Large craft of heat treatment of 45 steel connecting rod is improved (on)

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Middling speed of a kind of when my factory produces 45 steel is marine diesel engine connecting rod, lever body is sectional Ф 90mm, forging weight 145kg, it is my factory forgings at present the heaviest connecting rod of production. Ship's classification society of China of the classics after heat treatment (when CCS) product examines, in body of Ф 90mm lever sectional 1/2R is in sampling to undertake detecting, its function asks to be: 600MPa of σ B ≥ ; 300MPa of σ S ≥ ; 5 ≥ of δ 16 ％ ; 40 ％ of Ф ≥ ; Aku5 ≥ 20J; Hardness: 162 ～ 217HBS. Normal > 45 steel is a kind of model is medium carbon is high grade steel of carbolic element structure, through moving qualitative processing attainable intensity and tenacity cooperate to compare good put together join forces to learn function, because this applies extensively at medium or small of machine component make. And on the other hand, 45 steel use Yu Dazhong part when making, because be shown sexual effect by temper by dipping in water, performance demand is not normally high. Normal >1. The problem Normal >(1) to forging of this connecting rod, my factory uses wind of sparge of 850 ℃ normalizing at first cold + craft of 590 ℃ temper undertakes 550 ～ heat treatment. The equipment that install furnace is 9.

65m³ . Natural gas heats stage car furnace, ≤ of the quantity that install furnace 48. The connecting rod forging of date of every fusion furnace, match body of lever of date of same fusion furnace to try a club (200mm) of Ф 90mm × , have heat treatment with furnace. Two side distribute stage car 8 high-power fan, have sparge wind cold, time is 1 ～ 1.

5h. Normal > heat treatment is finished, try a club to anatomize sampling to undertake function experiments to body of connecting rod lever again (test data sees watch 1) . Data shows, function test result fails to achieve technical requirement. Via raising temper of temper temperature do poorly done work over again hind, because connecting rod integral performance is small tall, amount of intensity have more than needed is not large, although concussion result rises, achieved technical requirement, but lowered target of connecting rod intensity however, still requirement of agreement of short of technology, bring about do poorly done work over again of connecting rod heat treatment thereby rate is extremely high. Normal Align=center> expresses 1 classics wind of sparge of 850 ℃ normalizing is cold + 590 ℃ of 550 ～ Normal MARGIN of Center" Align=center> number: 0cm 0cm 0pt; LINE-HEIGHT: 24pt; TEXT-ALIGN: Temperature of Center" Align=center> temper / ℃ Normal Align=center> tensile strength / MPanormal Align=center> succumbs intensity / MPanormal Align=center> percentage elongation (％ ) Normal Align=center> section (％ ) Normal Align=center> pounds result Aku5/Jnormal Align=center>3-34-7-1normal Align=center>550normal Align=center>625normal Align=center>330normal Align=center>24normal Align=center>45normal Align=center>17normal Align=center>590normal Align=center>580normal Align=center>310normal Align=center>20normal Align=center>42normal Align=center>21normal Align=center>3-34-7-2normal Align=center>550normal Align=center>630normal Align=center>320normal Align=center>26normal Align=center>44normal Align=center>18normal Align=center>590normal Align=center>590normal Align=center>305normal Align=center>22normal Align=center>41normal Align=center>20normal >normal >(2) is led in view of do poorly done work over again of heat treatment of connecting rod normalizing tall, my factory connecting rod instead 850 ℃ oil is cold + craft of 640 ℃ temper undertakes 620 ～ tone is handled character. Quench medium uses oil for system of bad news of N32 total loss, quench cooling time is 15 ～ 20min. Instead of the equipment that install furnace 5.

77m³ . Natural gas heats stage car furnace, furnace of every furnace outfit measures ≤ 20, the connecting rod forging of date of every fusion furnace, match body of lever of date of same fusion furnace to try a club (200mm) of Ф 90mm × , have heat treatment with furnace. Normal > heat treatment is finished, try a club to anatomize sampling to thousand body, undertake function experiments, performance data sees a table 2. Classics function experiments, forging of connecting rod of date of occurrence part furnace, on the high side of its intensity, hardness, concussion result under 20J, cannot achieve the appearance that the technology asks. The connecting rod forging that asks to obtaining a technology again after, use raise temper temperature to come 700 ℃ of 690 ～ , lengthen time of temper heat preservation to have temper of do poorly done work over again at the same time, but concussion result still under 20J, short of technology asks. Normal Align=center> expresses 2 classics 850 ℃ quenching oil is cold + 690 ℃ of 630 ～ Normal MARGIN of Center" Align=center> number: 0cm 0cm 0pt; LINE-HEIGHT: 24pt; TEXT-ALIGN: Temperature of Center" Align=center> temper / ℃ Normal Align=center> tensile strength / MPanormal Align=center> succumbs intensity / MPanormal Align=center> percentage elongation (％ ) Normal Align=center> section (％ ) Normal Align=center> pounds result Aku5/Jnormal Align=center>4-88-2normal Align=center>630normal Align=center>775normal Align=center>445normal Align=center>25normal Align=center>61normal Align=center>13normal Align=center>690normal Align=center>675normal Align=center>385normal Align=center>26normal Align=center>63normal Align=center>19normal Align=center>4-88-3normal Align=center>630normal Align=center>725normal Align=center>415normal Align=center>26normal Align=center>63normal Align=center>10normal Align=center>690normal Align=center>675normal Align=center>390normal Align=center>28normal Align=center>64normal Align=center>16normal Align=left>2. Case study Normal Align=left> is aimed at fall in means of afore-mentioned two kinds of heat treatment, connecting rod heat treatment all appears the circumstance of big batch do poorly done work over again, we expect from the composition of raw material chemistry of connecting rod, 45 rolled steel characteristic, heat treatment installs furnace means and cooling means to undertake an analysis, search an account. Normal Align=left> (1) , the connecting rod forging of do poorly done work over again, the quantity that contain carbon (quality mark) all be in 0.

O of 42 ％ ～ .

Inside the limits of 46 ％ . Because contain carbon the amount is small, measure wind of big, sparge plus outfit furnace cold result is bad, classics normalizing and after high temperature temper is handled, forging cannot obtain higher intensity and tenacity. After because this appeared,increasing concussion result quota, the circumstance that technology of intensity index short of asks. Normal Align=left> (2) moves the connecting rod forging of do poorly done work over again of simple heat treatment, the quantity that contain carbon (quality mark) all be in 0.

46 ％ ～ 0.

Inside the limits of 50 ％ . Because contain carbon the volume is high, make dot of 45 steel Ac3 is reduced. Especially ω C=0.

O of 47 ％ ～ .

When 49 ％ , what Ac3 nods existence the shape of a saddle-a falling-off between two peak periods is unusual drop phenomenon. If still use 860 ℃ ,quench right now, rise as a result of what temper by dipping in water appears a gender, it is better that forging fights temper sex, although raise temper,temperature is mixed extend time of temper heat preservation, also cannot reduce intensity, hardness, raise connecting rod to pound a value. Normal Align=left> 3. Solution Normal Align=left>(1) basis above case study, we choose the quantity that contain carbon (quality mark) for 0.

42 ％ ～ 0.

45 ％ and 0.

47 ％ ～ 0.

The body of lever of two groups of connecting rod of 50 ％ tries a club, undertake craft of normalizing heat treatment experiments moving pledging mixing respectively. Curve of experiment of heat treatment craft sees a picture 1, graph 2. Graph 1 normalizing + Normal Align=center> pursues Normal Align=left>normal Align=left> handles to experiment of heat treatment craft tries a club, sampling undertakes function experiments, each index all achieves technical requirement. Data sees a table 3. Normal Align=center> expresses body of lever of 3 connecting rod to try Normal Align=left>normal MARGIN of Center" Align=center> number: 0cm 0cm 0pt; LINE-HEIGHT: 24pt; TEXT-ALIGN: Center" Align=center> contains carbon to measure (quality mark, ％ ) Normal MARGIN of means of Center" Align=center> heat treatment: 0cm 0cm 0pt; LINE-HEIGHT: 24pt; TEXT-ALIGN: Center" Align=center> tensile strength / MPanormal Align=center> succumbs intensity / MPanormal Align=center> percentage elongation (％ ) Normal Align=center> section (％ ) Normal Align=center> pounds result Aku5/Jnormal Align=center>1normal Align=center>0.

44normal Align=center> moves qualitative Normal Align=center>650normal Align=center>385normal Align=center>26normal Align=center>55normal Align=center>32normal Align=center>2normal Align=center>0.

45normal Align=center>685normal Align=center>415normal Align=center>28normal Align=center>60normal Align=center>30normal Align=center>3normal Align=center>0.

44normal Align=center>660normal Align=center>390normal Align=center>25normal Align=center>58normal Align=center>32normal Align=center>4normal Align=center>0.

48normal MARGIN of Center" Align=center> normalizing: 0cm 0cm 0pt; LINE-HEIGHT: 24pt; TEXT-ALIGN: Center" Align=center>690normal Align=center>375normal Align=center>26normal Align=center>46normal Align=center>24normal Align=center>5normal Align=center>0.

47normal Align=center>670normal Align=center>370normal Align=center>24normal Align=center>45normal Align=center>24normal Align=center>6normal Align=center>0.

47normal Align=center>670normal Align=center>385normal Align=center>25normal Align=center>46normal Align=center>23normal > (2) experiments according to heat treatment craft data, we undertake improvement to craft of heat treatment of this connecting rod. Consult 45 steel raw material enters result of factory answer test, undertake deciding carbon in group: ① is measured to carbon (quality mark) in 0.

42 ％ ～ 0.

The connecting rod forging inside 45 ％ limits, use technology of tone simple heat treatment; Quench medium still uses oil for system of bad news of N32 total loss, increase quench the circular agitate ability of medium, the temper by dipping in water that raises connecting rod forging appears a gender. ② is measured to carbon (quality mark) in 0.

O of 46 ％ ～ .

The connecting rod forging inside 50 ％ limits, use wind of sparge of 850 ℃ normalizing cold + 590 ℃ temper has heat treatment; Improve the way that install furnace, differ in roll end diameter of connecting rod forging is statified put, separate with mat iron between the layer, the largest amount that install furnace decreases by 48 reach 36; Put amlposition of discretion of machine of two side wind at the same time, improve the result with sparge cold wind, make forging refrigeration evener. Normal > classics is improved, sparge wind cold effect rises greatly, sparge wind cold time also shortens to 40 ～ 60min. CNC Milling CNC Machining