<p>Q345D钢板焊接需要先预热，因含碳量比较高。 　　1、热的目的是为了防止冷裂纹的产生。冷裂纹与碳当量有直接关系。因而要分清该材料的碳当量，Q345A（以前的牌号叫16Mn）、Q345D的碳当量是一样的。Q345的碳当量0.3%不到，可以说焊接性还可以（一般说碳当量0.4%上以冷裂纹敏感性增大）。 所以Q345A通常情况下是不预热的。但是当板很厚时，由于冷却很快，还是要预热。曾经20#钢用J422（E4303）焊裂过。如果板厚在70mm以上，不预热风险很大。 2、顺便说一下，这个Q345D与平时我们常用的Q345A区别就在于杂质S、P更少，低温冲击性能更好。从焊接角度说，当母材杂质元素少了，对于控制焊接热裂纹是有好处的。 3、当然既然母材选择Q345D材料（比Q345A贵，且供货少），一般说都是有特殊用途，所以焊接材料不会随便选用，最好是按焊接材料说明书使用，如果焊条说明书说要对母材预热，那就预热。因为没有按厂家说明书使用焊接材料，焊缝性能会大打折扣的。</p> <p>单品 品名 规格 材质 产地/厂家 地域 价格 (元/吨) 涨跌 报价日期 <br /> 无缝管 无缝管 %26Phi;426*11 20# 包钢 兰州 5850 0&nbsp; 12-05-25 <br /> 无缝管 无缝管 %26Phi;273*6 20# 包钢 兰州 5350 0&nbsp; 12-05-25 <br /> 无缝管 无缝管 %26Phi;219*7 20# 鞍钢 兰州 5550 0&nbsp; 12-05-25 <br /> 无缝管 无缝管 %26Phi;108*4.5 20# 鞍钢 兰州 5250 0&nbsp; 12-05-25 </p> <p>材质为10#、20#、45#、27SiMn、16Mn、WB36、T91、P91、12Cr1MoVG、10CrMo910、15CrMoG、35CrMo等。</p> <p>公司经营的进口合金管、厚壁钢管、<a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.hardonmb.com/">NM360耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.hardonmb.com/">NM450耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.hardonmb.com/">HARDOX400耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.hardonmb.com/">HARDOX500耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.500nmb.com/">NM360耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.500nmb.com/">HARDOX400耐磨板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.500nmb.com/">Q345C钢板</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.steels158.cn/">Cr5Mo合金钢管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.wffjg.com/">无缝方矩管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.wffjg.com/">大口径方矩管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.wffjg.com/">Q345B无缝方管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.wffjg.com/">Q345C无缝方矩管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.bxgangguan.cn/">天津合金管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.bxgangguan.cn/">天津无缝钢管厂</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;">、<span class="Apple-converted-space">&nbsp;</span></span><a style="word-spacing:0px;font:medium Simsun;text-transform:none;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;" href="http://www.bxgangguan.cn/">天津不锈钢管</a><span style="display:inline! important;float:none;word-spacing:0px;font:medium Simsun;text-transform:none;color:#000000;text-indent:0px;white-space:normal;letter-spacing:normal;background-color:#ffffff;orphans:2;widows:2;webkit-text-size-adjust:auto;webkit-text-stroke-width:0px;"><span class="Apple-converted-space">&nbsp;</span>、</span>不锈板等板材深受广大用户喜爱。</p> <p>多年来,本公司本着“质优高效,守约重誉”的经营理念和服务宗旨为广大客户提供质优价廉的产品和售后服务,得到了各界新老用户的支持和赞誉。如果您需要进口合金管、厚壁钢管、不锈板或者其它板材，希望您到本公司来光临。 </p>