焊前预热

实际中通常采用焊前预热工艺，来预防焊接裂纹的产生，但由于工艺复杂会提高焊接成本。

Preheating treatment is often undertaken to prevent weldments from cracking , while the complex processes may increase cost .

计算确定并控制管板焊前预热温度为200℃；

Controlling preheating temperature for tube plate welding at 200 ℃;

试验表明，采取焊前预热，焊后热处理的TIG焊工艺进行焊接可以减少焊接缺陷的产生。

The experiment results show that the welding defects can be decreased by using preheat and post-weld heat treatment .

根据美国UNOCAL企业标准的要求，此种管材的焊接应采用焊前预热+焊接+焊后热处理方法。因施工工期紧，焊后热处理时间不够，经试验，可免去焊后热处理工序。

Because the time limit for the project is packed , and the time for heat treatment after welding is insufficient , the section of heat treatment after welding is exempt based on the experiment .

焊前预热及焊后缓冷对抑制裂纹作用显著，且随着预热温度提高裂纹率呈下降趋势。

As preheat temperature increases , rate of beryllium welding cracking decreases .

为避免低温焊接出现微裂纹，采取了焊前预热的措施；

Preheating before welding was made to prevent microcracks .

分析了激光焊接时为克服焊接裂纹所采取的焊前预热、短焦距焊接及焊接工艺参数等因素对裂纹敏感性的影响。

Effect of preheat , smaller focus spot and welding processing parameter on sensitivity to cracking is studied .

六通管与支管采用对接焊缝，并实施焊前预热，焊后整体消除应力热处理，工艺方法可行，工艺参数合理。

Side pipes are jointed to the extruded main pipe by butt welding , with preheating before welding and stress relief after welding executed .

结果表明：采用焊前预热和焊后热处理的焊接工艺方案所获得的焊接接头比不采用以上措施获得的焊接接头更为合理，应用更安全、可靠。

The result shows that it is more reasonable , safe and reliable to adopt procedure with warm up before welding and post heat treatment after welding .

研究结果表明，模拟热影响区在上述三种状态下的冲击韧性值均远高于基材，且经焊前预热或激光回炎后激光焊热影响区最高硬度值下降。

Results indicate that toughness of the simulated HAZ is superior over the base metal and the maximum hardness of the simulated HAZ is depressed by laser tempering and the preheat treatment .

通过采取焊前预热、控制焊接线能量和层间温度、焊后保温缓冷等工艺措施，并采用相应的检测方法，保证了胺液吸收塔的低温焊接质量。

According to the test , the welding interlayer temperature of X60 pipeline in the normal and low temperature is analyzed in order to study the influence of its variable range on welding quality .

得出了导致反应器筒体焊缝开裂的主要因素是焊前预热温度偏低、焊后高温回火保温时间不足以及复合钢板过渡层焊接的复杂性；

The key factors that caused crack of reactor container are : warm-up temperature too low before welding , heat preservation time too short of high temperature temper , the welding complex of transition layer .

通过采取焊前预热、低氢焊接和焊后热处理等措施，成功地实现了650轧辊端头断裂的堆焊修复，即以焊代换。

By means of adopting preheating before welding , low hydrogen welding and heat treatment after welding and some other steps , the built-up welding repairing of the crackle in 650 mm roller tip end was successfully achieved .

文章通过对超高压汽轮机中联门材质的焊接性分析，确定坡口加工及焊缝形状、焊前预热温度、焊接工艺参数及焊后热处理温度，并严格控制焊接工艺过程。

By material welding characteristics analyses , edge preparation and weld preheat temperature , and weld process parameters , and heat treating temperature after welding are well considered , And the welding process is strictly controlled and crack defects are successfully removed .

结合氢应力腐蚀特点制定了修复方案，特别是焊前预热、焊后热处理、选择合适的焊条及板材，降低了焊道和热影响区硬度，消除残余应力。

Considering the characteristics of hydrogen stress corrosion , a restoration plan was made especially in weld preheating , post-weld heat treatment , welding rod and plate selection . Therefore , the hardness of the welding seam and heat - affected zone was reduced and residual stress was relieved .

焊前不预热不产生裂纹、可改善劳动条件，降低工艺成本，具有显著的经济效益和社会效益。

The electrode has the following advantages : a high resistance to cracking , low cost , high economical profit and society significance .

采用碱性药皮焊条和焊前接头预热的施焊方法，焊接的空间管道接头热应力小。

For overhead pipeline , welding with basic-compound coated electrodes and pre-welding heating of the joint will reduce the joint thermal - stress .

修理前，围绕兼顾解决焊接性、应力和变形问题，结合实际施工条件制定了以手工钨极氩弧焊、镍基焊丝、焊前低温预热、焊后锤击焊缝为要素的冷堆焊工艺。

Before repairing , basing on the actual working condition , concerning the weldability , stress and deformation issues , the scheme of the cold welding technology whose essential being GTAW , low temperature preheating , postweld hammer the welded seam was established .

CF-62钢具有优良的综合性能，厚度小于50mm的这种钢板焊前可不预热或少加预热而不产生裂纹。

This steel was verified as being excellent in weldability and low-temperature toughness , and producing no cracks in t ≤ 50mm plates without preheating or with slightly preheating before welding .

焊前工件的预热、表面清理的程度以及工艺参数的优化，都可以一定程度上降低焊缝中的气孔率。

Preheating of workpiece , surface cleaning before welding and choice of other proper welding parameters can reduce the porosity tendency .

推荐控制措施为焊前350℃预热，焊后980℃正火+720℃回火。

A controlling process was recommended-that is preheating at 350 ℃ before welding , normalizing at 980 ℃ and tempering at 720 ℃ after welding .