1、造口：單個造口回波高度低，波形為單縫，比較穩(wěn)定。 從各個方向檢測，反射波大致相同，但探頭稍微移動一點，就會在密集的孔隙中出現(xiàn)一簇反射波，波高隨孔隙大小而變化。 造成此類缺陷的主要原因是焊材未在規(guī)定溫度下干燥、焊條鍍層變質(zhì)、焊芯腐蝕、焊絲未清洗干凈、手工焊接時電流過大、 弧線過長； 埋弧焊時電壓過高。 或者網(wǎng)絡(luò)電壓波動太大； 氣體保護焊時保護氣體純度低。 如果焊縫中存在氣孔，不僅破壞了焊縫金屬的致密性，還會降低焊縫的有效截面積，降低力學(xué)性能。 特別是有鏈孔時，彎曲和沖擊韌性會明顯降低。 . 防止此類缺陷的措施是：不要使用涂層有裂紋、剝落、變質(zhì)和生銹的焊條，生銹的焊絲只能在除銹后使用。 所用焊接材料應(yīng)在規(guī)定溫度下干燥，坡口及兩面應(yīng)清洗干凈，并選擇合適的焊接電流、弧壓和焊接速度。
2、夾渣：點狀夾渣的回波信號與點狀氣孔相似。 條狀夾渣的回波信號多為低幅度的鋸齒波，波形多為樹枝狀。 主峰邊緣有小峰，探頭平移幅度不等。 ，當(dāng)從各個方向檢測時，反射波的幅度是不同的。 產(chǎn)生此類缺陷的原因有：焊接電流過小、速度過快、熔渣來不及上浮、焊邊及各層焊縫清理不干凈、原材金屬的化學(xué)成分和 焊接材料不當(dāng)，硫、磷含量較高。 等待。 預(yù)防措施包括：正確選擇焊接電流，焊件坡口角度不宜過小，焊前必須清理坡口，多層焊時必須逐層清除焊渣； 運輸角的焊接速度應(yīng)合理選擇。
3、不完全穿透：高反射率和高波幅。 探頭平移時，波形比較穩(wěn)定，在焊縫兩側(cè)探傷時，可以得到大致相同的反射波幅值。 此類缺陷不僅降低了焊接接頭的力學(xué)性能，而且在未完全熔透的間隙和端部形成應(yīng)力集中點，往往在加載后造成裂紋，是一種危險的缺陷。 造成這種情況的原因一般是：坡口純邊間隙太小，焊接電流太小或帶鋼速度太快，坡口角度小，帶鋼角度太小。 錯了，電弧就吹了。 預(yù)防措施包括：合理選擇坡口類型、裝配間隙和正確的焊接工藝。
4、不熔斷：探頭平移時，波形比較穩(wěn)定。 兩側(cè)檢測時，反射波幅度不同，有時只能從一側(cè)檢測。 原因：坡口不干凈，焊接速度太快，電流過小或過大，電極角度不對，電弧吹出等。預(yù)防措施：正確選擇坡口和電流，清潔 坡口、正確操作防止焊接偏差等
5、裂紋：回波高度大，波幅寬，會有多個波峰。 當(dāng)探頭平移時，反射波的幅度不斷變化。 當(dāng)探頭旋轉(zhuǎn)時，波峰上下移動。 裂紋是最危險的缺陷之一。 除了降低焊接接頭的強度外，裂紋的末端是一個尖銷的缺口。 焊件加載后引起應(yīng)力集中，成為結(jié)構(gòu)斷裂的起點。 裂紋分為三種類型：熱裂紋、冷裂紋和再熱裂紋。 產(chǎn)生熱裂紋的原因是：焊接時熔池冷卻速度很快，造成偏析； 焊縫受熱不均勻會產(chǎn)生拉應(yīng)力。 預(yù)防措施：限制母材和焊材中易偏析元素和有害雜質(zhì)的含量，主要是限制硫含量，提高錳含量； 增加電極或助焊劑的堿度，以降低雜質(zhì)含量，提高偏析程度； 改進(jìn)焊接結(jié)構(gòu)形式，采用合理的焊接順序，提高焊縫收縮時的自由度。
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1. Stomata: the echo height of a single stomata is low and the waveform is single slit, which is relatively stable. From each direction detection, reflection wave is roughly the same, but a little move probe will disappear, dense pores will appear a cluster of reflection wave, wave height with the size of pores and different, when the probe for fixed point rotation, there will be the phenomenon of up and down. The main reasons for such defects are that welding materials are not dried according to the specified temperature, electrode skin deterioration off, welding core corrosion, welding wire cleaning is not clean, manual welding current is too large, the arc is too long; When submerged arc welding voltage is too high or network voltage fluctuation is too large; Gas welding protection gas purity low. If there are pores in the weld, it not only destroys the density of the weld metal, but also reduces the effective cross-sectional area of the weld and reduces the mechanical properties, especially when there are chain pores, the bending and impact toughness will be significantly reduced. The measures to prevent this kind of defects are: do not use the coating cracking, peeling, deterioration and welding core corrosion electrode, rusty wire must be removed rust before use. The welding materials should be dried at the specified temperature, the groove and both sides should be cleaned, and appropriate welding current, arc voltage and welding speed should be selected.
2. Slag trap: the dotted slag trap echo signal is similar to the dotted porosity, and the strip slag trap echo signal is zigzag with low amplitude, and the waveform is dendritic. There are small peaks on the edge of the main peak. The reasons for this kind of defects are: welding current is too small, too fast, slag too late to float, welding edge and each layer of weld cleaning is not clean, the metal and welding material chemical composition is improper, containing sulfur, phosphorus and so on. Prevention measures are: the correct selection of welding current, welding parts of the groove Angle is not too small, the groove must be cleaned up before welding, multi-layer welding must be layer upon layer to remove welding slag; And reasonable selection of transport Angle welding speed.
3, incomplete welding: high reflectivity, high amplitude, the probe translation, waveform is more stable, in both sides of the weld can get roughly the same reflection amplitude. This kind of defect not only reduces the mechanical properties of the welded joint, but also forms stress concentration point in the gap and end of the incomplete welding, which often causes cracks after loading, and is a kind of dangerous defect. The reasons are generally as follows: too small pure edge clearance of groove, too small welding current or too fast strip moving speed, small groove Angle, incorrect strip moving Angle and arc blowing. The prevention measures include reasonable selection of groove type, assembly clearance and correct welding process.
4, not fused: the probe translation, waveform is more stable, both sides of the detection, reflection amplitude is different, sometimes only from one side to explore. The causes: the groove is not clean, the welding speed is too fast, the current is too small or too large, the Angle of the electrode is not right, the arc blowing. Prevention measures: correct selection of groove and current, groove clean, correct operation to prevent welding deviation.
5, crack: echo height is large, wave width is wide, there will be multiple peaks, the probe translation reflected wave continuously appear amplitude changes, when the probe turns, the peak is staggered up and down phenomenon. Crack is one of the most dangerous defects, in addition to reducing the strength of the welded joint, but also because the end of the crack is the notch of the pin, welded parts after bearing, resulting in stress concentration, become the origin of structural fracture. There are three kinds of cracks: hot crack, cold crack and rehot crack. The reasons for the hot crack are as follows: the cooling speed of the molten pool is very fast during welding, resulting in segregation; Uneven heating of weld produces tensile stress. Prevention measures: limit the content of segregation elements and harmful impurities in base metal and welding materials, mainly limit the content of sulfur, improve the content of manganese; Improve the alkalinity of the electrode or flux to reduce the impurity content and improve the degree of segregation; Improve the welding structure and adopt a reasonable welding sequence to improve the degree of freedom of weld shrinkage.
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