摘要：<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點</span> <p class="MsoNormal"> <span>(1)</span><span style="font-family:宋體;">焊接方法:</span><span style="font-family:宋體;">通常采用焊條電弧焊、</span><span>TIG</span><span style="font-family:宋體;">焊和</span><span>MIG</span><span style="font-family:宋體;">焊。<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點,</span>普通鐵素體不鏽鋼有時也用埋弧焊，但對耐蝕性和韌性要求高的高純鐵素體不鏽鋼不推薦埋弧焊，以防止過熱和氮、碳的汙染。</span> </p> <p class="MsoNormal"> <span>(2)</span><span style="font-family:宋體;">焊接材料:</span><span style="font-family:宋體;">主要有兩大類，即同質(zhì)鐵素體不鏽鋼和異質(zhì)的奧氏體型。<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點,</span>同質(zhì)鐵素體型焊接材料的優(yōu)點是焊縫顏色與母材相同、線膨脹係數(shù)和耐蝕性大體相同</span><span>;</span><span style="font-family:宋體;">缺點是同質(zhì)焊縫的抗裂性不高。當(dāng)要求具有高抗裂韌性，而且不能進行預(yù)熱和焊後熱處理，可采用異質(zhì)的奧氏體型焊接材料。但要注意：焊接材料應(yīng)是低碳的</span><span>;</span><span style="font-family:宋體;">焊後不可退火處理，因鐵素體鋼的退火溫度</span><span>(780~850</span><span style="font-family:宋體;">℃</span><span>)</span><span style="font-family:宋體;">正好是奧氏體鋼敏化溫度區(qū)間，易引起晶間腐蝕和脆化</span><span>;</span><span style="font-family:宋體;">奧氏體鋼焊縫的顏色和性能與母材不同。</span> </p> <p class="MsoNormal"> <span>(3)</span><span style="font-family:宋體;">焊接熱輸入:</span><span style="font-family:宋體;">因鐵素體不鏽鋼具有強烈的晶粒長大傾向和易於在焊接過程中析出有害的中間相，因此應(yīng)儘量采用小的熱輸入和窄焊道進行焊接，並采取適當(dāng)工藝措施，提高焊縫的冷卻速度，以控製接頭的過熱。</span> </p> <p class="MsoNormal"> <span>(4)</span><span style="font-family:宋體;">預(yù)熱和焊後熱處理:</span><span style="font-family:宋體;">普通鐵素體不鏽鋼有冷裂傾向，其脆性轉(zhuǎn)變溫度常在室溫以下，韌性低。<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點,</span>為了防止冷裂紋，含鉛預(yù)熱是不可少的。但這種鋼對過熱敏感，預(yù)熱溫度不宜高，隻可低溫預(yù)熱。*好控製在</span><span>150</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">以下，層間溫度應(yīng)控製在相應(yīng)水平，否則晶粒長大並可能產(chǎn)生</span><span>475</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">脆性。</span> </p> <p class="MsoNormal"> <span style="font-family:宋體;">采用同質(zhì)焊接材料焊接後應(yīng)進行熱處理，熱處理的目的在於使接頭的組織均勻化，提高其塑性和耐蝕性，同時也可消除焊接應(yīng)力。<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點,</span>熱處理溫度應(yīng)低於使晶粒粗化或形成奧氏體的亞臨界溫度</span><span>;</span><span style="font-family:宋體;">必須避免在</span><span>370~570</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">之間緩冷，以免產(chǎn)生</span><span>475</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">脆化。</span> </p> <p class="MsoNormal"> <span style="font-family:宋體;">對已產(chǎn)生</span><span>475</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">脆化和</span><span>σ</span><span style="font-family:宋體;">相脆化的焊接接頭，可短時加熱到</span><span>600</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">以上空冷消除</span><span>475</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">脆化，加熱到</span><span>930~980</span><span style="font-family:宋體;">℃</span><span style="font-family:宋體;">急冷消除</span><span>σ</span><span style="font-family:宋體;">相脆化。采用奧氏體鋼焊接材料不必預(yù)熱和焊後熱處理。</span> </p> <p class="MsoNormal"> <span></span> </p>