reflected. Some businesses report that the steel market looks like it is building a bottom, "but in the end it is not the bottom of the market, but it is not at the bottom of the heart".

The dual contradiction of shrinking demand and unrestricted supply in the steel industry has always been unable to be alleviated by a "big determination" in the industry. The steel plant's "no pain and no itching" reduction in production makes people feel that the factory is in a passive state restrained by many concerns. According to the latest data, although the average daily output of domestic crude steel and steel in May declined, it is still higher than the average daily output level in the previous four months. In mid-June, the estimated daily output of domestic crude steel is still close to a high of 2 million tons, indicating that steel mills have reduced or restricted their output. The traditional consumption season of high temperature and rain is approaching, and the high-level operation of crude steel output will further intensify the contradiction between supply and demand in the market. This is also the case for steel stocks. Although the decline is in the channel, the cycle is particularly long. The main products have reduced their positions by less than 20% for 18 consecutive weeks.

As the release of steel production cannot be effectively curbed, it stimulates upstream ore prices to "wait for opportunity" to rise. Since June, the price of domestic ore has been rising continuously, and the cumulative increase in the price of ton has reached 70 yuan. However, the steel mill's procurement is still more rational, and the market transactions are not satisfactory. In this situation, it is difficult to further increase the price of ore in the later period. The price of imported iron ore has also rebounded significantly, and the cumulative ton price has increased by about US $ 5 in one month. The pessimistic mentality of the mining market has improved slightly, and some steel mills have increased their purchases. However, as soon as the price of minerals rises, the direct market response is that buyers tend to wait and see, "this is also a natural constraint."

Steel industry operation

(1) Output hit a record high. From January to June 2013, the country's cumulative production of crude steel was 390 million tons, a year-on-year increase of 7.4%, an increase of 5.6 percentage points from the same period last year. In the first 6 months, the average daily output of crude steel was 2.154 million tons, equivalent to an annual output of 786 million tons of crude steel. Among them, in February it reached a record high of 2.208 million tons. Although it declined in March-June, it remained at a high level of more than 2.1 million tons. In terms of provinces and regions, the crude steel output of Hebei and Jiangsu increased by 6.8% and 13.2% year-on-year respectively from January to June. The combined new production of the two provinces accounted for 42.4% of the national increase of 26.94 million tons. Provinces such as Henan and Yunnan also increased output by more than 1 million tons. In terms of different types of enterprises, from January to June, the crude steel output of key large and medium-sized steel companies increased 5.5% year-on-year, which was 2 percentage points lower than the national average increase, but 60% of the increase in output was still from key large and medium-sized steel companies.

(2) Low steel prices. From January to June 2013, the overall performance of the domestic steel market was sluggish. With the substantial release of crude steel production capacity, the market supply and demand has fallen into an imbalance, and steel prices have entered a downward channel and have fallen weakly for more than 4 months. As of July 26, the steel price index had dropped to 100.48 points, which was lower than the 6.6 points at the beginning of the year. The prices of the eight steel varieties that the Iron and Steel Industry Association focused on have all fallen to varying degrees from the beginning of the year, with an average decrease of 5.7%. In terms of different types, the prices of construction wires and rebars, which accounted for a large proportion of China's steel production, fell by 4.9% and 6.7%, and the prices of plate and hot rolled coil fell by 5.7% and 9.7%, respectively.

(3) The export of steel products has grown rapidly. The imbalance between supply and demand in the domestic steel market has stimulated exports. From January to June, China exported 30.69 million tons of steel products, an increase of 12.6% year-on-year; imported steel products were 6.83 million tons, a decrease of 1.8%, and imported steel billets and ingots were 320,000 tons, an increase of 50%. Converting billets into crude steel, the cumulative net export was 25.06 million tons, a year-on-year increase of 17.3%, accounting for 6.4% of China's crude steel output. From the perspective of export prices, the average export price of rods and wires for the first six months of the year was US $ 624.3 / ton, a year-on-year decrease of 18%; sheet materials were US $ 835.2 / ton, a year-on-year decrease of 2.8%.

(4) Steel mills and social stocks are operating at high levels. The contradiction between market supply and demand has spread to the circulation field, and domestic steel stocks have continued the growth trend at the end of the previous year. On March 15, it reached a record high of 22.52 million tons, an increase of 3.51 million tons from the previous year's highest point, of which 14.32 million tons of construction steel stocks, accounting for 63.6% of the total inventory. After that, as seasonal consumption increased, the inventory gradually dropped, and it fell to 15.4 million tons on July 26. Oversupply in the market has also pushed up steel plant inventory. In mid-March, the steel stocks of key enterprises reached a historical record of 14.51 million tons, a year-on-year increase of 29.7%. In late June, it fell to 12.68 million tons, which is still a 29.9% increase from the beginning of the year, compared with 2012 The year-on-year growth was 11.4%.

(E) The profit level of steel mills has been decreasing month by month. In the first half of 2013, the metallurgical industry realized a profit of 73.69 billion yuan, an increase of 13.7% year-on-year, of which the ferrous metal smelting and rolling processing industry realized a profit of 45.44 billion yuan, an increase of 22.7% year-on-year. From January to May, the profitability of key large and medium-sized iron and steel enterprises is far lower than the overall level of the industry, and it has shown a downward trend from month to month. Although the profit has increased by 34%, it is only 2.8 billion yuan, and the sales profit margin is 0.19%. In May of that month, 86 key large and medium-sized steel companies only realized a profit of 150 million yuan, which has been a sequential decline for 5 consecutive months, of which 34 companies lost money, with a loss of up to 40%.

(6) The growth rate of investment in fixed assets in the steel industry dropped significantly. From January to June 2013, the investment in fixed assets in the steel industry was 303.5 billion yuan, an increase of 4.3% year-on-year, of which ferrous metal smelting and rolling investment was 235.6 billion yuan, an increase of 3.3% year-on-year, down 6.1 percentage points from the same period in 2012; The selected investment was 67.9 billion yuan, a year-on-year increase of 7.8%, and the growth rate fell sharply by 15 percentage points.

Views related to steel

Analysts of relevant institutions believe that construction site construction and construction progress have not significantly accelerated, and the release of demand for construction steel will generally remain low. Under the circumstances that demand cannot be effectively started, if the stalemate in the steel market is to be broken, the only way to force steel mills to substantially reduce production is to drive the reasonable return of raw material prices and gradually reduce the imbalance in the steel market. Until this substantive process is not effectively started, the steel market can only continue to oscillate.