無縫方矩管的力學性能是保證無縫方矩管使用性能（機械性能）的重要指標，它取決于鋼管的化學成分和熱處理制度。所以根據不同的使用要求，從抗拉強度、屈服點、伸長率這幾方面來具體的介紹下大口徑螺旋鋼管的力學性能。

The mechanical property of seamless rectangular tube is an important index to ensure the service performance (mechanical property) of seamless rectangular tube, which depends on the chemical composition and heat treatment system of steel tube. Therefore, according to different application requirements, the mechanical properties of large-diameter spiral steel pipe are introduced from the aspects of tensile strength, yield point and elongation.

無縫方矩管的力學性能是保證無縫方矩管使用性能（機械性能）的重要指標，它取決于鋼管的化學成分和熱處理制度。所以根據不同的使用要求，從抗拉強度、屈服點、伸長率這幾方面來具體的介紹下大口徑螺旋鋼管的力學性能。

The mechanical property of seamless rectangular tube is an important index to ensure the service performance (mechanical property) of seamless rectangular tube, which depends on the chemical composition and heat treatment system of steel tube. Therefore, according to different application requirements, the mechanical properties of large-diameter spiral steel pipe are introduced from the aspects of tensile strength, yield point and elongation.

1抗拉強度試樣在拉伸過程中，在拉斷時所承受的力（Fb），出以試樣原橫截面積（So）所得的應力（σ），稱為抗拉強度（σb），單位為N/mm2（MPa）。它表示金屬材料在拉力作用下抵抗破壞的能力。

1. The stress (FB) borne by the tensile strength sample during breaking in the tensile process is the stress obtained from the original cross-sectional area (so) of the sample（ σ）， Called tensile strength（ σ b) , in N / mm2 (MPA). It represents the ability of metal materials to resist failure under tension.

2屈服點具有屈服現象的金屬材料，試樣在拉伸過程中力不增加（保持恒定）仍能繼續伸長時的應力，稱屈服點。若力發生下降時，則應區分上、下屈服點。屈服點的單位為N/mm2（MPa）。

2 yield point the stress of the metal material with yield phenomenon when the specimen can continue to elongate without increasing (keeping constant) the stress during the tensile process, which is called the yield point. If the stress decreases, the upper and lower yield points shall be distinguished. The unit of yield point is n / mm2 (MPA).

3斷后伸長率在拉伸試驗中，試樣拉斷后其標距所增加的長度與原標距長度的百分比，稱為伸長率。以σ表示，單位為%。

3 elongation after fracture in the tensile test, the percentage of the length increased by the gauge length of the sample after breaking to the original gauge length is called elongation. with σ Expressed in%.

今年上半年q345b方管市場價格將會出現“慢漲快跌”的一種運行狀態，“慢漲”的原因是由于成本的推動，這種成本推動體現在鋼廠因原料市場價格的上漲，生產成本上升，促使鋼廠出廠價格的上調；再有，鋼材貿易商的采購成本提高，后期投放市場的采購價格普遍增，但考慮到下游終端用戶的承受能力，現貨市場上的價格不會一下子大幅上漲，而表現為緩慢穩步而上。而“快跌”則是受宏觀政策面、鋼材金融屬性以及人為的炒作等原因，一旦鋼價出現震蕩回落的情況，這些不利因素的疊加效應集中顯現，導致市場價格的快速下跌。

In the first half of this year, Q345B Fangguan's market price will be in a running state of "slow rise and fast fall". The reason for the "slow rise" is due to the promotion of cost, which is reflected in the increase of production cost of steel mills due to the rise of raw material Market price; In addition, the purchase cost of steel traders has increased, and the purchase price put on the market in the later stage has generally increased. However, considering the affordability of downstream end users, the price in the spot market will not rise sharply at once, but will rise slowly and steadily. The "rapid decline" is due to macro policy, steel financial attributes and artificial speculation. Once the steel price fluctuates and falls, the superposition effect of these adverse factors will appear, resulting in the rapid decline of market price.