外文翻譯---低合金結(jié)構(gòu)鋼的焊接性分析

1、<p><b>　　外文資料翻譯</b></p><p>　　WELDABILITY ANALYSIS OF Q345 STEEL</p><p>　　LOW STEEL ALLOY STRUCTURE OF WELDABILITY ANALYSIS</p><p>　　16Mn and 15MnV belong to the low

2、-alloy steel hot rolled steel, these steel prices lower, and has satisfied the mechanical properties and processing performance, first of all to analyze this type of steel welding, welding on two points of typically Bian

3、xian questions: First, due to a variety of welding defects, such types of steel for the main crack; Second, changes in material properties when welding on the type of steel is mainly embrittlement problem.</p><

4、;p><b>　　1. Crack</b></p><p>　　(1) Thermal crack: hot rolled carbon content generally lower, while the higher manganese content, so they Mn / S comparison, and has good resistance to thermal cr

5、acking performance. Normally, the weld hot cracking does not occur, but when the material component failure or serious segregation of carbon, sulfur content higher, Mn / S ratio is low, prone to hot cracking. Manganese i

6、n the steel with manganese sulfide sulfur to reduce the harmful effects of sulfur and enhance the performance of steel</p><p>　　(2) Cold crack: the crack depends on the cold steel, hardened steel, the tenden

7、cy of the tendency toward hardening just depends on its chemical composition. Hot rolled steel contains a small amount of alloying elements because of its low carbon steel when the carbon equivalent is slightly higher th

8、an some, so this low carbon steel hardened tend to be bigger than that, but with the increase of steel strength level, the increase in alloying elements, it The hardening tendency increases should be b</p><p&g

9、t;　　(3)Reheat cracking: Considerations from the chemical composition of steel, hot rolled steel does not contain as strong carbide forming elements, so again not sensitive to hot cracking, but also by increasing the preh

10、eating temperature and post weld heat such measures immediately after to prevent hot cracking.</p><p>　　2. Embrittled</p><p>　　(1)Hot zone embrittlement: hot rolled steel welding near the weld z

11、one is heated to above 100 ℃ coarse grain zone, easy to produce grain growth phenomenon is worst in welded joints of plastic parts, often to withstand the stress the role of the damage. To prevent the overheating zone em

12、brittlement measures is to improve the cooling rate, in particular, to improve the stability of austenite within the minimum cooling rate, shorten the residence time in this temperature range, reduce or prevent th</p&

13、gt;<p>　　(2) Heat should be crisp: the heat should be crisp is the thermal stress during the welding process because the plastic deformation to dislocation multiplication, while nitrogen and carbon atoms induced r

14、apid proliferation of dislocation accumulation area, there should be crisp of heat. 16Mn and 15MnV these two types of steel has got to be brittle tendency of heat, eliminating welding heat should be crisp and effective m

15、easures of post-weld annealing.</p><p>　　LOW ALLOY STRUCTURAL STEEL WELDING</p><p>　　1. Welding preparation:</p><p>　　(1) The design of groove type of welding should be avoided not

16、through or partial penetration of the groove, but also to minimize the weld cross-sectional area to reduce the residual stress in joints, it can also reduce the consumption of welding materials .</p><p>　　(2

17、) Groove to note when using thermal cutting edge of the base metal will prevent the formation of a certain depth of the hardened layer, this hardened layer of low ductility often cold cracking source.</p><p>

18、;　　(3) Weld area before welding steel to eliminate surface moisture, groove surface oxide, rust, grease and other contaminants.</p><p>　　(4)Before use welding materials manufacturer recommended specification

19、s should be dry.</p><p>　　(5)Orientation and assembly, and the formal weld seam must be the same type of electrode.</p><p>　　2. Welding heat input of choice:</p><p>　　Line energy pa

20、rameters is welding current, arc voltage and welding speed. Low-alloy structural steel welding, heat input parameters to the need to ensure that joint penetration and weld, but also consider their joint performance. Weld

21、ing of low carbon content and carbon content of hot-rolled steel lower side of the 16Mn steel, the welding heat input is not strictly limited, but improve the plasticity and toughness of hot zone or consider the use of s

22、maller line energy is more favorable; when wel</p><p>　　3. Preheating, heat and heat treatment after </p><p>　　(1) Preheating: welding low alloy steels, preheat the cold when the joints to preve

23、nt cracking, to improve the performance of joints, reducing the welding stress the importance of technological measures. Preheat the beneficial effect also in: ①Change in welding heat cycle, reduce the high temperature t

24、ransformation of various welded joints and low transition temperature of the cooling rate, to avoid or reduce the formation of hardened tissue; ②Reduce the welding area Wendu gradient, reducing the</p><p>　　

25、(2)After the heat and heat treatment: after heat is the weldment after welding the end of the entire weld immediately heated to 150 ~ 250℃ temperature range, and maintain a period of time, after such a process referred t

26、o as hot. Its role is to first reduce the joints at low temperature change of cooling rate, the more pronounced effect than warm, followed by the extension of the joint in more than 100℃ range of residence time, so that

27、the hydrogen in weld metal have sufficient time outside prol</p><p>　　Dehydroepiandrosterone treatment is welded immediately after the welding heat to 300 ~ 400℃ and the heat for some time, could accelerate

28、the spread of welded joints of hydrogen escape. The exclusion of hydrogen depends on temperature and time, high temperature holding time may be shorter, low temperature dehydrogenase time would lengthen. Eliminate the pr

29、oduction of hydrogen treatment temperature of 300 ~ 400℃, hydrogen consumption for 1 to 2 hours.</p><p>　　Elimination of stress treatment is welded evenly heated to a certain speed AC1 points below the tempe

30、rature high enough, holding a period of time evenly with the furnace cooled to 300 ~ 400℃, the last piece moved to the furnace will be cooled. Low alloy steel after welding to eliminate the purpose of dealing with stress

31、 the following points: ①To eliminate the hydrogen in weld metal, to improve the crack resistance of welded joints and toughness; ②Reduce the involvement of stress in the welded jo</p><p><b>　　Q345焊接性分析

32、</b></p><p>　　低合金結(jié)構(gòu)鋼的焊接性分析</p><p>　　16Mn和15MnV均屬于低合金結(jié)構(gòu)鋼中的熱軋鋼，這類鋼價格便宜，而且具有滿意的綜合力學(xué)性能和加工工藝性能，首先來分析一下這類鋼的焊接性，焊接性通常變現(xiàn)為兩方面的問題：一是焊接引起的各種缺陷，對這類鋼來說主要是各類裂紋問題；二是焊接時材料性能的變化，對這類鋼來說主要是脆化問題。</p>&

33、lt;p><b>　　一． 裂紋問題</b></p><p>　?。?）熱裂紋：熱軋鋼一般含碳量較低，而含錳量較高，因此它們Mn/S比較大，具有良好的抗熱裂性能。正常情況下焊縫中不會出現(xiàn)熱裂紋，但當材料成分不合格或有嚴重偏析，使碳、硫含量偏高，Mn/S比偏低，易出現(xiàn)熱裂紋。錳在鋼種可與硫形成硫化錳，減少了硫的有害影響，增強了鋼的抗熱裂性能。</p><p>　　

34、（2）冷裂紋：鋼材冷裂紋主要取決于鋼材的淬硬傾向，而剛才的淬硬傾向又主要取決于它的化學(xué)成分。熱軋鋼由于含有少量合金元素，其碳當量比低碳鋼碳當量略高些，所以這種鋼淬硬傾向比低碳鋼要大些，而且隨鋼材強度級別的提高，合金元素的增加，它的淬硬傾向逐漸增大，應(yīng)根據(jù)接頭形式和鋼材厚度來調(diào)整線能量、預(yù)熱和后熱溫度，以控制熱影響區(qū)的冷卻速度，同時降低焊縫金屬的含氫量等措施，防止冷裂紋的產(chǎn)生。</p><p>　?。?）再熱裂紋：

35、從鋼材的化學(xué)成分考慮，由于熱軋鋼中不含強碳化物形成元素，因此對再熱裂紋不敏感，而且還可以通過提高預(yù)熱溫度和焊后立即后熱等措施來防止再熱裂紋的產(chǎn)生。</p><p><b>　　二． 脆化問題</b></p><p>　?。?）過熱區(qū)脆化：熱軋鋼焊接時近縫區(qū)中被加熱到100℃以上粗晶區(qū)，易產(chǎn)生晶粒長大現(xiàn)象，是焊接接頭中塑性最差的部位，往往會承受不住應(yīng)力的作用而破壞。防止

36、過熱區(qū)脆化的措施是提高冷卻速度，尤其是提高奧氏體最小穩(wěn)定性范圍內(nèi)的冷卻速度，縮短在這一溫度區(qū)間停留時間，減少或防止奧氏體組織的出現(xiàn),以提高鋼的沖擊韌度，而且為防止過熱區(qū)粗晶脆化,也不宜采用過大線能量。</p><p>　?。?） 熱應(yīng)變脆化：熱應(yīng)變脆化是由于焊接過程中熱應(yīng)力產(chǎn)生塑性變形使位錯增殖，同時誘發(fā)氮碳原子快速擴散聚集在位錯區(qū)，出現(xiàn)熱應(yīng)變脆化。16Mn和15MnV這兩類鋼具有一定得熱應(yīng)變脆化傾向，焊接時消除

37、熱應(yīng)變脆化的有效措施是焊后退火處理。</p><p>　　低合金結(jié)構(gòu)鋼的焊接工藝</p><p><b>　　1.焊前準備：</b></p><p>　?。?）焊接坡口形式的設(shè)計應(yīng)避免采用焊不透或局部焊透的坡口，還要盡量減少焊縫的橫截面積，以降低接頭的殘余應(yīng)力，同時也可減少焊接材料的消耗量。</p><p>　　（2）坡

38、口加工采用熱切割時應(yīng)注意防止母材邊緣會形成一定深度的淬硬層，這種低塑性的淬硬層往往成為冷加工的開裂源。</p><p>　?。?）焊前必須消除焊接區(qū)鋼板表面的水分，坡口表面的氧化皮、銹斑、油脂以及其他污物。</p><p>　?。?）焊接材料在使用前應(yīng)按生產(chǎn)廠推薦的規(guī)范進行烘干。</p><p>　　（5）裝配定位焊縫必須采用與正式焊縫同一類型的焊條。</p&

39、gt;<p>　　2.焊接線能量的選擇：</p><p>　　線能量的參數(shù)是指焊接電流、電弧電壓和焊接速度。低合金結(jié)構(gòu)鋼焊接時，線能量參數(shù)除要保證接頭的熔透性和焊縫成型外，還要考慮其對接頭性能的影響。焊接含碳量低的熱軋鋼以及含碳量偏下限的16Mn鋼時，對焊接線能量沒有嚴格的限制，但從提高過熱區(qū)塑性和韌性考慮還是采用偏小線能量更為有利；當焊接含碳量偏高的16Mn鋼時，為降低淬硬傾向，防止冷裂紋產(chǎn)生，焊

40、接時線能量應(yīng)偏大些。</p><p>　　3.預(yù)熱、后熱及熱處理</p><p>　?。?）預(yù)熱：焊接低合金結(jié)構(gòu)鋼時，焊前預(yù)熱時防止接頭冷裂，改善接頭組織性能，減小焊接應(yīng)力的重要工藝措施。焊前預(yù)熱的有利作用還在于：①改變了焊接過程的熱循環(huán)，降低焊接接頭各區(qū)高溫轉(zhuǎn)變和低溫轉(zhuǎn)變溫度區(qū)間的冷卻速度，避免或減少了淬硬組織的形成；②減少焊接區(qū)的溫度梯度，降低了焊接接頭的內(nèi)應(yīng)力，并使之較均勻地分布；③

41、擴大了焊接區(qū)的溫度場，使焊接接頭在較寬的區(qū)域內(nèi)處于塑性狀態(tài)，減弱了焊接應(yīng)力的不利影響；④延長了焊接區(qū)在100℃以上溫度的停留時間，有利于氫從焊縫金屬中逸出。預(yù)熱溫度的確定，隨鋼材碳當量、板厚、結(jié)構(gòu)的拘束度的增加而增加，環(huán)境溫度的升高而降低。</p><p>　?。?）后熱及熱處理：后熱是指焊接結(jié)束后將焊件或整條焊縫立即加熱到150~250℃溫度范圍內(nèi)，并保持一段時間，這種工藝簡稱后熱。其作用在于首先是降低了接頭低

42、溫轉(zhuǎn)變區(qū)的冷卻速度，其效果比預(yù)熱更顯著，其次是延長了接頭在100℃以上溫度區(qū)間的停留時間，使焊縫金屬中的氫有充分時間向外擴散。在寒風(fēng)金屬氫擴散階段，從根本上消除了導(dǎo)致冷裂紋形成的力學(xué)因素。后熱的溫度和時間，取決于被焊鋼的冷裂敏感性，焊接材料的含氫量和接頭的拘束度。后熱溫度愈高，保溫時間愈長，去氫效果愈明顯。</p><p>　　去氫處理是將焊件在焊后立即加熱到300~400℃并保溫一段時間，可加速焊接接頭氫的擴散

43、逸出。氫的排除程度取決于加熱溫度和時間，溫度高保溫時間可短一些，溫度低去氫時間就要加長。生產(chǎn)中消氫處理的溫度為300~400℃，消氫時間為1~2小時。</p><p>　　消除應(yīng)力處理是將焊件均勻地以一定的速度加熱到AC1點以下足夠高的溫度，保溫一段時間后隨爐均勻地冷卻到300~400℃，最后將工件移到爐外空冷。低合金結(jié)構(gòu)鋼焊后消除應(yīng)力處理的目的有以下幾點：①消除焊縫金屬中的氫，提高焊接接頭的抗裂性和韌性；②降低