Analysis of the material type and characteristics of Adjustable Screw Jack

Analysis of the material type and characteristics of Adjustable Screw Jack

As the core stressed component of the scaffolding support system,the material of the Adjustable Screw Jack support directly determines the bearing capacity,durability and applicable scenarios.At present,the mainstream top support material on the market is mainly steel,according to mechanical properties,processing technology and application needs,it can be divided into the following categories,different materials have significant differences in composition,performance and applicable scenarios:

1.Mild steel(representative model:Q235)

Mild steel is the most widely used topping material,its carbon content is usually between 0.12%-0.20%,the core advantage is low cost,easy processing,and basic bearing capacity,which meets the needs of most civil buildings.

Performance characteristics:yield strength≥235MPa,tensile strength 375-500MPa,good toughness,easy to cut,weld and other processing at room temperature;However,the fatigue resistance and corrosion resistance are weak,and it is easy to rust after long-term exposure to moisture.

Processing and protection:The lead screw and support disc of the top support are mostly formed by hot rolling,and the surface is often hot-dip galvanized(zinc layer thickness≥85μm,rust prevention cycle 1-2 years)or electro-galvanizing(zinc layer thin,about 10-20μm,only suitable for drying indoor scenes)treatment,and some low-end products are only painted and anti-rust(poor rust prevention effect,easy to fall off).

Applicable scenarios:mainly used in medium and light load scenarios such as residential floors and ordinary beams(single top support bearing≤8kN),such as multi-storey civil buildings and interior decoration supports,and is not suitable for long-term outdoor or high-humidity environments(such as open-air construction and underground engineering in rainy season).

2.Low-alloy high-strength steel(representative model:Q355)

Low-alloy high-strength steel is made of manganese,silicon,vanadium and other alloying elements(total alloy content≤5%)on the basis of low-carbon steel,which significantly improves its bearing capacity and durability compared with Q235 steel,and is the preferred material for medium and heavy loads and harsh environments.

Performance characteristics:yield strength≥355MPa,tensile strength 470-630MPa,fatigue resistance 30%-50%higher than Q235,and good toughness at low temperature(still maintain good toughness at-40°C),atmospheric corrosion resistance is 2-3 times stronger than that of mild steel(the oxide film formed by alloying elements can slow down rust).

Processing and protection:Due to the influence of alloy composition,the processing difficulty is slightly higher than that of mild steel,and special welding processes(such as low-hydrogen welding rods)need to be used to avoid weld cracking;The surface is mostly thick hot-dip galvanized(zinc layer thickness≥100μm,rust prevention cycle 3-5 years),and some high-end products will do"hot-dip galvanizing+passivation"dual treatment to further improve salt spray resistance.

Applicable scenarios:suitable for high-heavy-duty,long-term outdoor or harsh environments,such as core cylinder support of high-rise buildings,pouring of bridge box girders,secondary lining of tunnels(load-bearing≤12kN),as well as construction projects in coastal areas(high salt spray)and severe cold areas in the north.

3.Alloy structural steel(representative model:45#steel,40Cr)

Alloy structural steel is a medium and high-strength steel,with a high carbon content(45#steel carbon content 0.42%-0.50%),and some elements such as chromium and molybdenum(such as 40Cr chromium 0.80%-1.10%)are mainly used in special scenarios with extremely high load-bearing and precision requirements,belonging to"customized materials",and the proportion of applications is relatively low.

Performance characteristics:45#steel yield strength≥355MPa,after quenching and tempering treatment(quenching+high-temperature tempering),the hardness can reach HB220-250,and the wear resistance is significantly improved;40Cr steel has a yield strength of≥800MPa and a tensile strength of≥980MPa,and its impact resistance and deformation resistance far exceed that of Q355,making it suitable for withstanding repeated loads or instantaneous impacts.

Processing and protection:It needs to be precisely processed by tempering and fine turning,and the thread accuracy of the lead screw can reach 6G level(reducing the lag during adjustment);The surface is mostly phosphating treatment+anti-rust oil(used for mechanical interior or closed support system to avoid external corrosion),or chrome plating(high surface hardness,wear-resistant and rust-proof,suitable for frequent adjustment scenarios).

Applicable scenarios:Only used for special high-demand projects,such as long-span crane beam support in industrial plants,auxiliary support for hoisting prefabricated components(load bearing≥12kN),or precision formwork systems that require frequent height adjustment(such as pouring curved concrete components).