摘要：<span style="font-family:宋體;">鐵素體不鏽鋼的焊接工藝要點(diǎn)</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(diǎn),</span>普通鐵素體不鏽鋼有時(shí)也用埋弧焊，但對(duì)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(guò)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(diǎn),</span>同質(zhì)鐵素體型焊接材料的優(yōu)點(diǎn)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(diǎn)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(jìn)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(qiáng)烈的晶粒長(zhǎng)大傾向和易於在焊接過(guò)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(jìn)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(guò)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(diǎn),</span>為了防止冷裂紋，含鉛預(yù)熱是不可少的。但這種鋼對(duì)過(guò)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(zhǎng)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(jìn)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(shí)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(diǎn),</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(duì)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(shí)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>