Analysis of Reasons for Unqualified Reinforcement Quality Project

　　重量偏差是指鋼筋實際重量與理論重量的允許偏差，部分中、小型企業(yè)不按標準規(guī)定組織生產，超負偏差軋制，嚴重影響了抽樣合格率。同時，重量偏差不合格也可能會導致尺寸及工藝、力學性能不合格。表10-5是近幾年對熱軋帶肋鋼筋的抽查不合格統(tǒng)計結果，由此看出抽查重量偏差是主要的不合格項。重量偏差超出標準值低的為-14.30%，高的高達-180%，多數(shù)超出標準值-20%-40%的范圍。

　　Weight deviation refers to the allowable deviation between the actual weight of steel bar and the theoretical weight. Some small and medium-sized enterprises do not organize production according to the standard and roll with excessive negative deviation, which seriously affects the sampling qualified rate. At the same time, unqualified weight deviation may also lead to unqualified size, process and mechanical properties. Table 10-5 is the statistical results of unqualified national spot checks of hot-rolled ribbed steel bars in recent years, which shows that the weight deviation of spot checks is the main unqualified item. The lowest deviation of weight exceeded the standard value was - 14.30%, the highest was - 180%, most exceeded the range of - 20% to - 40%.

　　造成這種現(xiàn)象的原因主要是：

　　The main reasons for this phenomenon are:

　　(l)市場競爭激烈，企業(yè)為了降低生產成本，采取不正當?shù)氖侄蝸硖嵋妫诠芾砩习粗亓科钕孪藿M織生產，造成重量偏差成為主要的不合格項；

　　(l) Competition in the market is fierce. In order to reduce production costs, enterprises adopt improper means to improve efficiency and organize production according to the lower limit of weight deviation in management, resulting in weight deviation as the main unqualified item;

　　(2)企業(yè)為迎合中間商的要求，追求利潤大化，刻意生產負偏差和超負偏差產品；

　　(2) In order to meet the requirements of middlemen, enterprises pursue profit maximization and deliberately produce negative deviation and ultra-negative deviation products.

　　(3)重量偏差項目未列入建筑工地抽檢項目中，是超負偏差產品能存在的原因之一。

　　(3) Weight deviation items are not included in the sampling inspection items of construction sites, which is one of the reasons for the existence of super negative deviation products.

　　歷次監(jiān)督抽查十分重視重量偏差，數(shù)據(jù)顯示，近年來，重量偏差不合格的數(shù)量逐年下降，2011年抽查結果未出現(xiàn)重量偏差不合格項，說明了近年來將重量偏差作為檢查項目取得了較好的成果。

　　Previous national supervision spot checks attach great importance to weight deviation. Data show that in recent years, the number of unqualified weight deviation declines year by year. In 2011, no unqualified items of weight deviation appeared in the results of spot checks, which shows that good results have been achieved in recent years by taking weight deviation as a key inspection item.

　　尺寸及外形不合格主要表現(xiàn)為肋間距、橫肋高及內徑，鋼筋的外形影響鋼筋與混凝土的黏結力。造成此現(xiàn)象的主要原因為：生產企業(yè)為了節(jié)約成本，普遍按內徑負偏差組織生產，易造成內徑、橫肋高偏小，肋間距偏大的情況。另一方面，部分企業(yè)的產品質量管理意識較低，未能使用符合標準的軋輥及嚴格執(zhí)行換輥換槽制度。

　　The unqualified dimensions and shapes are mainly rib spacing, transverse rib height and inner diameter. The shape of steel bar affects the bond strength between steel bar and concrete. The main reason for this phenomenon is that in order to save costs, production enterprises generally organize production according to negative deviation of inner diameter, which easily results in smaller inner diameter and transverse rib height and larger rib spacing. On the other hand, some enterprises have low awareness of product quality management, fail to use standard rolls and strictly implement the roll change slot system.

　　化學成分主要表現(xiàn)為C.P.S含量超標。鋼中含c量增加，塑性和沖擊性降低，鋼材的焊接性能變差，冷脆性和時效敏感性增大，耐大氣銹蝕性下降；含P愈高，冷脆性愈大，冷脆使鋼材的冷加工及焊接性變壞；S含量愈高，熱脆現(xiàn)象愈嚴重，降低鋼材的各種力學性能，也使鋼材的可焊性、沖擊韌性、耐疲勞性和抗腐蝕性等均降低。鋼中含C量增加有助于屈服點和抗拉強度的升高，有些企業(yè)為了保證屈服點和抗拉強度，C含量就容易超標。另外，P、S含量超標主要是在煉鋼過程中控制得不嚴或沒有嚴格執(zhí)行鋼坯驗收制度造成的。

　　The main chemical constituents are C.P.S content exceeding the standard. The higher the content of C in steel, the lower the plasticity and impact, the worse the weldability of steel, the greater the cold brittleness and aging sensitivity, and the lower the atmospheric corrosion resistance; the higher the content of P, the greater the cold brittleness, the worse the cold working and weldability of steel; the higher the content of S, the more serious the hot brittleness, and the lower the various mechanical properties of steel. It also reduces the weldability, impact toughness, fatigue resistance and corrosion resistance of steel. Increasing C content in steel helps to increase yield point and tensile strength. In order to ensure yield point and tensile strength, some enterprises tend to exceed the standard C content. In addition, the content of P and S exceeded the standard mainly due to improper control in steelmaking process or lack of strict implementation of billet acceptance system.

　　力學性能主要為屈服強度不合格，除化學成分、尺寸、重量偏差會對力學及工藝性能造成影n向之外，煉鋼、連鑄及軋制過程控制不當也是力學性能不合格的原因之一。

　　The main mechanical properties are unqualified yield strength. In addition to the influence of chemical composition, size and weight deviation on mechanical and technological properties, improper control of steelmaking, continuous casting and rolling process is also one of the reasons for unqualified mechanical properties.

　　表面標志不合格項，主要是由于產品標準修訂，企業(yè)管理沒有及時跟進。

　　The unqualified items of surface marks are mainly due to the revision of product standards and the failure of enterprise management to follow up in time.