What defects should be had on quality that part of the bearing is hot and treated?
1.Overheated
Can observe after quenching organize overheatedly while being micro- at the intersection of bearing and the intersection of part and coarse mouth.
Want precise to judge his overheated intensity must observe micro- organization. If horse’s body of thick needle appears while organizing in the quenching in GCr15 steel, in order to quench the overheated tissue. Forming the reason may be caused by quenching the heating temperature too high or heating temperature retention time too long overallly and overheatedly; Whether or primitive organizes the belt carbide seriously, the low carbon district between two strips forms some horse’s needle of body thickly, the ones that cause are some and overheated. Remain body and increase in the overheated tissue, the stability decline of the size. Because quench and organize overheatedly, the crystal of the steel is thick, will lead to the fact the toughness of the part drops, resist and assault performance to reduce, the life-span of the bearing is reduced too. Overheated will even cause and quench the crackle seriously.
2.Owe heat
Quench on the low side temperature or it cools bad to be can in produce above standard the intersection of support and body that stipulate, organize organize, while being micro-, called and owed heat to organize, it makes the hardness drop, the wearability is reduced sharply, influence the bearing life-span. Bearing navigation
3.Quench the crackle
The crackle that the part of the bearing forms because of internal stress in the course of quenching cooling is called quenching the crackle. The reason to cause this kind of crackle is as follows, to cool too urgent in temperature because of quench heating, organization stress when heat stress and metal quality volume change greater than resisting the fracture intensity of steel products; Work a superficial one former and defective ‘ For instance, very small crackle of surface or scratch Inside or the steel products the defect ‘ Nonmetal inclusion, white point, hole remnants of contracting substantially as inserting the dreg, serious,etc. It is centralized to form the stress while quenching; The serious surface takes off carbon and carbide to simply analyse; The tempered and insufficient or not flash back in time after the part is quenched; Whom preceding process cause cold to wash stress to be too big forging folding, dark the intersection of turning and tool marks, the intersection of oil and the intersection of ditch and sharp raised angle,etc.. In a word, lead to the fact the reason for quenching the crackle may be one or more of the above-mentioned factor, the existence of internal stress forms the main reason for quenching the crackle. It is dark and slender to quench the crackle, the fracture is straight, the broken section has not oxidized the color. It longitudinal straight crackle or annular to fracture often at the intersection of bearing and sets of circle; The shape on the bearing steel ball has S shape, T shape or ring type. It is that both sides of crackle have not taken off carbon phenomenon, obvious difference and forging crackle and material crackle to quench the organization characteristic in the crackle.
4.The heat treatment is out of shape
When the part of the bearing is in the heat treatment, there is heat stress and organize the stress, this kind of internal stress can be superposed each other or offsetted partly, complicated and changeable, because it can change and with the intersection of heating and temperature, the intersection of heating and speed, the intersection of cooling and way, the intersection of cooling and speed, the intersection of part and shape and change of size, so the heat treatment is out of shape it is unavoidable. Know and know the intersection of change and law of it can make the intersection of bearing and part out of shape ‘ For instance the ellipse, size of one set of circles rise largely Locate in the controllable range, the ones that help to produce go on. Certainly it will make the part deformed too that the machinery in heat treatment collides, but this kind out of shape can use and improve and operate reducing and avoiding. Bearing type inquiry of the car
5.The surface takes off carbons
The bearing part in heat treatment, if heat in the oxidative medium, the oxidation will take place to make the quality mark of part surface carbon reduce in the surface, cause the surface to take off carbons. The ones that took off the carbon floor on the surface will make the part scrap when exceeding the allowance processed finally deeply. The surface can use metallography law and micro- hardness law in the metallography is examined while taking off the determination of one layer of depth of carbon. That distribution curve of one floor of micro- hardness of surface measures the law serves as the standard, can do arbitration criteria.
6.A bit softer
Heat insufficient, cool bad, quench misoperation wait for the intersection of bearing and the intersection of part and the intersection of surface and some hardness that reason cause enough phenomenon call, quench soft a bit. It can cause the dropping seriously of superficial wearability and fatigue strength as the surface takes off carbons. Inquire about the software in bearing type
