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Application of martensitic stainless steel self drilling screws in the building system.

2016-02-01 11:19:08 Jiaxing Unitek Machinery Co., Ltd. Read

[Abstract]: corrosion or failure of engineering construction or mechanical equipment is usually the first failure of the fastener system. Due to the special structure and special environment of the building and the mission of the special environment, the fastener is the first and most easily corroded in the corrosion environment. Therefore, it is necessary to improve the corrosion resistance of the fastener, and it is necessary to improve the life of the building. This paper introduces a new type of SUS410 martensitic stainless steel fasteners, the mechanical properties and corrosion resistance of the high standard, is the future of light steel structure in the field of high quality fasteners development direction.

 

The application status of self drilling screws, China steel structure building system

Steel enclosure system including roofing and wall system, lighting belt, wrapping and flashing, gutter and insulation cotton etc.. Retaining system is one of the most important components of light steel structure, which determines the architectural appearance of the ornamental, waterproof and thermal insulation effect of the building. Self drilling screws as an auxiliary fasteners, all aspects of the performance of the whole building performance, quality and life plays a vital role. There must be no optimism, as such an important one of the basic components, we pay attention to and study lags far behind in the attention and the research on the construction of the main body member, the most prominent is ignore the fastening piece and the building envelope systems is the main component of the performance matching.

And one of the biggest factors of corrosion failure or collapse of all structures or equipment is the first failure or collapse of the fastening system! Due to the special structure of the fastener and the environment and responsible for the mission, the fastener in the corrosion environment in the first, the most vulnerable to corrosion. Therefore, to improve the corrosion resistance of fasteners, is the human and the corrosion of war must first overcome the most basic type of campaign. At present, in the field of industrial manufacturing and construction errors using the screw examples abound, common cause is ignored screws and fasteners life matching, such as stainless steel material or do the high-grade anti-corrosion treatment of the surface of the device or component using ordinary carbon steel fasteners fastening. The results shown as follows:


1450935269977427.jpg

Carbon steel screws on the stainless steel exhaust pipe of motor vehicles and motorcycles (6 months later)

1450935479649268.jpg

After general plating of carbon steel screws used in the surface of the surface of the air conditioning on the machine (8 months later)


1450935314146840.jpg

Screws (3 years later) on power distribution cabinets for municipal street lamps

1450935523712807.jpg

The air conditioner using the SUS410 screw intact after 3 years

 

We know that the ordinary carbon steel corrosion resistance is low, if there is rust, rust comminuted. Impairment of the screw connection mainly depends on fine threads are meshed to achieve, so threaded portion once comminuted corrosion screw anti pulling capacity immediately, screws with the building materials concluded strength will be greatly reduced, future, once encounter rain and storm, car or accidental flareup sudden burst, enclosure system is facing collapse danger.

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At present, the use of fasteners in the construction area of our country is worrying!

Two, the characteristics and advantages of martensitic stainless steel fasteners

Stainless steel material family, only the martensitic stainless steel can be heat-treated hard if from mechanical properties, corrosion resistance, easy processing and economic point of view, sus410 (national label 1gr13) martensitic stainless steel is the most suitable.

The content of carbon in SUS410 material is lower than 0.15%, chromium content is more than 12%, which belongs to the category of martensite stainless steel SUS410

Screw after vacuum heat treatment for special, the surface hardness of up HV580-700, hardness of the core HV350-450, above the surface hardness and core hardness difference can be as HV150, so both guarantee the screw strong drilling and tapping ability, has guaranteed the screw superior flexibility, the tensile strength, mechanical torque is more than 150% of the ordinary carbon steel.

In addition, sus410 red hard far more than carbon steel, in above 500 DEG C Yobo has tough drilling and tapping ability, which for some extra thick, super hard or stainless steel building materials of the fastening pieces to create very favorable conditions.

Through the corrosion test, sus410 screw shows than carbon steel screw superior corrosion resistance, from the point of view of the experimental results, sus410 screw corrosion resistance is much higher than carbon steel screws, the performance can meet or exceed the standard in the construction industry required is a deserves full attention and vigorously promote the building fasteners.

A table before and after immersion screw pullout force (test for the Q235 iron substrate, the thickness of 3.8mm)


序号

规格

品名

拉拔力(N

产地

腐蚀前

腐蚀48小时后

腐蚀72小时后

1

ST5.5-24*38(材质1022A)

碳素钢镀锌螺钉(表面72小时镀锌)

11000

8000

4900

韩国

2

ST5.5-14*38(材质1022A

碳素钢涂层螺钉(表面1500小时涂层)

12000

9000

7000

澳洲

3

ST5.5-24*38(材质1022A

410螺钉(表面不锈钢本色)

13000

13000

12300

合邦

Note: through the immersion corrosion test (the corrosion solution is 5% pure NaCl+3% analysis pure HNO3)

 

Three. The economy of the martensite stainless steel screw

At present, the domestic market price of martensitic stainless steel fine line about 12000 yuan / ton, the price of carbon steel fine line about 6000 yuan / ton, the processing cost of the two tables:

成本项目

类别

原材料

(元吨)

加工

(元/吨)

热处理

(元/吨)

表面处理

(元/吨)

总计成本

(元/吨)

1022A镀锌 螺钉

6,000

4,000

2,000

2,000

14,000

1022A涂层螺钉

6,000

4,000

2,000

10,000

22,000

SUS410螺钉(本色)

12,000

4,500

2,000

1,000

19,500

SUS410涂层螺钉

1,200

4,500

2,000

3,500

22,000

备注

1,、碳素钢以1022A为典型代表,马氏体不锈钢以SUS410为代表

2、涂层螺钉均中性盐雾试验1000小时以上的涂覆处理

 Can be seen from the above table, the carbon steel galvanized screw cost minimum, but according to the, the corrosion resistance is too low, should maintain the system abandoned, and martensitic stainless steel screw cost and carbon steel layer screw compared, both cost quite, but martensitic screw in fastening strength, safety factor, and the corrosion resistance of the performance is much higher than carbon steel coated screws, so martensite screw has great market value.

    

Four, martensitic stainless steel self drilling screws applications

Sus410 screw surface passivation color is the true color of stainless steel, widely used in the construction of the high strength marine environment or heavy industrial pollution of the environment (ISO class 4) maintenance system, and also can be used under the same environmental conditions all outdoor facilities or equipment; sus410 screw surface after coating treatment, for extreme heavy industrial pollution of the environment or extreme ocean environment ISO5.

Currently in China, sus410 color screws and coated screws has been Capital International Airport T3 terminal, Xi'an Xianyang International Airport T3 terminal, Shougang Caofeidian project, high iron Shanghai Hongqiao Station, south high-speed railway station in Guangzhou, aluminum in Jiaozuo Wanfang aluminum key construction project by, and has been widely praised.

Sus410 material can also produce dry wall screw, fiber board screw, above the surface hardness of 650, can directly penetrate below 1.2mm iron keel, can be used for decorative wall dry hanging construction or light steel plasterboard partitions, due to its superior mechanical, toughness and corrosion resistance, the maintenance system with aseismic and wind resistant ability, fastening life of up to 70 years.

Five, martensitic stainless steel fasteners market outlook

Compared with the steel structure building with brick concrete structure building. In the aspect of environmental protection, energy saving, high efficiency, factory production has obvious advantages, so the industry and government agencies were generally optimistic about the steel structure building system. The steel structure building not only the presence of housing construction and large-scale public service facilities construction (such as the airport, railway station, gymnasium, etc.) in using increasingly sophisticated and extensive, and in high-rise buildings and residential construction technology is becoming more and more mature.

On April 27, 2012, China National Ministry of finance, the Ministry of housing and urban construction jointly issued the the on accelerating the US green building development and the implementation of the opinions "of the notice, made it clear through the establishment of financial incentive mechanism, improve the standards and the evaluation indicator system and promote relevant science and technology progress and industrial development and so on many kinds of methods, and strive to 2020, new construction of light steel structure of green building accounted for the proportion of more than 30%!

At present, China's annual new construction area of up to 2 billion - 1 billion 800 million square meters, according to the proportion of 30%, the future annual steel construction area will be more than 500 million square meters! As the steel structure and the key parts, sus410 with excellent performance of self drilling tapping screws will replace carbon steel fasteners, vertically and horizontally in the vast building battle, turned national assets strong guardian, to all walks of life to tens of thousands of households, deliver energy efficiency, green environmental protection requirements of the times! Therefore, SUS410 self drilling screws will have a broad market space.